JP2004197834A - Pressure relief device and pressure accumulation type fuel supply system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure relief device capable of preventing the fuel leakage in accompany with the pressure pulsation by reducing the pressure pulsation at an upstream side of the relief valve, regardless of a rotating speed of a fuel supply pump, and increasing a capacity efficiency. <P>SOLUTION: A pressure pulsation reducing mechanism 61 for reducing the pressure pulsation is mounted at the upstream side of the relief valve 60, and the pulsation reducing mechanism 61 is composed of an accommodating member 62 having a channel 62a, and a gap member 70 accommodated in the channel of the accommodating member 62 for forming the gap flow. The gap (clearance 71) for forming the gap flow may be formed between the accommodating member 62 and the gap member 70, or on the gap member itself. Further the pressure pulsation reducing mechanism 61 may have the accommodating member 62 provided with the channel 62a, and a shielding member mounted on the accommodating member 62 to shield the channel 62a for blocking the direct advance of the fluid. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pressure relief device used for a system for supplying fuel to an internal combustion engine such as a gasoline engine, and a pressure accumulating fuel supply system using the same.
[0002]
[Prior art]
A pressure-accumulation fuel supply system that accumulates high-pressure fuel supplied from a fuel supply pump in a common rail and supplies the high-pressure fuel accumulated in the common rail to each cylinder via an injector provided for each cylinder of the internal combustion engine. Is dangerous if the pressure in the common rail rises abnormally, and may hinder the valve opening operation of the injector. For this reason, when the pressure in the common rail becomes equal to or higher than a predetermined value, a relief valve for discharging fuel in the common rail to the low-pressure side region is provided, and this relief valve is usually mounted on the common rail. . (For example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-2002-5319 (columns 0002 to 0003, FIG. 7)
[0004]
[Problems to be solved by the invention]
However, in the above-described configuration, since the relief valve is attached to the common rail, a line for releasing pressure to the low-pressure side region must be provided in the relief valve, and extra piping work is required. In addition, there is a disadvantage that the cost increases. For this reason, it has been considered that the relief valve is built in the fuel supply pump to eliminate the need for a pipeline and to reduce piping work and cost.
[0005]
By the way, a so-called single plunger pump that reciprocates one plunger to pump the fuel is often used for the above-described fuel supply pump. In such a pump, the pressure pulsation of the fuel supplied to the common rail increases because the discharge stroke of the fuel is intermittent, but the volume in the common rail is large, and the pulsation for reducing the pulsation is provided before the common rail. Since the throttle is provided, the pressure in the common rail does not largely pulsate. For this reason, in the conventional configuration in which the relief valve is mounted on the common rail, there is no fuel leak due to the pressure pulsation, so that the volumetric efficiency of the pump is large and an accurate pressure relief operation is guaranteed.
[0006]
However, in the case where the relief valve is incorporated in the fuel supply pump, the relief valve is easily affected by the pressure pulsation, so that there is an inconvenience that the pressure pulsation causes a fuel leak and the volume efficiency is reduced.
[0007]
For this reason, it is conceivable to provide an orifice on the upstream side of the relief valve for such inconvenience.If the diameter of the orifice is reduced to, for example, 0.4 mm in order to reduce the pulsation, the pressure pulsation at the time of abnormal pressure is reduced. Although reduced, the pressure on the upstream side of the orifice (the pressure immediately after the discharge valve of the fuel supply pump) increases as the pump rotational speed (Np) increases due to the effect of the orifice throttle as shown in FIG. Get higher. For this reason, if the valve opening pressure of the relief valve is set in accordance with the pressure at the time of low rotation of the pump, the relief valve opens at the time of high rotation of the pump, and there is a disadvantage that the volumetric efficiency of the pump is reduced. If the valve opening pressure is set to match the pressure at high rotation, the injector valve opening operation must be ensured even when the pressure in the common rail increases, resulting in a higher voltage for the injector driver and higher costs There are inconveniences.
[0008]
On the other hand, when the orifice diameter is increased to, for example, φ1.0 mm, the pressure immediately after the discharge valve of the fuel supply pump becomes larger as the pump rotation speed (Np) increases, as shown in FIG. It becomes large, and the effect of the diaphragm cannot be seen.
