JP6681448B2 - High pressure fuel supply pump - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-pressure fuel supply pump, and more particularly to a cup-shaped cylinder.

  In the high-pressure fuel supply pump described in Japanese Patent Publication No. 2007-231959, a cup (in Japanese Patent Publication No. 2007-231959, referred to as a plug) and an inner cylindrical surface (inner peripheral surface) provided in a recess of the pump housing are provided. A structure is disclosed in which a pressurizing chamber is formed by fitting a cylindrical cylinder, and the cylinder including this cup is configured to be pressed and fixed to the inner peripheral surface of the pump housing by the screw thrust of the cylinder holder. There is. Further, it is described that the cup and the cylinder may have an integrated structure.

Patent Publication 2007-231959

  However, the cup and the cylinder fitted to the inner cylindrical surface (inner peripheral surface) of the pump housing cannot be fixed unless they are pressed and held by a thrust force by another member such as a cylinder holder.

  Therefore, it is necessary to provide the cylinder holder in the lower part of the pump housing, which increases the number of parts and the size of the high-pressure fuel supply pump as a whole.

  Since pressure is applied to the cylinder used as a part of the pressurizing chamber in the direction of coming out of the pump housing when pressurizing the fuel, it is necessary to increase the fixing force of the cylinder holder as the discharge pressure of the fuel increases. Therefore, there is a concern that the cylinder holder will be large and complicated.

  In order to solve the above problems, an object of the present invention is to provide a high-pressure fuel supply pump that is low in cost, small in size, light in weight, high in pressure, and highly reliable.

In the high-pressure fuel supply pump according to the present invention, a cylindrical cylinder having a bottom, in which a ceiling portion and a cylindrical portion are integrally formed, a plunger arranged so as to reciprocate in the cylinder, and the inner peripheral surface side having the above-mentioned A pump housing in which a cylinder is housed, wherein the cylinder has a sliding portion on the inner peripheral surface of the tubular portion on which the plunger slides, and the ceiling side is the tip side in the press-fitting direction. Is press-fitted and fixed to the inner peripheral surface of the pump housing, and the plunger has a large diameter portion arranged on the inner peripheral side of the sliding portion and a small diameter portion having an outer diameter smaller than the large diameter portion. However , the pump housing has an intake passage for replacing the fuel in contact with the small diameter portion of the plunger on the opening end side of the cylinder and the fuel on the low pressure fuel chamber side into which the low pressure fuel sucked from the intake joint flows. is formed, the sheet The second press-fitting portion is provided with a first press-fitting portion that abuts the inner peripheral surface of the pump housing on an outer peripheral surface of the ceiling portion, and abuts a convex portion formed on the inner peripheral surface of the pump housing. Is provided on the outer peripheral surface of the tubular portion, and the convex portion is provided on the inner peripheral surface of the pump housing at a position further away from the opening end in the press-fitting direction .

  The high-pressure fuel supply pump according to the present invention is configured as described above, and thus provides a high-pressure fuel supply pump that is low in cost and highly reliable even when the fuel discharge pressure (pressure in the pressurizing chamber) is increased. be able to.

1 is an example of a fuel supply system using a high pressure fuel supply pump according to a first embodiment of the present invention. 1 is a vertical cross-sectional view of a high pressure fuel supply pump according to a first embodiment of the present invention. FIG. 3 is a vertical cross-sectional view of the high-pressure fuel supply pump according to the first embodiment of the present invention, showing a vertical cross section with respect to FIG. 2. 2 shows the dimensions of the plunger 2 and the cylinder of the high-pressure fuel supply pump according to the first embodiment of the present invention. FIG. 4 is an enlarged view of the electromagnetic suction valve mechanism 30 of the high-pressure fuel supply pump according to the first embodiment of the present invention, showing a state in which the electromagnetic coil 52 is not energized. FIG. 4 is an enlarged view of the electromagnetic suction valve mechanism 30 of the high-pressure fuel supply pump according to the first embodiment of the present invention, showing a state in which the electromagnetic coil 52 is energized. It is an enlarged view of the electromagnetic suction valve mechanism 30 of the high-pressure fuel supply pump according to the conventional example, and shows a state in which the electromagnetic coil 52 is not energized. FIG. 3 shows a state where the electromagnetic suction valve mechanism 30 of the high-pressure fuel supply pump according to the first embodiment of the present invention is installed in the pump housing 1 before being installed. 1 is an external view of a flange 41 and a bush 43 of a high pressure fuel supply pump according to a first embodiment of the present invention. In this figure, only the flange 41 and the bush 43 are shown, and other parts are not shown. The enlarged view of the welding part 41a vicinity of the high pressure fuel supply pump by 1st Example by which this invention was implemented is shown. The high pressure fuel supply pump by 1st Example by which this invention was implemented, the enlarged view of the welding part 41a vicinity is shown, and is expanded rather than FIG. FIG. 5 is a vertical cross-sectional view of a high pressure fuel supply pump according to a second embodiment of the present invention. FIG. 6 is a vertical sectional view of a high-pressure fuel supply pump according to a third embodiment of the present invention. FIG. 7 is a vertical cross-sectional view of a high pressure fuel supply pump according to a fourth embodiment of the present invention. FIG. 9 is a cross-sectional view of a high pressure fuel supply pump according to a fifth embodiment of the present invention. FIG. 16 is a cross-sectional view of a high-pressure fuel supply pump according to a fifth embodiment of the present invention, showing a cylinder fixing position different from that of FIG. 15.

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

  An embodiment of the present invention will be described with reference to FIGS. 1 to 11.

