JP2010174903A - High pressure fuel supply pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the opening of a relief valve even when the pressure of discharged fuel momentarily rises into abnormally high pressure in the transient state where a high pressure fuel pump compresses fuel with a discharge valve opened. <P>SOLUTION: In a fuel discharge passage upstream from the relief valve in a fuel relief passage (namely, the side of the discharge valve), a mechanism is provided for preventing the propagation of momentary pressure rise in the passage into the relief valve. Specifically, the discharge valve shuts off the relief passage during valve opening operation of the high pressure fuel pump. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a high-pressure fuel supply pump used in a cylinder fuel injection type internal combustion engine when pressurizing fuel fed from a feed pump and pumping the fuel to a fuel injection valve of the internal combustion engine.

  In particular, the present invention relates to a high-pressure fuel supply pump in which a relief valve mechanism as a safety valve for avoiding abnormally high fuel pressure in a high-pressure side fuel passage is incorporated in a pump housing.

  A conventional high-pressure fuel supply pump of this type includes a high-pressure fuel passage downstream of a discharge valve and a low-pressure fuel passage upstream of a suction valve in a pump housing of a high-pressure fuel supply pump, as disclosed in Japanese Patent Application Laid-Open No. 2003-343395. A fuel relief passage to be connected is provided, and a check valve as a relief valve for allowing fuel to pass only from the high pressure fuel passage side to the low pressure fuel passage side is provided inside the fuel relief passage.

  Thus, when the high-pressure fuel discharge passage side becomes abnormally high in pressure, the relief valve constituted by this check valve is opened, and a part of the high-pressure fuel is discharged to the low-pressure passage side, thereby eliminating the abnormal high pressure.

JP 2003-343395 A

  However, in the high pressure fuel supply pump configured as described above, in a transient state in which the discharge valve is open and the high pressure fuel pump pressurizes the fuel, the pressure of the discharged fuel instantaneously exceeds the valve opening pressure of the relief valve. Occurs.

  Since such an instantaneous high pressure state is not an abnormal state as a system, the relief valve does not need to operate, but rather does not want to operate.

  The opening operation of the relief valve under such a situation has a problem that the discharge amount as the high-pressure fuel supply pump is reduced and the energy efficiency is reduced.

  In view of this point, the present invention has an object to prevent the relief valve from opening even when the pressure of the discharged fuel increases instantaneously in a transient state where the discharge valve is opened and the high-pressure fuel pump pressurizes the fuel. And

  The object is to prevent an instantaneous pressure increase generated in the fuel discharge passage upstream of the relief valve in the fuel relief passage (that is, the discharge valve side) from propagating to the relief valve. This is achieved by providing a mechanism.

  Specifically, it is achieved by providing an energy damping mechanism in the relief passage that attenuates the energy applied to the relief valve based on a short-term pressure increase on the discharge passage side that occurs while the high-pressure fuel pump is opening. Is done.

  Preferably, the energy attenuating mechanism can be constituted by a discharge valve during a valve opening operation that throttles or shuts off the high-pressure fuel passage in the vicinity of the relief valve.

  According to the present invention configured as described above, when an abnormally high pressure occurs due to a failure of the fuel injection valve or the like, the fuel pressurized to an abnormally high pressure is released through the relief valve, and the piping or other equipment is abnormally high. It is possible to provide a high-pressure fuel supply pump with a high compression rate, that is, energy efficiency, while maintaining the effect of being not damaged by the above.

  The fuel opened through the relief valve can be discharged not only into the low pressure passage but also into the pressurizing chamber.

1 is an overall longitudinal sectional view of a high-pressure fuel supply pump in which the present invention is implemented. 1 is an overall cross-sectional view of a high-pressure fuel supply pump in which the present invention is implemented. 1 is an example of a fuel supply system using a high-pressure fuel supply pump in which the present invention is implemented. It is a pressure waveform in each part and common rail in the high-pressure fuel supply pump in which the present invention is implemented. It is an example of the orifice plate as a reference example of this invention. It is another example of the orifice plate as a reference example of this invention. It is the figure which showed the relationship between the high pressure discharge flow rate by the high pressure fuel supply pump with which this invention is implemented, and the pressure in a common rail. It is an assembly figure of the relief valve mechanism of the high-pressure fuel supply pump in which the present invention is implemented. It is a longitudinal cross-sectional view of the high-pressure fuel supply pump with which this invention was implemented, and shows a perpendicular direction with FIG. It is a cross-sectional view of a high-pressure fuel supply pump in which the present invention is implemented. 1 is an example of a fuel supply system using a high-pressure fuel supply pump in which the present invention is implemented. It is the figure which represented typically the operation | movement of the discharge valve mechanism of the high pressure fuel supply pump with which this invention was implemented, and shows the time of a high pressure fuel supply pump being in a discharge process. It is the figure which represented typically the operating principle of the discharge valve mechanism of the high-pressure fuel supply pump with which this invention was implemented, and shows the time when a high-pressure fuel supply pump exists in a discharge process. It is the figure which represented typically the operating principle of the discharge valve mechanism of the high-pressure fuel supply pump with which this invention was implemented, and shows the time when the high-pressure fuel supply pump is in the suction and return process. It is the figure which showed the structure of the discharge valve mechanism of the high pressure fuel supply pump with which this invention was implemented, and shows the time when the high pressure fuel supply pump exists in a discharge process. It is the figure which showed the structure of the discharge valve mechanism of the high-pressure fuel supply pump with which this invention was implemented, and shows the time when the high-pressure fuel supply pump is in the suction and return process. It is the figure which showed the structure of the discharge valve mechanism of the high-pressure fuel supply pump with which this invention was implemented by the vertical sectional view and the horizontal sectional view, and shows the time when the high-pressure fuel supply pump is in the discharge process. It is the figure which showed the structure of the discharge valve mechanism of the high pressure fuel supply pump with which this invention was implemented by the vertical sectional view and the horizontal sectional view, and shows the time when the high pressure fuel supply pump is in the suction and return process.