[0009]
Therefore, in the present invention, it is possible to avoid inconvenience due to excessive throttling, effectively reduce pressure pulsation upstream of the relief valve, prevent fuel leakage due to pressure pulsation, and increase volumetric efficiency. A main object is to provide a pressure relief device and an accumulator-type fuel supply system using the same.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a pressure relief device according to the present invention is provided between a high-pressure side region and a low-pressure side region, and when the fluid pressure in the high-pressure side region becomes equal to or higher than a predetermined value, A relief valve that allows a fluid to flow from the side region to the low-pressure side region; and a pulsation reducing unit that reduces pressure pulsation upstream of the relief valve. The present invention is characterized in that it has a housing member and a gap constituting body that is housed in a flow path of the housing member and forms a gap flow (claim 1).
[0011]
Here, the gap (clearance) for forming the gap flow may be formed between the housing member and the gap member, or may be formed in the gap member itself ( Claims 2 and 3).
[0012]
Therefore, since the pulsation reducing means utilizes the gap flow, even if the gap is reduced, the entire passage area can be increased, and the influence of the throttle can be eliminated. Further, since the gap can be reduced, it is possible to suppress the pressure pulsation of the fluid toward the relief valve.
[0013]
Further, the pressure relief device according to the present invention is disposed between the high-pressure side region and the low-pressure side region, and when the fluid pressure in the high-pressure side region becomes equal to or higher than a predetermined value, A relief valve that allows a flow of fluid to the region, pulsation reducing means for reducing pressure pulsation is provided upstream of the relief valve, and the pulsation reducing means includes a housing member having a flow path formed therein, It may be configured to have a shield attached to the member so as to shield the flow path and prevent the fluid from going straight (claim 4).
[0014]
Here, the shielding body is provided with a plurality of shielding plates having orifices of a predetermined diameter formed at intervals in the flow path, and when the orifices of the adjacent shielding plates are projected in the direction in which the flow path is formed, the weight of the shielding body may be reduced. Even if it arranges so that it may not become, it is also provided so as to block the flow path of the housing member, and the axial passage extending in the direction of forming the flow passage between the housing member and the diameter substantially perpendicular to the axial passage. And a directional passage (claims 5 and 6).
[0015]
Therefore, according to such a configuration, since the fluid directed to the relief valve collides with the shield and is prevented from going straight, the pulsating energy of the fluid can be attenuated by the shield, and the pressure pulsation can be reduced without causing a restriction. Can be suppressed.
[0016]
By the way, the relief valve is disposed between the high-pressure side region downstream of the discharge valve of the fuel supply pump and the low pressure side region upstream of the suction valve of the fuel supply pump, and discharges from the discharge valve. When the pulsation reducing means is provided on a relief passage branched from a fuel supply passage for supplying fuel, the pulsation reducing means may be provided on a relief passage. In addition, the fuel supply passage and the relief passage may be provided on the upstream side of a branch portion (claim 8).
[0017]
According to the former configuration, the pressure pulsation between the pulsation reducing means of the relief passage and the relief valve can be reduced. According to the latter configuration, the pressure pulsation of not only the relief passage but also the fuel supply passage can be reduced. be able to.
[0018]
Further, in the configuration in which the relief valve is incorporated in the fuel supply pump, integrating the relief valve, the discharge valve, and the pulsation reducing means eliminates piping, reduces cost, and reduces the fuel supply pump. This is preferable for miniaturization (claim 9).
[0019]
The pressure relief device as described above has a fuel supply pump, a common rail for storing fuel, and an injector provided for each cylinder of the internal combustion engine, and a fuel supply passage connecting the fuel supply pump and the common rail. In a pressure-accumulation fuel supply system in which the fuel pressurized by the fuel supply pump can be supplied to the common rail via the fuel supply pump, and the fuel accumulated in the common rail can be supplied to the injector, the fuel supply pump is suitable for providing the fuel supply pump ( Claim 10).
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a configuration example in the case where the pressure relief device according to the present invention is applied to a pressure accumulating fuel supply system will be described with reference to the drawings.