  In FIG. 1, 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 show that the pump housing 1 of the high-pressure pump is integrally incorporated. .

  The fuel in the fuel tank 20 is pumped up by a 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 introduced through a suction pipe 28 into a suction port 10a of the high-pressure fuel supply pump. Sent to.

  The fuel that has passed through the suction port 10a passes through the filter 102 fixed in the suction joint 101, and further, via the suction passage 10b, the metal diaphragm damper 9, and the low-pressure fuel chamber 10c, an electromagnetic drive type The intake port 30a of the valve mechanism 30 is reached.

  The suction filter 102 in the suction joint 101 has a function of preventing foreign substances existing between the fuel tank 20 and the suction port 10a from being absorbed in the high-pressure fuel supply pump by the flow of fuel.

  FIG. 4 is an enlarged view of the electromagnetic suction valve mechanism 30, showing a non-energized state in which the electromagnetic coil 53 is not energized.

  FIG. 5 is an enlarged view of the electromagnetic suction valve mechanism 30, showing a state in which the electromagnetic coil 53 is energized.

  A recess 1A for accommodating a cylinder 6 including a pressurizing chamber 11 is formed in the center of the pump housing 1, and a hole 30A for mounting the electromagnetic suction valve mechanism 30 is formed so as to communicate with the pressurizing chamber 11. Has been done.

  The plunger rod 31 is composed of three parts: a suction valve portion 31a, a rod portion 31b, and an anchor fixing portion 31c, and an anchor 35 is welded and fixed to the anchor fixing portion 31c by a welding portion 37b.

  The spring 34 is fitted into the inner circumference 35a of the anchor and the inner circumference 33a of the first core portion as shown in the figure, and the spring force is generated by the spring 34 in the direction of separating the anchor 35 and the first core portion 33 from each other.

  The valve seat 32 includes a suction valve seat portion 32a, a suction passage portion 32b, a press-fitting portion 32c, and a sliding portion 32d. The press-fitting portion 32c is press-fitted and fixed to the first core portion 33. The intake valve seat portion 32a is press-fitted and fixed to the pump housing 1, and the press-fitting portion completely shuts off the pressurizing chamber 11 and the intake port 30a.

  The first core portion 33 is welded and fixed to the pump housing 1 by a welded portion 37c, and isolates the suction port 30a from the outside of the high-pressure fuel supply pump.

  The second core portion 36 is fixed to the first core portion 33 by the welded portion 37a, and completely shuts off the internal space and the external space of the second core portion 36. Further, the second core portion 36 is provided with a magnetic orifice portion 36a.

  When the electromagnetic coil 53 is not energized and in a non-energized state, and when there is no fluid pressure difference between the suction passage 10c (suction port 30a) and the pressurizing chamber 11, the plunger rod 31 is moved by the spring 34 to As shown in FIG. 4, it is moved to the right in the figure. In this state, the intake valve portion 31a and the intake valve seat portion 32a are in a closed state and the intake port 38 is closed.

  When the plunger 2 is in the suction process state in which it is displaced downward in FIG. 2 due to the rotation of the cam 5, which will be described later, the volume of the pressurizing chamber 11 increases and the fuel pressure in the pressurizing chamber 11 decreases. In this process, when the fuel pressure in the pressurizing chamber 11 becomes lower than the pressure in the low pressure fuel chamber 10c (intake port 30a), the intake valve portion 31a has a valve opening force due to the fluid pressure difference of the fuel (intake valve portion 31a The force to displace to the left of 1) is generated.

  Due to the valve opening force due to this fluid pressure difference, the suction valve portion 31a is set to overcome the biasing force of the spring 34 to open the valve and open the suction port 38. When the fluid pressure difference is large, the suction valve portion 31a is completely opened and the anchor 31 is in contact with the first core portion 33. When the fluid pressure difference is small, the suction valve portion 31a does not open completely and the anchor 31 does not contact the first core portion 33.

  In this state, when the control signal from the ECU 27 is applied to the electromagnetic suction valve mechanism 30, a current flows through the electromagnetic coil 53 of the electromagnetic suction valve mechanism 30, and between the first core portion 33 and the anchor 31, A magnetic biasing force that attracts each other is generated. As a result, a magnetic biasing force is applied to the plunger rod 31 to the left in the figure.

  When the suction valve portion 31a is completely open, the valve open state is maintained. On the other hand, when the suction valve portion 31a is not completely opened, the valve opening movement of the suction valve portion 31a is promoted and the suction valve portion 31a is completely opened, so that the anchor 31 is in contact with the first core portion 33, After that, the state is maintained.

  As a result, the state where the suction valve portion 31a opens the suction port 38 is maintained, and the fuel flows from the suction port 30a through the suction passage portion 32b of the valve seat 32 and the suction port 38 into the pressurizing chamber 11.

  When the plunger 2 finishes the suction process while maintaining the state of applying the input voltage to the electromagnetic suction valve mechanism 30 and shifts to the compression process in which the plunger 2 is displaced upward in FIG. 2, the magnetic biasing force is still maintained. The suction valve section 31a is still open.

  The volume of the pressurizing chamber 11 decreases with the compression movement of the plunger 2. In this state, the fuel once sucked into the pressurizing chamber 11 again passes through the intake port 38 in the valve opened state (intake channel 10c (suction)). Since it is returned to the port 30a), the pressure in the pressurizing chamber does not rise. This process is called a returning process.

