Fuel Pump

Abstract

To provide a fuel pump which enables a relief valve mechanism to return into a valve closed state easily after the relief valve mechanism is released.SOLUTION: A fuel pump of the invention includes a suction valve chamber 30, a compression chamber 11, a relief valve chamber 1b, and a relief valve mechanism 4. Further, the relief valve mechanism 4 includes: a relief valve holder 42 disposed in the relief valve chamber 1b; a relief valve 43 which engages with the relief valve holder 42; a relief spring 41 which biases the relief valve 43 and the relief valve holder 42 in a valve closing direction; and a limiting part which limits moving amounts of the relief valve 43 and the relief valve holder 42 in a valve opening direction.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a fuel pump that supplies fuel to an engine at high pressure. [Background technology]

[0002] An example of a fuel pump is described in Patent Document 1. The high-pressure fuel supply pump described in Patent Document 1 includes a housing, an intake valve, a discharge valve, and a relief valve. The housing has a cylinder that is a stepped cylindrical space that accommodates a cylinder liner that slidably holds a plunger and forms a pressurizing chamber. The intake valve opens when no current is supplied to an electromagnetic solenoid, and opens when current is supplied to the electromagnetic solenoid to draw fuel into the pressurizing chamber.

[0003] The discharge valve is attached to a discharge valve accommodating portion of the housing, and the discharge valve accommodating portion is in communication with the pressurizing chamber via a fuel discharge hole. High-pressure fuel pressurized in the pressurizing chamber is supplied to the discharge valve. The discharge valve opens when the pressure of the supplied fuel reaches or exceeds a predetermined pressure, and the fuel that passes through the discharge valve is pumped to the pressure accumulator.

[0004] The relief valve is mounted in a relief valve accommodating portion of the housing, and the relief valve accommodating portion communicates with a high pressure region downstream of the discharge valve and with a pressurizing chamber via a communication passage. The relief valve opens when the pressure of the fuel in the high pressure region reaches or exceeds a specific pressure, and returns the high pressure fuel to the pressurizing chamber (see, for example, Patent Document 1). The relief valve is interposed between a relief valve holder and a seat member. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2018-523778 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the technology described in Patent Document 1, when the relief valve opens to release the high-pressure fuel, there is a risk that the relief valve may come out from between the relief valve holder and the seat member. Therefore, in the technology described in Patent Document 1, the relief valve does not return to a predetermined position, making it difficult to reset the released relief valve mechanism.

[0007] SUMMARY OF THE PRESENT EMBODIMENT In consideration of the above problems, an object of the present invention is to provide a fuel pump which can easily return to a closed valve state after a relief valve mechanism is released. [Means for solving the problem]

[0008] In order to solve the above problems and achieve the object of the present invention, a fuel pump of the present invention includes a suction valve chamber, a pressurization chamber, a relief valve chamber, and a relief valve mechanism. The pressurization chamber is formed downstream of the suction valve chamber. The relief valve chamber is formed downstream of the pressurization chamber. The relief valve mechanism is disposed in the relief valve chamber. The relief valve mechanism also includes a relief valve holder disposed in the relief valve chamber, a relief valve engaging with the relief valve holder, a relief spring that biases the relief valve and the relief valve holder in a valve closing direction, and a restriction portion that restricts the amount of movement of the relief valve and the relief valve holder in a valve opening direction. Effect of the Invention

[0009] According to the fuel pump having the above configuration, after the relief valve mechanism is released, the valve can be easily returned to the closed state. Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0010] [Figure 1] 1 is an overall configuration diagram of a fuel supply system using a high-pressure fuel pump according to an embodiment of the present invention; [Diagram 2] 1 is a vertical sectional view (part 1) of a high-pressure fuel pump according to an embodiment of the present invention. [Diagram 3] 2 is a vertical sectional view (part 2) of the high-pressure fuel pump according to one embodiment of the present invention. FIG. [Figure 4] 1 is a horizontal cross-sectional view of a high-pressure fuel pump according to an embodiment of the present invention, as viewed from above. FIG. [Diagram 5] FIG. 4 is a vertical sectional view (part 3) of the high-pressure fuel pump according to one embodiment of the present invention. [Figure 6] 2 is an enlarged cross-sectional view showing a relief valve mechanism of the high-pressure fuel pump according to the embodiment of the present invention; FIG. [Figure 7] 4 is a cross-sectional view showing a state in which a relief valve mechanism of the high-pressure fuel pump according to the embodiment of the present invention is open; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 1. One embodiment of a high pressure fuel pump Hereinafter, a high-pressure fuel pump according to an embodiment of the present invention will be described with reference to Figures 1 to 7. Note that the same reference numerals are used to designate common members in each figure.