As shown in FIG. 1, the accumulator type fuel supply system includes a fuel tank 1, a feed pump 2 that pumps up fuel from the fuel tank 1, and temporarily increases the pumped fuel, and a fuel pumped from the feed pump 2. A low-pressure regulating valve 3 for setting the pressure of the fuel, a fuel supply pump 4 for pressurizing the fuel sent from the feed pump 2 by a required amount, and a common rail 5 for accumulating the high-pressure fuel sent from the fuel supply pump 4. An injector 6 is provided for each cylinder of the internal combustion engine and injects fuel stored in the common rail 5 at a predetermined timing.
[0021]
The fuel supply pump 4 includes a filter 7, a low-pressure damper 8, a suction valve 9, a high-pressure pump unit 10, a discharge valve 11, a flow control device 12, and a pressure relief device 13. As shown in FIG. 2, these are provided on a housing 15 of the fuel supply pump 4 and are configured as an integral assembly.
[0022]
A single plunger barrel 16 is fixed to the barrel mounting hole 17 in the housing 15, and a plunger 18 is slidably inserted in the plunger barrel 16. The plunger 18 is connected to a tappet 19 protruding from the housing 15 and provided to face a cam (not shown). The tappet 19 is pressed against the cam by a return spring 21 elastically mounted between the tappet 19 and a spring receiver 20 fixed to the pump housing 15, and the plunger 18 reciprocates by rotation of the cam.
[0023]
Further, the housing 15 is assembled with a first valve holder 22 in which the suction valve 9 and the flow control device 12 are integrally formed, and a second valve holder 23 in which the discharge valve 11 and the pressure relief device 13 are integrally formed. Have been.
[0024]
The first valve holder 22 is hermetically inserted into a first valve holder mounting hole 24 formed following the barrel mounting hole 17, and defines a compression chamber 25 with the plunger 18. The second valve holder 23 is hermetically inserted into a second valve holder mounting hole 27 that communicates with the compression chamber 25 via the communication passage 26.
[0025]
Further, the housing 15 includes a suction passage 30 communicating with the feed pump 2, a damper chamber 31 communicating the suction passage 30 with the first valve holder mounting hole 24, a second valve holder mounting hole 27 and the suction passage 30. A return passage 32 is formed, and an inflow pipe 33 provided with a filter 7 is inserted into the suction passage 30, and a metal constituting a low-pressure damper 8 for reducing fuel pulsation is provided in the damper chamber 31. The diaphragm 34 is housed.
[0026]
The first valve holder 22 is formed with a fuel supply passage 35 having one end communicating with the damper chamber 31 and the other end communicating with the compression chamber 25, and the fuel supply passage 35 is provided with a suction valve 9 that opens and closes the fuel supply passage 35. . Here, the suction valve 9 includes a valve seat 36 fixed to the first valve holder 22, a stopper 37 caulked at an end of the first valve holder 22, and a valve hole 36 a formed in the valve seat 36. And a spring 39 that is elastically mounted between the valve body 38 and the stopper 37 and biases the valve body 38 in a direction to close the valve hole 36a. During the suction stroke of the plunger 18 in which the capacity of the plunger 18 increases, the fuel pressure in the fuel supply passage 35 causes the valve body 38 to lift against the urging force of the spring 39 so that the fuel flows into the compression chamber 25. Has become.
[0027]
The suction valve 9 also functions as a normally closed (normally closed) solenoid valve. That is, the first valve holder 22 forms a stator, defines an armature accommodating chamber 41 between the first valve holder 22 and the end body 40 assembled thereto, and an armature in which the rod 43 is fixedly mounted in the armature accommodating chamber 41. A rod 43 fixed to the armature 44 projects into the fuel supply passage 35 through a through hole 42 formed in the first valve holder 22 so that the rod 43 can contact the valve body 38. Then, by energizing an exciting coil 46 provided around the end body 40, the armature 44 is displaced against the urging force of a spring 45 elastically mounted between the armature 44 and the valve holder 22, and the rod 43 is moved to the valve body. 38 to lift the valve element 38.