  In this state, when the control signal from the ECU 27 is released and the energization of the electromagnetic coil 53 is cut off, the magnetic biasing force acting on the plunger rod 31 is fixed time (after magnetic and mechanical delay time). Erased. Since the biasing force of the spring 34 acts on the suction valve portion 31a, when the electromagnetic force acting on the plunger rod 31 disappears, the suction valve portion 31a closes the suction port 38 by the biasing force of the spring 34. When the suction port 38 is closed, the fuel pressure in the pressurizing chamber 11 increases from this time with the upward movement of the plunger 2. Then, when the pressure exceeds the pressure of the fuel discharge port 12, high pressure discharge of the fuel remaining in the pressurizing chamber 11 is performed via the discharge valve unit 8 and is supplied to the common rail 23. This process is called a discharge process. That is, the compression process of the plunger 2 (the rising process from the lower start point to the upper start point) includes a returning process and a discharging process.

  The amount of high-pressure fuel discharged can be controlled by controlling the timing at which the electromagnetic coil 53 of the electromagnetic suction valve mechanism 30 is de-energized.

  If the timing of releasing the power supply to the electromagnetic coil 53 is advanced, the ratio of the returning process is small and the ratio of the discharging process is large during the compression process.

  That is, less fuel is returned to the intake passage 10c (intake port 30a), and more fuel is discharged under high pressure.

  On the other hand, if the timing of releasing the input voltage is delayed, the ratio of the returning process in the compression process is large and the ratio of the discharging process is small. That is, a large amount of fuel is returned to the suction passage 10c, and a small amount of fuel is discharged under high pressure. The timing of releasing the power supply to the electromagnetic coil 53 is controlled by a command from the ECU.

  With the above configuration, the amount of fuel discharged at high pressure can be controlled to the amount required by the internal combustion engine by controlling the timing at which the power supply to the electromagnetic coil 53 is released.

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

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

  At this time, the suction valve portion 31a repeats the opening / closing motion of the suction port 38 as the plunger 2 moves down and up, and the plunger rod 31 repeats the horizontal motion in the figure. At this time, the movement of the plunger rod 31 is limited to the movement in the left-right direction in the figure by the sliding portion 32d of the valve seat 32, and the sliding portion 32d and the rod portion 31b repeat the sliding movement. Therefore, the sliding portion needs to have a sufficiently low surface roughness so as not to resist the sliding movement of the plunger rod 31. The selection of the sliding clearance is as follows.

  If the clearance is too large, the plunger rod 31 touches the sliding portion like a pendulum, and the anchor 35 and the second core portion 36 come into contact with each other. If the plunger rod 31 makes a sliding movement, the anchor 35 and the second core portion 36 will also slide, so that the resistance of the sliding movement of the plunger rod 31 increases and the responsiveness of the opening / closing movement of the suction port 38 deteriorates. Become. Further, since the anchor 35 and the second core portion 36 are made of ferritic magnetic stainless steel, abrasion powder or the like may be generated when sliding. Further, as will be described later, the smaller the gap between the anchor 35 and the second core portion 36, the greater the magnetic biasing force. If the gap is too large, the magnetic biasing force is insufficient and the amount of fuel discharged at high pressure cannot be controlled appropriately. For these reasons, it is necessary that the gap between the anchor 35 and the second core portion 36 be as small as possible and not be in contact with each other.

  Therefore, the number of sliding portions is one, and the sliding length L of the sliding portion 32d is sufficiently long as shown in the figure. The sliding portion is formed by the inner diameter of the sliding portion 32d and the outer shape of the rod portion 31b. However, both of them require a tolerance when machining, and a clearance of the sliding portion also requires a tolerance. On the other hand, the clearance between the anchor 35 and the second core portion 36 has an upper limit value due to the magnetic biasing force as described above. In order to absorb the clearance tolerance and prevent the anchor 35 and the second core portion 36 from coming into contact with each other, the sliding length L may be increased to reduce the pendulum motion.

  As a result, when the plunger rod 31 tries to make a pendulum movement, the sliding portion 32d and the rod portion 31b contact and slide at both ends of the sliding portion, so the gap between the anchor 35 and the second core portion 36 is reduced. It has become possible.

  If the clearance is too small, the suction valve portion 31a and the suction valve seat portion 32a do not come into full surface contact when the suction port 38 is closed. This is because the verticality between the intake valve portion 31a and the rod portion 31b of the plunger rod 31 and the verticality between the intake valve seat portion 32a and the sliding portion 32d of the valve seat 32 cannot be absorbed by the clearance of the sliding portion. . If the suction valve portion 31a and the suction valve seat portion 32a do not completely come into surface contact with each other, excessive torque may be applied to the plunger rod 31 due to the high pressure fuel in the pressurizing chamber 11 that is high in pressure during the discharge process, and the plunger rod 31 may be damaged. There is. Further, an excessive load may be applied to the sliding portion, and the sliding portion may be damaged or worn.

  For these reasons, it is necessary that the suction valve portion 31a and the suction valve seat portion 32a be in full surface contact with each other when the suction port 38 is closed. Particularly, if the pendulum movement of the plunger rod 31 is suppressed by increasing the sliding length L as described above, the verticality of the suction valve portion 31a and the rod portion 31b of the plunger rod 31, and the suction of the valve seat 32. The accuracy required for the verticality of the valve seat portion 32a and the sliding portion 32d becomes high.

  Therefore, the intake valve seat portion 32a and the sliding portion 32d are provided on the valve seat 32. The intake valve seat portion 32a and the sliding portion 32d are made of the same member, and the verticality of the intake valve seat portion 32a and the sliding portion 32d can be accurately adjusted. If the suction valve seat portion 32a and the sliding portion 32d are separate members, a factor that deteriorates the squareness inevitably occurs in the portion to be processed / joined, but the suction valve seat portion 32a and the sliding portion 32d should be a single member. Will solve this problem.

