JP2007218212A - High pressure fuel supply pump and high pressure discharge joint used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive high pressure fuel supply pump capable of sealing fuel by an easily replaceable elastic body, since there is a case of being obliged to replace a pipe being a metal contact part and a high pressure fuel supply pump itself, due to having risk of damaging a seal surface, when removing the pipe from the high pressure fuel supply pump. <P>SOLUTION: An orifice part is arranged between a fuel pipe and a seal part, and can be attained by reducing pressure pulsation directly acting on the seal part. This invention can supply the inexpensive high pressure fuel supply pump with a highly reliable fuel seal structure, by sealing a high pressure fuel discharge pipe part by the easily replaceable elastic body, without requiring a special device for reducing pulsation in a high pressure pipe part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high pressure fuel supply pump that supplies pressurized fuel to a fuel injection valve of an internal combustion engine and a high pressure discharge joint used therefor.

  As a seal structure for the connection portion between the high-pressure fuel supply pump and the fuel pipe, in an environment where pressure pulsation occurs in the pipe, a structure in which the high-pressure fuel supply pump and the pipe are in metal contact to seal fuel has been used.

US Pat. No. 6,671,706 Japanese Patent Laid-Open No. 11-343945

  In the above conventional example, when the pipe is removed from the high-pressure fuel supply pump, there is a risk of damaging the sealing surface, and the pipe serving as the metal contact portion and the high-pressure fuel supply pump itself may have to be replaced.

  An object of the present invention is to provide a low-cost high-pressure fuel supply pump that can seal fuel with an elastic body that can be easily replaced.

  The above object of the present invention can be achieved by providing a throttle portion between the high pressure fuel passage in the fuel pipe and the seal portion to reduce pressure pulsations that act directly on the seal portion.

  According to the present invention, there is no need for a device for reducing pipe pulsation, and it is possible to seal fuel with an elastic body that can be easily replaced, and a low-cost high-pressure fuel supply pump with a highly reliable fuel seal structure. Can be supplied.

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

  FIG. 1 shows a vertical section of the entire pump, and FIG. 2 shows a fuel injection system configuration diagram.

  A fuel suction passage 10, a discharge passage 11, a pressurizing chamber 12, and a return passage 41 are formed in the pump body 1. The suction passage 10 and the discharge passage 11 are provided with a suction valve 5 and a discharge valve 6, respectively, which are held in one direction by springs 5a and 6a, respectively, and serve as check valves that limit the direction of fuel flow. . The pressurizing chamber 12 is formed by a pump chamber 12 a in which the plunger 2 as a pressurizing member slides, a suction hole 5 b communicating with the suction valve 5, and a discharge hole 6 b communicating with the discharge valve 6. The return passage 41 passes through the gap between the plunger 2 and the cylinder 20 and is connected to the lateral hole passage 21 a of the cylinder holder 21.

  A solenoid 200 is held in the pump body 1 in the suction chamber 10a, and an engaging member 201 and a spring 202 are disposed on the solenoid 200. When the solenoid 200 is OFF, the engaging member 201 is biased by a spring 202 in a direction to open the suction valve 5. Since the biasing force of the spring 202 is larger than the biasing force of the suction valve spring 5a, when the solenoid 200 is OFF, the suction valve 5 is in an open state as shown in FIG. The fuel is led from the tank 50 to the fuel inlet of the pump body 1 by the low-pressure pump 51, adjusted to a constant pressure by the pressure regulator 52. After that, the pump body 1 is pressurized and is pumped from the fuel discharge port to the common rail 53. An injector 54, a relief valve 55, and a pressure sensor 56 are attached to the common rail 53. The injectors 54 are mounted in accordance with the number of cylinders of the engine and inject with signals from an engine control unit (ECU) 40. The relief valve 55 opens when the pressure in the common rail 53 exceeds a predetermined value, and prevents damage to the piping system.

  With the above configuration, the operation will be described below.

  A lifter 3 provided at the lower end of the plunger 2 is pressed against a cam 7 by a spring 4. The plunger 2 is slidably held by the cylinder 20 and reciprocates by the cam 7 rotated by an engine cam shaft or the like to change the volume in the pressurizing chamber 12.

