JP2019090366A - Relief valve mechanism and fuel supply pump comprising the same - Google Patents

Abstract

To provide a fuel supply pump capable of preventing cavitation damage at a relief valve seat part under high pressure, and also capable of reducing pressure loss of a relief valve upon releasing abnormal high pressure.SOLUTION: A relief valve mechanism comprises: a relief valve; a seat surface formed with a seat part on which the relief valve is seated, and inclined at a first angle to a valve axis direction; a downstream side inner diameter enlarged part formed so as to connect to the seat surface on a downstream side with respect to the seat part, and formed so as to enlarge from a lower end of the seat surface to a radially outward side with respect to the seat surface; and a downstream side end surface formed from a lower end of the downstream side inner diameter enlarged part to the radially outward side.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a relief valve mechanism and a fuel supply pump provided with the same.

  In order to reduce the pressure loss of the check valve installed in the fuel supply pump, it is known that the fuel flow is divided into multiple times and bent in the vicinity of the seat that seals the fuel by contacting the valve. (See, for example, Patent Document 1).

  According to this document, "at the side facing the section having a relatively large diameter in the bearing surface, at least one surface is followed, which is inclined more than the bearing surface with respect to the longitudinal axis of the connection. On the side facing the section having a relatively small diameter, the bearing surface is followed by at least one surface, which is inclined less than the bearing surface with respect to the longitudinal axis of the connection. Are described as being ".

Japanese Patent Application Publication No. 2007-533882

  In the technique disclosed in Patent Document 1, when the flow is rapidly expanded to reduce pressure loss, flow separation may cause cavitation. Also, when applying to a relief valve or the like where the load of the return spring is high, if the valve body is directly biased by the return spring, wear may occur at the contact portion, so a relief between the valve body and the return spring It is desirable to sandwich the valve holder. In such a case, when the technology disclosed in Patent Document 1 is applied, it is difficult to secure a space for arranging a relief valve holder and to form a flow that smoothly flows around the periphery.

  An object of the present invention is to provide a fuel supply pump which achieves both prevention of cavitation erosion in a relief valve seat at the time of high pressure and reduction of pressure loss at the time of releasing abnormal high pressure.

  In order to achieve the above object, in the present invention, a relief valve and a seat portion on which it is seated are formed, and a seat surface inclined at a first angle with respect to the valve axis direction, and a seat surface downstream of the seat portion And a downstream side inner diameter enlarged portion formed to expand radially outward from the lower end of the sheet surface and a downstream side formed radially outward from the lower end of the downstream side inner diameter expanded portion And an end face.

  According to the present invention, it is possible to provide a fuel supply pump that achieves both prevention of cavitation erosion in the relief valve seat at the time of high pressure and reduction of pressure loss at the time of releasing abnormal high pressure. Problems, configurations, and effects other than those described above will be apparent from the description of the embodiments below.

FIG. 1 is a longitudinal cross-sectional view of a fuel supply pump embodying the present invention as viewed from the lateral direction. FIG. 1 is a horizontal cross-sectional view from above of a fuel supply pump embodying the present invention; FIG. 2 is a longitudinal cross-sectional view of a fuel supply pump embodying the present invention, viewed from the side different from FIG. 1; It is an expanded sectional view of an electromagnetic suction valve mechanism carried in a fuel feed pump which carries out the present invention. FIG. 1 is a block diagram of a fuel supply system including a fuel supply pump embodying the present invention. FIG. 5 is an enlarged cross-sectional view of the seat member and the periphery of the relief valve mechanism according to the first embodiment of the present invention. FIG. 10 is an enlarged cross-sectional view of a seat member and the periphery of a relief valve mechanism according to a modification of the first embodiment of the present invention. It is an expanded sectional view in the sheet member circumference of the relief valve mechanism by a 2nd embodiment of the present invention. It is an expanded sectional view in the sheet member circumference of the relief valve mechanism by the modification of the 2nd embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, although the up-down direction in drawing may be designated and demonstrated in the following description, this up-down direction does not mean the up-down direction in the mounting state of a fuel supply pump.

  FIG. 5 is a block diagram showing an example of a fuel supply system including a fuel supply pump. The portion surrounded by a broken line shows the pump body 1 of the fuel supply pump, and the mechanism shown in the broken line shows that the parts and components are integrally incorporated into the pump body 1 of the fuel supply pump.

