JP2019100190A - High-pressure fuel supply pump - Google Patents

Abstract

To provide a high-pressure fuel supply pump having a relief valve structure for reducing a frequency of the occurrence of a rise of transient pressure.SOLUTION: A high-pressure fuel supply pump has: a relief passage; a first relief seat arranged in the relief passage; a second relief seat arranged at a downstream side rather than the first relief seat; a first relief valve for opening and closing the first relief seat; a first relief valve holder for holding the first relief valve; a first relief spring for energizing the first relief valve holder toward an upstream side from a downstream side; a first spring stopper abutting on a downstream side of the first relief spring; a second movable seat arranged at a downstream side rather than the first spring stopper, opening and closing the second relief seat, and operating as the second relief valve; a second relief spring for energizing the second movable seat toward an upstream side from a downstream side; and a second spring stopper abutting on a downstream side of the second relief spring. The second movable seat operates integrally with the first spring stopper.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a high pressure fuel supply pump, and more particularly to a high pressure fuel supply pump provided with a relief valve mechanism.

  In a direct injection type in which fuel is directly injected into the combustion chamber among internal combustion engines such as automobiles, a high pressure fuel supply pump for increasing the pressure of the fuel is widely used. As background art of this high-pressure fuel supply pump, there is JP-A-2009-114868. The relief valve structure of the high pressure fuel supply pump is configured to have a squeezing effect between the housing in the fuel passage and the valve presser in the fuel passage in which the fluid flows from the high pressure side to the low pressure side. . As a result, the pressure in the high-pressure piping can be rapidly reduced by causing the stroke in the valve-opening direction to be largely stroked by the differential pressure generated on the high pressure side and the low pressure side of the valve body presser.

JP, 2009-114868, A

  The relief valve of the high-pressure fuel supply pump has a role of releasing the pressure in the high-pressure pipe by opening the valve when the pressure in the common rail rises abnormally, for example, when the direct injector fails. On the other hand, when the high pressure fuel supply pump is operating normally, it is desirable that the relief valve does not open because the relief valve causes the flow rate to decrease and the pumping efficiency of the pump decreases. In order not to open the relief valve, it is necessary to set the opening pressure of the relief valve high. However, when the opening pressure is set high, the transient pressure at the time of pump failure increases. In the conventional structure, since the relief valve repeats the on-off valve operation every discharge of the high pressure fuel supply pump, a transient pressure rise repeatedly occurs, and it is necessary to increase the rigidity of the high pressure pipe from the viewpoint of fatigue strength.

  Therefore, an object of the present invention is to provide a high pressure fuel supply pump having a relief valve structure that reduces the number of occurrences of transient pressure rise.

  In order to solve the problems described above, the present invention connects a discharge passage for discharging fuel pressurized in a pressure chamber, the discharge passage and the pressure chamber, or the discharge passage and the pressure chamber. A relief passage connecting the suction passage, a first relief sheet provided in the relief passage, a second relief sheet provided downstream of the first relief sheet in the relief passage, and the first relief sheet , A first relief valve holder for holding the first relief valve, and a first relief spring for biasing the first relief valve holder from the downstream side to the upstream side of the relief passage A first spring stopper abutting on the downstream side of the relief passage of the first relief spring, and a downstream side of the relief passage with respect to the first spring stopper; A second movable seat operating as a second relief valve for opening and closing the second relief sheet, a second relief spring biasing the second movable seat from the downstream side to the upstream side in the relief passage, and And a second spring stop abutting on the downstream side of the relief passage of the two relief springs, wherein the second movable sheet is configured to operate integrally with the first spring stop. I assume.

  According to the present invention configured as described above, it is possible to reduce the number of transient pressure increases caused by the opening of the relief valve at the time of abnormality.

  Problems, configurations, and effects other than those described above will be apparent from the description of the embodiments below.

