JPH07310854A - Method and equipment for reducing cavitation and dynamic unbalance in hydraulic valve - Google Patents

Abstract

PURPOSE: To prevent damage by cavitation and provide certain work by arranging control elements on the inside of a bore by making 4 their respective axes align with each other and arranging a means to balance force working on the control elements under existence of pressure fluid in the inside of the bore. CONSTITUTION: A fluid control device 70 makes a valve stem arranged on the inside of a bore 74 formed in a main body, that is, in a valve main body 76, that is, a check 72, and it includes a movable control element to control a flow of pressure fluid passing through a fuel injection spray orifice. Additionally, the valve stem 72 includes two end parts 88, 90 separated by an intermediate part 92 contracted in diameter. Consequently, force working on the valve stem 72 is balanced by making cross-section areas of the both end parts 88, 90 equal to each other. In the meantime, fluid vortically flows and stagnation is removed by inclining an inlet passage 78 relative to a vertical axis of the valve stem 72.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates generally to fluid control systems. More particularly, the present invention relates to methods and apparatus for improving the durable life and operation of hydraulic valves.

[0002]

BACKGROUND OF THE INVENTION High pressure fluid control devices, such as hydraulic valves used in fuel injection systems for diesel cycle engines, typically include a valve stem, or other flow control device located in the bore. A valve inlet passage opens into the bore to direct fluid flow directly onto the valve stem. This type of fluid flow control device suffers from operational difficulties. In particular, the impingement of the inlet flow on the valve stem creates a flow stagnation region at the first end of the valve proximate the inlet passage, which creates a fairly high pressure at this end of the valve stem. Become. When the valve opens, a high velocity, relatively uniform local flow occurs at the second end of the valve stem proximate the valve seat, locally reducing the pressure in this region. The resulting pressure differential across the valve stem leads to unfavorable actuation characteristics, even when the forces acting on the valve stem are designed to be totally balanced to form a valve. Further, for example, the fuel may be about 103 to 130 megapascals (MPa) (about 15,000 to 20,000 pounds per square inch).
Cavitation occurs, especially when the valve is opened, especially when high working fluid pressures are encountered, such as when injected at or above high pressures, which usually damages the components of the valve that are punctured.

In the construction of fuel injection systems, it is known to impart a whirling motion to the fuel in the vortex chamber before the fuel is injected into the combustion chamber. For example, U.S. Pat. Nos. 3,450,353 and 4,192,466 are described. The vortex flow of the fuel results in a more uniform flow of fuel during injection into the combustion chamber.

[0004]

The fluid control device according to the present invention can perform a reliable operation without substantially damaging the high-pressure fluid due to cavitation.

[0005]

More particularly, a fluid control system includes a main body having a through bore and an inlet port. The bore has a bore center axis and the inlet port has an inlet port center axis at the intersection of the inlet port and the bore. The inlet port center axis coincides with the predetermined line, and the predetermined line does not intersect with the bore center axis. The control element is located within the bore and includes a control element centerline axis that is substantially coincident with the bore centerline axis and further provides a substantially balanced force exerted on the control element in the presence of the pressurized fluid within the bore. It includes the means to The projection of a given line on the bore center axis preferably forms an interior angle that is not a right angle. This angle consists of an acute angle. With respect to the first other aspect of the invention, the inlet port enters the bore along a passage having a tangential component and a longitudinal component. In a second alternative aspect, the inlet port enters the bore along a passageway that induces a swirling fluid flow in the pressurized fluid towards the outlet port.
Further, in the third embodiment, the inlet port enters the bore along a passage that substantially prevents cavitation of the pressurized fluid.