  The fuel of the fuel tank 20 is pumped up by a feed pump 21 based on a signal from an engine control unit (ECU) 21. The fuel is pressurized to an appropriate feed pressure and sent through the suction pipe 28 to the low pressure fuel inlet 10a of the fuel supply pump. The fuel that has passed through the suction joint 51 from the low pressure fuel suction port 10a reaches the suction port 31b of the electromagnetic suction valve mechanism 300 that constitutes the capacity variable mechanism through the pressure pulsation reduction mechanism 9 and the suction passage 10d.

  The fuel flowing into the electromagnetic suction valve mechanism 300 passes through the suction valve 30 and flows into the pressurizing chamber 11. The cam mechanism 93 (see FIG. 1) of the engine provides the plunger 2 with power to reciprocate. The reciprocating motion of the plunger 2 sucks the fuel from the suction valve 30 during the downward stroke of the plunger 2 and the fuel is pressurized during the upward stroke. The pressurized fuel is pressure-fed through the discharge valve mechanism 8 to the common rail 23 on which the pressure sensor 26 is mounted.

  The common rail 23 is provided with an injector 24 (so-called direct injection injector) for injecting fuel directly to a cylinder of an engine (not shown) and a pressure sensor 26. The direct injectors 24 are mounted in accordance with the number of cylinders (cylinders) of the engine, and open and close according to the control signal of the ECU 27 to inject fuel into the cylinders. The fuel supply pump (fuel supply pump) of this embodiment is applied to a so-called direct injection engine system in which the injector 24 injects fuel directly into the cylinder of the engine.

  When an abnormal high pressure occurs in the common rail 23 due to a failure of the direct injection injector 24 or the like, the differential pressure between the pressure of the fuel discharge port 12 of the fuel supply pump and the pressure of the pressurizing chamber 11 is equal to or higher than the opening pressure of the relief valve mechanism 200 Then, the relief valve 202 opens. In this case, the fuel that has become abnormally high pressure in the common rail 23 passes through the inside of the relief valve mechanism 200 and is returned to the pressurizing chamber 11 from the relief passage 200 a. This makes it possible to protect the common rail 23 (high pressure piping). The present invention can be similarly applied to a system in which the relief passage 200a is connected to the low pressure fuel chamber 10 (see FIG. 1) and the fuel which has become abnormally high pressure is returned to the low pressure passage.

  The fuel supply pump of this embodiment will be described with reference to FIGS. 1, 2 and 3. FIG. FIG. 1 is a cross-sectional view showing a cross section parallel to the central axis direction of a plunger in the fuel supply pump of the present embodiment. FIG. 2 is a horizontal sectional view of the fuel supply pump of the present embodiment as viewed from above. FIG. 3 is a cross-sectional view of the fuel supply pump of this embodiment as viewed from a direction different from FIG.

  Although the suction joint 51 is provided on the side surface of the body in FIG. 2, the present invention is not limited to this, and the invention is also applied to a fuel supply pump having the suction joint 51 provided on the upper surface of the damper cover 14. It is possible. The suction joint 51 is connected to a low pressure pipe for supplying fuel from the fuel tank 20 of the vehicle, and the fuel flowing from the low pressure fuel suction port 10 a of the suction joint 51 is a low pressure passage formed in the pump body 1 Flow through. A suction filter (not shown) press-fit into the pump body 1 is provided at the inlet of the fuel passage formed in the pump body 1, and foreign matter present between the fuel tank 20 and the low pressure fuel suction port 10a Prevents it from flowing into the fuel supply pump.

  The fuel flows from the suction joint 51 upward in the axial direction of the plunger and flows into the low pressure fuel chamber 10 formed by the damper upper portion 10b and the damper lower portion 10c shown in FIG. The low pressure fuel chamber 10 is formed by being covered by a damper cover 14 attached to the pump body 1. The fuel whose pressure pulsation has been reduced by the pressure pulsation reducing mechanism 9 in the low pressure fuel chamber 10 reaches the suction port 31b of the electromagnetic suction valve mechanism 300 via the low pressure fuel passage 10d. The electromagnetic suction valve mechanism 300 is attached to a lateral hole formed in the pump body 1 and supplies fuel of a desired flow rate to the pressure chamber 11 through the pressure chamber inlet flow path 1 a formed in the pump body 1. An O-ring 61 is fitted into the pump body 1 for sealing between the cylinder head 90 and the pump body 1 to prevent engine oil from leaking to the outside.