[0028]
Therefore, the fuel flowing from the inflow pipe 33 through the filter 7 enters the damper chamber 31, and the pulsation is reduced by the metal diaphragm 34 provided therein, so that the pulsation noise and the vibrational load are reduced. Has become. The fuel that has passed through the damper chamber 31 flows into the compression chamber 25 via the suction valve 9 during the suction stroke in which the plunger 18 moves rightward in the drawing, and the pumping stroke in which the plunger 18 moves leftward in the drawing. In some cases, the valve 38 closes the valve hole 36a unless the excitation coil 46 is energized, and pressurized fuel is fed to the discharge valve 11 described below via the communication passage 26.
[0029]
When the excitation coil 46 is energized, the valve body 38 is forcibly opened, and the fuel in the compression chamber 25 passes through the valve hole 36a without being pressurized even during the pressure feeding stroke. Returned to the side. Therefore, by adjusting the timing of energizing the excitation coil 46, the amount of pressurized fuel to be pumped can be adjusted.
[0030]
The discharge valve 11 is provided at the end of the second valve holder 23 facing the communication passage 26. As shown in FIG. 3, the discharge valve 11 includes a valve seat 51 fixed to an end of the second valve holder 23 via a wave washer 50, and a gap between the valve seat 51 and the second valve holder 23. Between a valve body 53 housed in a valve housing chamber 52 formed in the valve seat 51 and opening and closing a valve hole 51a formed in the valve seat 51, and a spring guide 54 fixed to the valve body 53 and the second valve holder 23. And a spring 55 that urges the valve body 53 in a direction to close the valve hole 51a. When the pressurized fuel is fed through the communication passage 26 during the pressure feeding stroke, the pressure is increased by the fuel pressure. The valve body 53 is lifted against the urging force of the spring 55, and pressurized fuel flows into the valve housing 52.
[0031]
Further, the second valve holder 23 has one end connected to the valve storage chamber 52, the other end connected to a discharge port 56 communicating with a common rail, and one end connected to the valve storage chamber 52, and the like. A relief passage 59 whose end is connected to the return passage 32 through an annular groove 58 formed around the second valve holder 23 is formed.
[0032]
On the relief passage 59, a relief valve 60 constituting the pressure relief device 13 and a pressure pulsation reducing mechanism 61 disposed upstream thereof are provided. In other words, a part of the pressure pulsation reducing mechanism 61 is formed on the relief passage 59, and the housing member 62 in which the flow path 62a is formed is inserted into the second valve holder 23, and the housing member 62 and the A valve housing chamber 63 is formed in a space surrounded by the two valve holders 23. The relief valve 60 includes a ball valve 64 that comes into contact with a seat portion 62b formed at an end of the housing member 62 from a downstream side, a valve guide 65 that holds the ball valve 64, a valve guide 65, and a second valve. A spring 67 is provided between the spring member 66 formed in the holder 23 and a spring 67 for urging the ball valve 64 in a direction to close the passage 62a of the housing member 62, and is guided into the passage. When the fuel pressure reaches a predetermined value or more, the ball valve 64 lifts against the urging force of the spring 67, and high-pressure fuel flows into the valve chamber 63.
[0033]
Further, the pressure pulsation reducing mechanism 61 is configured to house a gap forming member 70 that forms a gap flow on the flow path of the housing member 62. As shown in FIG. 4, the gap constituting member 70 has its downstream end press-fitted into the housing member 62, and the diameter of the outer peripheral surface is slightly smaller than the diameter of the inner peripheral surface of the housing member 62 from the upstream end to the middle. A clearance 71 having a predetermined space between the housing member 62 and the housing member 62 is formed. An annular groove 72 communicating with the clearance 71 is formed on the outer peripheral surface in the middle of the gap member 70, and is formed in the gap member 70 in the axial direction from the downstream end to the middle. A shaft passage 73 having one end connected to the shaft hole 73 and the other end connected to the annular groove 72 is formed.
[0034]
Therefore, the fuel supplied via the discharge valve 11 passes through the clearance 71, and is thereafter guided to the back of the ball valve 64 through the annular groove 72, the radial passage 74, and the shaft hole 73, and the gap configuration A gap flow is formed between the body 70 and the housing member 62 by the clearance 71.