  If the magnetic biasing force generated when the magnetic coil 53 is energized is insufficient, the amount of fuel discharged at high pressure cannot be controlled appropriately. Therefore, the magnetic circuit formed around the magnetic coil 53 must generate a sufficient magnetic biasing force.

  For that purpose, it is necessary to make the magnetic circuit such that more magnetic flux flows when the magnetic coil 53 is energized and a magnetic field is generated around it. Generally, the thicker and shorter the magnetizing path is, the smaller the magnetic resistance is, so that the magnetic flux passing through the magnetic circuit is increased and the generated magnetic biasing force is also increased.

  In this embodiment, the members constituting the magnetic circuit are the anchor 35, the first core portion 33, the yoke 51, and the second core portion 36, as shown in FIG. 5, all of which are magnetic materials.

  Although the first core portion 33 and the second core portion 36 are joined by welding at the welded portion 37a, the magnetic flux does not directly pass between the first core portion 33 and the second core portion 36, and the anchor 35 is interposed. Need to pass through. This is for generating a magnetic biasing force between the first core portion 33 and the anchor 35, and the magnetic flux directly passes between the first core portion 33 and the second core portion 36, and the magnetic flux passing through the anchor. If is reduced, the magnetic biasing force is reduced.

  Therefore, in the conventional structure, the intermediate member is provided between the first core portion 33 and the second core portion 36. Since this intermediate member is a non-magnetic material, magnetic flux does not directly pass between the first core portion 33 and the second core portion 36, but all magnetic flux passes through the anchor 35.

  However, when the intermediate member is provided, the number of parts increases, and it is necessary to join the intermediate member and the first core portion 33 and the second core portion 36, respectively, so that there is a problem that the cost increases.

  Therefore, in this embodiment, the first core portion 33 and the second core portion 36 are directly joined by the welded portion 37, and the magnetic orifice portion 36a is provided in the second core portion. The magnetic orifice portion 36a is as thin as possible in terms of strength, while the other portions of the second core portion 36 are sufficiently thick. Further, the magnetic orifice portion 36a is provided near the portion where the first core portion and the anchor 35 are in contact with each other.

  As a result, most of the generated magnetic flux passes through the anchor 37, and the magnetic flux that directly passes through the first core portion 33 and the second core portion is extremely small, which is generated between the first core portion 33 and the anchor 35. The decrease in the magnetic biasing force is within the allowable range.

  When the first core portion 33 and the anchor 35 are in contact with each other, the largest gap in the magnetic circuit is between the second core portion 36 and the anchor 35. Since the air gap is filled with fuel, not a magnetic material, the larger the air gap, the greater the magnetic resistance of the magnetic circuit. Therefore, the smaller the void, the better.

  In this embodiment, as described above, the gap between the second core portion 36 and the anchor 35 is reduced by increasing the sliding length L of the sliding portion.

The magnetic coil 53 is configured by winding a lead wire 54 around the axis of the plunger rod 31. Both ends of the lead wire 54 are welded and connected to the terminal 56 by the lead wire welding portion 55. The terminal is a conductive substance and has an opening in the connector portion 58, and when a mating connector from the ECU is connected to the connector portion 58, the terminal comes into contact with the mating terminal and transmits a current to the coil.

  FIG. 6 shows a conventional structure. In the conventional structure, the lead wire welding portion 55 is arranged inside the magnetic circuit. Since the lead wire welding portion 55 requires a considerable volume, the total length of the magnetic circuit becomes longer accordingly. Since this increases the magnetic resistance of the magnetic circuit, there is a problem that the magnetic biasing force generated between the first core portion 33 and the anchor 35 is reduced.

  In the present embodiment, the lead wire welding portion 55 is arranged outside the yoke 51. Since the lead wire welding portion 55 is arranged outside the magnetic circuit, the total length of the magnetic circuit can be shortened because there is no space required for the lead wire welding portion 55, and the space between the first core portion 33 and the anchor 35 can be reduced. It became possible to generate sufficient magnetic biasing force.

  FIG. 7 shows a state before the electromagnetic suction valve mechanism 30 is incorporated into the pump housing 1.

  In the present embodiment, first, the intake valve unit 37 and the connector unit 38 are individually formed. Next, the suction valve seat portion 32a of the suction valve unit 37 is press-fitted and fixed to the pump housing 1, and then the welded portion 37c is welded over the entire circumference. In this embodiment, the welding is laser welding. In this state, the connector 38 is press-fitted and fixed to the first core portion 33. This allows the orientation of the connector 58 to be freely selected.

  A recess 1A for accommodating a cylinder 6 including a pressurizing chamber 11 is formed at the center of the pump housing 1, and a hole 11A for mounting the discharge valve mechanism 8 is formed in the cylinder so as to open in the pressurizing chamber 11. It is formed in a direction intersecting with the recess 1A for housing 6.

  A discharge valve mechanism 8 is provided at the outlet of the pressurizing chamber 11. The discharge valve mechanism 8 includes a seat member (seat member) 8a, a discharge valve 8b, a discharge valve spring 8c, and a holding member 8d as a discharge valve stopper. The discharge valve mechanism 8 is welded outside the pump housing 1 by welding a welded portion 8e. Assemble the mechanism 8. Then, the discharge valve mechanism 8 assembled from the left side in the drawing is press-fitted and fixed to the pump housing 1. The press-fitting part also has a function of blocking the pressurizing chamber 11 and the discharge port 12.