  As shown in FIG. 1, the pump body 1 is provided with a cylinder 6 for guiding the reciprocating motion of the plunger 2. The cylinder 6 is fixed to the pump body 1 by press fitting and caulking on the outer peripheral side thereof. The cylindrical press-fit portion of the cylinder 6 seals the fuel pressurized from the gap with the pump body 1 so as not to leak to the low pressure side. The cylinder 6 has a double seal structure in addition to the seal of the cylindrical press-fit portion of the pump body 1 and the cylinder 6 by bringing the upper end face into axial contact with the plane of the pump body 1.

  At the lower end of the plunger 2 is provided a tappet 92 which converts the rotational movement of the cam 93 attached to the camshaft of the internal combustion engine into vertical movement and transmits it to the plunger 2. The plunger 2 is crimped to the tappet 92 by a spring 4 through a retainer 15. As a result, the plunger 2 can be reciprocated up and down with the rotational movement of the cam 93.

  Further, a plunger seal 13 held at the lower end portion of the inner periphery of the seal holder 7 is installed in a state where the plunger seal 13 slidably contacts the outer periphery of the plunger 2 at the lower portion in the drawing of the cylinder 6. Thus, when the plunger 2 slides, the fuel in the sub chamber 7a is sealed to prevent the fuel from flowing into the internal combustion engine. At the same time, the plunger seal 13 prevents lubricating oil (including engine oil) for lubricating the sliding portion in the internal combustion engine from flowing into the pump body 1.

  As shown in FIG. 2, the pump body 1 has a lateral hole for mounting the electromagnetic suction valve mechanism 300, a lateral hole for mounting the discharge valve mechanism 8 at the same position in the plunger axial direction, a lateral hole for mounting the relief valve mechanism 200, A lateral hole for mounting the discharge joint 12c is formed. The fuel pressurized in the pressure chamber 11 through the electromagnetic suction valve mechanism 300 flows through the discharge passage 12b through the discharge valve mechanism 8 and is discharged from the fuel discharge port 12 of the discharge joint 12c.

  The discharge valve mechanism 8 (FIGS. 2 and 3) provided on the outlet side of the pressure chamber 11 directs the discharge valve seat 8a, the discharge valve 8b contacting with and separating from the discharge valve seat 8a, and the discharge valve 8b toward the discharge valve seat 8a. It comprises a discharge valve spring 8c, a discharge valve plug 8d, and a discharge valve stopper 8e for determining the stroke (moving distance) of the discharge valve 8b. The discharge valve plug 8d and the pump body 1 are joined by a weld 401. This joint shuts off the inside space from which the fuel flows and the outside. Further, the discharge valve seat 8 a is joined to the pump body 1 by the press-fit portion 402.

  In the state where there is no differential pressure between the fuel pressure of the pressure chamber 11 and the fuel pressure of the discharge valve chamber 12a, the discharge valve 8b is crimped to the discharge valve seat 8a by the biasing force of the discharge valve spring 8c and is closed. . Only when the fuel pressure in the pressure chamber 11 becomes higher than the fuel pressure in the discharge valve chamber 12a, the discharge valve 8b opens against the discharge valve spring 8c. The high pressure fuel in the pressure chamber 11 is discharged to the common rail 23 through the discharge valve chamber 12 a, the discharge passage 12 b, and the fuel discharge port 12. When the discharge valve 8 b is opened, the discharge valve 8 b contacts the discharge valve stopper 8 e and the stroke is limited. Therefore, the stroke of the discharge valve 8b is appropriately determined by the discharge valve stopper 8e. This makes it possible to prevent the fuel discharged at high pressure into the discharge valve chamber 12a from flowing back again into the pressurizing chamber 11 due to the stroke being too long and the closing of the discharge valve 8b, and the efficiency of the fuel supply pump is lowered. Can be suppressed. Further, when the discharge valve 8b repeats the opening and closing operations, the discharge valve 8b is guided by the outer peripheral surface of the discharge valve stopper 8e such that the discharge valve 8b moves only in the stroke direction.

  As described above, the pressure chamber 11 is configured by the pump body 1, the electromagnetic suction valve mechanism 300, the plunger 2, the cylinder 6, and the discharge valve mechanism 8. Further, as shown in FIGS. 2 and 3, the fuel supply pump of this embodiment is in close contact with the flat surface of the cylinder head 90 of the internal combustion engine using the mounting flange 1b provided on the pump body 1 and fixed by a plurality of bolts not shown. Be done.