The control element includes a valve stem having a first end and a second end, and the balancing means includes a first end surface and a second end surface having substantially equal effective cross-sectional areas, respectively. It is preferable to have the first end portion and the second end portion. In another aspect of the invention, a fluid valve that controls the flow of pressurized fluid includes a throughbore and a valve body with an inlet port and an outlet port. The bore has a bore center axis and the inlet port has an inlet center axis at the intersection of the inlet port and the bore. The bore center axis and the line that coincides with the inlet port center axis do not intersect, and the projection of the line on the bore center axis forms an acute angle so that the swirling flow of the pressurized fluid enters the bore. It is designed to be induced between the port and the outlet port. The valve stem is disposed within the bore and has a valve stem centerline axis that is substantially coincident with the bore centerline axis. Means are provided for responding to the pressurized fluid to approximately balance the forces acting on the valve stem.
Further, in another aspect of the invention, a method of operating a device for controlling a pressure balanced fluid comprises the step of positioning the control element such that the inlet passage is in fluid communication with the bore and the outlet passage. Directing fluid from the inlet passage into the bore along a passage offset from the longitudinal axis of the control element, causing the fluid to spirally flow around the control element to the outlet passage. .

The fluid control system of the present invention can be reliably operated by minimizing the local pressure differential which adversely affects performance. The present invention also minimizes cavitation in areas of locally high pressure, thereby reducing damage such as puncture.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring initially to FIGS. 1 and 2, a prior art fluid control system 10 used in, for example, a high pressure fluid delivery system, such as a fuel injection system for a diesel cycle engine, has a main body, namely, It includes a control element that forms a valve stem 12 located within a bore 14 formed in a valve body 16. Entrance passage 18
Extends through the valve body 16 and enters the bore 14 at the confluence 20. The inlet passage 18 includes the valve stem 12
A vertical axis 24 that coincides with a line 22 that intersects the vertical axis 24 at a right angle. Referring in detail to FIG. 1, pressurized fluid flows from the inlet passage 18 into the bore 14 and the incoming flow impinges directly on the reduced diameter section 26 of the valve stem 12 such that the pressure in region 28 is approximately at the inlet pressure. , Which will form a stagnation region within region 28. Further, as the flow proceeds in two separate directions about the reduced diameter region 26, another stagnation region is formed in the region 30 on the opposite side of the valve stem 12 from the region 28 where the flow portion impinges. It Further, as the valve stem 12 opens to allow fluid to pass to the outlet 32, a relatively uniform high velocity fluid flow is proximate the valve seat 36 due to the high pressure fluid flow within the bore 14. It is formed in the valve peripheral region 34.
As a result, the relatively high pressure fluid in regions 28 and 30 and the region 3
A low pressure fluid in 6 creates a differential pressure. The fluid control device 10 is configured for balanced operation such that the magnitudes of the normal forces on the first and second ends of the valve stem 12 are equal and opposite in direction. This differential pressure causes operational difficulties even when there is.

FIG. 3 illustrates the inlet passage 42 through the bore 44 extending from the main body 46 to the outlet passage 48 from the inlet passage 42.
5 illustrates another type of prior art fluid control device 40 that regulates the flow of pressurized fluid flowing from. In this case, the control element or valve stem 50 is axially movable and the inlet passage 42 is in fluid communication with the outlet passage 48 via an annular passage 52 formed by the reduced diameter portion 54 of the valve stem 50. Can be selectively arranged. As described with respect to the apparatus of FIGS. 1 and 2, the inlet passage 42 includes a longitudinal axis that coincides with a line 56 that intersects the longitudinal axis 58 of the valve 50 at substantially right angles. Figure 3
During operation of the fluid control device 40 in FIG. 3, the flow cross-sectional area at the confluence 60 of the bore 44 and the inlet passage 42 is quite small, especially when the valve stem 50 moves to the right and is in the position shown in FIG. . Therefore, the flow velocity is rather high and cavitation is formed. With the valve stem 50 moving axially further to the right as shown in FIG. 3, as the area of the flow passage at the confluence 60 increases, the pressure change of the fluid across the flow passage at the point 60 decreases. , The flow velocity at this point becomes slower. This recovery of pressure collapses bubbles previously created in the region at low pressure, releasing energy that causes the wall 68 forming valve stem 50 and bore 44 to be punctured.

