JP2018009495A - High-pressure fuel supply pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that a structure for connecting a pressurization chamber and a low-pressure damper chamber to each other from a fuel suction port by a communication passage is complicated, a diameter of the passage is formed of two-stage shape, and man-hours become large.SOLUTION: In a high-pressure fuel supply pump having a seal chamber whose capacity becomes small when a plunger is descended, a pump body in which a pressurization chamber is formed, and a pressure pulsation reduction mechanism arranged in a damper chamber at a suction side of the pressurization chamber, the high-pressure fuel supply pump comprises a seal chamber communication passage which is formed at the pump body, and makes the seal chamber and the damper chamber communicate with each other, and a suction joint inserted into the pump body. A direction of the shortest route in which a distance from the outermost peripheral end part of the seal chamber communication passage up to an external peripheral part of the pump body becomes the shortest, and an axial direction of the suction joint are arranged so as to be substantially overlapped on each other when seen from a plunger axial direction.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a high-pressure fuel supply pump.

  There exists a thing shown in patent document 1 as a prior art of this invention. This Patent Document 1 discloses that the number of parts at the time of assembling a metal diaphragm damper into a low-pressure fuel passage is reduced, and parts shortage and erroneous assembly are prevented. Therefore, in Patent Document 1, the pressure pulsation reducing mechanism includes a pair of metal dampers in which two disk-shaped metal diaphragms are joined over the entire circumference, and a sealed space is formed inside the joined portion, and the sealed space of the damper is provided. Has a pair of pressing members that apply a pressing force to both outer surfaces of the metal damper at positions closer to the inner diameter side than the joint, and the pair of pressing members sandwich the metal damper. Are combined into a unit. (See summary)

JP 2009-264239 A

  In the above Patent Document 1, the structure in which the pressurization chamber and the low-pressure damper chamber are connected to each other by a communication passage from the fuel suction port is partly complicated, and is formed in a two-stage shape having different passage diameters. An eccentric structure that is not the same diameter is seen, which increases the number of processing steps. Therefore, an object of the present invention is to reduce the number of steps by shortening the processing time and to perform a processing method at the shortest position.

  In order to solve the above problems, the present invention provides a seal chamber whose volume is reduced when the plunger moves downward, a pump body in which a pressurizing chamber is formed, and a damper chamber on the suction side of the pressurizing chamber A pressure pulsation reducing mechanism disposed in the pump body, wherein the pump body is inserted into the pump body, and a seal chamber communication passage formed in the pump body and communicating the seal chamber and the damper chamber. A suction joint, and when viewed from the plunger axial direction, the shortest route direction in which the distance from the outermost peripheral end portion of the seal chamber communication path to the outer peripheral portion of the pump body is shortest, and the axial direction of the suction joint Were arranged so as to almost overlap.

  In the above high-pressure fuel supply pump, it is desirable that an extension when the seal chamber communication path is extended is formed so as to overlap the pressure pulsation reducing mechanism in a vertical sectional view. Further, when viewed from the plunger axis direction, the extension portion when the seal chamber communication path is extended is formed to overlap the pressure pulsation reducing mechanism in the horizontal direction. The pressure pulsation reducing mechanism 9 preferably has two diaphragms whose outer periphery is sealed by a welded portion. Furthermore, it is desirable that the outer peripheral portion of the extended portion when the seal chamber communication path is extended is formed at a position corresponding to the welded portion.

According to the present invention, the communication path is straight, and machining with the same shape shortens the machining time and improves the efficiency of the setup work, thereby reducing the cost.

1 shows a fuel supply system to which a high-pressure fuel supply pump of the present embodiment is applied. It is a longitudinal cross-sectional view of a high pressure fuel supply pump. It is comparison sectional drawing of the channel | path shape of the high pressure fuel supply pump by a present Example.

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

  A first embodiment of the present invention will be described.

First, the basic operation of the high-pressure fuel pump will be described with reference to FIGS.
FIG. 1 shows a fuel supply system including a high-pressure fuel supply pump.
FIG. 2 shows a longitudinal sectional view of the high-pressure fuel supply pump.
FIG. 3 shows a comparative cross-sectional view of the communication path shape.

  In FIG. 1, a portion surrounded by a broken line indicates a pump housing 1 of the high-pressure pump, and mechanisms and components shown in the broken line indicate that they are integrated into the pump housing 1 of the high-pressure pump. .