  Embodiments of the present invention will be specifically described below with reference to the drawings.

The basic configuration of the present invention will be specifically described with reference to FIGS. First, the configuration and operation of the system will be described with reference to the overall configuration diagram of the system shown in FIG.

  A portion surrounded by a broken line shows the pump housing 1 of the high-pressure pump, and the mechanism and parts shown in the broken line are integrated in the pump housing 1 of the high-pressure pump.

  The fuel in the fuel tank 20 is pumped up by the feed pump 21 and sent to the suction joint 10 a of the pump housing 1 through the suction pipe 28. At that time, the intake fuel to the pump housing 1 is adjusted to a constant pressure by the pressure regulator 22.

  The fuel that has passed through the suction joint 10a reaches the suction port 30a of the electromagnetic suction valve mechanism 30 that constitutes a variable capacity mechanism via the pressure pulsation reducing mechanism 9 and the suction passages 10c and 10d. The pressure pulsation reduction mechanism 9 will be described in detail later.

  The electromagnetic intake valve mechanism 30 includes an electromagnetic coil 30b. When the electromagnetic coil 30b is energized, the electromagnetic plunger 30c is moved rightward in FIG. 1, and the compressed state of the spring 33 is maintained.

  At this time, the suction valve body 31 attached to the tip of the electromagnetic plunger 30c opens the suction port 32 connected to the pressurizing chamber 11 of the high-pressure pump.

  When the electromagnetic coil 30b is not energized and there is no fluid differential pressure between the suction passage 10d (suction port 30a) and the pressurizing chamber 11, the biasing force of the spring 33 causes the suction valve body 31 to The suction port 32 is energized in the valve closing direction and is closed.

  Specifically, it operates as follows.

  When the plunger 2 is displaced downward in FIG. 1 due to the rotation of the cam, which will be described later, and is in the suction process state, the volume of the pressurizing chamber 11 increases and the fuel pressure in the pressurizing chamber 11 decreases. When the fuel pressure in the pressurizing chamber 11 becomes lower than the pressure in the suction passage 10d (suction port 30a) in this step, the valve opening force (suction valve body 31 shown in FIG. Force to displace to the right).

  By the valve opening force due to this fluid differential pressure, the suction valve body 31 is set to open over the biasing force of the spring 33 and open the suction port 32.

  In this state, when a control signal from the engine control unit 27 (hereinafter referred to as ECU) is applied to the electromagnetic intake valve mechanism 30, an electric current flows through the electromagnetic coil 30b of the electromagnetic intake valve mechanism 30, and the electromagnetic force is applied to the electromagnetic coil 30b. The plunger 30c moves to the right in FIG. 1, and the state where the spring 33 is compressed is maintained. As a result, the state in which the suction valve body 31 opens the suction port 32 is maintained.

  When the plunger 2 finishes the suction process and shifts to the compression process while maintaining the application state of the input voltage to the electromagnetic suction valve mechanism 30, the plunger 2 moves to the compression process (a state in which the plunger 2 moves upward in FIG. 1). Then, since the energized state of the electromagnetic coil 30b is maintained, the magnetic biasing force is maintained, and the intake valve body 31 is still opened.

  The volume of the pressurizing chamber 11 decreases with the upward movement of the plunger 2. In this state, the fuel once sucked into the pressurizing chamber 11 passes through the suction valve body 31 that is opened again, and the suction passage 10 d (suction). Since the pressure is returned to the port 30a), the pressure in the pressurizing chamber does not increase. This process is called a return process.

  In this state, when the control signal from the ECU 27 is canceled and the energization to the electromagnetic coil 30b is cut off, the magnetic biasing force acting on the electromagnetic plunger 30c is after a certain time (after magnetic and mechanical delay time). Erased. Since the biasing force by the spring 33 is acting on the suction valve body 31, the suction valve body 31 closes the suction port 32 by the biasing force by the spring 33 when the electromagnetic force acting on the electromagnetic plunger 30 c disappears. When the suction port 32 is closed, the fuel pressure in the pressurizing chamber 11 increases with the upward movement of the plunger 2 from this time.

  When the fuel remaining in the pressurizing chamber 11 is pressurized and the fuel pressure in the pressurizing chamber 11 becomes equal to or higher than the pressure in the discharge port 12, the high pressure pipe 29 is connected via the discharge valve mechanism 8 and the discharge port 12. It is discharged and supplied to the common rail 23. This process is called a discharge process. That is, the compression process of the plunger 2 (the ascending process from the lower start point to the upper start point) includes a return process and a discharge process.

  And the quantity of the high-pressure fuel discharged can be controlled by controlling the timing which cancels | releases the electricity supply to the electromagnetic coil 30b of the electromagnetic suction valve mechanism 30. FIG. If the timing of releasing the energization of the electromagnetic coil 30b is advanced, the ratio of the return process in the compression process is small and the ratio of the discharge process is large.

  That is, the amount of fuel returned to the suction passage 10d (suction port 30a) is small, and the amount of fuel discharged at high pressure is large. On the other hand, if the timing for releasing the input voltage is delayed, the ratio of the return process in the compression process is large and the ratio of the discharge process is small.