  In the state where there is no fuel pressure difference 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 the closed state. Only when the fuel pressure in the pressure chamber 11 becomes higher 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 pressure chamber 11 increases. The fuel is discharged to the common rail 23 through the discharge port 12.

  When the discharge valve 8b opens, it contacts 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 flows back into the pressurizing chamber 11 again due to the closing delay of the discharge valve 8b, and the efficiency of the high-pressure pump decreases. . The holding member 8d guides the discharge valve 8b so that the discharge valve 8b moves only in the stroke direction when the discharge valve 8b repeats opening and closing movements. With the above configuration, the discharge valve mechanism 8 serves as a check valve that limits the flow direction of fuel.

  The cylinder 6 is formed in a cup shape having a bottom and a ceiling portion 6A. A concave portion serving as a pressurizing chamber 11 is formed on the inner peripheral portion of the cylindrical member forming the cylinder.

  Around the cylinder 6, there are formed a plurality of through holes 6a that connect the pressurizing chamber 11 to the suction port 38 and a plurality of through holes 6b that connect the pressurizing chamber 11 to the fuel outlet 12.

  The outer cylindrical surface (outer peripheral surface) of the cylinder 6 is fitted to the inner cylindrical surface (inner peripheral surface) of the recess 1A of the pump housing 1, and is fitted and held by the press-fitting portion 6c.

  The cylinder 6 is fixed at two points of a fitting portion 6c on the inner cylindrical surface (inner peripheral surface) and a fitting portion 6d on the inner cylindrical surface (inner peripheral surface) of the pump housing 1 so that the central axis of the pump housing 1 and the cylinder 6 are fixed. The degree of coaxiality with the central axis of 6 is improved.

  By providing the press-fitting portions 6c and 6d at positions different from the sliding portions of the cylinder 6 and the plunger 2, deterioration of coaxiality due to press-fitting can be suppressed.

  A hole 10d communicating with the low-pressure fuel chamber 10c is provided in the ceiling portion 10A of the inner cylindrical surface (inner peripheral surface) of the pump housing 1 and serves as an air vent hole when the cylinder 6 is press-fitted. By providing the air vent hole 10d, the press-fitting load of the cylinder 6 can be reduced and deformation due to buckling can be prevented.

  By making the inner diameter of the communication hole 10d smaller than the outer diameter of the cylinder 6, the cylinder 6 functions as a stopper so as not to come off to the low pressure fuel chamber 10c side.

  The communication hole 10d keeps the diameter D of the hole such that "area AD> ADc-Ad", so that the high-pressure fuel passes through the fitting portion of the cylinder 6 and the pump housing 1 even if the high-pressure fuel passes through the low-pressure fuel chamber. The cylinder 6 can be fixed without coming off from the pump housing 1 due to the pressure difference.

  By forming the cylinder 6 into a cup shape, the ceiling of the ceiling 6A of the cylinder 6 is brought into pressure contact with the ceiling 10A of the pump housing 1 by the pressure in the pressurizing chamber 11 to perform metal sealing.

  As the pressure inside the pressurizing chamber 11 increases, the sealing property of the metal contact portion improves.

  The plunger seal 13 is held at the lower end of the spring holder 7 by the seal holder 15 and the spring holder 7, which are press-fitted and fixed to the inner peripheral cylindrical surface 7 c of the spring holder 7. The central axis of the plunger seal 13 is held coaxially with the central axis of the inner peripheral cylindrical surface 7c of the spring holder 7, and at the same time, the central axis of the cylindrical fitting portion 7e is also held coaxially. The plunger 2 and the plunger seal 13 are slidably installed at the lower end of the cylinder 6.

  The plunger seal 13 prevents the fuel in the seal chamber 10f from flowing into the engine on the tappet 3 side. At the same time, lubricating oil (including engine oil) that lubricates sliding parts in the engine room is prevented from flowing into the pump body 1.

  The spring holder 7 is fitted by an inner cylindrical surface (inner peripheral surface) portion provided in the lower portion of the pump housing 1 and an outer cylindrical surface (outer peripheral surface) portion 7e of the spring holder 7, and in this embodiment, laser welding is performed. It is fixed.

  A groove 7d for fitting the O-ring 61 is provided on the outer peripheral cylindrical surface 7b of the pump housing 1. The O-ring 61 blocks the cam side of the engine from the outside by the inner wall of the fitting hole 70 on the engine side and the groove 7d of the pump housing 1, and prevents the engine oil from leaking to the outside.

  As described above, the cylinder 6 can hold the plunger 2 that moves forward and backward in the pressurizing chamber 11 so as to be slidable along the direction of forward and backward movement.

  At the lower end of the plunger 2, a tappet 3 is provided which converts the rotational movement of a cam 5 attached to the camshaft of the engine into vertical movement and transmits the vertical movement to the plunger 2. The plunger 2 is pressed against the tappet 3 by a spring 4 via a retainer 15. The retainer 15 is fixed to the plunger 2 by press fitting. As a result, the plunger 2 can be moved up and down (reciprocating) with the rotational movement of the cam 5.

  Here, the low-pressure fuel chamber 10c is connected to the seal chamber 10f via the suction flow passage 10d and the suction flow passage 10e provided in the cylinder holder 7, and the seal chamber 10f is always connected to the pressure of the suction fuel. ing. When the fuel in the pressurizing chamber 11 is pressurized to a high pressure, a small 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 inflowing high-pressure fuel is released to the suction pressure. Therefore, the plunger seal 13 is not damaged by high pressure.