  There is a plunger seal 30 that prevents fuel leaking from the gap between the plunger 2 and the cylinder 20 from flowing out to the cam 7 side during the reciprocating motion of the plunger 2. The fuel whose leakage is prevented by the plunger seal 30 can return the fuel to the tank 50 from the side hole passage 21a of the cylinder holder through the return passage 41.

  A rubber X-ring 31 is provided downstream of the plunger seal 30 to prevent the lubricating oil supplied to the sliding portion of the cam 7 and the lifter 3 from flowing into the pump.

  When the suction valve 5 is closed during the compression process of the plunger 2, the pressure in the pressurizing chamber 12 rises, whereby the discharge valve 6 is automatically opened and the fuel is pumped to the common rail 53.

  The suction valve 5 is automatically opened when the pressure in the pressurizing chamber 12 becomes lower than the fuel inlet, but the closing is determined by the operation of the solenoid 200.

  When the solenoid 200 is kept in the ON (energized) state, an electromagnetic force greater than the urging force of the spring 202 is generated, and the engaging member 201 is pulled toward the solenoid 200, so that the engaging member 201 and the suction valve 5 are separated. The In this state, the intake valve 5 is an automatic valve that opens and closes in synchronization with the reciprocating motion of the plunger 2. Therefore, during the compression process, the suction valve 5 is closed, and the fuel corresponding to the volume reduction of the pressurizing chamber 12 pushes the discharge valve 6 and is pumped to the common rail 53.

  On the other hand, when the solenoid 200 is kept OFF (non-energized), the engagement member 201 is engaged with the suction valve 5 by the biasing force of the spring 202, and the suction valve 5 is held in the open state. Accordingly, even during the compression process, the pressure in the pressurizing chamber 12 is maintained at a low pressure that is substantially equal to that of the fuel introduction port, so that the discharge valve 6 cannot be opened, and the volume reduction of the pressurizing chamber 12 The fuel is returned to the fuel inlet side through the intake valve 5.

  Further, if the solenoid 200 is turned on during the compression process, the fuel is fed to the common rail 53 from this time. In addition, once the pressure feeding is started, the pressure in the pressurizing chamber 12 is increased. Thereafter, even if the solenoid 200 is turned off, the suction valve 5 is maintained in the closed state, and the suction process is automatically performed in synchronization with the start. Open the valve.

  Next, referring to FIG. 1 and FIG. 3, the high pressure discharge joint and the discharge valve unit are fixed to the pump body, and the high pressure discharge joint, the high pressure pipe having the high pressure fuel passage, and the high pressure discharge joint are connected to the high pressure pipe. The structure of the connecting portion connected by the members and the fuel seal structure inside the connecting portion will be described.

  FIG. 3 shows an enlarged view of the sealing structure of the connecting portion between the pipe connected to the common rail 53 and the high-pressure fuel supply pump.

  The pump body 1 and the common rail 53 have a seal structure in which a joint 42 fastened to the pump body 1 and a high-pressure pipe connecting member 46 connected to the common rail 53 are fitted.

  The joint 42 has a built-in discharge valve 6 that restricts the flow direction of fuel, a threaded portion 71 for fastening with the pump body 1, a cylindrical resin material 44, an elastic body 43, and a backup ring from the distal end side of the joint 42. A groove for mounting in the order of 45 and a discharge passage 11 which is a passage of fuel discharged from the pump are constituted.

  A threaded portion 71 is formed on the outer periphery of the distal end portion of the joint 42, and the joint 42 is fastened to the pump body 1 by the threaded portion 71.

  The metal spacer 70 </ b> A is sandwiched between the valve seat 60 </ b> B and the pump body 1. A cylindrical projection to be inserted into the discharge hole 6b of the pump body 1 is provided at the center of the metal spacer 70A.

  The discharge valve 6 is held between the valve seat 60B and the valve holder 60. The valve holder 60 is formed with a head portion guided by the tubular portion of the valve seat 60B and a stopper portion 60C for regulating the stroke of the discharge valve 6.