  The fuel in the fuel tank 20 is pumped up by the feed pump 21 based on a signal from an engine control unit 27 (hereinafter referred to as ECU), pressurized to an appropriate feed pressure, and passed through the suction pipe 28 to the suction port 10a of the high-pressure fuel supply pump. Sent to.

  In FIG. 2, a damper cover 14 is fixed to the head of the pump housing 1. The damper cover 14 is provided with a suction joint 101, which forms a low-pressure fuel suction port 10a. The fuel that has passed through the low-pressure fuel suction port 10a passes through the filter 102 fixed inside the suction joint 101, and passes through the low-pressure fuel passage 10b (damper chamber 10b), the pressure pulsation reduction mechanism 9, and the low-pressure fuel passages 10b and 10c (damper). It reaches the intake port 30a of the electromagnetic intake valve mechanism 30 via the chambers 10b, 10c).

  The suction filter 102 in the suction joint 101 serves to prevent foreign matter existing between the fuel tank 20 and the low-pressure fuel inlet 10a from being absorbed into the high-pressure fuel supply pump by the flow of fuel.

  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 30 b is not energized and there is no fluid differential pressure between the suction passage 10 c (suction port 30 a) 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.

  When the plunger 2 is in the suction process state in which the plunger 2 is displaced downward in FIG. 2 due to the rotation of the cam described later, 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 10c (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 ECU 27 is applied to the electromagnetic intake valve 30, an electric current flows through the electromagnetic coil 30b of the electromagnetic intake valve 30, and the electromagnetic plunger 30c is moved to the right in FIG. The spring 33 is maintained in a compressed state. 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 while maintaining the application state of the input voltage to the electromagnetic suction valve 30 and moves to the compression process in which the plunger 2 is displaced upward in FIG. 2, the magnetic urging force remains maintained. The suction valve body 31 remains open.

  Although the volume of the pressurizing chamber 11 decreases as the plunger 2 compresses, 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 10c (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 electromagnetic coil 30b is de-energized, 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 pressure in the fuel discharge port 12 or higher is reached, high pressure discharge of the fuel remaining in the pressurizing chamber 11 is performed via the discharge valve unit 8 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 30c of the electromagnetic suction valve 30. FIG.

  If the timing of releasing the energization of the electromagnetic coil 30c is advanced, the ratio of the return process is small during the compression process, and the ratio of the discharge process is large. That is, the amount of fuel returned to the suction passage 10c (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 10c is large, and the amount of fuel discharged at high pressure is small. The timing for releasing the energization of the electromagnetic coil 30c is controlled by a command from the ECU.

  By configuring as described above, the amount of fuel discharged at high pressure can be controlled to an amount required by the internal combustion engine by controlling the timing of releasing the energization of the electromagnetic coil 30c.

  Thus, the fuel guided to the fuel inlet 10a is pressurized to a high pressure by the reciprocating motion of the plunger 2 in the pressurizing chamber 11 of the pump body 1, and is pumped from the fuel outlet 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.

  A convex portion 1A as a pressurizing chamber 11 is formed at the center of the pump housing 1, 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. ing. Further, a hole 30A for mounting an electromagnetic suction 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 8. .

  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 in a direction intersecting, A discharge valve mechanism 8 for discharging fuel from the discharge passage 11 is provided. A cylinder 6 that guides the reciprocating motion of the plunger 2 is attached so as to face the pressurizing chamber.

  Next, the high-pressure fuel supply pump of the present invention will be described with reference to FIG. As shown in the left diagram of FIG. 3, in the configuration of FIG. 2, the fuel drawn from the suction passage 10 a on the inner peripheral side of the suction joint 101 flows through the low pressure damper chambers 10 b and 10 c through the filter 102. The fuel in the low pressure damper chamber 10 c reaches the suction port 30 a of the electromagnetic suction valve mechanism 30. On the other hand, the low pressure damper chamber 10c communicates with the seal chamber 10f through the seal chamber communication path 10d.

