FI120214B - Arrangement for damping the vibration in a fuel feed system at a piston engine - Google Patents

Abstract

An arrangement for dampening the pressure vibration of a fuel feed system (1 ) of a piston engine, the arrangement comprising a vibration dampener (11) having a body part (12) inside which is a space (13) containing a movably arranged intermediate piece (16), a first opening (14) arranged to open in the space (13) on the first side of the intermediate piece (16) for connecting the space (13) with the fuel feed system (1 ), and a second opening (15) arranged to open into the space (13) on the second side of the intermediate piece (16), the second opening (15) being in flow connection with a gas source (22) comprising pressurized gas.

Description

ARRANGEMENT FOR DETERMINING THE PRESSURE VIOLATION OF PISTON ENGINE FUEL SUPPLY

The invention relates to an arrangement for damping the pressure oscillation of a piston engine fuel supply system 5.

Fuel injection systems for internal combustion engines use injection pumps to supply pressurized fuel to the cylinders via injection nozzles. The injection pump comprises a cylindrical element having a pressure chamber having a front-to-back movable piston whose movement causes the fuel pressure to rise. The Sylin blade element usually has one or two suction passages through which fuel is led from the low pressure side of the fuel system to the pressure space with the piston at its lower dead center. In the pressure space, the upwardly moving piston covers the fuel inlet ducts, and pressurized fuel flows from the pressure space to the high pressure pipe leading to the injection nozzle. The fuel flow to the injection nozzle stops when the screw-like cut in the piston comes into contact with the intake duct and opens the intake duct, whereupon the high pressure fuel is discharged through the intake duct to the low pressure side of the fuel system. This in turn causes a pressure pulse on the low pressure side of the fuel system. Typically, the low pressure side pääpolttoaineputkeen 20 is in fluid connection with a plurality of injection pumps, wherein the pressure tube oscillates continuously during engine operation.

If the fuel pressure in the fuel system of the low-pressure side is low, the operation of the injection due to the pressure variation causes kavitaa-25 quota low pressure side of the tubes. In the worst case, cavitation destroys low pressure pipes in a short time. The problem of cavitation is particularly serious in engines that use crude oil as fuel.

The pressure vibration of the fuel system can be damped by various dampers, such as gas dampers and mechanical dampers. The gas absorber comprises a gas space separated from the fuel system by a diaphragm. As the fuel pressure changes, the diaphragm moves and the volume of the fuel space changes, which dampens the pressure oscillation in the fuel system. This type of damper has a limited lifetime because the diaphragm is easily broken, rendering the damper unusable.

5

The mechanical damper comprises a piston or other spacer fitted into the space inside the damper. The space is in fluid communication with the fuel system whereby the piston moves and thus the volume of the fuel system changes as pressure varies. The piston is supported on the damper by one or more springs 10 which dampen the movement of the piston. The service life of this type of mechanical damper is limited by the durability of the springs.

It is an object of the invention to provide an improved arrangement for damping the pressure oscillation of a piston engine fuel system.

15

The arrangement of the invention for damping the pressure oscillation of a piston engine fuel system comprises a vibration damper having a body portion provided with a space provided with a movable spacer. The body has a first opening in the space on the first side of the spacer to connect the space 20 to the fuel supply system and a second opening in the space on the other side of the spacer that is in fluid communication with the source of pressurized gas.

More specifically, the arrangement according to the invention is characterized by what is set forth in the characterizing part of claim 1.

The invention provides considerable advantages.

The damper used in the damping arrangement according to the invention has no air and fuel separating diaphragm or mechanical spring, which makes the damper safe and durable. If necessary, the damping properties of the 3 damper can be easily adjusted by changing the pressure of the gas acting on the damper spacer.