FIG. 1 is a diagram showing an overall configuration of a system including a high pressure fuel supply pump according to an embodiment of the present invention. It is a detailed section enlarged view of a relief sheet in a relief valve mechanism in a reference example. It is a figure which shows the pressure behavior in the reference example of FIG. It is a detailed sectional view at the time of valve closing of the relief sheet of Example 1 of the present invention. (A) And (b) is a detailed sectional view at the time of valve opening of a relief sheet of Example 1 of the present invention. It is a figure which shows the pressure behavior in Example 1 of this invention of FIG. 4 and FIG. (A) is a detailed sectional view of a relief sheet in Example 1 of the present invention, (b) is a perspective view of a disc spring 102c of (a). It is the longitudinal cross-sectional view seen from the horizontal direction of the high pressure fuel supply pump which concerns on the Example of this invention. It is a horizontal direction sectional view seen from the upper direction of the high pressure fueling pump concerning the example of the present invention. It is the longitudinal cross-sectional view seen from the transverse direction different from FIG. 8 of the high pressure fuel supply pump which concerns on the Example of this invention. It is an expanded sectional view of the electromagnetic suction valve mechanism mounted in the high pressure fuel supply pump concerning the example of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The configuration and operation of the system will be described using FIG. FIG. 1 is a view showing the overall configuration of a system including a high pressure fuel supply pump according to an embodiment of the present invention.

  A portion surrounded by a broken line shows a high pressure fuel supply pump (hereinafter also referred to as "high pressure pump") 1, and the mechanism and parts shown in the broken line are integrally incorporated into the high pressure pump 1. Indicates

  The fuel of the fuel tank 20 is pumped up by the feed pump 21 and is sent to the suction joint 51 of the high pressure pump (pump body) 1 through the suction pipe 28. The fuel that has passed through the suction joint 51 reaches the suction port 30a of the electromagnetic suction valve 30 that constitutes the capacity variable mechanism through the pressure pulsation reduction mechanism 9 and the suction passage 10b.

  The electromagnetic suction valve 30 is provided with an electromagnetic coil 308. When the electromagnetic coil 308 is not energized, the anchor (electromagnetic plunger) 305 and the suction valve body 301 are biased by the biasing force of the difference between the biasing force of the anchor spring 303 and the biasing force of the valve spring 304, as shown in FIG. As shown in, it has moved to the right. At this time, the suction valve body 301 is biased in the valve opening direction, and the suction port 30 d is in an open state.

The biasing force of the anchor spring 303 and the biasing force of the valve spring 304 are as follows:
The biasing force of the anchor spring 303 is set to be the biasing force of the valve spring 304.

  On the other hand, when the electromagnetic coil 308 is energized, the anchor 305 moves to the left in FIG. 1 and the anchor spring 303 is in a compressed state. The suction valve body 301 attached to the tip of the anchor 305 so that the tip of the anchor 305 contacts coaxially closes the suction port 30 d by the biasing force of the valve spring 304. The suction port 30 d is a fuel passage (fuel flow passage) connecting the pressurizing chamber 11 of the high pressure pump 1 and the suction port 30 a.

  Hereinafter, the operation of the high pressure pump 1 will be described.

  When the plunger 2 is displaced downward in FIG. 1 and is in the suction stroke state by the rotation of a cam (not shown) arranged to abut the lower end of the plunger 2, the volume of the pressure chamber 11 is increased. The fuel pressure in the pressure chamber 11 is reduced. When the fuel pressure in the pressure chamber 11 becomes lower than the pressure in the suction passage 10b (the suction port 30a) in this process, the fuel flows into the pressure chamber 11 through the suction port 30d in the open state.

  When the plunger 2 ends the suction stroke and shifts to the compression stroke, the plunger 2 shifts to the compression stroke (a state of moving upward in FIG. 1). Here, the electromagnetic coil 308 remains in the non-energized state, and no magnetic biasing force acts on the anchor 305. Thus, the suction valve body 301 remains open due to the biasing force of the anchor spring 303.