  As a result, when the plunger 2 moves downward, the volume of the seal chamber 10 f decreases, and the fuel in the seal chamber f flows into the seal chamber communication path 10 d, the low-pressure damper chamber 10 c, and the intake port 30 a of the electromagnetic intake valve mechanism 30. Therefore, the filling efficiency of the compression chamber 12 can be improved. On the other hand, in order to control the flow rate when the plunger 2 performs the upward movement, the above-described return step is configured. That is, the electromagnetic coil 30b is controlled so as to hold the electromagnetic intake valve 30 in the valve open position, but at this time, the volume of the seal chamber f increases due to the upward movement of the plunger 2. Then, since the return fuel from the pressurizing chamber 12 flows into the seal chamber f, the fuel flowing into the suction passage 10a of the suction joint 101 decreases, and the pressure pulsation here is reduced.

  Here, in this embodiment, the suction joint 101 is inserted into a hole formed in the horizontal direction of the pump body 1 as shown in the right view of FIG. 3. That is, the seal chamber communication path 10d is formed in the pump body 1 with the same shape φC substantially parallel to the plunger axis direction, but the suction joint 101 is inserted in a direction substantially perpendicular thereto. In the present embodiment, the suction joint 101 and the seal chamber communication path 10d are configured so that the central axis of the suction passage 10a of the suction joint 101 directly intersects the seal chamber communication path 10d.

  The pump body 1 has a substantially cylindrical shape, and the seal chamber communication path 10d is formed so as to communicate with the direction toward the seal chamber f (downward in FIG. 2) when viewed from the pressure pulsation reducing mechanism 9 side. Further, in the vertical cross-sectional view of FIG. 3, an extension when the seal chamber communication path 10 d is extended is formed to overlap the pressure pulsation reducing mechanism 9. Further, when viewed from the plunger axis direction, the extension portion when the seal chamber communication path 10d is extended is formed so as to overlap the pressure pulsation reducing mechanism 9 in the horizontal direction. In the pressure pulsation reducing mechanism 9, the outer periphery of the two diaphragms is sealed by the welded portion, but the outer peripheral portion of the extended portion when the seal chamber communication path 10d is extended is formed at a position corresponding to the welded portion.

  Further, when viewed from the plunger axial direction, the suction direction is such that the direction of the shortest route where the distance from the outermost peripheral end portion of the seal chamber communication passage 10d to the outer peripheral portion of the pump body 1 is the shortest and the axial direction of the suction joint 101 substantially overlap. The joint 101 is inserted into the pump body 1.

  As shown in FIG. 2, a recess 11 </ b> A is formed in the pump body 1 for mounting the discharge valve mechanism 8. The pump body 1 is formed with a mounting hole 30A for mounting the electromagnetic suction valve mechanism 30. In this embodiment, the recesses 11 </ b> A and the mounting holes 30 </ b> A have the same axis. According to this, the mounting hole 30A for mounting the electromagnetic suction valve mechanism 30 can be assembled straight into the mounting recess 11A of the discharge valve mechanism 8. Alternatively, a force for press-fitting the discharge valve mechanism 8 can be applied from the mounting hole 30A for mounting the electromagnetic suction valve mechanism 30. In this case, the diameter of the mounting hole 30A needs to be larger than the maximum outer diameter of the discharge valve mechanism 8 in the minimum diameter portion.

  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 is opened 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.

Also, the high pressure fuel supply pump is fixed to the engine by a flange integrated with the pump housing.

  The pump housing 1 is further provided with a relief passage 211 communicating with the downstream side of the discharge valve 8b and the suction passage 10c.

  The relief passage 211 is provided with a relief valve mechanism B200 that restricts the flow of fuel in only one direction from the discharge passage to the suction passage 10c, and the relief valve mechanism B200 has an inlet downstream of the discharge valve 8b through a passage (not shown). Communicated with the side.

  Hereinafter, the operation of the relief valve mechanism B200 will be described. The relief valve B202 is pressed against the relief valve seat B201 by a relief spring B204 that generates a pressing force, and when the pressure difference between the suction chamber and the relief passage exceeds a specified pressure, the relief valve B202 is moved to the relief valve seat. The set valve opening pressure is set so that the valve opens away from B201. Here, the pressure when the relief valve B202 starts to open is defined as the set valve opening pressure.

  The relief valve mechanism B200 includes a relief valve housing 206, a relief valve 202, a relief press 203, a relief spring 204, and a relief spring adjuster 205 that are integral with the relief valve seat B201. The relief valve mechanism 200 is assembled as a subassembly outside the pump housing 1 and then fixed to the pump housing 1 by press fitting. In this case, the valve opening pressure of the relief valve 200 is set to a pressure higher than the maximum pressure in the normal operation range of the high-pressure fuel supply pump.