In order to solve the above problems, the present invention provides
It creates an inlet passageway in relation to the longitudinal axis of the control element that prevents the stagnation area, which reduces local differential pressure and cavitation damage. More specifically, FIGS. 4 and 5 are adapted for use in a high pressure fluid delivery system, as described above,
1 illustrates a fluid control device or mechanism 70 in accordance with the present invention. The device 70 includes a fuel injector that can be used in a fuel injection system applied to a direct injection internal combustion engine, such as a diesel cycle engine, the device being formed within a main body, or valve body 76. A valve stem located in the bore 74, i.e. check 7
2 and includes a control element movable to control the flow of pressurized fluid through at least one fuel injection spray orifice. The inlet passage 78 is formed by the valve body 76.
Extends through and joins bore 74 at junction 80. The line 82 coincides with the longitudinal axis 82 of the inlet passage 18 and is offset with respect to the longitudinal axis 84 of the valve stem 72. A line 86 parallel to the line 82 and intersecting the longitudinal axis 84 of the valve stem 72 (hence consisting of a projection of the line 82 onto the longitudinal axis 84) is located a distance d from the line 82. As can be seen with reference to FIG. 4, it forms an acute angle θ with the longitudinal axis 84 of the valve stem 72. Given the appropriate dimensions of the elements of device 70, the magnitudes of d and θ can be selected to provide the advantages described below, as known to those skilled in the art.

The valve stem 72 includes a first end 88 and a second end 90 separated by a reduced diameter intermediate portion 92. The end 90 is slightly larger in diameter than the end 88 and the annular sealing surface 94 is
6 except that the first end portion 88 and the second end portion 90 exposed to the pressurized fluid in the bore 74 have substantially the same effective cross-sectional areas. . By making the effective cross-sectional areas of ends 88 and 90 approximately equal, the vertical or non-local fluid forces exerted on valve stem 72 are approximately balanced.
This allows the position of the valve stem to be controlled using a low force actuator. Further, the entrance passage 78
By sloping and offsetting at a confluence 80 with respect to the longitudinal axis 84 of the valve stem 72, the fluid flow proceeds into a passage having an axial component and a tangential component, which causes the fluid to flow through the valve. It will flow in a spiral passage around the stem 72. This swirling flow eliminates the stagnation described with respect to the fluid control devices of FIGS. 1 and 2, thus minimizing the localized fluid pressure differential, which adversely affects the operation of the device. become. 6 and 7 illustrate novel features of the present invention as applied to a fluid control device or mechanism 100, such as device 40 of FIG. Entrance passage 102 and bore 10
4 is formed in the main body 106. Exit passage 108
Are disposed in fluid communication with bore 104 and extend through main body 106. A control element, or valve stem 110, is located within bore 104 and is located in bore 10
4, a reduced diameter portion 112 forming an annular passage 114 in the
Includes ends 111 and 112 separated by. The effective cross-sectional areas of the ends 111 and 112 are equal so that, when pressurized fluid is present in the bore 114, approximately equal opposing axial forces are exerted on the valve stem 110. Thus, the device 100 is designed to operate in a balanced manner, allowing low force actuators to be used with the device 100.

As described with respect to the embodiment of FIGS. 4 and 5, the inlet passage 102 has a longitudinal axis at the confluence 15 which coincides with a line 116 offset with respect to the longitudinal axis 118 of the valve stem 110. Contains. That is, the line 116 is parallel to the line 116, but offset by a distance d with respect to a line 120 extending through the longitudinal axis 118. Also, the line 120 consisting of the projection of the longitudinal axis 116 onto the longitudinal axis 118 forms an acute angle θ with the axis 118, as seen in FIG.
With this configuration, the longitudinal axis 118 of the valve stem 110 is
By locating the longitudinal axis 116 of the inlet passage 102 with respect to, the fluid flow through the annular passage is created within the spiral passage, which significantly reduces or eliminates the stagnation area. To do. Thus, before significant damage occurs to the components within device 100,
The cavitational flow is quickly discharged from the annular passage 114 to the outlet passage 108. As mentioned above, the dimensions of d and θ can be selected to provide the device 100 with dimensions and to obtain the desired results. The features of the invention disclosed herein are not limited to fluid control devices of the type disclosed in the drawings, which features include
It can be applied to any fluid control device where a local pressure difference or cavitation occurs. Further, the inlet passages 78 and 102 shown in FIGS. 4-7 need not be linear, but need only be configured to form a spiral flow passage that substantially eliminates the stagnation area. It Thus, the entrance passages 78 and 102
May be curvilinear or of different shapes, only required that the fluid flow does not impinge directly on the individual control elements, i.e. valve stem 84, or 110.