  In the compression stroke, the volume of the pressure chamber 11 decreases with the compression movement of the plunger 2. However, in this state, the fuel once sucked into the pressurizing chamber 11 is returned to the suction passage 10b (the suction port 30a) through the suction valve body 301 in the open state again. Therefore, the pressure in the pressure chamber 11 does not rise. This process is called a return process.

  In this state, when a control signal from the engine control unit 27 (hereinafter, also referred to as “ECU”) is applied to the electromagnetic suction valve 30, a current flows in the electromagnetic coil 308 of the electromagnetic suction valve 30. At this time, a magnetic biasing force acts on the anchor 305, and the anchor 305 moves to the left in FIG. 1 and the anchor spring 303 is compressed. As a result, the biasing force of the anchor spring 303 does not act on the suction valve body 301, and the biasing force of the valve spring 304 and the fluid force by the fuel flowing into the suction passage 10b (suction port 30a) work. Therefore, the suction valve body 301 closes and closes the suction port 30d.

  When the suction port 30d is closed, the fuel pressure in the pressure chamber 11 rises with the upward movement of the plunger 2 from this point on. Then, when the fuel pressure in the pressure chamber 11 becomes equal to or higher than the fuel pressure on the fuel discharge port 12 side, high pressure discharge of the fuel remaining in the pressure chamber 11 is performed via the discharge valve mechanism 8. The high pressure fuel discharged to the discharge joint side constituting the fuel discharge port 12 is supplied to the common rail 23. This stroke is called a discharge stroke.

  That is, the compression stroke (the rising stroke from the lower start point to the upper start point) of the plunger 2 consists of a return stroke and a discharge stroke. Then, by controlling the energization timing of the electromagnetic coil 308 of the electromagnetic suction valve 30, the amount of high pressure fuel to be discharged can be controlled. If the timing for energizing the electromagnetic coil 308 is advanced, the proportion of the return stroke in the compression stroke becomes smaller and the proportion of the discharge stroke becomes larger. That is, the fuel returned to the suction passage 10b (the suction port 30a) decreases, and the fuel discharged at high pressure increases.

  On the other hand, if the timing for energizing the electromagnetic coil 308 is delayed, the proportion of the return stroke in the compression stroke becomes large, and the proportion of the discharge stroke becomes small. That is, the amount of fuel returned to the suction passage 10b increases, and the amount of fuel discharged at high pressure decreases.

  The energization timing of the electromagnetic coil 308 is controlled by a command from the ECU 27. By configuring as described above, by controlling the energization timing of the electromagnetic coil 308, it is possible to control the amount of high pressure discharged fuel to the amount required by the internal combustion engine.

  A discharge valve mechanism 8 is provided at the outlet of the pressure chamber 11. The discharge valve mechanism 8 includes a discharge valve seat (discharge valve seat portion) 8a, a discharge valve 8b, and a discharge valve spring 8c. In the state where there is no fuel pressure difference between the pressurizing chamber 11 and the fuel discharge port 12, the discharge valve 8b is pressed against the discharge valve seat 8a by the biasing force of the discharge valve spring 8c, and is in a closed state. The discharge valve 8b opens against the discharge valve spring 8c only when the fuel pressure in the pressure chamber 11 becomes larger than the fuel pressure on the discharge joint side constituting the fuel discharge port 12. When the discharge valve 8 b is opened, the fuel in the pressurizing chamber 11 is discharged at high pressure to the common rail 23 through the fuel discharge port 12.

  Thus, the fuel introduced to the suction joint 51 is pressurized to a high pressure by the reciprocating motion of the plunger 2 in the pressurizing chamber 11 of the high pressure pump 1, and the necessary amount of fuel is pressure-fed from the fuel discharge port 12 to the common rail 23 .