The plunger 2 is composed of a large diameter portion 2a that slides on the cylinder 6 and a small diameter portion 2b that slides on 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 they are coaxial with each other. The sliding portion with the cylinder 6 is the large diameter portion 2a, and the sliding portion with the plunger seal 13 is the small diameter portion 2b. As a result, the joint between the large-diameter portion 2a and the small-diameter portion 2b exists inside the seal chamber 10f, so the volume of the seal chamber 10f changes with the sliding movement of the plunger 2, and the fuel is sucked accordingly. passage 10d, through the intake passage 10 e moves between the seal chamber 10f and the intake passage 10c.

  Since the plunger 2 repeatedly slides on the plunger seal 13 and the cylinder 6, frictional heat is generated. Due to this heat, the large diameter portion 2a of the plunger 2 thermally expands, but the plunger seal 13 side of the large diameter portion 2a is closer to the heat source than the pressurizing chamber 11 side. Therefore, the thermal expansion of the large diameter portion 2a is not uniform, and as a result, the coaxiality is deteriorated and the plunger 2 and the cylinder 6 are seized and adhered.

  In the present embodiment, the fuel in the seal chamber 10f is constantly exchanged with the sliding movement of the plunger 2, so that this fuel has an effect of removing the generated heat. As a result, it is possible to prevent deformation of the large diameter portion 2a due to frictional heat, and seizure and sticking of the plunger 2 and the cylinder 6 caused thereby.

  Further, the smaller the diameter of the sliding portion with the plunger seal 13 is, the smaller the friction area is, so that the frictional heat generated by the sliding motion is also reduced. In this embodiment, since the small-diameter portion 2b of the plunger 2 slides on the plunger seal 13, the amount of heat generated by friction with the plunger seal 13 can be suppressed to a small amount, and seizure sticking can be prevented.

  The metal diaphragm damper 9 is composed of two metal diaphragms, and the outer peripheries thereof are fixed to each other by welding at the welded portions while the gas is sealed in the space between the two diaphragms. When low-pressure pressure pulsations are applied to both sides of the metal diaphragm damper 9, the metal diaphragm damper 9 changes its volume, thereby reducing the low-pressure pressure pulsations.

  The high pressure fuel supply pump is fixed to the engine by the flange 41, the set screw 42, and the bush 43. The flange 41 is welded and connected to the pump housing 1 at the welded portion 41a. In this embodiment, laser welding is used.

  FIG. 8 shows an external view of the flange 41 and the bush 43. In this figure, only the flange 41 and the bush 43 are shown, and other parts are not shown.

  The two bushes 43 are attached to the flange 41, and are attached to the side opposite to the engine. The two setscrews 42 are screwed into the respective screws formed on the engine side, and the two bushes 43 and the flange 41 are pressed against the engine to fix the high-pressure fuel supply pump to the engine.

  FIG. 9 shows an enlarged view of the flange 41, the set screw 42, and the bush 43 portion.

  The bush 43 has a collar portion 43a and a caulking portion 43b. First, the caulking portion 43b is caulked and coupled to the mounting hole of the flange 41. After that, the pump housing 1 and the welded portion 41a are welded to each other by laser welding. After that, the resin fastener 44 is inserted into the bush 43, and the set screw 42 is further inserted into the fastener 44. The fastener 44 serves to temporarily fix the set screw 42 to the bush 43. That is, the set screw 42 is fixed so as not to fall off the bush 43 before the high-pressure fuel supply pump is attached to the engine. When fixing the high-pressure fuel supply pump to the engine, the set screw 42 is screwed and fixed to the screw portion provided on the engine side. In that case, the set screw 42 is rotated in the bush 43 by the tightening torque of the set screw 42. it can.

  When the high-pressure fuel supply pump repeats high-pressure discharge, the pressure in the pressurizing chamber 11 repeats high pressure and low pressure as described above. When the pressure chamber 11 is at a high pressure, a force acts so that the pump housing 1 is lifted upward in the drawing due to this pressure. When the pressure chamber 11 has a low pressure, this force does not work. Therefore, the pump housing is repeatedly loaded upward in the figure.

  As shown in FIG. 9, the flange 41 fixes the pump housing 1 to the engine by two setscrews 42. Therefore, when the pump housing 1 is lifted upward as described above, the two set screws 42 and the bush 43 of the flange 42 are fixed, and the bending load is repeatedly applied to the central portion. Due to the repeated load, the flange 41 and the pump housing 1 are deformed, so that there is a problem that repeated stress is generated and fatigue failure occurs. Further, the sliding portion of the cylinder 6 is also deformed, and the above-mentioned seizure and sticking of the plunger 2 and the cylinder 6 occur.

  The flange 41 is manufactured by press molding for the reason of productivity. Therefore, the plate thickness t1 of the flange 41 has an upper limit, and in this embodiment, t1 = 4 mm. A welded portion 41, which is a joint portion between the pump housing 1 and the flange 42, is welded and joined by laser welding. For laser welding, it is necessary to irradiate the beam from the lower side in the figure. From the upper side in the figure, there are other components and it is impossible to irradiate the laser over the entire circumference. Further, the laser welding must penetrate the plate thickness t = 4 mm of the flange 41. If the weld does not penetrate the flange 41, the end face of the weld becomes a notch, and stress is concentrated in this notch due to the repeated load described above, causing fatigue failure.

  The laser output may be increased in order to penetrate the flange 41 by laser welding, but heat is always generated in welding, so the flange 41 is thermally deformed by the heat. In addition, a large amount of spatter is generated during welding and adheres to the pump housing 1 and other parts. From the above viewpoints, it is preferable that the welding length for penetration welding by laser welding is short.