  The relief valve mechanism 200 includes a seat member 201, a relief valve 202, a relief valve holder 203, a relief spring 204, and a holder member 205. The relief valve mechanism 200 is a valve configured to operate when a problem occurs in the common rail 23 or the member beyond it and becomes abnormally high, and the pressure in the common rail 23 or the member beyond that increases. In this case, it has the role of opening the valve and returning the fuel to the pressurizing chamber 11 or the low pressure passage (such as the low pressure fuel chamber 10 or the suction passage 10d). Therefore, it is necessary to maintain the valve closing state below a predetermined pressure, and has a very strong spring 204 to counter the high pressure.

  The electromagnetic suction valve mechanism 300 will be described with reference to FIG. FIG. 4 is an enlarged cross sectional view showing a cross section parallel to the drive direction of the suction valve in the electromagnetic suction valve mechanism of the present embodiment, and is a cross sectional view showing a state in which the suction valve is opened.

  In the non-energized state, the strong rod biasing spring 40 causes the suction valve 30 to operate in the valve opening direction and is normally open. When a control signal from the ECU 27 is applied to the electromagnetic suction valve mechanism 300, a current flows in the electromagnetic coil 43 via the terminal 46. When current flows through the electromagnetic coil 43, the movable core 36 is attracted in the valve closing direction by the magnetic attraction force of the magnetic core 39 on the magnetic attraction surface S. The rod biasing spring 40 is disposed in a recess formed in the magnetic core 39 and biases the flange portion 35a. The flange portion 35 a engages with the recess of the movable core 36 on the side opposite to the rod biasing spring 40.

  The magnetic core 39 is configured to be in contact with the lid member 44 covering the electromagnetic coil chamber in which the electromagnetic coil 43 is disposed. When the movable core 36 is attracted and moved by the magnetic core 39, the flange 35a of the rod 35 is engaged, and the rod 35 is moved together with the movable core 36 in the valve closing direction. Between the movable core 36 and the suction valve 30, a valve closing spring 41 for urging the movable core 36 in the valve closing direction and a rod guide member 37 for guiding the rod 35 in the opening and closing direction are disposed. Ru. The rod guide member 37 constitutes a spring seat 37 b of the valve closing biasing spring 41. Further, a fuel passage 37a is provided in the rod guide member 37 to allow the fuel to flow into and out of the space in which the movable core 36 is disposed.

  The movable core 36, the valve closing spring 41, the rod 35 and the like are contained in an electromagnetic suction valve mechanism housing 38 fixed to the pump body 1. Further, the magnetic core 39, the rod biasing spring 40, the electromagnetic coil 43, the rod guide member 37 and the like are held by the electromagnetic suction valve mechanism housing 38. The rod guide member 37 is attached to the electromagnetic suction valve mechanism housing 38 on the opposite side to the magnetic core 39 and the electromagnetic coil 43, and includes the suction valve 30, the suction valve biasing spring 33 and the stopper 32. Do.

  On the opposite side of the magnetic core 39 of the rod 35, an intake valve 30, an intake valve biasing spring 33 and a stopper 32 are provided. The suction valve 30 is formed with a guide portion 30 b which protrudes toward the pressurizing chamber 11 and is guided by the suction valve biasing spring 33. The suction valve 30 is opened by moving in the valve opening direction (direction away from the valve seat 31a) by the gap of the valve body stroke 30e along with the movement of the rod 35, and the supply passage 10d enters the pressure chamber 11. Fuel is supplied. The guide portion 30 b stops its movement by colliding with a stopper 32 which is press-fitted and fixed inside the housing (rod guide member 37) of the electromagnetic suction valve mechanism 300. The rod 35 and the suction valve 30 are separate and independent structures. The suction valve 30 closes the flow path to the pressurizing chamber 11 by coming into contact with the valve seat 31a of the valve seat member 31 disposed on the suction side, and by separating from the valve seat 31a, the flow path to the pressurizing chamber 11 Configured to open.

  When the plunger 2 moves in the direction (downward direction) of the cam 93 by the rotation of the cam 93 in FIG. 1 and in the suction stroke state, the volume of the pressure chamber 11 increases and the fuel pressure in the pressure chamber 11 increases. descend. When the electromagnetic coil 43 is deenergized in this suction stroke, the sum of the biasing force of the rod biasing spring 40 and the fluid force due to the pressure of the suction passage 10d is greater than the fluid force due to the fuel pressure in the pressurizing chamber 11. The suction valve 30 is biased in the valve opening direction by the rod 35 to be in the valve opening state.