  Direct injectors 24 (hereinafter also referred to as “direct injectors”) and pressure sensors 26 are mounted on the common rail 23. The direct injection injector 24 is mounted according to the number of cylinders of the internal combustion engine, and opens and closes the valve according to the control signal of the engine control unit (ECU) 27 to inject fuel into the cylinder (combustion chamber) of the internal combustion engine. .

  The high pressure pump 1 is further provided with a relief valve mechanism 100. The relief valve mechanism 100 is provided with a relief passage (return passage) 101 communicating the downstream side of the discharge valve 8b with the pressure chamber 11, separately from the discharge passage 110, bypassing the discharge valve mechanism 8. . The discharge passage 110 discharges the fuel pressurized in the pressure chamber 11. The relief passage (return passage) 101 is configured to connect the discharge passage 110 and the pressure chamber 11, but not the pressure chamber 11, but the discharge passage 110 and the suction passage (the suction joint 51 or the suction passage). 10b) may be connected. The relief passage 103 is provided with a relief valve 103 (see a reference example in FIG. 2) in the relief valve mechanism 100. The relief valve 103 restricts the flow of fuel to only one direction from the discharge passage 110 to the pressurizing chamber 11.

  The relief valve 103 is pressed against the relief sheet 104 (see the reference example in FIG. 2) by a relief spring 102 (see the reference example in FIG. 2) that generates a pressing force (biasing force).

  When an abnormal high pressure is generated in the common rail 23 etc. due to a failure of the direct injection injector 24 or the like, the pressure difference between the fuel pressure in the discharge passage 110 and the fuel pressure in the pressurizing chamber 11 becomes equal to or more than the opening pressure The valve 103 opens. When the relief valve 103 is opened, the fuel of the common rail 23 at the abnormally high pressure is returned from the relief passage 101 to the pressurizing chamber 11. Thereby, high pressure part piping, such as common rail 23, is protected.

  Next, the fuel supply pump of this embodiment will be described with reference to FIGS. 8, 9 and 10. FIG. FIG. 8 is a cross-sectional view showing a cross section parallel to the central axis direction of the plunger in the fuel supply pump of this embodiment. FIG. 9 is a horizontal sectional view of the fuel supply pump of the present embodiment as viewed from above. FIG. 10 is a cross-sectional view of the fuel supply pump of this embodiment as viewed from a direction different from that of FIG.

  Although the suction joint 51 is provided on the side surface of the body in FIG. 9, 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 to the low pressure fuel chamber 10 formed by the damper upper portion 10U and the damper lower portion 10L 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 of the low pressure fuel chamber 10 reaches the suction port 30a of the electromagnetic suction valve mechanism 300 via the suction 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. 8, a cylinder 6 for guiding the reciprocating motion of the plunger 2 is attached to the pump body 1. 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. 9, 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, and a lateral hole for mounting the relief valve mechanism 100 further. 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. 9 and 10) 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. 9 and 10, 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 100 is a valve configured to operate when a problem occurs in the common rail 23 and the members beyond it and becomes abnormally high, and the pressure in the common rail 23 and the members beyond it 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. 11 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 where 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 308 via the terminal 46. When current flows through the electromagnetic coil 308, the anchor 305 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 anchor 305 on the side opposite to the rod biasing spring 40.

  The magnetic core 39 is configured to be in contact with a lid member 44 covering the electromagnetic coil chamber in which the electromagnetic coil 308 is disposed. When the anchor 305 is moved by being attracted by the magnetic core 39, the flange portion 35a of the rod 35 is engaged, and the rod 35 moves together with the anchor 305 in the valve closing direction. Between the anchor 305 and the suction valve 30, a valve closing biasing spring 41 for biasing the anchor 305 in the valve closing direction and a rod guide member 37 for guiding the rod 35 in the opening and closing direction are disposed. The rod guide member 37 constitutes a spring seat 37 b of the valve closing biasing spring 41. Further, the rod guide member 37 is provided with a fuel passage 37a to allow the fuel to flow into and out of the space where the anchor 305 is disposed.