  It is inserted and fixed to the inner wall surface 42A of the fuel discharge passage formed inside the cylindrical portion 60D of the valve seat 60B.

The tip end surface portion of the joint 42 faces the gasket 70 and the valve seat 60. When the screw portion 71 is screwed into the screw portion of the pump body 1, the tip end surface of the joint 42 presses the gasket 70, the valve seat 60B and the spacer 60A against the pump body. And fix. As a result, leakage from the joint 42 between the joint 42 and the pump body 1 is sealed by the gasket 70.

  The spring 6a is arranged around the stopper portion 60C of the valve holder 60, one end abuts against the head of the valve holder 60, and the other end is held by the spring holder 60E. The spring holder 60E is inserted into and fixed to the inner wall surface 42A of the discharge passage portion formed in the inner portion of the screw portion 71 along with the cylindrical portion 60D of the valve seat 60B in order at the center of the joint 42. .

  The fitting portion between the joint 42 and the high-pressure pipe connecting member 46 has a structure in which the elastic body 43 is disposed and sealed in a cylindrical groove 72 surrounded by the outer diameter of the joint 42 and the inner diameter of the high-pressure pipe connecting member 46. . A backup ring 45 is provided next to the elastic body 43 to prevent the elastic body 43 from protruding from the fitting portion gap between the joint 42 and the high-pressure pipe connecting member 46 due to high-pressure fuel. The high-pressure pipe connecting member 46 is fixed to the pump body 1 with a bolt 46A.

  In this embodiment, the fuel pressure pulsation in the high-pressure fuel passage directly acts on the elastic body 43 to prevent the wall surface of the cylindrical groove 72 and the elastic body 43 from sliding and wearing. The throttle part for reducing the fuel pressure pulsation is formed. The throttle portion is formed by mounting a cylindrical resin material 44 in a groove provided at the tip of the joint 42, and is a gap formed between the outer diameter of the cylindrical resin material 44 and the inner diameter of the high-pressure pipe. It has a structure to narrow down.

  With this throttle structure, it has been confirmed that the fuel pressure pulsation acting on the elastic body 43 suppresses the pressure amplitude to about ½ or less at a pump rotational speed of 3000 r / min.

  When the cylindrical resin material 44 is mounted in the groove of the joint 42, it is necessary to expand the inner diameter of the resin material 44 and further correct the outer diameter of the resin material 44 that has been expanded after mounting. The attachment to the joint 42 can be improved by forming a cross-sectional C shape by cutting one portion of the material 44.

  FIG. 4 shows an example in which a throttle structure is formed by an end surface gap 47 formed between the tip of the joint 42 and the high-pressure pipe brought into contact therewith. The end face gap 47 is a drawing structure using gap leakage at the contact portion. The structure can be simplified, each contact surface can be used as a normal processing surface, and the drawing portion can be formed at low cost. .

  FIG. 5 shows an example in which a throttle structure is formed by a cylindrical circumferential gap 48 formed between the tip of the joint 42 and the high-pressure pipe brought into contact therewith.

  Further, when the fuel pressure or pulsation is large, in order to use an easily replaceable elastic body as the seal member, a device for reducing the pressure pulsation in the pipe is necessary. On the other hand, according to the present embodiment, the throttle structure that reduces the pressure pulsation acting on the fuel seal portion is arranged in the vicinity of the seal portion, so that the fuel can be sealed with an elastic body that can be easily replaced. An inexpensive high-pressure fuel supply pump can be provided.

  Further, since the high pressure pipe connecting member 46 is directly fixed to the pump body by the bolt 46A, the external force acting on the high pressure pipe connecting member 46 is not applied to the screw portion 71 of the discharge joint 42, and the screw portion 71 is loosened. And damage can be prevented.

  Further, since the force for removing the high-pressure pipe connection member 46 is small, no excessive force is applied to the screw portion of the discharge joint 42, and the screw portion 71 is not loosened or damaged in the same manner as described above. .