[0035]
Here, when the outer diameter (diameter) of the upstream end portion of the gap member 70 is set to 5 mm, a gap between the inner circumferential surface of the housing member 62 (the inner circumferential surface of the housing member 62 and the gap The radius difference from the outer peripheral surface is set to about 50 μm, and the passage area of the entire gap (隙間 5π × 0.05 = π × (（)) ^Two ) Is equivalent to an orifice having a diameter of approximately 1 mm.
[0036]
Therefore, according to the above-described configuration, even if pressure pulsation occurs on the downstream side of the discharge valve 11, the fuel is sent to the relief valve 60 via the clearance 71 between the housing member 62 and the gap constituting member 70. Pulsation is reduced in the process of passing through the clearance 71. For this reason, the pressure can be stabilized on the upstream side of the relief valve 60, so that fuel leakage due to pressure pulsation can be eliminated, and accurate relief operation of the relief valve 60 can be guaranteed. Efficiency can be increased. Further, since the passage area of the gap (clearance 71) is set to be equivalent to the orifice having a diameter of 1 mm, the influence of the throttle does not occur, and the pressure immediately after the discharge valve 11 is, as shown in FIG. Even when the fuel supply pump 4 rotates at a high speed, it does not rise.
[0037]
FIG. 5 shows another example of the structure of the gap structure 70. In this example, the gap constituting member 70 partially presses the inner peripheral surface of the housing member 62 at both axial ends (the upstream end and the downstream end), and the inner periphery of the housing member 62 at the remaining portion. There are press-fit ends 75, 76 formed with separation surfaces 75a, 76a separated from the surfaces, and a cylindrical portion 79 integrally connected between the press-fit ends via small-diameter connecting portions 77, 78. Have. The cylindrical portion 79 is formed so that the diameter of the outer peripheral surface thereof is slightly smaller than the diameter of the inner peripheral surface of the housing member 62, and a clearance 80 having a predetermined interval between the cylindrical portion 79 and the inner peripheral surface of the housing member 62 is formed. The gap 80 is formed by the clearance 80. Here, the separation surfaces 75a and 76a are formed by flat cuts formed at right angles to the radial direction at positions symmetrical with respect to the axis, and the outer diameter (diameter) of the cylindrical portion 79 of the gap constituting body 70. Is set to 5 mm, the gap between the inner peripheral surface of the housing member 62 (the radius difference between the inner peripheral surface of the housing member 62 and the outer peripheral surface of the gap constituting member 70) is set to 50 μm, and the gap (clearance 80) is set. Is approximately equivalent to an orifice having a diameter of 1 mm.
[0038]
Therefore, according to this configuration, the fuel discharged from the discharge valve 11 flows around the connecting portion 77 through the gap between the separation surface 75a formed at the press-fit end 75 and the inner peripheral surface of the housing member 62. After that, the ball valve 64 passes through the clearance 80 between the housing member 62 and the columnar portion 79 to reach the periphery of the connection portion 78, and passes through the gap between the separation surface 76 a of the press-fit end 76 and the housing member 62. Guided behind.
[0039]
Therefore, even if pressure pulsation occurs downstream of the discharge valve 11, the pressure pulsation is reduced in the process of passing through the clearance 80, so that the pressure upstream of the relief valve 60 can be stabilized. Therefore, fuel leakage due to pressure pulsation is eliminated, and accurate relief operation of the relief valve 60 can be ensured, and the volumetric efficiency of the fuel supply pump can be increased. Further, since the passage area of the clearance (clearance 80) is set to be equivalent to the orifice having a diameter of 1 mm, the influence of the throttle does not occur. The inconvenience of rising disappears.
[0040]
In the configuration described above, the gap for forming the gap flow is formed between the housing member 62 and the gap configuration body 70. However, the gap for forming the gap flow is the gap configuration body 70. It may be formed on itself. In particular, when it is necessary to reduce the gap to 20 μm in order to reduce pulsation, the number of gaps may be increased to cope with the situation.