  The anchor 305, 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 308, 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 308, 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 suction 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.

  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 suction pipe 28. In addition, an upper damper portion 10U and a lower damper portion 10L are provided at upper and lower portions of the pressure pulsation reducing mechanism 9 with intervals, respectively. Once the fuel flowing into the pressure chamber 11 is returned to the suction passage 10d through the suction valve 30 in the open state again for volume control, the pressure returned to the low pressure fuel chamber 10 by the fuel returned to the suction passage 10d. Pulsation 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 bonded on the outer periphery and an inert gas such as argon is injected into the inside. 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 by a fuel passage 10e (see FIG. 10). 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.

  FIG. 2 is a detailed cross-sectional enlarged view of the relief sheet 104 in the relief valve mechanism 100 in the reference example.

  The relief valve 103 is preferably a ball valve from the viewpoint of seat performance, and a relief valve holder 107 is installed between the relief valve 103 and the relief spring 102. The relief valve holder 107 transmits the pressing force of the spring to the relief valve 103 and plays a role of holding the relief valve 103.

  The relief sheet 104 and the portion of the relief valve holder 107 in contact with the relief valve 103 have a conical concave shape for holding the relief valve 103. Since the lift amount of the relief valve 103 is determined based on the pressure difference between the front and rear of the relief valve 103, it is possible to calculate the lift amount in terms of fluid dynamics. By setting the distance L (see FIG. 2) from the relief sheet flat portion to the lower end of the relief valve to be equal to or greater than the lift amount, the relief valve 103 is prevented from falling off from the relief sheet 104.

  The relief valve 103 is set so that the relief valve 103 separates from the relief sheet 104 and opens when the pressure in the common rail 23 becomes equal to or higher than a specified pressure. The specified pressure at this time is referred to as the valve opening pressure Ps.

  FIG. 3 is a view showing pressure behavior in the reference example of FIG.

  As the lift of the plunger 2 rises, the high pressure pump 1 discharges the flow rate. The discharge process ends when the plunger 2 reaches the top dead center. That is, the high-pressure pump 1 repeats the discharge presence or absence according to the period of the plunger lift of the plunger 2. The pressure in the common rail 23 rises with the main discharge process. When the pressure in the common rail 23 exceeds the valve opening pressure Ps described above, the relief valve 103 starts the valve opening operation. When the relief valve 103 opens, the flow rate in the common rail 23 passes through the relief valve 103 and flows downstream, so the pressure in the common rail 23 decreases with the opening operation of the relief valve 103.

  At this time, since a predetermined response delay occurs in the valve opening operation of the relief valve 103, a transient pressure Pd higher than the valve opening pressure Ps is generated before and after the opening operation. In the structure of the reference example, as shown in FIG. 3, since the relief valve 103 is generated every cycle of the plunger lift and the relief valve 103 repeats the on-off valve operation, the transient pressure Pd is also generated every cycle of the plunger lift. .

  On the other hand, a stress proportional to the pressure is generated in the common rail 23. Therefore, the common rail 23 needs to have a fatigue strength sufficient to withstand multiple occurrences of the transient pressure Pd, and there is a problem of an increase in size and cost.

  The first embodiment of the present invention will be further described below.

  The structure of the relief valve mechanism 100 in the first embodiment of the present invention is shown in FIG. 4 and FIG. In FIGS. 5A and 5B, the same reference numerals as in FIG. 4 are partially omitted. Further, in FIGS. 4 and 5, the dimensions of the drawings are different from the actual dimensions and the necessary portions are exaggerated for ease of explanation. In addition, the relief passage (return passage) 101 may be configured to connect the discharge passage 110 and the pressure chamber 11, and instead of the pressure chamber 11, the discharge passage 110 and the suction passage (suction joint 51 or suction It may be configured to connect the passage 10b). In the following, the discharge passage 110 and the suction passage 10 b are connected by the relief passage (return passage) 101. Each configuration in FIG. 4 may be formed of stainless steel, or other materials may be used.