That is, the amount of fuel returned to the suction passage 10d is large, and the amount of fuel discharged at high pressure is small.
The timing for releasing the energization of the electromagnetic coil 30b is controlled by a command from the ECU.

  By configuring as described above, it is possible to control the amount of fuel pressurized and discharged to the amount required by the internal combustion engine by controlling the timing of releasing the energization of the electromagnetic coil 30b. it can.

  Thus, the fuel guided to the fuel suction port 10 a is pressurized to a high pressure by the reciprocation of the plunger 2 in the pressurizing chamber 11 of the pump housing 1, and is pumped from the discharge port 12 to the common rail 23.

  An injector 24 and a pressure sensor 26 are attached to the common rail 23. The injectors 24 are mounted in accordance with the number of cylinders of the internal combustion engine, open and close according to a control signal from an engine control unit (ECU) 27, and inject fuel into the cylinders.

  An orifice 25 is provided at the inlet of the common rail 23, whereby the propagation of pressure overshoot into the common rail 23 is blocked, and fuel with a stable pressure can be supplied to the injector 24.

  The pump housing 1 is further provided with relief passages 210 and 215 communicating the downstream side of the discharge valve 8b and the suction passage 10c.

  The relief passages 210 and 215 are provided with a relief valve 202 that restricts the flow of fuel in only one direction from the discharge passage to the suction passage 10c. A specific configuration will be described with reference to FIG.

  The relief valve mechanism 200 includes a relief valve seat 201, a relief valve 202, a relief press 203, a relief spring 204, and a relief spring adjuster 205.

  The relief valve seat 201 is press-fitted and fixed to the pump housing 1, and the orifice plate 214 is fixed by being sandwiched between the pump housing 1 and the relief valve seat 201. The relief valve 202 is pressed against the relief valve seat 201 by the pressing force of the relief spring 204 via the relief press 203. The valve opening pressure of the relief valve 202 is determined by the pressing force generated by the relief spring 204, and this pressing force is screwed into the pump housing 1 by a screw threaded on the outer periphery of the relief spring adjuster 205. It is determined by incorporating into the screw and adjusting the amount of compression of the relief spring 204. The fuel is sealed to the outside by an O-ring 213.

  The operation of the relief valve will be described below. The relief valve 202 is pressed against the relief valve seat 201 by a relief spring 204 that generates a pressing force. When the pressure difference between the suction chamber and the relief passage exceeds a specified pressure, the relief valve 202 is pressed against the relief valve seat. The valve is set to open from 201. The orifice plate 214 is provided in the middle of the relief passage 210, and prevents the relief valve 202 from opening sensitively due to a sudden change in pressure in the relief passage 210.

  When an abnormally high pressure is generated in the common rail 23 or the like due to a failure of the injector 24 or the like, if the differential pressure between the relief passage 210 and the suction passage 10c exceeds the opening pressure of the relief valve 202, the relief valve 202 is opened and The resulting fuel is returned from the relief passage 210 to the suction passage 10c, and the high-pressure piping such as the common rail 23 is protected.

  In the first embodiment, the discharge valve mechanism 8 and the electromagnetic suction valve mechanism 30 are coaxially arranged in series with the pressurizing chamber 11 in between, and the relief valve mechanism 200 is attached to the discharge valve mechanism 8 and the electromagnetic suction valve mechanism 30. It is assembled in a relief valve mounting hole formed in the pump housing in parallel to the axis.

  Hereinafter, the configuration and operation of the high-pressure fuel pump will be described in more detail with reference to FIGS.

  The pump housing 1 is formed with a recess 1A as a pressurizing chamber 11 at the center, and a recess 11A for mounting the discharge valve mechanism 8 is formed between the inner peripheral wall of the pressurizing chamber 11 and the discharge port 12. Yes. Further, a hole 30A for mounting an electromagnetic intake valve mechanism 30 for supplying fuel to the pressurizing chamber 11 is provided on the outer wall of the pump housing on the same axis as the recess 11A for mounting the discharge valve mechanism.

  With respect to the central axis of the recess 1A as the pressurizing chamber 11, the recess 11A for mounting the discharge valve mechanism 8 and the axis of the hole for attaching the electromagnetic suction valve mechanism 30 are formed to intersect at right angles.

  A discharge valve mechanism 8 for discharging fuel from the pressurizing chamber 11 to the discharge passage is provided.

  A cylinder 6 that guides the forward / backward movement of the plunger 2 is attached so as to face the pressurizing chamber 11.

  In the first embodiment, the recess 11A for mounting the discharge valve mechanism 8 and the axis of the hole 30A for attaching the electromagnetic suction valve mechanism 30 are formed to be the same axis. The hole 30A for attaching the mechanism 30 can be assembled straight into the recess 11A for mounting the discharge valve mechanism 8. Alternatively, a force for press-fitting the discharge valve mechanism 8 can be applied from the hole 30 </ b> A for attaching the electromagnetic suction valve mechanism 30. In this case, the diameter of the hole 30A needs to be larger than the maximum outer diameter of the discharge valve mechanism 8 in the minimum diameter portion.

  However, the axes of these holes and recesses can be shifted in the circumferential direction or in the vertical direction.

  In this case, the discharge valve mechanism 8 is assembled from the opening 1B side for mounting the cylinder 6.

  The cylinder 6 has an outer periphery held by a cylinder holder 7 and is fixed to the pump housing 1 by screwing a male screw engraved on the outer periphery of the cylinder holder 7 into a female screw engraved in the pump housing 1. The cylinder 6 holds the plunger 2 that moves forward and backward in the pressurizing chamber 11 so as to be slidable along the forward and backward movement direction.