  When the plunger 2 reaches the bottom dead center and the suction stroke is finished, the plunger 2 starts to move upward. Here, the electromagnetic coil 43 remains in the non-energized state, and the magnetic bias does not act. The volume of the pressure chamber 11 decreases with the compression movement of the plunger 2. In this state, the fuel once sucked into the pressure chamber 11 passes through the opening of the suction valve 30 in the open state again through the suction passage. Since the pressure is returned to 10d, the pressure in the pressure chamber 11 does not rise. This process is called a return process.

  Thereafter, by turning on the energization of the electromagnetic coil 43 at a desired timing, the magnetic attraction force is generated as described above, whereby the rod 35 moves together with the movable core 36 in the valve closing direction, and the tip 35b of the rod 35 Leaves the suction valve 30. In this state, the suction valve 30 is a check valve that opens and closes according to the differential pressure, so the valve is closed by the biasing force of the suction valve biasing spring 33. After the suction valve 30 is closed, since the plunger 2 is raised, the volume of the pressure chamber 11 is reduced and the fuel is pressurized. This is called a compression stroke. When the fuel in the pressure chamber 11 is pressurized and exceeds the sum of the fuel pressure in the discharge valve chamber 12a and the biasing force of the discharge valve spring 8c, the discharge valve 8b is opened to discharge the fuel.

  By controlling the energization timing of the electromagnetic coil 43 of the electromagnetic suction valve mechanism 300, the amount of high pressure fuel to be discharged can be controlled. If the timing for energizing the electromagnetic coil 43 is advanced, the proportion of the return stroke in the compression stroke is small, and the proportion of the discharge stroke is large. That is, the amount of fuel returned to the suction passage 10d decreases, and the amount of fuel discharged to the common rail 23 at high pressure increases. On the other hand, if the timing of energization is delayed, the proportion of the return stroke during the compression stroke is large, and the proportion of the discharge stroke is small. That is, the amount of fuel returned to the suction passage 10d increases, and the amount of fuel discharged to the common rail 23 at high pressure decreases. The energization timing of the electromagnetic coil 43 is controlled by a command from the ECU 27.

As described above, by controlling the energization timing of the electromagnetic coil 43, the amount of high-pressure discharged fuel can be controlled to the amount required by the internal combustion engine.
The low pressure fuel chamber 10 is provided with a pressure pulsation reducing mechanism 9 for reducing the pressure pulsation generated in the fuel supply pump from spreading to the fuel pipe 28. Moreover, the damper upper part 10b and the damper lower part 10c are provided at intervals above and below the pressure pulsation reducing mechanism 9, respectively. In the case where the fuel that has once flowed into the pressure chamber 11 is returned to the suction passage 10d through the suction valve 30 that is in the open state again for volume control, pressure pulsation is generated in the low pressure fuel chamber 10 by the fuel Occurs. However, the pressure pulsation reducing mechanism 9 provided in the low pressure fuel chamber 10 is formed by a metal diaphragm damper in which two corrugated disc-like metal plates are laminated at their outer periphery and an inert gas such as argon is injected therein. The pressure pulsation is absorbed and reduced by the expansion and contraction of the metal damper. Reference numeral 9a denotes a mounting bracket for fixing the metal damper to the inner peripheral portion of the pump body 1, and is installed on the fuel passage, so the supporting portion with the damper is not a full circumference but a part of the mounting bracket 9a. The fluid is allowed to freely move back and forth.

  The plunger 2 has a large diameter portion 2a and a small diameter portion 2b, and the volume of the sub chamber 7a is increased or decreased by the reciprocating motion of the plunger 2. The sub chamber 7a communicates with the low pressure fuel chamber 10 through a fuel passage 10e (see FIG. 3). When the plunger 2 is lowered, a flow of fuel is generated from the sub chamber 7a to the low pressure fuel chamber 10, and when it is raised, a flow of fuel from the low pressure fuel chamber 10 to the sub chamber 7a.

  As a result, the fuel flow rate into and out of the pump in the suction stroke or return stroke of the pump can be reduced, and the pressure pulsation generated inside the fuel supply pump can be reduced.

  Further, the operation of the relief valve mechanism will be described in detail. As shown in FIG. 2, the relief valve mechanism 200 includes a seat member 201, a relief valve 202, a relief valve holder 203, a relief spring 204, and a relief spring stopper 205. The relief valve 202, the relief valve holder 203, and the relief spring 204 are sequentially inserted into the seat member 201, and the relief spring stopper 205 is fixed by press fitting or the like. The pressing force of the relief spring 204 is defined by the position of the relief spring stopper 205. The valve opening pressure of the relief valve 202 is set to a specified value by the pressing force of the relief spring 204. The relief valve mechanism 200 thus unitized is fixed to the pump body 1 by press fitting or the like as shown in FIG. Although FIG. 1 shows the unitized relief valve mechanism 200, the present invention is not limited to this.