  When the conically shaped seat surface 111 of the first relief sheet 104a abuts against the spherical first relief valve 103a, it forms a circular seat portion 113 of diameter φ d1 and prevents the flow of fuel while in abutment. The first relief valve 103a is pressed against the first relief sheet 104a by one end of the first relief spring 102a via the first relief valve holder 107a.

  The other end of the first relief spring 102a is held by a first spring stop 108a. The first spring stop 108a is press-fit and fixed to one end of the pin 109 and the second movable sheet 103b to the other end of the pin 109, and the first spring stop 108a and the second movable sheet 103b operate integrally Do. The second movable sheet 103b serves as a second relief valve. When the second movable sheet 103b abuts on the second relief sheet 104b, the second movable sheet 103b forms an annular sheet portion 114. In the present embodiment, the second movable sheet 103b and the first spring stop 108a have the same shape. By doing this, it is possible to use the same shape parts, and the cost can be reduced. The second movable sheet 103b and the first spring stop 108a may have different shapes.

  The second relief sheet 104b is press-fit and fixed to the first relief sheet 104a. A second movable seat 103b is provided at one end of the second relief spring 102b, and a second spring stop 108b is provided at the other end of the second relief spring 102b. The second spring stop 108b is press-fit and fixed to the first relief sheet 104a.

  When the fuel pressure in the discharge passage 110 on the high pressure side rises, a load F1 due to the pressure difference ΔP1 between the inside of the first relief valve 112 on the low pressure side and the discharge passage 110 on the high pressure side is applied to the first relief valve 103a. When the load F1 exceeds the spring load Fsp1 of the first relief spring 102a (F1> Fsp1), the first relief valve 103a opens. The load F1 can be calculated by multiplying the area of the seat portion 113 and the fuel pressure, and is expressed by the following equation (1). * Is an operator indicating multiplication.

  When both the first relief valve 103a and the second movable seat 103b (that is, the second relief valve) are closed, the spring load Fsp1 of the first relief spring 102a is lower than the spring load FsP2 of the second relief spring 102b (Fsp1 < FsP2) is set. Therefore, as shown in FIG. 5A, even if the first relief valve 103a starts to open, the second movable sheet 103b (that is, the second relief valve) is not open.

  When the first relief valve 103 is opened, the fuel pressure in the first relief valve interior 112a is increased. At this time, a load F1 from the first relief spring 102a is applied to the second movable sheet 103b via the first spring stop 108a. Further, a load Fp is applied to the second movable sheet 103b by the pressure difference ΔP2 between the second relief valve interior 112b on the low pressure side and the first relief valve interior 112a on the relatively high pressure side, and the combined load F2 If the spring load of the second relief spring 102b exceeds (F2> FsP2), the second movable sheet 103b (that is, the second relief valve) opens as shown in FIG. 5 (b). Assuming that the diameter of the seat portion 114 which is a pressure receiving portion of the second movable seat 103 b (that is, the second relief valve) is φd 2, the following equation (2) is obtained.

  The pressure in the first relief valve interior 112a before the first relief valve 103a is opened and the pressure in the second relief valve interior 112b are the same as the pressure in the suction passage 10b on the low pressure side. There is. Therefore, the specified valve opening pressure Ps1 of the first relief valve 103a is the same as the valve opening pressure Ps of the reference example shown in FIG.

  Here, since the second movable sheet 103b (that is, the second relief valve) and the first relief spring stop 108a operate integrally, the lift in which the second movable sheet 103b (that is, the second relief valve) is moved by opening the valve. The first relief spring stop 108a also shifts to the low pressure side by an amount (x2 shown in FIG. 5 (b)). Assuming that the spring constant of the second relief spring 102b is k2, the lift amount x2 is represented by the following equation (3).