Furthermore, it will be appreciated that the distance d and the angle θ need not be the same in the embodiments of FIGS. 4 and 5 and in the embodiments of FIGS. 6 and 7. Variations and modifications of the invention will be apparent to those skilled in the art in view of the foregoing. Therefore, this description
It is constructed as an example only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of this construction can be changed substantially without departing from the spirit of the invention, ensuring the use of all modifications within the scope of the claims.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first type prior art fluid control device.

2 is a cross-sectional view taken substantially along line 2-2 of FIG.

FIG. 3 is a cross-sectional view of a second type prior art fluid control device.

FIG. 4 is a view similar to FIG. 1 of a fluid control device according to the present invention.

5 is a cross-sectional view taken substantially along the line 5-5 of FIG.

FIG. 6 is a view of another embodiment of the fluid control system according to the present invention.
It is a figure similar to.

7 is a cross-sectional view taken substantially along the line 7-7 in FIG.

[Code]

 70, 100 Fluid control device 72 Check 74, 114 Bore 76, 106 Valve body 78, 102 Inlet passageway 80 Confluence point 82 Line 84 Vertical axis 88, 111 First end portion 90, 112 Second end portion 108 Outlet passageway 110 Valve Stem 114 annular passage

Claims (11)

[Claims] 1. A through bore having a bore center axis and an inlet port, wherein the inlet port is a predetermined line that does not intersect the bore center axis at a point where the inlet port and the bore intersect. A main body having a coincident inlet port central axis and a control element disposed in the bore such that a central axis of the control element substantially coincides with the bore axis, wherein the control element is under pressure within the bore. A fluid control device comprising means for substantially balancing the forces acting on said control element in the presence of fluid. 2. The fluid control device of claim 1, wherein the projection of the predetermined line on the central axis of the bore forms an interior angle other than a right angle. 3. The fluid control device according to claim 2, wherein the interior angle is an acute angle. 4. The fluid control device of claim 1, wherein the inlet port enters into the bore along a passage having a tangential component and a longitudinal component. 5. The fluid control device of claim 1, wherein the inlet port enters the bore along a passage that induces a swirling fluid flow in the pressurized fluid toward the output port. . 6. The fluid control device of claim 1, wherein the inlet port enters the bore along a passage that substantially prevents cavitation of pressurized fluid. 7. The control element comprises a valve stem having a first end and a second end, the balancing means comprising:
The fluid control according to claim 1, wherein each of the first end portion and the second end portion has a first end surface and a second end surface having substantially the same effective area. apparatus. 8. A valve body having a through bore having a bore center axis, an inlet port having an inlet port center axis at a point intersecting the bore, and an outlet port, the bore center axis and the inlet port. The projection of the predetermined line on the central axis of the bore does not intersect with the predetermined line that coincides with the central axis, and the spiral flow of the pressurized fluid is between the inlet port and the outlet port. Forming a sharp angle as induced in the bore at, the valve check being provided in the bore so that the central axis of the valve check substantially coincides with the central axis of the bore, the valve check acting on this A fluid valve for controlling the flow of pressurized fluid, characterized in that it comprises means for responding to said pressurized fluid so as to approximately balance the forces. 9. The cavitation can be largely avoided by directing substantially all flow of the pressurized fluid through the inlet port to a spiral flow in the bore. Item 8. The fluid valve according to Item 8. 10. The fluid valve is disposed within a fuel injector that includes an orifice and is moveable to control the flow of the pressurized fuel through the orifice. The fuel valve according to claim 8. 11. An inlet passageway, a bore, a control element within the bore, and an outlet passageway, the control element having a surface on which a pressurized fluid acts, the control element being generally in opposite directions. A method of operating a fluid control device adapted to generate equal and opposing forces to balance pressure, wherein the control element is positioned such that the inlet passage is in fluid communication with the bore and the outlet passage, Directing fluid from the inlet passage to the bore along a passage offset from the longitudinal axis of the control element such that the fluid spirals around the control element and into the outlet passage. The method consisting of and.