  In the embodiment, after the discharge valve mechanism 8 is mounted in the recess 11A, the cylinder 6 is mounted in the mounting opening 1B.

  As a result, the tip of the cylinder 6 can be inserted to a position facing the inner end of the discharge valve mechanism 8 mounted in the recess 11A, and the fuel storage volume of the pressurizing chamber 11 can thereby be reduced. Compression efficiency can be improved.

  Further, in the embodiment, a metal seal portion is constituted by a butting surface S1 between the flange-shaped annular surface portion formed on the outer periphery of the cylinder 6 and the end surface of the opening 1B of the pump housing 1, and the pressurizing chamber 11 is isolated from the atmosphere. Yes. In general, in a high-pressure fuel supply pump, there is a possibility that the butt surface S1 may be eroded by cavitation generated by pressure fluctuation in the pressurizing chamber 11, but by projecting the cylinder 6 into the pressurizing chamber in this way, the seal Therefore, the abutting surface S1 can be kept away from the cavitation occurrence location, and the possibility of erosion can be reduced.

  In the embodiment, after the discharge valve mechanism 8 is mounted, the tubular member 11D is pressed into the inner periphery of the bottom (upper end in FIG. 1) of the recess 1A and fixed to prevent the discharge valve mechanism 8 from coming off. ing.

  The cylindrical member 11D also has a function of increasing the compression efficiency of the fuel by reducing the volume of the pressurizing chamber 11. When the cylindrical member 11D is not attached, the cylinder 6 can be used to prevent the discharge valve mechanism 8 from coming off.

  When this cylindrical member 11D is provided, it is not necessary to use the cylinder 6 as a retaining member. Therefore, the length of the cylinder 6 can be shortened so that it does not reach the position of the discharge valve mechanism 8.

  Further, after the discharge valve mechanism 8 is press-fitted into the recess 11A, the discharge valve mechanism 8 itself can be provided with a stopper by, for example, crimping the peripheral edge of the pressurizing chamber 11 to the inner wall of the pump housing. In this case, the cylindrical member 11D is not necessary. Further, if the length of the cylinder 6 is shortened so that it does not reach the position of the discharge valve mechanism 8, it is possible to fix the cylinder 6 first and then attach the discharge valve mechanism 8 to the recess 11A. It is.

  The lower end of the plunger 2 is provided with a tappet 3 that converts the rotational motion of the cam 5 attached to the camshaft of the engine into vertical motion and transmits it to the plunger 2. The plunger 2 is pressure-bonded to the tappet 3 by a spring 4 through a retainer 15. Thereby, the plunger 2 can be moved back and forth (reciprocated) up and down with the rotational movement of the cam 5.

  Further, the plunger seal 13 held at the lower end of the inner periphery of the cylinder holder 7 is installed in a state in which the plunger seal 13 slidably contacts the outer periphery of the plunger 2 at the lower end of the cylinder 6 in the drawing, and fuel leaks to the outside. To prevent. At the same time, lubricating oil (including engine oil) for lubricating the sliding portion in the engine room is prevented from flowing into the pump housing 1.

  Fixed to the damper cover 14 is a pressure pulsation reduction mechanism 9 that reduces the spread of pressure pulsation generated in the pump to the fuel pipe 28.

  The damper cover 14 is fixed to the pump housing 1, and the suction passages as low pressure passages include 10a, 10b, and 10c. The pressure pulsation reducing mechanism 9 that reduces the pulsation of the pressure pulsation generated in the pump with the reciprocating motion of the plunger 2 to the fuel pipe 28 includes two metal diaphragm assemblies 9A and 9B. In the metal diaphragm assemblies 9A and 9B, two metal diaphragms are welded together at the outer periphery thereof, and an inert gas is injected therein. The pump housing 1 is provided with a damper housing 10B constituting a part of the suction passage, and two sets of metal diaphragm assemblies 9A and 9B are accommodated in the damper housing 10B. Support members 10A1 and 10A2 are arranged at the peripheral edge portions of the two sets of metal diaphragm assemblies 9A and 9B so as to maintain a specific distance from each other. By screwing a screw engraved on the outer periphery of the damper cover 14 into a screw groove 10C provided on the inner periphery of the damper housing 10B and pressing and sealing the seal member 10D, the damper chamber is sealed. Thereby, a damper chamber is defined in the suction passage 10, and the pressure pulsation reduction mechanism 9 is formed. The intake fuel is guided by the passage 10E between the damper cover 14 and the metal diaphragm assembly 9A and between the metal diaphragm assemblies 9A and 9B, and basically the same pressure acts on the four diaphragms.

  In this embodiment, the damper cover 14 is fixed to the pump housing by screwing. However, the damper cover 14 may be fixed by welding the entire circumference at the P position, for example. In this case, since sealing can be performed by welding, the seal member 10D of the first embodiment can be eliminated.

  In this case, since the force for fixing the metal diaphragm assembly is lost, it is preferable to fix the metal diaphragm assemblies 9A and 9B separately from the fixing of the damper cover 14.

  It can also be welded after screwing. In this case, the seal member can be abolished, and the metal diaphragm assemblies 9A and 9B can be fixed with a tightening torque of screwing as in the present embodiment.

A discharge port (discharge side pipe connection portion) 12 is formed in the pump housing 1, and a pressurizing chamber 11 for pressurizing fuel is formed in the middle of a fuel passage from the suction port 10 a to the discharge port 12. An electromagnetic suction valve mechanism 30 is provided at the entrance of the pressurizing chamber 11. The suction valve body 31 is biased by a suction valve spring 33 provided in the electromagnetic suction valve mechanism 30 in the direction of closing the suction port. Thus, the electromagnetic intake valve mechanism 30 becomes a check valve that restricts the flow direction of the fuel.
The specific configuration and operation are as described above.