[0012] [Fuel supply system] First, a fuel supply system using a high-pressure fuel pump according to this embodiment will be described with reference to FIG. FIG. 1 is an overall configuration diagram of a fuel supply system using a high-pressure fuel pump according to this embodiment.

[0013] 1, the fuel supply system includes a high-pressure fuel pump (fuel pump) 100, an ECU (Engine Control Unit) 101, a fuel tank 103, a common rail 106, and a plurality of injectors 107. The components of the high-pressure fuel pump 100 are integrally assembled into a pump body 1.

[0014] Fuel in a fuel tank 103 is pumped up by a feed pump 102 that is driven based on a signal from an ECU 101. The pumped up fuel is pressurized to an appropriate pressure by a pressure regulator (not shown) and sent through a low-pressure pipe 104 to a low-pressure fuel intake port 51 provided in the intake joint 5 (see FIG. 3) of the high-pressure fuel pump 100.

[0015] High-pressure fuel pump 100 pressurizes fuel supplied from a fuel tank 103 and pumps it to a common rail 106. A plurality of injectors 107 and a fuel pressure sensor 105 are attached to common rail 106. The plurality of injectors 107 are attached in accordance with the number of cylinders (combustion chambers), and inject fuel in accordance with a drive current output from ECU 101. The fuel supply system of this embodiment is a so-called direct injection engine system in which injector 107 injects fuel directly into the cylinders of the engine.

[0016] The fuel pressure sensor 105 outputs the detected pressure data to the ECU 101. The ECU 101 calculates an appropriate fuel injection amount (target fuel injection duration) and an appropriate fuel pressure (target fuel pressure) based on engine state quantities (e.g., crank rotation angle, throttle opening, engine speed, fuel pressure, etc.) obtained from various sensors.

[0017] Furthermore, ECU 101 controls the operation of high-pressure fuel pump 100 and a plurality of injectors 107 based on the calculation results of the fuel pressure (target fuel pressure) etc. That is, ECU 101 has a pump control unit that controls high-pressure fuel pump 100 and an injector control unit that controls injector 107.

[0018] The high-pressure fuel pump 100 has a plunger 2, a pressure pulsation reduction mechanism 9, an electromagnetic intake valve mechanism 3 which is a variable displacement mechanism, a relief valve mechanism 4 (see FIG. 2), and a discharge valve mechanism 8. The fuel that flows in from a low-pressure fuel intake port 51 reaches the intake port 31b of the electromagnetic intake valve mechanism 3 through the pressure pulsation reduction mechanism 9 and an intake passage 10b.

[0019] The fuel that has flowed into the electromagnetic intake valve mechanism 3 passes through the valve portion 32, flows through a supply communication hole 1g (see FIG. 2) formed in the pump body 1, and then flows into the pressurizing chamber 11. The pump body 1 slidably holds the plunger 2. The plunger 2 reciprocates when power is transmitted by a cam 91 (see FIG. 2) of the engine. One end of the plunger 2 is inserted into the pressurizing chamber 11, and increases or decreases the volume of the pressurizing chamber 11.

[0020] In the pressurization chamber 11, fuel is sucked in through the electromagnetic intake valve mechanism 3 during the downward stroke of the plunger 2, and the fuel is pressurized during the upward stroke of the plunger 2. When the fuel pressure in the pressurization chamber 11 exceeds a set value, the discharge valve mechanism 8 opens and the high-pressure fuel is pumped through a discharge passage 12a of the discharge joint 12 to a common rail 106. The discharge of fuel by the high-pressure fuel pump 100 is controlled by opening and closing the electromagnetic intake valve mechanism 3. The opening and closing of the electromagnetic intake valve mechanism 3 is controlled by an ECU 101.

[0021] In the event that abnormally high pressure occurs in the common rail 106 or the like due to a malfunction of the injector 107, etc., the relief valve mechanism 4 opens when the pressure difference between the discharge passage 12a of the discharge joint 12 communicating with the common rail 106 and the pressurized chamber 11 becomes equal to or greater than the valve opening pressure (predetermined value) of the relief valve mechanism 4. This causes the abnormally high pressure fuel to pass through the relief valve mechanism 4 and return to the pressurized chamber 11. As a result, the piping of the common rail 106, etc. is protected.