[0041]
For example, as shown in FIG. 6, a gap member 70 is formed by forming a cylindrical portion 81 having an outer diameter of 4 mm, a cylindrical portion 82 having an outer diameter of 4.5 mm provided outside thereof, and an outer diameter 5 mm provided further outside thereof. And a cylindrical portion 83 between the cylindrical portion 81 and the cylindrical portion 82, between the cylindrical portion 82 and the cylindrical portion 83, and between the cylindrical portion 83 and the housing member 62 in a concentric annular shape of 0.02 mm. The gaps 84, 85, 86 may be formed. In such a configuration, the passage area of the gap (≒ 5π × 0.02 + 4.5π × 0.02 + 4π × 0.02> π × (1/2)) ^Two ) Is larger than the orifice having a diameter of 1 mm, so that it is possible to more effectively reduce pulsation while suppressing the influence of the throttle (pressure increase at high rotation of the pump).
[0042]
As shown in FIG. 7, the gap constituting body 70 is constituted by a plurality of constituent elements 87 having mating surfaces along the axial direction, and the gap constituting body is formed with a gap 88 in a lattice shape. May be obtained.
[0043]
FIG. 8 shows another configuration example of the pressure pulsation reduction mechanism 61. In this example, the pressure pulsation reducing mechanism 61 is attached to the housing member 62 so as to shield the flow path 62a, and is configured by a shield 90 that prevents the fuel from going straight.
[0044]
The shield 90 is configured by arranging a plurality of shield plates 92 having orifices 91 of a predetermined diameter at intervals in the flow path 62a. The annular press-fit fixing members 93 that are press-fitted and fixed to the housing member 62 in the forming direction of 62 a are alternately arranged, and the distance between the shielding plates is defined by the thickness of the press-fit fixing members 93. Here, the orifices 91 of each shield plate 92 are formed to have a size of about 1 mm in diameter, and the orifices 91 formed in the adjacent shield plates 92 overlap when projected in the direction in which the flow path 62a is formed. It is formed in the position where it does not become necessary.
[0045]
Therefore, according to such a configuration, the fuel discharged from the discharge valve 11 is sent to the downstream side through the orifices formed at different positions of the respective shield plates 91, and the direction of the fuel is changed to the shield plates. Each time, the energy is attenuated and the pulsation is reduced. In addition, since each orifice 91 is set to a diameter that is less likely to be affected by the throttle, there is no inconvenience that the pressure increases when the fuel supply pump 4 rotates at a high speed when the pressure is abnormal. Therefore, regardless of the rotation speed of the fuel supply pump 4, fuel leakage from the relief valve 60 due to the pressure pulsation is eliminated, and the volume efficiency of the fuel supply pump 4 is increased, and an accurate relief operation of the relief valve 60 is guaranteed. It becomes possible.
[0046]
FIG. 9 shows another configuration example of the shield 90. The shielding body 90 used here includes a plug portion 95 press-fitted into the housing member 62 so as to shield the flow path 62a of the housing member 62, and a flange portion 96 having a diameter larger than the inner diameter of the housing member 62. It is formed integrally, and flat cut portions 97, which are cut flat along the axial direction from the tip of the plug portion 95 to the middle of the flange portion 96, are formed at two locations symmetrical with respect to the axis. The portion of the portion 96 where the flat cut portion is formed is formed to be thin. For this reason, when the shield 90 is attached to the housing member 62, an axial passage 98 a extending between the housing member 62 and the shield 90 in the direction in which the flow path 62 a is formed, and a diameter substantially orthogonal to the axial passage 98 a. The direction passage 98b is formed. The sum of the passage areas of the respective axial passages 98a and the sum of the passage areas of the respective radial passages 98b are equivalent to an orifice having a diameter of 1 mm.
