WO1996029513A1

WO1996029513A1 - Apparatus for suppressing cavitation in a fuel system

Info

Publication number: WO1996029513A1
Application number: PCT/US1996/001500
Authority: WO
Inventors: Scott A. Chockley; Thomas R. Fenelon
Original assignee: Caterpillar Inc.
Priority date: 1995-03-20
Filing date: 1996-02-05
Publication date: 1996-09-26

Abstract

An apparatus (2) is provided for suppressing cavitation in an actuating fluid system (4) of a hydraulically-actuated fuel injection system (6). The apparatus (2) has first and second cummunicating oil conduits (20, 22). The conduits (20, 22) have respective cross-sectional flow areas and lenghts which fall within a preselected interrelationship.

Description

Apparatus for Suppressing Cavitat on In A Fuel System

Technical Field

The present invention resides in an apparatus for suppressing cavitation in a fuel system. More particularly, the present invention resides in an apparatus for suppressing cavitation in an actuating fluid system of a hydraulically-actuated fuel injection system.

Background Art

In the art of diesel engines and more particularly the art of hydraulically-actuated fuel injection systems, the actuating fluid pressures required to efficiently actuate the fuel injection system are extreme by our present day standards. Under such high pressures, all impacts, vibrations, and unnecessary forces on the fuel injection system should be eliminated in order to prolong and enhance the efficient life of the system. One such undesirable force is cavitation that can occur with the formation of partial vacuums in high pressure flowing liquid such as the actuating fluid as a result of separation of the fluid's parts into liquid and vapor phases. The result of cavitation, as is known in the art, is the pitting of the metal parts which can adversely affect fuel system components. One cause of cavitation is the propagation through fuel system components of pressure waves which typically occur when a hydraulically actuated fuel injector is alternately actuated and deactuated to respectively accept and obstruct entry thereinto of high pressure acutating fluid. Disclosure of the Invention

In one aspect of the invention, an apparatus is provided for suppressing cavitation in an actuating fluid system of a hydraulically-actuated fuel injection system. A first conduit having a cross sectional flow area Al and a length LI fluidly connects a hydraulically-actuated fuel injector with an actuating fluid manifold which is fluidly connected to a pressurized fluid source. A second conduit having a cross sectional flow area A2 and a length L2 fluidly connects the fuel injector with the actuating fluid manifold. The conduits are sized relative one to the other by the formula

(Al) (L2)

(A2) (LI)

where X has a magnitude in the range of about 1.8 to about 2.2.

Brief Description of the Drawings

The drawing is a diagrammatic view of the apparatus of this invention connected between a pressurized fluid manifold and a fuel injector.

Best Mode for Carrying Out the Invention

Referring to the drawing, an apparatus 2 is provided for suppressing cavitation in an actuating fluid system 4 of a hydraulically-actuated fuel injection system 6. Since actuating fluid systems 4, hydraulically-actuated fuel injection systems 6 and fuel injectors 8 are well known in the art, the drawing and the text have been simplified for purposes of brevity.

The apparatus 2, has a first oil manifold 10. The first oil manifold 10 has a chamber 12 which is fluidly connected to and supplied with oil from a pressurized, actuating fluid source 14.

A second oil manifold or connection block 16 having a chamber 18 is fluidly connected to the first oil manifold chamber 12 and to a fuel injector 8 via first and second actuating fluid conduits 20, 22. While only one injector 8 is shown connected to such conduits 20, 22, the present invention may be used in conjunction with multiple injectors 8 as is typical for multi-cylinder engines. It is to be further understood that connection block 16 is provided to simplify conduit connection and for other reasons not related to the present invention. Connection block 16 need not, within the purview of the present invention, be used but instead the conduits 20,22 may be connected directly to the manifold 10. The fluid conduits 20 and 22 have respective cross sectional actuating fluid flow areas Al and A2 and respective lengths from the manifold 16 to the fuel injector 8 of LI and L2. The conduits cross sectional flow areas and lengths are sized relative to one another by the formula:

(Al) (L2)

X (A2) (LI)

where X has a magnitude in the range of about 1.8 to about 2.2.

Conduit constructions where X is less than about 1.8 or greater than about 2.2 are undesirable because pressure waves propagating through the conduits from various causes such as injector actuation/deactuation and pulses from the source 14 will not cancel one another whereupon cavitation may not be damped. In the preferred embodiment of this invention, X has a magnitude of about 2.

It is also preferred that the first and second manifolds 10,16 and all actuating fluid carrying members are of a construction sufficient to withstand a pressure greater than about 6000 psi. Such high pressures are necessary in order to efficiently operate modern fuel injection systems.

Industrial Applicability By so constructing the apparatus of this invention, vibrations induced in the first and second conduits 20, 22 are at the same frequency but are about 180O out of phase relative to one another causing such vibrations to be cancelled and effectively suppressing cavitation of the actuating fluid flowing through the system.

Other aspects, objects and advantages of this invention can be obtained from a study of the drawing, the disclosure and the appended claims.

Claims

Clai s

1. An apparatus (2) for suppressing cavitation in an actuating fluid system (4) of a hydraulically-actuated fuel injection system (6) , comprising: an actuating fluid manifold (10) ; a first actuating fluid conduit (20) having a cross sectional flow area Al and a length LI and being connectable to said actuating fluid manifold (10) ; and a second actuating fluid conduit (22) having a cross sectional flow area A2 and a length L2 and being connectable to said actuating fluid manifold (16); said conduits (20,22) being sized by the formula

(A1)(L2)

(A2) (LI)

where X has a magnitude in the range of about 1.8 to about 2.2.

2. An apparatus (2), as set forth in claim 1, wherein X has a magnitude of about 2.

3. An apparatus (2), as set forth in claim l, wherein the first and second conduits (20,22) are of a construction sufficient to withstand a chamber pressure greater than about 6000 psi. AMENDED CLAIMS

[received by the International Bureau on 22 July 1996 (22.07.96); original claim 1 amended; remaining claims unchanged (1 page )]

1. An apparatus (2) for suppressing cavitation in an actuating fluid system (4) of a hydraulically-actuated fuel injection system (6) , comprising: an actuating fluid manifold (10); an actuating fluid utilizing device (8) ; a first actuating fluid conduit (20) having a cross sectional flow area Al and a length LI and being connectable to said actuating fluid manifold

(10) and to said actuating fluid utilizing device (8) ; a second actuating fluid conduit (22) having a cross sectional flow area A2 and a length L2 and being connectable to said actuating fluid manifold (16) and to said actuating fluid utilizing device (8) ; and said conduits (20,22) being sized by the formula

(Al) (L2)

(A2) (LI)

where X has a magnitude in the range of about 1.8 to about 2.2.

3. An apparatus (2), as set forth in claim 1, wherein the first and second conduits (20,22) are of a construction sufficient to withstand a chamber pressure greater than about 6000 psi.