[0022] [High pressure fuel pump] Next, the configuration of the high-pressure fuel pump 100 will be described with reference to FIGS. Fig. 2 is a vertical cross-sectional view (part 1) of the high-pressure fuel pump 100 taken along a cross section perpendicular to the horizontal direction. Fig. 3 is a vertical cross-sectional view (part 2) of the high-pressure fuel pump 100 taken along a cross section perpendicular to the horizontal direction. Fig. 4 is a horizontal cross-sectional view of the high-pressure fuel pump 100 taken along a cross section perpendicular to the vertical direction. Fig. 5 is a vertical cross-sectional view (part 3) of the high-pressure fuel pump 100 taken along a cross section perpendicular to the horizontal direction. Fig. 6 is an explanatory diagram showing an enlarged view of the relief valve mechanism 4.

[0023] As shown in Figures 2 to 5, the pump body 1 of the high-pressure fuel pump 100 is formed in a substantially cylindrical shape. As shown in Figures 2 and 3, the pump body 1 is provided therein with a first chamber 1a, a second chamber 1b, a third chamber 1c, a blocking wall 1d, a supply communication hole 1g, and a suction valve chamber 30. The pump body 1 is in close contact with a fuel pump mounting portion 90 and is fixed thereto with a plurality of bolts (screws) (not shown).

[0024] The first chamber 1a is a cylindrical space provided in the pump body 1, and a center line 1A of the first chamber 1a coincides with the center line of the pump body 1. One end of a plunger 2 is inserted into the first chamber 1a, and the plunger 2 reciprocates within the first chamber 1a. A pressurizing chamber 11 is formed by the first chamber 1a and one end of the plunger 2. The first chamber 1a is also connected to a suction valve chamber 30 via a supply communication hole 1g, which will be described later. A second chamber 1b, which is a relief valve chamber, is formed downstream of the pressurizing chamber 11.

[0025] The second chamber 1b is a cylindrical space provided in the pump body 1, and the center line of the second chamber 1b is perpendicular to the center line of the pump body 1 (first chamber 1a). A relief valve mechanism 4, which will be described later, is disposed in the second chamber 1b to form a relief valve chamber. The diameter of the second chamber 1b, which is the relief valve chamber, is smaller than the diameter of the first chamber 1a.

[0026] The first chamber 1a and the second chamber 1b are connected to each other through a circular communication hole 1e. The diameter of the communication hole 1e is the same as the diameter of the first chamber 1a, and the communication hole 1e extends one end of the first chamber 1a. The diameter of the communication hole 1e is larger than the outer diameter of the plunger 2. This prevents the plunger 2, which reciprocates in the pressurizing chamber 11, from colliding with the periphery of the communication hole 1e, thereby improving the durability of the plunger 2.

[0027] In addition, the center line of the communication hole 1e is perpendicular to the center line of the second chamber 1b. This allows the fuel that has passed through the relief valve mechanism 4 to pass through the communication hole 1e efficiently, and the improvement of the relief performance is not hindered. In addition, the shape of the pump body 1 is not complicated, and the productivity of the pump body 1 and the high-pressure fuel pump 100 can be improved.

[0028] 3 and 5, the diameter of the communication hole 1e is larger than the diameter of the second chamber 1b. The communication hole 1e has a tapered surface 1f that reduces in diameter toward the second chamber 1b in a cross section perpendicular to the center line of the second chamber 1b. This allows the fuel that has passed through the relief valve mechanism 4 arranged in the second chamber 1b to smoothly return to the pressurization chamber 11 along the tapered surface 1f.

[0029] The third chamber 1c is a cylindrical space provided in the pump body 1, and is continuous with the other end of the first chamber 1a. The center line of the third chamber 1c coincides with the center line 1A of the first chamber 1a and the center line of the pump body 1, and the diameter of the third chamber 1c is larger than the diameter of the first chamber 1a. A cylinder 6 that guides the reciprocating motion of the plunger 2 is disposed in the third chamber 1c. This allows the end face of the cylinder 6 to abut against a step between the first chamber 1a and the third chamber 1c, preventing the cylinder 6 from shifting toward the first chamber 1a.