In one embodiment of the invention, the spacer comprises a space in the first 5-aperture-facing portion of the space and a space in the second aperture-facing portion of the space in the second portion of the space. Further, the surface area of the first surface is smaller than that of the second surface. In this case, the pressure of the gas acting on the spacer may be less than the pressure of the fuel to keep the spacer in balance. Due to the low pressure, the load on the gas-10 system is low and the system can be made simple in structure.

The invention will now be described in more detail with reference to the accompanying schematic drawings.

15

Figure 1 shows a part of an internal combustion engine fuel supply system provided with pressure oscillation dampers according to one embodiment of the invention.

Figure 2 is a cross-sectional view of the vibration dampener of Figure 1.

Figure 1 schematically illustrates a portion of the internal combustion engine fuel supply system 1. The internal combustion engine is, for example, a large, multi-cylinder diesel engine used in ships or power plants. The fuel used for the engine is 25 for example crude oil. The fuel is supplied from the fuel tank 2 by a fuel pump 3 at a relatively low pressure via a low pressure fuel line 4 to each injection pump 5. The low pressure piping 4 extends from the pressure side of pump 3 to each injection pump connected to the injection nozzle 9 by high pressure pipes 10. The injection pump 5 takes care of the fuel injection together with the injection nozzles 9. The injection pump raises the fuel pressure to a level such that sufficient injection pressure is achieved by the injection nozzles 9. The fuel supply system also has low pressure return channels 8 from each injection pump 5 back to the fuel tank 2 through which the fuel 5 is fed back to the injection pump 5.

The fuel supply system 1 is provided with one or more pressure oscillation dampers 11 for damping the fuel pressure fluctuations in the fuel supply system 1. For example, pressure fluctuations occur as the high-pressure fuel in the injection pumps 10 discharges into the low pressure piping 4 at the end of the injection. Since several injection pumps 5 are connected to the same main line 6, the fuel pressure in the main line 6 oscillates rapidly. The vibration damper 11 is arranged, for example, in connection with a low pressure piping 4. In the embodiment of Fig. 1, there are two dampers 11 and they are arranged in the main line 6, preferably in the vicinity of the orifices of the branch passages 7 leading to the injection pumps 5. Alternatively or additionally, the pressure oscillation dampers 11 may be installed at other locations in the low pressure piping 4 or elsewhere in the fuel system, for example in connection with the injection pump 5.

Fig. 2 illustrates in more detail the pressure oscillation damper nose 11 shown in Fig. 1. The damper comprises a body 12 which delimits a space 13. The body 12 has a first opening 14 for communicating the space 13 with the fuel piping of the fuel supply system 1, for example, main line 6. Further, the body 12 has a second opening 15 which allows the space 13 to be in fluid communication with a gas pipe 20 containing pressurized gas, for example air. The gas pressure in the gas pipe 20 is higher than the ambient pressure. The space 13 of the space 13 on the side of the first opening 14 is smaller than on the side of the second opening 15. The space 13 has a reciprocating spacer, for example a piston 16. The first opening 14 opens to the first side of the piston 16 and the second opening 15 to the other side of the piston 16. The other side is on the opposite side of the piston 16 to the first side. The piston 16 moves in space 13 as the pressure difference between the first opening 14 and the second opening 15 changes.

The piston 16 comprises a space 13 in a portion 13 of the first opening 14 and a space 13 in the portion 13 of the second opening 15 defining a space 13 in the direction of movement of the piston 16. The first surface 17 has a smaller surface area than the second surface 18.

An annular seal 19,19 'is provided around the piston 16 to seal the clearance between the piston 16 and the body 12. The first seal 19 is disposed adjacent the first surface 17 of the piston 16 and the second seal 19 'adjacent the second surface 18 of the piston 16. In addition, the body member 12 has a drainage opening 24 and an associated drainage tube 25 through which the fuel and / or gas that has passed between the seals 19,19 'between the piston 16 and the body member 12 is discharged from the space 13. This prevents fuel from passing through the piston 16 one side, and no gas passes from piston 16 from one side to the first side.