  A discharge valve mechanism 8 is provided at the outlet of the pressurizing chamber 11. The discharge valve mechanism 8 includes a sheet member (sheet member) 8a, a discharge valve 8b, a discharge valve spring 8c, and a holding member 8d as a discharge valve stopper. In a state where there is no fuel differential pressure between the pressurizing chamber 11 and the discharge port 12, the discharge valve 8b is pressed against the seat member 8a by the urging force of the discharge valve spring 8c and is in a closed state. Only when the fuel pressure in the pressurizing chamber 11 becomes larger than the fuel pressure in the discharge port 12 by a predetermined value, the discharge valve 8b opens against the discharge valve spring 8c, and the pressure in the pressurizing chamber 11 is increased. The fuel is discharged to the common rail 23 through the discharge port 12.

  When the discharge valve 8b is opened, the discharge valve 8b comes into contact with the holding member 8d and its operation is restricted. Therefore, the stroke of the discharge valve 8b is appropriately determined by the holding member 8d. If the stroke is too large, the fuel discharged to the fuel discharge port 12 will flow back into the pressurizing chamber 11 again due to the delay in closing the discharge valve 8b, and the efficiency of the high-pressure pump will decrease. . Further, when the discharge valve 8b repeats opening and closing movements, the holding member 8d guides the discharge valve 8b to move only in the stroke direction. By configuring as described above, the discharge valve mechanism 8 becomes a check valve that restricts the flow direction of fuel.

  During the returning process, pressure pulsation is generated in the suction passage 10 by the fuel returned to the suction passage 10d. This pressure pulsation is absorbed and reduced as the metal diaphragm assemblies 9A and 9B expand and contract. During the returning process, the fuel only flows back slightly from the suction passage 10a through the suction pipe 28, and most of the fuel is absorbed by the volume change of the metal diaphragm assemblies 9A and 9B.

  Returning to FIG. 2, a reference example of the present invention will be described. The relief passage 215 is connected to the suction passage 10c. As a result, the outlet of the relief valve 202 is connected between the pressure pulsation reducing mechanism 9 and the suction valve 32.

  As shown in FIGS. 5 and 6, the orifice plate 214 is provided with one or more orifices.

  Next, the basic operation will be described in the case where the fuel is normally sent to the common rail 23 by high pressure by the high pressure fuel supply pump.

  A pressure overshoot occurs in the pressurizing chamber 11 from the moment when the plunger 2 is moving up, that is, during the compression process, from the moment when the return process is shifted to the pressurizing process. The pressure overshoot generated in the pressurizing chamber 11 propagates from the discharge port 12 to the relief passage 210 and the orifice plate 214. The pressure overshoot that has propagated to the orifice plate 214 is prevented from propagating to the relief passage 211 by the orifices 214a, 214b, and 214c, and the pressure overshoot in the relief passage 211 does not exceed the valve opening pressure of the relief valve 201. Therefore, the pressure difference between the inlet and outlet of the relief valve does not exceed the opening pressure of the relief valve, the relief valve does not malfunction, and the amount of fuel discharged at high pressure does not decrease.

  In the above pump configuration, the holding member 8d as a discharge valve stopper is fitted into the seat member 8a by light press-fitting with the discharge valve 8b and the discharge valve spring 8c inserted therein. 11 is assembled into the pump housing 1 by press fitting.

  As a result, the assemblability can be improved. Further, by connecting a fuel passage leading to the relief valve between the discharge valve mechanism 8 and the discharge pipe connecting portion 12, the relief valve can be easily built in the pump.

  The pump housing 1 is provided with a stopper portion of the discharge valve mechanism 8, the cylinder 6 provided with a retaining portion for the seat member 8 a is provided on the pressurizing chamber 11 side, and the seat member 8 a and the cylinder 6 are provided with a seat member 8 a and a pump. A clearance smaller than the press-fitting length of the housing 1 is provided.

  As a result, the seat member does not come out even if the press-fitting fitting force (press-fit tightening allowance) between the seat member and the pump housing is reduced, so there is no need to increase the press-fit fitting force (press-fit tightening allowance), and the seat during press fitting The deterioration of the valve seat property due to the deformation of the part can be prevented. Accordingly, the tolerance width of the press-fitting fitting force (press-fit tightening allowance) can be roughly controlled, and inexpensive processing can be performed.

  In addition, since there is a gap between the seat member 8a and the cylinder 6, misalignment due to the dimensional tolerance of each part during assembly can be absorbed by the gap, and even if the seat member 8a moves by the gap during pump operation, it is press-fitted Since the portion can be secured, the sealability of the press-fit portion can be maintained.

  In this embodiment, the inner diameter of the discharge port 12 into which the discharge side pipe joint is screwed can be the same as or smaller than the outer diameter of the seat member 8a having the largest outer diameter of the discharge valve mechanism 8. As a result, the area of the seal part between the discharge port and the joint can be reduced, and the pressure receiving area of the seal part can be reduced.

  The outer periphery of the cylinder 6 is held by a cylinder holder 7. The cylinder holder 7 obtains thrust by screwing a screw threaded on the inner periphery of the flange holder 40 into a screw threaded on the pump housing 1, and fixes the cylinder 6 to the pump housing 1. The cylinder 6 holds the plunger 2 as a pressurizing member so as to be slidable up and down.