  Further, the high-pressure pipe connection member 46 also functions as a stopper for the discharge joint 42, and the safety is increased accordingly.

  The present invention is suitable as a high-pressure fuel pump of an internal combustion engine that pressurizes fuel to a high pressure and sends it to a common rail, and a discharge joint used therefor.

It is the figure which showed the vertical cross section of the whole pump. 1 is a system diagram showing a configuration of a fuel injection system. It is an enlarged view of the connection part of a high pressure joint and high pressure piping. It is an enlarged view which shows another Example of the connection part of a high pressure joint and high pressure piping. It is an enlarged view which shows other Example of the connection part of a high pressure joint and high pressure piping.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pump main body, 2 ... Plunger, 3 ... Lifter, 4, 5a, 6a, 202 ... Spring, 5 ... Suction valve, 5b ... Suction hole, 6 ... Discharge valve, 6b ... Discharge hole, 7 ... Cam, 10 ... Suction Passage, 10a ... suction chamber, 11 ... discharge passage, 12 ... pressurization chamber, 12a ... pump chamber, 20 ... cylinder, 21 ... cylinder holder, 21a ... side hole passage, 30 ... plunger seal, 31 ... X-ring, 40 ... engine Control unit (ECU) 41 ... return passage 42 ... joint 43 ... elastic body 44 ... resin material 45 ... backup ring 46 ... high-pressure pipe connecting member 47 ... end face gap 48 ... circumferential gap 50 ... Tank, 51 ... Low pressure pump, 52 ... Pressure regulator, 53 ... Common rail, 54 ... Injector, 55 ... Relief valve, 56 ... Pressure sensor, 70 ... Gasket, 71 ... Parts, 72 ... cylindrical groove, 200 ... solenoid, 201 ... engaging member.

Claims (10)

Having a high-pressure discharge joint with a high-pressure fuel passage fixed to the pump body;
In the high-pressure discharge joint, a high-pressure pipe provided with a high-pressure fuel passage is connected by a high-pressure pipe connecting member,
An elastic seal member is provided on the outer periphery of the high-pressure discharge joint,
The high-pressure pipe connection member is concentrically connected to the outer periphery of the high-pressure discharge joint across the seal member,
A high-pressure fuel supply pump in which a throttle portion is formed between a surface of the seal member on which high-pressure fuel pressure acts and the high-pressure fuel passage. In claim 1,
A high-pressure fuel supply pump in which a discharge valve unit is mounted between the high-pressure discharge joint and the pump body. In claim 2,
A high-pressure fuel supply pump in which the discharge valve unit is disposed inside the high-pressure discharge joint. In claim 1,
The high-pressure fuel supply pump, wherein the seal member includes a ring having a circular cross section having elasticity and a backup ring having a rectangular cross section. In claim 1,
The high-pressure fuel supply pump, wherein the throttle portion is formed by a cylindrical gap formed between an outer peripheral portion of the joint and an inner peripheral portion of the high-pressure pipe connecting member. What is described in claim 5
A high-pressure fuel supply pump in which the cylindrical gap is formed between a cylindrical resin material attached to an outer peripheral portion of the high-pressure discharge joint and an inner peripheral portion of the high-pressure pipe connecting member. In claim 1,
A high-pressure fuel supply pump in which the throttle portion is formed by an annular gap formed between an outlet-side front end surface of the joint and an inner wall of the high-pressure pipe connecting member facing the joint. In claim 1,
The high-pressure pipe connection member is a high-pressure fuel supply pump fixed to the pump body by bolts. In claim 1,
The high-pressure discharge joint has a threaded portion at one end outer peripheral portion, and the threaded portion is screwed into a threaded portion provided in the pump body and fixed. A threaded portion for screwing and fixing to the pump body is formed on the outer periphery of one end, an annular seal member is attached to the outer periphery of the other end, and the other wall is close to the inner wall surface of the high-pressure pipe connecting member The high-pressure discharge joint used for the high-pressure fuel pump according to claim 1, wherein the high-pressure fuel pump has an end face or an outer peripheral face forming a gap.

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