The pressurized gas is supplied to the gas pipe 20 from a source 22, for example from a container filled with pressurized gas. The gas pipe 20 has a non-return valve 21 which allows flow through the space 13 but prevents flow away from the space 13. The non-return valve 21 opens when the pressure at its inlet side, i.e. gas side 22, is greater than at the outlet side, i.e. space 13. The gas pipe 20 25 has a pressure control valve 23 which opens to allow flow therethrough when the pressure at the inlet side, i.e. the gas pipe 20, is greater than the pressure control of the valve 23 to close. The outlet side of the pressure control valve 23 is at a lower pressure than the inlet side, for example at ambient pressure. By means of the pressure control valve 23, the pressure in the gas pipe 20 can be kept as desired. In the embodiment of Figure 2, the pressure control valve 23 is spring-loaded, i.e. the closing force of the valve is achieved by a spring.

6

As the fuel pressure rises in the fuel system fuel line to which space 13 is in fluid communication through first opening 14, piston 16 moves in space 13 toward second opening 15 and compresses gas 5 on one side of piston 16. Since the non-return valve 21 blocks the flow of gas through it, the gas pressure increases as the piston 16 moves, and the increased gas pressure impedes the movement of the piston 16. The volume of the space 13 on the first side of the piston 16 increases, which dampens the increase in fuel pressure in the fuel line. As the pressure in the fuel pipe decreases, the piston 16 moves in the opposite direction. As a result, the volume of space 10 13 on the first side of the piston is reduced, which compensates for the pressure drop in the fuel line. Since the surface of the second surface 18 of the piston 16 is larger than the surface of the first surface 17, the gas pressure of the second piston 16 may be lower than the fuel pressure of the first side of the piston 16 to maintain the piston 16 in equilibrium. The pressure damping characteristics of the pressure suppressor 11 can be changed by changing the pressure of the gas in the gas pipe 20.

Claims (8)

An arrangement for damping the pressure oscillation of a piston engine fuel supply system (1), comprising an oscillation damper 5 (11) having a body member (12) having a space (13) having a movable spacer (16) therein. (13) a first opening (14) opening on the first side of the spacer (16) for connecting a space (13) to the fuel supply system (1), and a second opening (15) opening on the other side of the spacer (16) 10, characterized in that a gas pipe (20) is provided between the second aperture (15) and the gas source (22) having a non-return valve (21) which allows flow from the gas source (22) to the space (13). but prevents flow from space (13) to gas source (22). Arrangement according to claim 1, characterized in that the spacer 15 (16) comprises a space (13) in the part facing the first opening (14) and in the part facing the first opening (17) defining the space (13) and the space (13) a second surface (18) defining the space (13), and that the surface of the first surface (17) is smaller than the surface of the second surface (18). Arrangement according to one of the preceding claims, characterized in that a drain opening (24) is provided in the body (12) for removing fuel and / or gas leaked from the space (13) between the body (12) and the spacer (16). Arrangement according to one of the preceding claims, characterized in that the gas pipe (20) is provided with a pressure control valve (23) between the pressure source (22) and the non-return valve (21) to maintain the gas pressure in the gas pipe section. Arrangement according to one of the preceding claims, characterized in that a sealing arrangement (19, 19 ') is arranged on the circumference of the spacer (16) to prevent the passage of fuel and / or gas between the spacer (16) and the body (12). Piston engine fuel supply system (1), characterized by an arrangement according to any one of claims 1 to 6 for damping the supply system pressure oscillation. Fuel supply system (1) according to Claim 6, characterized in that the system comprises injection pumps (5) for supplying fuel to the injection nozzles (9), a main line (6) for supplying fuel to the injection system (1), and a main line (6) 5) interposed branch lines (7) for supplying fuel from the main line (6) to the injection pumps (5), and that the vibration damper (11) is arranged in connection with the main line (6). Fuel supply system according to claim 6 or 7, characterized in that the vibration damper (11) is arranged in connection with the injection pump (5).