  The high-pressure fuel supply pump is fixed to the engine by the flange holder 40 and the flange 41. The flange holder 40 is fixed to the engine by a set screw 42 via a flange 41. Since the flange holder 40 is fixed to the pump housing 1 by a screw threaded on the inner periphery, the pump housing is thereby fixed to the engine.

  The relief passage 215 is connected via a suction passage 10c to a suction passage 10b provided with a pressure pulsation reduction mechanism 9. As a result, the outlet of the relief valve 202 is connected between the pressure pulsation reducing mechanism 9 and the suction valve 32.

The orifice plate 214 of the reference example is provided with one or more orifices.
5 and 6 show examples of the orifice plate 214 of the reference example. FIG. 5 shows an example in which one orifice 214a is provided. FIG. 6 shows an example in which four orifices 214b and a large number of orifices 214c are provided. In this case, the plurality of orifices have such a small diameter as to affect the viscosity of the fuel. Hereinafter, the function of the orifice as the reference example will be described.

  First, a case where the fuel is normally fed to the common rail 23 by high pressure by the high pressure fuel supply pump will be described.

  During the discharge process of the high pressure fuel supply pump, pressure overshoot occurs in the pressurizing chamber 11. The pressure overshoot generated in the pressurizing chamber 11 propagates from the discharge port 12 to the relief passage 210 and the orifice plate 214. The pressure overshoot that has propagated to the orifice plate 214 is blocked from propagating to the relief passage 211 by the orifice 214a (214b, 214c), and the pressure overshoot in the relief passage 211 can be reduced. As a result, the malfunction of the relief valve can be eliminated, and the amount of fuel discharged at high pressure can be reduced. That is, the efficiency as a high-pressure fuel supply pump can be maintained at a high level.

  Note that the pressure overshoot generated in the pressurizing chamber 11 propagates from the high-pressure pipe 29 to the common rail 23 via the discharge port 12. An orifice 25 is provided at the inlet of the common rail 23, whereby the propagation of pressure overshoot into the common rail 23 is blocked, and fuel with a stable pressure can be supplied to the injector 24.

  Next, a case where an abnormally high pressure is generated in the high pressure portion such as the common rail 23 due to a failure of the injector 24 or the like will be described.

  FIG. 7 shows the relationship between the amount of fuel discharged at high pressure from the high-pressure fuel supply pump and the pressure in the common rail 23. In general, even when the valve opening pressure of the relief valve 202 is the same, the fuel pressure in the common rail 23 necessarily increases as the amount of fuel discharged at high pressure increases.

  On the other hand, when the orifice is provided at the inlet of the relief valve 202 by the orifice plate 214 of the reference example as shown in FIG. 2, the malfunction of the relief valve 202 due to the pressure overshoot generated in the passage 210 as described above can be reduced. it can. However, to block the propagation of pressure overshoot to the relief valve 202, the orifice 214a must be very small. When an abnormally high pressure occurs, the high-pressure fuel passes through the orifice 214a and is returned from the relief passage 215 to the suction passage 10b. However, pressure loss occurs in the orifice 214, resulting in fuel in the common rail 23 and the like. The pressure becomes much larger than the valve opening pressure of the relief valve 202. In this case, the pressure resistance and cost of the high-pressure piping part becomes a problem.

On the other hand, if a plurality of orifices 214b and 214c that are so small as to affect the viscosity of the fuel are provided as shown in FIG. 6, the propagation of the pressure overshoot to the relief valve 202 can be blocked, and even when an abnormal high pressure occurs. The increase in pressure of the common rail 23 and the like can be suppressed.
This is because the passage area of each of the orifices 214b and 214c is small, but the total passage area of these orifices can be made sufficiently large, and no pressure loss occurs at the orifice 214 portion. Thereby, the pressure | voltage resistance and cost of a high voltage | pressure piping part can avoid a problem.

  Further, when the fuel having an abnormally high pressure is released to the suction passage 10b, the pressure of the fuel rapidly decreases, and thereby a very large pressure pulsation is generated in the suction passage 10b. However, since the pressure pulsation reducing mechanism 9 is provided in the suction passage 10b, and this pressure pulsation can be sufficiently reduced, the pressure pulsation propagation to the low-pressure pipe 28 can be prevented, and the pipe is prevented from being damaged. Is done.

  Further, the same effect can be obtained by providing a sintered metal having a mesh structure instead of the orifice plate 214.

  In this embodiment, the outlet of the relief passage is connected to the suction (low pressure) passage. However, the relief valve can be provided at a position close to the pressurizing chamber, preferably in the pressurizing chamber. If the pressure does not decrease, the outlet of the relief passage can be connected to the pressurizing chamber, and the fuel can be returned to the pressurizing chamber at an abnormally high pressure.

  Next, a first embodiment will be described based on FIG. 1 and FIGS.

  First, the specific structure of the relief valve mechanism B200 will be described with reference to FIGS.

  The relief valve mechanism B200 includes a relief valve housing B206, a relief valve B202, a relief press B203, a relief spring B204, and a relief spring adjuster B205 that are integral with the relief valve seat B201. The relief valve mechanism B200 is assembled outside the pump housing 1 as a subassembly, and then fixed to the pump housing 1 by press fitting.

  First, the relief valve B202, the relief presser B203, and the relief spring B204 are sequentially inserted into the relief valve housing B206 in this order, and the relief spring adjuster B205 is press-fitted and fixed to the relief valve housing B206. The set load of the relief spring B204 is determined by the fixed position of the relief spring adjuster B205. The valve opening pressure of the relief valve B202 is determined by the set load of the relief spring B204. The relief valve mechanism B200 thus formed is press-fitted and fixed to the pump housing 1. In the second embodiment, the relief passage 211 is formed integrally with the pump housing 1 in parallel with the cylinder 6.