  Therefore, in this embodiment, only the plate thickness t2 of the welded portion 41a is set to t2 = 3 mm. As a result, the flange 41a can be welded through by laser welding, and the generation of spatter can be minimized. Further, since this t2 = 3 mm portion can be molded by press molding, the productivity is high.

  A step portion having a plate thickness t2 of the welded portion 41a of t2 = 3 mm and a step portion of t1 = 4 mm is provided on the engine side. As a result, the recess 45 is formed. The upper end surface and the lower end surface of the welded portion 41a are always raised above the base metal. By providing the recess 45, it is possible to prevent the protrusion from interfering with the engine. When the bulge and the engine are in contact with each other, when the high-pressure fuel supply pump is fixed to the engine with the setscrew 42, bending stress is generated in the flange 41, which leads to damage of the flange 41.

  As a result, it is possible to prevent the flange 41 from being damaged by the repeated load generated by the high-pressure discharge. Further, it is possible to prevent the flange 41 from being damaged due to the swelling of the welded portion 41a and the contact of the engine.

  As described above, when a repeated load is applied to the pump housing 1, the two setscrews 42 and the bush 43 are fixed, and the pump housing 1 bends in the direction of the repeated load. The welded portion 41a is welded through the entire circumference by laser welding, and the curvature of the flange 41 spreads to the pump housing 1. On the other hand, the cylinder holder 7 and the pump housing 1 are in contact only with the screws 7g and 1b. The screw 1b of the pump housing 1 and the welded portion 41a are present at positions that are desired to be separated by a distance m. The minimum thickness at the distance m is n. Even if the pump housing 1 is deformed due to the bending of the flange 41, the values of m and n are selected so that the deformation is absorbed at the distance m and the wall thickness n and does not reach the screw 1b.

  By doing so, the deformation of the cylinder 6 due to the bending of the flange 41 can be prevented. However, all the bends of the flange 41 must be absorbed by the pump housing 1, and if the repeated stress generated in the pump housing 1 exceeds the allowable value, the pump housing 1 will be fatigue fractured and a fuel leak accident will occur. I will end up.

  There are the following two methods to prevent such fatigue damage of the pump housing 1.

  (1) The stress generated by the shape effect of the pump housing 1 is set to be equal to or less than an allowable value.

  (2) The curvature generated in the flange 41 is reduced.

  Hereinafter, these two methods will be described.

  First, (1) will be described. FIG. 9 shows an enlarged view of the vicinity of the welded portion 41a. The maximum stress generated when the pump housing 1 is pulled upward in the drawing by the repeated load and the flange 41 is bent is indicated by an arrow on the surface of the pump housing 1 as shown as the maximum stress in FIG. Occurs in the direction. The generated stress may be dispersed as much as possible by the shape effect so that the stress is not concentrated.

  In this embodiment, as shown in the figure, the R portion 1c and the R portion 1e are connected by the straight portion 1d, and the optimum value is selected. A straight line portion 1d exists between the two R portions 1c and 1e, and the stress generated on the straight line portion 1d is evenly distributed. As a result, the maximum value of generated stress could be reduced without stress concentration.

  Next, (2) will be described. The only way to reduce the curvature of the flange 41 is to increase the rigidity of the flange 41. However, it is very difficult to set the plate thickness t of the flange 41 to 4 mm or more from the viewpoint of productivity as described above. Therefore, the diameter of the bush 43 provided only for fixing the set screw 42 is increased. Here, the bending effective distance: O indicates the shortest distance between the end portions of the two bushes 43, and this portion is substantially bent by the repeated load. If the bending effective distance O can be reduced, the rigidity of the flange 41 is improved as a result.

  In this embodiment, the bush 43 is provided with the collar portion 43a to reduce the effective bending distance: O. The height of the bush 43 is required to insert the fastener 44. If the outer shape of the bush 43 is increased at that height, there are problems such as interference with the pump housing 1 and increase in the material of the bush 43. By providing the collar portion 43a, these problems can be prevented and the effective bending distance: O can be reduced.

  With the above configuration, the methods (1) and (2) can be achieved, and the stress repeatedly generated in the pump housing 1 can be set to be equal to or less than the allowable value for fatigue failure of the pump housing 1.

  Next, the configuration of the second embodiment according to the present invention will be described with reference to FIG.

  In this embodiment, the spring holder 7A and the plunger seal holder 7B are provided separately, and the outer shape of the pump housing 1 is made small, thereby reducing the cost.

  A groove 7d for fitting the O-ring 61 is provided in the outer cylindrical portion 7b of the spring holder 7A. The O-ring 61 blocks the cam side of the engine from the outside by the inner wall of the fitting hole 70 on the engine side and the groove 7d of the spring holder 7A, and prevents engine oil from leaking to the outside.

  The plunger seal holder 7B and the cylinder holder 7A are fixed in advance before being fixed to the pump housing 1. In this embodiment, it is fixed by laser welding 7j to seal the fuel.

  The outer peripheral cylindrical surface portion 7k of the spring holder 7A is press-fitted and fixed to the inner peripheral cylindrical surface portion of the pump housing 1, and further fixed by laser welding 7h to seal the fuel.

  The plunger seal 13 is held at the lower end of the spring holder 7A by a seal holder 15 and a spring holder 7A which are press-fitted and fixed to the inner peripheral cylindrical surface of the plunger seal holder 7B. The shaft of the plunger seal 13 is held coaxially with the shaft of the cylindrical fitting portion 7e by the inner peripheral cylindrical surface 7c of the spring holder 7A. The plunger 2 and the plunger seal 13 are slidably installed at the lower end of the cylinder 6 in the figure.