[0047]
Therefore, according to such a configuration, the flow of the fuel discharged from the discharge valve 11 is changed at the flange 96 of the shield 90, the fuel flows around from the side of the flange 96, and the radial passage 98 b and the axial passage 98 a are formed. Is guided behind the ball valve 64, the energy is attenuated in the process of colliding with the flange portion 96 and pulsation is reduced. Further, since the axial passage 98a or the radial passage 98b is set to an area that is hardly affected by the throttle, there is no inconvenience that a pressure rise occurs when the fuel supply pump 4 rotates at a high speed when the pressure is abnormal. Therefore, regardless of the rotation speed of the fuel supply pump 4, fuel leakage from the relief valve 60 due to the pressure pulsation is eliminated, and the volume efficiency of the fuel supply pump 4 is increased, and an accurate relief operation of the relief valve 60 is guaranteed. It becomes possible.
[0048]
In the above-described configuration, the pressure pulsation reducing mechanism 61 is provided downstream of the discharge valve 11 and on the relief passage 59 branched from the fuel supply passage 57, but as shown in FIG. The pressure pulsation reducing mechanism 61 may be provided downstream of the discharge valve 11 of the fuel supply pump 4 and upstream of the branch between the fuel supply passage 57 and the relief passage 59. According to such a configuration, regardless of the rotation speed of the fuel supply pump 4, the pressure pulsation of the fuel discharged from the discharge valve 11 is reduced to prevent fuel leakage, and in addition to the effect of improving the volumetric efficiency, the fuel is supplied to the common rail 5. If the throttle α (see FIG. 1) is provided before the common rail 5, the throttle α can be removed.
[0049]
Further, in the above-described configuration example, since the relief valve 60, the discharge valve 11, and the pressure pulsation reducing mechanism 61 are integrated and provided in the fuel supply pump 4, the piping connection is unnecessary, and the cost is also advantageous. However, they may be formed separately without being integrated. Further, in the above-described configuration example, the configuration example in which the housing member 62 provided with the gap configuration body 70 and the shielding body 90 is also used as a valve seat and assembled to the valve holder 23 is shown. May be used separately, or the valve holder 23 may be used as a housing member on which the gap constituting body 70 and the shielding body 90 are provided.
[0050]
【The invention's effect】
As described above, according to the present invention, the pulsation reducing means for reducing the pressure pulsation is provided on the upstream side of the relief valve, and the pulsation reducing means is provided by accommodating the gap component forming the gap flow in the housing member. Or a shield attached to the flow path to prevent the fluid from moving forward is provided in the housing member, so that the pressure pulsation on the upstream side of the relief valve is effectively reduced to accompany the pressure pulsation. Fuel leakage can be prevented and volumetric efficiency can be increased. Further, since the pulsation reducing means is provided, the upstream side of the relief valve is not throttled, so that an adverse effect due to excessive throttling can be avoided.
[0051]
In addition, since pressure pulsation can be reduced while avoiding the inconvenience caused by throttling, it is suitable when a relief valve is provided in the fuel supply pump, and the valve opening pressure is set low even when the relief valve is provided in the fuel supply pump. It is possible to do. In addition, noise and vibration caused by pressure pulsation can be reduced, and durability of the relief valve can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a fuel system of an accumulator type fuel supply device according to the present invention.
FIG. 2 is a cross-sectional view showing a main part of a fuel supply pump.
FIG. 3 is a sectional view showing a pressure relief device according to the present invention.
FIG. 4 is a side sectional view showing an example of a gap structure used in the pressure pulsation reduction mechanism.
5 shows another example of the gap structure used in the pressure pulsation reducing mechanism. FIG. 5 (a) is a side sectional view, and FIG. 5 (b) is a perspective view thereof.
6A and 6B show another example of the gap structure used in the pressure pulsation reduction mechanism. FIG. 6A is a cross-sectional view taken along a plane perpendicular to the axis, and FIG. ) Is its perspective view.
7A and 7B show another example of the gap structure used in the pressure pulsation reduction mechanism. FIG. 7A is a cross-sectional view taken along a plane perpendicular to the axis, and FIG. ) Is its perspective view.
FIG. 8 is a side sectional view showing an example of a shield used in the pressure pulsation reduction mechanism.
9 shows another example of a shield used in the pressure pulsation reducing mechanism, wherein FIG. 9 (a) is a side sectional view and FIG. 9 (b) is a perspective view thereof.
FIG. 10 is a diagram illustrating another portion where the pressure pulsation reduction mechanism is provided.