  When the abnormal high pressure in the common rail 23 caused by the failure of the fuel injection valve that supplies fuel to the engine or the failure of the ECU 27 that controls the fuel injection valve, the high-pressure fuel supply pump, etc. exceeds the set opening pressure of the Lily valve The fuel passes through the relief passage 211 from the downstream side of the discharge valve 8b and reaches the relief valve B202. Then, the fuel that has passed through the relief valve B202 passes through the relief inner passage and is released to the suction passage 10c that is a low pressure portion. As a result, the high-voltage portion such as the common rail 23 is protected.

  The outer periphery of the cylinder 6 is held by a cylinder holder 7, and the cylinder holder 7 is held inside the pump housing 1. The cylinder 6 is fixed to the pump housing 1 via the cylinder holder 7 by screwing the screw threaded on the outer periphery of the cylinder holder 7 into the screw threaded on 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.

  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 a 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. The retainer 15 is fixed to the plunger 2 by press-fitting. As a result, the plunger 2 can be moved back and forth (reciprocated) up and down as the cam 5 rotates.

  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 is slidably in contact with the outer periphery of the plunger 2 at the lower end of the cylinder 6 in the figure. Is prevented from flowing into the tappet 3 side, that is, inside the engine. 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 body 1.

  Here, the suction passage 10c is connected to the seal chamber 10f via the seal chamber communication passage 10d and the throttle passage 10e provided in the cylinder 6 as shown in the left diagram of FIG. Connected to intake fuel pressure. When the fuel in the pressurizing chamber 11 is pressurized to a high pressure, a minute amount of high-pressure fuel flows into the seal chamber 10f through the sliding clearance between the cylinder 6 and the plunger 2, but the inflowed high-pressure fuel is released to the suction pressure. Therefore, the plunger seal 13 is not damaged by the high pressure.

  The plunger 2 includes a large-diameter portion 2 a that slides with the cylinder 6 and a small-diameter portion 2 b that slides with the plunger seal 13. The diameter of the large diameter portion 2a is set larger than the diameter of the small diameter portion 2b, and is set coaxially with each other. In the present embodiment, the diameter of the large diameter portion 2a is set to 10 mm, and the diameter of the small diameter portion 2b is set to 6 mm. By doing so, it is possible to reduce the pressure pulsation on the low-pressure side that occurs on the low-pressure side upstream of the electromagnetic suction valve 30 as the plunger moves up and down.

DESCRIPTION OF SYMBOLS 1 ... Pump housing, 2 ... Plunger, 8 ... Discharge valve mechanism, 9 ... Pressure pulsation reduction mechanism, 10c ... Suction passage, 11 ... Pressurization chamber, 12 ... Discharge passage, 20 ... Fuel tank, 23 ... Common rail, 24 ... Injector , 26 ... Pressure sensor, 30 ... Electromagnetic suction valve mechanism, 200 ... Relief valve mechanism, 201 ... Relief valve,

Claims (4)

A seal chamber whose volume decreases when the plunger moves downward;
A pump body in which a pressurizing chamber is formed;
A pressure pulsation reducing mechanism disposed in a damper chamber on the suction side of the pressurizing chamber;
A seal chamber communication passage formed in the pump body and communicating the seal chamber and the damper chamber;
A suction joint inserted into the pump body,
When viewed from the plunger axial direction, the shortest route direction in which the distance from the outermost peripheral end portion of the seal chamber communication passage to the outer peripheral portion of the pump body is the shortest and the axial direction of the suction joint are substantially overlapped. High pressure fuel supply pump. The high-pressure fuel supply pump according to claim 1,
In the vertical cross-sectional view, the high-pressure fuel supply pump is formed such that an extension portion when the seal chamber communication path is extended overlaps the pressure pulsation reduction mechanism. The high-pressure fuel supply pump according to claim 1,
When viewed from the plunger axis direction, an extension when the seal chamber communication path is extended is formed to overlap the pressure pulsation reducing mechanism in the horizontal direction. The pressure pulsation reducing mechanism 9 is a high-pressure fuel supply pump in which two diaphragms are sealed at the outer periphery with a welded portion. The high-pressure fuel supply pump according to claim 1,
A high-pressure fuel supply pump in which an outer peripheral portion of an extension when the seal chamber communication path is extended is formed at a position corresponding to a welded portion.

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