  Since the fuel supply pump needs to pressurize the fuel to a very high pressure of several MPa to several tens MPa, the set valve opening pressure of the relief valve 202 must be higher than that. When the set valve opening pressure is set to the set discharge pressure or less, the relief valve 202 opens even if the fuel is normally pressurized by the fuel supply pump. The malfunction of the relief valve 202 may cause cavitation erosion in the vicinity of the sheet portion of the sheet member 201, a decrease in the discharge amount, a decrease in energy efficiency, and the like. The occurrence of cavitation erosion is one of the most important problems at the time of high pressure, because the effect becomes remarkable as the fuel pressure increases.

  From the above, it is necessary to set the set valve opening pressure of the relief valve 202 to the set discharge pressure or more. This is because abnormal high pressure occurs and the relief valve 202 opens to release the fuel. It leads to the increase of the maximum pressure. Since the maximum pressure of the common rail 23 is a pressure obtained by adding the pressure loss of the relief valve 202 itself to the set valve opening pressure of the relief valve 202, the maximum pressure of the common rail 23 is increased while increasing the set valve opening pressure of the relief valve 202. In order to reduce the pressure loss, it is important to reduce the pressure loss.

  The present embodiment for solving these problems will be described with reference to FIG. The upper part of FIG. 6 shows a cross-sectional view of the relief valve mechanism 200 of the present embodiment, and the lower part shows an enlarged cross-sectional view of the vicinity of the seat portion 201a surrounded by a frame line. In the vicinity of the seat portion 201a, the flow passage area is extremely high because the flow passage cross-sectional area formed between the relief valve 202 and the seat member 201 is narrow. Therefore, if the flow direction is sharply bent in the vicinity of this, the flow is separated as shown by a dashed dotted line, which may cause cavitation erosion. In order to prevent this, the relief valve 202 lifts although it can be expected to prevent cavitation erosion if it is separated from the seat portion 201a by a certain distance and shaped like a two-dot chain line bending the flow at a place where the flow velocity is reduced. Also in this case, since the distance between the relief valve 202 and the sheet member 201 is short, a sufficient channel cross-sectional area can not be obtained, and there is a concern that the pressure loss may increase.

  Therefore, in the relief valve mechanism 200 of the present embodiment, the relief valve 202 and the seat portion 201a on which the relief valve 202 is seated are formed, and the seat surface 201c inclined at the first angle AC with respect to the valve axial direction, and the seat portion 201a A downstream side inner diameter enlarged portion 201d formed to be connected to the sheet surface 201c on the downstream side than the sheet surface 201c and formed so as to expand radially outward from the downstream side end of the sheet surface 201c And a downstream end face 201e formed radially outward from the downstream end of the portion 201d. Further, the downstream inner diameter enlarging portion 201d is formed to be connected to the seat surface 201c on the downstream side of the seat portion 201a, and a second angle larger than the first angle AC with respect to the valve axis direction from the downstream end of the seat surface 201c. It is formed to be inclined by AD. Furthermore, the fourth angle DE at which the downstream end surface 201e is inclined with respect to the downstream inner diameter expanding portion 201d is larger than the third angle CD at which the downstream inner diameter expanding portion 201d is inclined with respect to the sheet surface 201c. There is.

  By doing this, since the change in the flow direction becomes larger as the flow velocity separates from the sheet portion 201a, separation of the flow is less likely to occur, and prevention of cavitation erosion can be expected. At the same time, the distance between the relief valve 202 and the seat member 201 when the relief valve 202 is lifted by the downstream inner diameter enlarged portion 201d is increased, and a decrease in pressure loss can be expected by increasing the flow path cross-sectional area.

  Although the case where the present invention is applied to the downstream of the sheet portion 201a has been described so far, the present invention can be applied to the upstream of the sheet portion 201a. Details will be described below with reference to FIG.

  In FIG. 7, an upstream side of the seat portion 201a is connected to the upstream end of the seat surface 201c, and the downstream end (point A) of the introduction passage 201f is smaller than the first angle AC with respect to the valve axis direction. The upstream inner diameter enlarged portion 201b is inclined at five angles AB. Further, the third angle CD at which the downstream inner diameter enlarged portion 201d is inclined with respect to the sheet surface 201c is formed to be smaller than the fifth angle AB. Furthermore, the degree of hexagonalness BC at which the sheet surface 201c is inclined with respect to the upstream inner diameter enlarged portion 201b is formed to be larger than the third angle CD.