  Next, the function of the discharge valve mechanism 8 will be described with reference to FIGS. 11, 12, and 13. A discharge valve mechanism 8 is provided at the outlet of the pressurizing chamber 11. The discharge valve mechanism 8 includes a discharge valve seat 8a, a discharge valve 8b, a discharge valve spring 8c, and a discharge valve holder 8d. The discharge valve 8b is slidably held by the discharge valve holder 8d, and the discharge valve 8b is opened and closed. When the valve motion is repeated, the discharge valve holder 8d guides it so as to move only in the stroke direction. Further, when the discharge valve 8b is opened, the discharge valve 8b comes into contact with the contact portion 8d3 of the discharge valve holder 8d to restrict the operation. By doing so, the fuel discharged at high pressure to the discharge port 12 flows back into the pressurizing chamber 11 again due to delay in closing of the discharge valve 8b, and the efficiency of the high pressure pump does not decrease.

  The discharge valve holder 8d has a discharge port 8d1, a relief port 8d2, and a return port 8d4. The relief port 8d2 communicates with the relief passage 211. When the high-pressure fuel supply pump is in the discharge process, the discharge valve 8b is open as shown in FIG. The discharge valve 8b is in contact with the discharge valve holder 8d at the contact portion 8d3 and seals the fuel at this portion. Therefore, the discharge port 12 and the relief passage 211 are blocked and are not in communication.

  On the other hand, when the high-pressure fuel supply pump is in the suction and return process, the discharge valve 8b is in the closed state as shown in FIG. The discharge valve 8b blocks the discharge passage 12 and the pressurizing chamber 11 at the sheet portion 8a3 on the discharge valve seat 8a. Thereby, even if the pressure in the pressurizing chamber 11 becomes low due to the movement of the plunger 2, the high-pressure fuel in the discharge passage 12 does not flow back into the pressurizing chamber 11. In the contact portion 8d3, a gap corresponding to the stroke of the discharge valve 8b is formed between the discharge valve 8b and the discharge valve holder 8d, and the discharge port 12 and the relief passage 211 are communicated with each other through this gap. That is, the discharge port 12 and the relief passage 211 are not communicated during the discharge process, and the discharge port 12 and the relief passage 211 are communicated during the suction process and the return process.

  Next, the case where the fuel is normally fed to the common rail 23 by high pressure by the high pressure fuel supply pump will be described.

  During the discharge process, the fuel pressurized to a high pressure in the pressurizing chamber 11 is supplied to the common rail 23 through the discharge port 12 and the high-pressure pipe 29 as shown in FIG.

  At this time, pressure overshoot occurs in the pressurizing chamber 11. The pressure overshoot generated in the pressurizing chamber 11 is transmitted to the discharge port 12, and at this time, the discharge valve 8b is in the open state. That is, as described above, since the discharge port 12 and the relief passage 211 are not in communication, this pressure overshoot does not propagate to the relief passage 211.

  Therefore, even if a pressure overshoot occurs in the pressurizing chamber 11, the relief valve B202 does not malfunction. This means that the flow rate discharged from the high-pressure fuel supply pump to the common rail 23 does not decrease.

  On the other hand, in the suction process and the return process, the discharge port 12 and the relief passage 211 are communicated with each other, but there is no pressure overshoot, so that the relief valve B202 does not malfunction. That is, the flow rate discharged from the high pressure fuel supply pump to the common rail 23 does not decrease.

  Furthermore, a case where an abnormally high pressure occurs in the high-voltage portion such as the common rail 23 due to a failure of the injector 24 or the like will be described.

  During the discharge process, as described above, the discharge passage 12 and the relief passage 211 are not in communication, so the fuel having an abnormally high pressure cannot reach the relief valve B202.

  During the suction process and the return process, the discharge port 12 and the relief passage 211 are in communication as described above.

  Therefore, the fuel having an abnormally high pressure reaches the relief valve B202 from the discharge port 12 through the relief passage 211. The fuel that has passed through the relief valve B202 is released to the suction passage 10b, which is a low-pressure portion, through a relief passage B205a opened in the relief spring adjuster B205. As a result, the high-voltage portion such as the common rail 23 is protected.

  Further, when the fuel having an abnormally high pressure is released to the suction passage 10b, the pressure of the fuel rapidly decreases, and thereby a very large pressure pulsation is generated in the suction passage 10b. However, a pressure pulsation reduction mechanism 9 is provided further upstream of the suction passage 10b, and this pressure pulsation can be sufficiently reduced. Therefore, propagation of the pressure pulsation to the low pressure pipe 28 can be prevented, and Breakage can be prevented.

  Next, the structure of the discharge valve mechanism 8 having the above functions will be described with reference to FIGS. 14, 15, 16, 17, and 18. FIG.

  The discharge valve mechanism 8 is assembled as a subassembly outside the pump housing 1 before being assembled into the pump housing 1. A discharge valve spring 8c, a discharge valve 8b, and a discharge valve seat 8a are sequentially inserted into the discharge valve holder 8d in this order, and the discharge valve sheet 8a is press-fitted and fixed to the discharge valve holder 8d by a press-fit portion 8a1.

  The discharge valve mechanism 8 thus formed is press-fitted and fixed to the pump housing. The press-fitting locations are a press-fit portion 8a2 that is a side surface portion of the discharge valve seat 8a and a press-fit portion 8d5 that is a side surface of the discharge valve holder 8d. The side surface of the discharge valve holder 8d has a shape obtained by cutting two flat surfaces 8d6 parallel to the cylindrical shape. That is, the side surface of the discharge valve holder 8d includes a cylindrical press-fit portion 8d5 and a flat portion 8d6.