  Then, the spring load of the first relief spring 102a is reduced, and an effect of continuing the valve opening to a pressure lower than the pressure at which the first relief valve 103a is initially opened can be obtained. That is, assuming that the spring constant of the first relief spring 102a is k1, and the spring load of the first relief spring 102a after the second movable sheet 103b (that is, the second relief valve) is opened is Fsp1 ′, equation (3) is also used It is shown by the following equation (4).

  The effect of reducing the spring load of the first relief valve 103a can be obtained as shown by the equation (4).

  The diameter φd2 of the seat portion 114 of the second movable seat 103b (that is, the second relief valve) is larger than the direct system φd1 of the seat portion 113, and the second movable seat 103b (that is, the second relief valve) opens even if ΔP2 is small. It is easy to configure. The spring constant k1 of the first relief spring 102a is set larger than the spring constant k2 of the second relief spring 102b. These are for the effect that the second movable sheet 103b (that is, the second relief valve) can maintain the valve open even if ΔP2 is sufficiently smaller than ΔP1. By taking the above-mentioned structure, it is possible to reduce the valve closing pressure Ps2 at which the fuel pressure drops again and the first relief valve 103a closes again (Ps1> Ps2) with respect to the valve opening pressure Ps1 at the first relief valve 103a. it can.

  The pressure behavior in this structure is shown in FIG.

  The flow rate discharge of the high pressure pump 1 repeats the discharge presence or absence according to the period of the plunger lift of the plunger 2 similarly to the reference example shown in FIG. The valve opening operation of the first relief valve 103a is opened when the valve opening pressure Ps1 is reached according to the above-mentioned structure. Thereafter, the valve opening is maintained until the valve closing pressure Ps2 is smaller than the specified valve opening pressure Ps1, and the valve is closed when the pressure of the common rail 23 becomes equal to the valve closing pressure Ps2. Thereafter, although the pressure of the common rail 23 is increased by the flow discharge of the high pressure pump 1, the flow discharge of a plurality of times is required to reach the predetermined valve opening pressure Ps1 again. In FIG. 6, the first relief valve 103 a is opened by exceeding the predetermined valve opening pressure Ps <b> 1 at the second flow discharge for the sake of description. As the valve closing pressure Ps2 is lower, the number of times of discharge Nt required to reach the predetermined valve opening pressure Ps1 increases again, and the number of times Npd of the pressure transient stress Pd of the common rail 23 is proportional to 1 / Nt. To decrease. For this reason, the rigidity of the high-pressure pipe can be lowered as compared with the structure of the reference example, and space saving and cost reduction can be achieved by reducing the thickness.

  The high-pressure fuel supply pump of this embodiment includes at least the discharge passage 110, the relief passage 101, the first relief sheet 104a, the second relief sheet 104b, the first relief valve 103a, the first relief valve holder 107a, and the first relief spring. A first spring stop 108a, a second movable seat 103b, a second relief spring 102b, and a second spring stop 108b are provided. The discharge passage 110 discharges the fuel pressurized in the pressure chamber 11. The relief passage 101 connects the discharge passage 110 and the pressure chamber 11 or connects the discharge passage 110 and the suction passage 10 b of the pressure chamber 11. The first relief sheet 104 a is provided in the relief passage 101. The second relief sheet 104 b is provided downstream of the first relief sheet 104 a in the relief passage 101. The first relief valve 103a opens and closes the first relief sheet 104a. The first relief valve holder 107a holds the first relief valve 103a. The first relief spring 102 a biases the first relief valve holder 107 a from the downstream side to the upstream side of the relief passage 101. The first spring stop 108a abuts on the downstream side of the relief passage 101 of the first relief spring 102a. The second movable sheet 103b is provided downstream of the first spring stop 108a in the relief passage 101, and operates as a second relief valve that opens and closes the second relief sheet 104b. The second relief spring 102 b biases the second movable sheet 103 b from the downstream side to the upstream side of the relief passage 101. The second spring stop 108b abuts on the downstream side of the relief passage 101 of the second relief spring 102b. The second movable sheet 103b operates integrally with the first spring stop 108a.