FIG. 11 is a characteristic diagram showing a relationship between a pump rotation speed at the time of abnormal pressure and a pressure change immediately after a discharge valve of a fuel supply pump. FIG. 11 (a) is a diagram illustrating an orifice having a diameter of 0.4 mm and a relief valve. (B) is a characteristic diagram in which an orifice having a diameter of 1.0 mm is provided upstream of the relief valve, and (c) is a pulsation reducing means according to the present invention. FIG. 4 is a characteristic diagram when the filter is provided on the upstream side of FIG.
[Explanation of symbols]
4 Fuel supply pump
5 common rail
6. Injector
13 Pressure relief device
60 relief valve
61 Pressure pulsation reduction mechanism
62 accommodation member
62a flow path
70 gap structure
90 Shield
91 Oifis
92 Shield plate
98a Axial passage
98b radial passage

Claims (10)

A relief valve disposed between a high-pressure side region and a low-pressure side region, for allowing a flow of a fluid from the high-pressure side region to the low-pressure side region when a fluid pressure in the high-pressure side region becomes a predetermined value or more. In a pressure relief device provided with
Pulsation reducing means for reducing pressure pulsation is provided on the upstream side of the relief valve,
A pressure relief device, characterized in that the pulsation reducing means includes a housing member having a flow path formed therein, and a gap component housed in the flow path of the housing member to form a gap flow. The pressure relief device according to claim 1, wherein a gap for forming the gap flow is formed between the housing member and the gap structure. The pressure relief device according to claim 1, wherein a gap for forming the gap flow is formed in the gap structure. A relief valve disposed between a high-pressure side region and a low-pressure side region, for allowing a flow of a fluid from the high-pressure side region to the low-pressure side region when a fluid pressure in the high-pressure side region becomes a predetermined value or more. In a pressure relief device provided with
Pulsation reducing means for reducing pressure pulsation is provided on the upstream side of the relief valve,
The pulsation reducing means includes a housing member having a flow path formed therein, and a shielding body attached to the housing member so as to shield the flow path and hinders the fluid from going straight. Pressure relief device. The shield is configured by arranging a plurality of shield plates having orifices of a predetermined diameter at intervals in the flow path, and projecting orifices of adjacent shield plates in the direction in which the flow path is formed. 5. The pressure relief device according to claim 4, wherein the pressure relief device does not overlap with the pressure relief device. The shielding body is provided so as to shield the flow path of the housing member, and has an axial passage extending in a direction in which the flow path is formed between the housing member and a radial passage substantially perpendicular to the axial passage. The pressure relief device according to claim 4, wherein the pressure relief device is configured by: The relief valve is disposed between a high pressure side region downstream of a discharge valve of the fuel supply pump and a low pressure side region upstream of a suction valve of the fuel supply pump, and discharges from the discharge valve. The pressure relief device according to claim 1, wherein the pressure relief device is provided on a relief passage branched from a fuel supply passage that supplies the fuel, and the pulsation reducing unit is provided on the relief passage. The relief valve is disposed between a high pressure side region downstream of a discharge valve of the fuel supply pump and a low pressure side region upstream of a suction valve of the fuel supply pump, and discharges from the discharge valve. The pulsation reducing means is provided on a relief passage branched from a fuel supply passage for supplying the fuel, and the pulsation reduction means is located downstream of the discharge valve, and is located between a branch portion between the fuel supply passage and the relief passage. The pressure relief device according to claim 1, wherein the pressure relief device is provided on an upstream side. The pressure relief device according to claim 7, wherein the relief valve, the discharge valve, and the pulsation reducing unit are integrated. The fuel supply pump includes a fuel supply pump, a common rail for storing fuel, and an injector provided for each cylinder of the internal combustion engine. The fuel supply pump is connected to the fuel supply pump via a fuel supply passage connecting the common rail. In a pressure-accumulation fuel supply system that enables pressurized fuel to be supplied to the common rail and fuel that is accumulated in the common rail to be supplied to the injector,
An accumulator-type fuel supply system, wherein the fuel supply pump is provided with the pressure relief device according to any one of claims 1 to 9.

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