  The two discharge ports 8d1 are processed so as to be connected to the two flat portions 8d6. The two relief ports 8d2 are processed so as to be connected to the cylindrical press-fit portion 8d5. Thus, when the discharge valve mechanism 8 is press-fitted into the pump housing 1, it is press-fitted and fixed so that the relief port 8 d 2 processed in the discharge valve holder 8 d and the relief passage 211 processed in the pump housing 1 overlap. . The press-fitting portion of the pump housing is processed into a cylindrical shape.

  At the time of the discharge process, as shown in FIGS. 15 and 17, the fuel pressurized in the pressurizing chamber 11 passes through the gap between the flat portion 8d6 processed on the side surface of the discharge valve holder 8d and the pump housing 1 from the discharge port 8d1. It is discharged to the discharge passage 12 through. At this time, the relief passage 211 and the discharge passage 12 are disconnected and disconnected from each other by the contact portion 8d3 on the discharge valve holder 8d. Therefore, the pressure overshoot generated in the pressurizing chamber 11 does not propagate to the relief valve B202.

  Further, when an abnormally high pressure is generated in the high pressure portion such as the common rail 23 due to a failure of the injector 24 or the like, as shown in FIGS. 16 and 18, in the contact portion 8d3, the discharge valve is disposed between the discharge valve 8b and the discharge valve holder 8d. A gap corresponding to the stroke of 8b is generated, and the discharge port 12 and the relief passage 211 are communicated with each other through the communication port 8d4 and the relief port 8d2 provided in the discharge valve holder 8d.

  Accordingly, the fuel having an abnormally high pressure can reach the relief valve B202, and is released to the suction passage 10b, which is a low pressure portion, through the relief passage B205a opened in the relief spring adjuster B205.

  The discharge valve mechanism 8 assembled outside the pump housing 1 is press-fitted and fixed between the pump housing 1 by the press-fitting portion 8d5 of the discharge valve holder 8d and the discharge valve seat 8a2. In particular, the press-fitting portion between 8d5 and the pump housing 1 is structured to block between the discharge passage 12 and the relief passage 211.

  The clearance between the press-fitted portion 8d5 and the pump housing 1 may be so small that the viscosity of the fuel is affected. Thereby, the press-fit load to the pump housing 8 of the discharge valve mechanism 8 can be reduced while obtaining the same effect as the above effect, and the assemblability of the high-pressure fuel supply pump is improved.

  The present invention is applied to a high-pressure fuel supply pump used in a cylinder injection type internal combustion engine. In the embodiment, a so-called single-cylinder high-pressure fuel supply pump having only one pressurizing chamber has been described, but it can also be used for a so-called multi-cylinder pump having a plurality of pressurizing chambers.

  DESCRIPTION OF SYMBOLS 1 ... Pump housing, 2 ... Plunger, 6 ... Cylinder, 8 ... Discharge valve mechanism, 9 ... Pressure pulsation reduction mechanism, 11 ... Pressure chamber, 30 ... Electromagnetic suction valve mechanism, 200, B200 ... Relief valve mechanism, 214 ... Orifice Plate, 210, 211, 215 ... suction passage.

Claims (5)

A low pressure suction passage for sucking fuel into the pressurizing chamber;
A discharge passage for discharging the fuel from the pressurizing chamber;
A suction valve in the suction passage, and a discharge valve in the discharge passage,
Connect the downstream side of the discharge passage from the discharge valve and the upstream side of the suction valve of the suction passage, or connect the downstream side of the discharge valve and the pressurizing chamber, and connect the discharge passage side to the upstream side. A relief passage having the suction passage side downstream, the discharge passage side upstream, and the pressurizing chamber side downstream,
A relief valve for restricting the flow of fuel in only one direction from the upstream side to the downstream side in the relief passage;
In the high-pressure fuel supply pump configured to open the relief valve when a pressure difference between the inlet and the outlet exceeds a specified valve opening pressure,
The high-pressure fuel supply pump includes a passage opening / closing mechanism that disconnects the relief passage and the discharge passage during a high-pressure fuel discharge step, and communicates the relief passage and the discharge passage in other steps. A high-pressure fuel supply pump characterized by comprising. The high-pressure fuel supply pump according to claim 1,
A high-pressure fuel supply pump using the discharge valve as the passage opening / closing mechanism, and restricting or blocking a connection portion between the discharge passage and the relief passage by the discharge valve when the discharge valve is opened. . The high-pressure fuel supply pump according to claim 2,
A connection opening between the relief passage and the discharge passage is formed on a side surface of a cylindrical holding member that guides the reciprocating motion of the discharge valve, and the connection opening is opened by the discharge valve when the discharge valve is opened. A high-pressure fuel supply pump configured to be throttled or shut off. The high-pressure fuel supply pump according to claim 3,
A high-pressure fuel supply pump, characterized in that a side surface of the cylindrical holding member is provided with a conduction path for guiding the fuel in the pressurizing chamber to the discharge passage during the valve opening operation of the discharge valve. The high-pressure fuel supply pump according to claim 3,
The cylindrical holding member is fixed to the discharge opening of the pressurizing chamber, and a sheet member for the discharge valve is fixed to the end of the cylindrical holding member on the pressurizing chamber side. A high-pressure fuel supply pump, wherein the discharge valve is pressed against the seat portion by a spring held by the valve.

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