  Next, the configuration of the third embodiment according to the present invention will be described with reference to FIG.

  A cylinder 6 is provided on the outer peripheral surface of the cylinder 6 with two or more stepped portions 6f formed of a portion having a large diameter and a portion having a small diameter, and the stepped portion 6f is machined coaxially with the inner cylindrical side surface (inner peripheral surface) of the cylinder 6. A groove 6g is provided. By providing the cylindrical groove 6g, strain generated by press-fitting into the pump housing 1 or thermal expansion is absorbed, and the coaxiality of the sliding surface 6h with the plunger 2 that slides on the inner peripheral surface of the cylinder 6 is deteriorated or biting is prevented. Suppress.

  Next, the configuration of the fourth embodiment according to the present invention will be described with reference to FIG.

  A sliding portion 6m smaller than the large diameter portion 2a of the plunger 2 is provided on the ceiling portion 6A of the cylinder 6. The sliding portion 6m is machined coaxially with the sliding portion 6h of the large diameter portion 2a of the plunger 2.

  A small-diameter portion 2c is provided on the upper surface of the plunger 2 coaxially with the axis line, and by fitting it into a sliding portion 6m provided on the ceiling portion 6A of the cylinder 6, the sliding area between the plunger 2 and the cylinder 6 is increased, and the plunger 2 The shape is such that the axis deviation and inclination of the plunger 2 are reduced and the galling and sticking of the plunger 2 are reduced.

  Next, the configuration of the fifth embodiment according to the present invention will be described with reference to FIG.

  In this embodiment, a plurality of lateral holes 6p serving as fuel passages (6a, 6b) penetrating the inside and the outside are provided in the side surface of the cylinder 6, and the lateral holes 6p serving as the fuel passages (6a, 6b) are the same as those of the cylinder 6. Two or more locations are provided at positions where the fuel can pass from the intake passage to the discharge passage regardless of the angle of the circumferential direction.

  The features described in the embodiments described above are summarized as follows.

  (1) There is a hole in the ceiling of the pump housing.

  This hole functions as an air vent hole when the cylinder cup is press-fitted. If there is no air vent hole, the press-fit load will be several tons. In that case, the body housing and the cylinder are deformed. In the embodiment, the press-fitting is performed at a rating of 1 ton, usually 8000N or less.

  (2) The more pressure is applied to the inside of the cylinder, the higher the surface pressure of the contact seal surface between the outer circumference of the cylinder and the inner circumference of the pump housing, and the better the sealing performance.

  (3) The outer cylindrical portion (outer peripheral surface) of the cup-shaped cylinder member is press-fitted and fixed to the inner cylindrical portion (inner peripheral surface) of the pump housing. When the plunger enters the suction process, the cylinder is press-fitted with a force that prevents the cylinder from coming off the pump housing due to the pressure difference between the outside and the inside of the cylinder.

  (4) The cylinder is formed into a cup shape with a ceiling, and a hole is formed between the ceiling portion of the pump body and the low pressure chamber side. If this hole diameter D is set to a diameter satisfying "area AD of hole D> outer diameter area ADc of cylinder-outer diameter area Ad of plunger", it is possible to surely avoid generation of a force for pulling downward due to in-cylinder pressure. You can

  (5) By forming the press-fitting surface closer to the ceiling than the inner diameter finishing portion of the cylinder, deformation of the inner diameter due to press-fitting is eliminated.

1 Pump Housing 1A Recess 2 Plunger 6 Cylinder 6A Ceiling (of cylinder)
10A Ceiling (of pump housing)
11 Pressurizing chamber 30 Electromagnetic suction valve mechanism

Claims (4)

A bottomed cylindrical cylinder integrally formed with a ceiling part and a cylindrical part ;
A plunger arranged reciprocally in the cylinder,
A pump housing in which the cylinder is housed on the inner peripheral surface side,
The cylinder has a sliding part on which the plunger slides on the inner peripheral surface of the tubular part, and is press-fitted and fixed to the inner peripheral surface of the pump housing so that the ceiling side is the tip side in the press-fitting direction. ,
The plunger has a large diameter portion arranged on the inner peripheral side of the sliding portion, and a small diameter portion having an outer diameter smaller than the large diameter portion,
An intake passage is formed in the pump housing for replacing the fuel in contact with the small diameter portion of the plunger on the opening end side of the cylinder and the fuel on the low pressure fuel chamber side into which the low pressure fuel sucked from the intake joint flows. ,
The cylinder is provided with a first press-fitting portion that abuts the inner peripheral surface of the pump housing on an outer peripheral surface of the ceiling portion, and a second press-fitting portion that abuts a convex portion formed on the inner peripheral surface of the pump housing. A portion is provided on the outer peripheral surface of the tubular portion,
The convex portion, the high-pressure fuel supply pump according to claim Rukoto provided at a position away in the press-fitting direction than the opening end in the inner peripheral surface of the pump housing. The high-pressure fuel supply pump according to claim 1,
The high pressure fuel supply pump according to claim 1, wherein the cylinder has an inner diameter enlarged portion having an inner diameter larger than that of the sliding portion, formed between the sliding portion and the ceiling portion . The high-pressure fuel supply pump according to claim 1 or 2, wherein
The high pressure fuel supply pump according to claim 1, wherein the pump housing is formed with a hole closed by the ceiling portion of the cylinder. The high-pressure fuel supply pump according to claim 3, wherein
The high-pressure fuel supply pump, wherein the hole communicates with the low-pressure fuel chamber.

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