  By doing this, the direction change becomes larger as the distance from the location where the flow direction changes to the sheet portion 201a increases, so separation of the flow is similarly difficult to occur, and prevention of cavitation erosion is expected. it can. At the same time, the distance between the relief valve 202 and the seat member 201 when the relief valve 202 is lifted by the upstream inner diameter enlarged portion 201a is increased, and a decrease in pressure loss can be expected by increasing the flow passage cross-sectional area. In addition, as the flow velocity is increased as the sheet portion 201a is approached, the pressure is decreased.

  On the other hand, in the case of the shape as shown by the alternate long and short dash line in FIG. 7, a pressure drop occurs on the outer diameter side than A, and the substantial pressure receiving diameter decreases with respect to the geometric sheet diameter. The fluid force that causes the valve 202 to open may be reduced. This reduces the lift amount of the relief valve 202 and can cause an increase in pressure loss. However, in the above-described embodiment, the distance between the relief valve 202 and the sheet member 201 is increased by the upstream inner diameter expanding portion 201b, and the flow passage cross-sectional area is increased, whereby the flow velocity can be gradually increased. As a result, the pressure drop toward the seat portion 201a is made gentle to prevent a substantial decrease in the pressure receiving diameter, and in turn, prevention of an increase in pressure loss can be expected.

  The connection point of the introduction passage 201f and the upstream inner diameter expanding portion 201b is a point A, the connecting point of the upstream inner diameter expanding portion 201b and the sheet surface 201c is a point B, and the connecting point of the sheet surface 201c and the downstream inner diameter expanding portion 201d is a point C In this case, in FIG. 7, the distances from the sheet portion are longer in the order of point A, point B, and point C. Therefore, the direction change of the flow corresponds to the third angle CD <the sixth degree BC <the fifth angle AB. On the other hand, the distance from the sheet portion to each point is not limited in this order, and it is desirable to change the magnitude relationship of the angles according to the distance, that is, to increase the angle as the distance increases.

  A second embodiment of the present invention will be described with reference to FIG. In the relief valve mechanism 200 targeted by the present invention, as described above, it is necessary to use a strong spring because it is necessary to increase the valve opening pressure against the fuel pressure. For this reason, if the relief valve 202 is directly pressed by the spring seat at the end of the relief spring 204, there is a concern that the deformation or wear of the contact portion. In order to prevent this, the relief valve holder 203 is sandwiched between the two, and the relief valve 202 is pressed against the seat member 201 via it. In this case, the flow passing through the seat portion 201 a has to go around the relief valve holder 203 and flow to the outer periphery of the relief valve holder 203. In this embodiment, in addition to the shape of the seat portion 201a, the flow in the downstream of the seat portion 201a is smoothly relieved by defining the shape of the relief valve holder 203 provided at the opposite position and the position for the flow. It leads to the outer periphery of the valve holder 203.

  In the present embodiment, the relief valve 202 is formed in a ball shape, includes the relief valve holder 203 that holds the relief valve 202 at the inner circumferential portion 203a and urges the relief valve 202 toward the seat portion 201a. A holder bottom surface portion 203b is disposed to face the end face 201e. Further, as shown by dotted lines in the drawing, these surfaces are arranged such that the surface forming the holder bottom surface portion 203b intersects the extension of the surface forming the downstream side inner diameter enlarged portion 201d.

  FIG. 9 shows a modification of FIG. In FIG. 9, as indicated by dotted lines in the drawing, the holder bottom surface portion 203b is formed not only on the extension of the surface forming the downstream side inner diameter enlarged portion 201d but also on the extension of the surface forming the sheet surface 201c. These faces are arranged so that the faces intersect.

  By doing this, the main flow having passed through the sheet portion 201 a can smoothly flow toward the outer periphery of the relief valve holder 203 through the gap formed between the downstream end surface 201 e and the holder bottom surface portion 203 a. Since the flow passage cross-sectional area is expanded as going to the outer periphery, the flow velocity can be reduced, separation of the flow can be prevented, and in turn, prevention of cavitation erosion can be expected. In addition, since the main flow passing through the sheet portion 201a does not face the inner peripheral portion 203a, cavitation bubbles enter into the inner peripheral portion 203a to cause corrosion and the change in the main flow direction is increased. It is expected that an increase in pressure loss can be prevented at the same time.