  A second embodiment of the present invention will be described. In the second embodiment, the configuration is the same as in FIGS. 1 and 4, and a disc spring 102c is used instead of the first relief spring 102a in FIG.

  The structure of the relief valve mechanism 100 in Embodiment 2 of the present invention is shown in FIG. FIG. 7A is a detailed cross-sectional view of the relief sheet of the second embodiment. FIG.7 (b) is a perspective view of the disc spring 102c of FIG. 7 (a).

  In the second embodiment, in order to make the spring constant k1 sufficiently larger than k2, the first relief spring 102a is configured as a hollow tapered disc spring 102c as shown in FIG. 7A. FIG. 7 (b) shows a perspective view of the disc spring 102c.

  Thereby, according to the present Example 2, the effect of Example 1 or more can be acquired. In addition, it is possible to achieve a smaller size and a smaller space than the first embodiment.

  The present invention is not limited to the embodiments described above, but includes various modifications. For example, the embodiments described above are described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. In addition, with respect to a part of the configuration of each embodiment, it is possible to add, delete, and replace other configurations.

  DESCRIPTION OF SYMBOLS 1 ... high pressure fuel supply pump, 2 ... plunger, 8 ... discharge valve mechanism, 9 ... pressure pulsation reduction mechanism, 51 ... suction joint, 10b ... suction passage, 11 ... pressure chamber, 12 ... fuel discharge port, 20 ... fuel tank 23, common rail, 24 direct injection injector, 26 pressure sensor, 27 ECU, 30 electromagnetic suction valve, 100 relief valve mechanism, 101 relief passage, 102 relief spring, 103 relief valve, 104 relief Seat 107: relief valve holder 110: discharge passage 301: suction valve body 303: anchor spring 304: valve spring 305: anchor 308: electromagnetic coil 102a first relief spring 103a first relief Valve, 104a: first relief sheet, 107a: first relief valve holder, 108a: first spring stop, 109: pin, 11 ... conical seat surface, 102b ... second relief spring, 103b ... second movable sheet, 104b ... second relief sheet, 108b ... second spring stop.

Claims (4)

A discharge passage for discharging the fuel pressurized by the pressure chamber;
A relief passage which connects the discharge passage and the pressure chamber, or which connects the discharge passage and a suction passage of the pressure chamber;
A first relief sheet provided in the relief passage;
A second relief sheet provided downstream of the first relief sheet in the relief passage;
A first relief valve for opening and closing the first relief seat;
A first relief valve holder for holding the first relief valve;
A first relief spring for biasing the first relief valve holder from the downstream side to the upstream side of the relief passage;
A first spring stopper abutting on the downstream side of the relief passage of the first relief spring;
A second movable sheet provided on the downstream side of the relief passage with respect to the first spring stop and operating as a second relief valve for opening and closing the second relief sheet;
A second relief spring for biasing the second movable sheet from the downstream side to the upstream side in the relief passage;
A second spring stopper abutting on the downstream side of the relief passage of the second relief spring;
Have
The second movable sheet is configured to operate integrally with the first spring stop,
High pressure fuel supply pump. In the high pressure fuel supply pump according to claim 1,
The diameter φd2 of the seat portion of the second relief valve is larger than the diameter φd1 of the seat portion of the first relief valve.
High pressure fuel supply pump. In the high pressure fuel supply pump according to claim 1,
The spring constant k1 of the first relief spring is configured to be larger than the spring constant k2 of the second relief spring.
High pressure fuel supply pump. In the high pressure fuel supply pump according to claim 1,
The first relief spring is a hollow tapered disc spring,
High pressure fuel supply pump.

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