  As described above, the fuel supply pump of the present embodiment includes the relief valve mechanism 200 described above, and the relief valve mechanism 200 is added when the fuel in the discharge passage 12 on the downstream side of the discharge valve mechanism 8 exceeds the set pressure. The fuel is returned to the pressure chamber 11 or to the low pressure passage (such as the low pressure fuel chamber 10 or the suction passage 10d).

  In addition to the relief valve mechanism 200, as described above, the present embodiment is also applicable to functional components for satisfying the performance of the fuel supply pump, such as the electromagnetic suction valve mechanism 300 and the discharge valve mechanism 8. The present invention is also applicable to functional components other than the above.

  This completes the description of the examples, but the present invention can be widely modified without being limited to the above embodiment. For example, although the said embodiment applies this invention to the fuel supply pump, you may apply to the hydraulic equipment which requires a non-return valve. Also in the arrangement position and arrangement method of the functional parts in the fuel supply pump, it is not limited to the example of the above-mentioned embodiment.

  DESCRIPTION OF SYMBOLS 1 ... pump body, 2 ... plunger, 6 ... cylinder, 7 ... seal holder, 8 ... discharge valve mechanism, 200 ... relief valve mechanism, 201 ... sheet member, 201 a ... sheet part, 201 b ... upstream inner diameter enlarged part, 201 c ... Seat surface, 201d ... downstream inner diameter enlarged portion, 201e ... downstream end surface, 201f ... introduction passage, 202 ... relief valve, 203 ... relief valve holder, 203a ... inner circumferential portion, 203b ... holder bottom surface, 204 ... relief spring, 205 ... spring holder, 300 ... electromagnetic suction valve mechanism.

Claims (10)

  A relief valve and a seat portion on which the relief valve is seated are formed, and a seat surface inclined at a first angle with respect to the valve axial direction and a seat surface downstream of the seat portion are connected to the seat surface. A downstream inner diameter enlarged portion formed to expand radially outward from the downstream side of the sheet surface from the downstream end of the surface, and a downstream end surface formed radially outward from the downstream end of the downstream inner diameter enlarged portion And a relief valve mechanism.   The relief valve mechanism according to claim 1, wherein the downstream inner diameter enlargement portion is formed on the downstream side of the seat portion and connected to the seat surface, and from the downstream end of the seat surface in the valve axial direction A relief valve mechanism formed to be inclined at a second angle larger than the first angle.   The relief valve mechanism according to claim 1, wherein a fourth angle at which the downstream end surface is inclined with respect to the downstream inner diameter expanding portion with respect to a third angle at which the downstream inner diameter expanding portion is inclined with respect to the seat surface Relief valve mechanism formed to be large.   The relief valve mechanism according to claim 1, wherein the relief valve mechanism is formed on the upstream side of the seat portion and connected to the upstream end of the seat surface, and the first angle from the downstream end of the relief passage to the valve axis direction A relief valve mechanism with an upstream inner diameter enlargement that inclines at a small fifth angle.   5. The relief valve mechanism according to claim 4, wherein a third angle at which the downstream inner diameter enlarging portion is inclined with respect to the seat surface is smaller than the fifth angle.   The relief valve mechanism according to claim 1, wherein a hexagonal degree at which the seat surface inclines with respect to the upstream inner diameter enlarged portion is larger than the third angle.   The relief valve mechanism according to claim 1, wherein the relief valve is formed in a ball shape, and includes a relief valve holder that holds the relief valve at an inner peripheral portion and biases the relief valve toward the seat portion. A relief valve mechanism having a holder bottom portion arranged to face the downstream end surface of the holder.   The relief valve mechanism according to claim 7, wherein in the extension of the surface forming the downstream side inner diameter enlarged portion, the surfaces forming the holder bottom surface portion intersect with each other. .   9. The relief valve mechanism according to claim 8, wherein the surfaces forming the bottom surface of the holder intersect with the extension of the surfaces forming the seat surface.   A fuel supply pump comprising a discharge valve mechanism for discharging fuel pressurized in a pressure chamber, comprising the relief valve mechanism according to any one of claims 1 to 9, wherein the relief valve mechanism comprises the discharge valve mechanism. A fuel supply pump configured to return the fuel to the pressurizing chamber or to the low pressure passage when the fuel in the discharge passage on the downstream side exceeds the set pressure.

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