[0030] The cylinder 6 is formed in a cylindrical shape, and its outer periphery is press-fitted into the third chamber 1c of the pump body 1. One end of the cylinder 6 abuts against a step between the first chamber 1a and the third chamber 1c, which is the top surface of the third chamber 1c. The plunger 2 is in slidable contact with the inner periphery of the cylinder 6.

[0031] 2, an O-ring 93 is interposed between the fuel pump mounting portion 90 and the pump body 1. This O-ring 93 prevents engine oil from passing between the fuel pump mounting portion 90 and the pump body 1 and leaking to the outside of the engine (internal combustion engine).

[0032] A tappet 92 is provided at the lower end of the plunger 2. The tappet 92 converts the rotational motion of a cam 91 attached to the camshaft of the engine into vertical motion and transmits it to the plunger 2. The plunger 2 is biased toward the cam 91 by a spring 16 via a retainer 15, and is pressed against the tappet 92. The plunger 2 reciprocates together with the tappet 92, changing the volume of the pressurizing chamber 11.

[0033] In addition, a seal holder 17 is disposed between the cylinder 6 and the retainer 15. The seal holder 17 is formed in a cylindrical shape into which the plunger 2 is inserted. An auxiliary chamber 17a is formed at the upper end of the seal holder 17 on the cylinder 6 side. On the other hand, a lower end of the seal holder 17 on the retainer 15 side holds a plunger seal 18.

[0034] The plunger seal 18 is in slidable contact with the outer periphery of the plunger 2. When the plunger 2 reciprocates, the plunger seal 18 seals the fuel in the sub-chamber 17a to prevent the fuel from flowing into the inside of the engine. The plunger seal 18 also prevents lubricating oil (including engine oil) that lubricates the sliding parts in the engine from flowing into the inside of the pump body 1.

[0035] 2, the plunger 2 reciprocates up and down. When the plunger 2 descends, the volume of the pressurizing chamber 11 increases, and when the plunger 2 ascends, the volume of the pressurizing chamber 11 decreases. That is, the plunger 2 is disposed so as to reciprocate in a direction that increases and decreases the volume of the pressurizing chamber 11.

[0036] The plunger 2 has a large diameter portion 2a and a small diameter portion 2b. When the plunger 2 reciprocates, the large diameter portion 2a and the small diameter portion 2b are located in the sub-chamber 17a. Therefore, the volume of the sub-chamber 17a increases and decreases as the plunger 2 reciprocates.

[0037] The sub-chamber 17a communicates with the low-pressure fuel chamber 10 through a fuel passage 10c (see FIG. 5). When the plunger 2 descends, fuel flows from the sub-chamber 17a to the low-pressure fuel chamber 10, and when the plunger 2 ascends, fuel flows from the low-pressure fuel chamber 10 to the sub-chamber 17a. This makes it possible to reduce the amount of fuel flowing into and out of the pump during the suction stroke or return stroke of the high-pressure fuel pump 100, and to reduce pressure pulsation generated inside the high-pressure fuel pump 100.

[0038] Further, a relief valve mechanism 4 communicating with the pressurizing chamber 11 is provided in the second chamber 1b of the pump body 1. The relief valve mechanism 4 has a seat member 44, a relief valve 43, a relief valve holder 42, and a relief spring 41. The detailed configuration of the relief valve mechanism 4 will be described later.

[0039] As shown in Fig. 3, a low-pressure fuel chamber 10 is provided in the upper part of pump body 1. An suction joint 5 is attached to the side part of pump body 1. Suction joint 5 is connected to low-pressure piping 104 through which fuel supplied from a fuel tank 103 (see Fig. 1) passes. The fuel in fuel tank 103 is supplied from suction joint 5 to the inside of high-pressure fuel pump 100.

[0040] The suction joint 5 has a low-pressure fuel suction port 51 connected to the low-pressure pipe 104, and an suction passage 52 communicating with the low-pressure fuel suction port 51. An suction filter 53 is provided in the suction passage 52. The fuel that passes through the suction passage 52 passes through the suction filter 53 provided inside the pump body 1 and is supplied to the low-pressure fuel chamber 10. The suction filter 53 removes foreign matter present in the fuel and prevents the foreign matter from entering the high-pressure fuel pump 100.

[0041] The low-pressure fuel chamber 10 is provided with a low-pressure fuel flow path 10a and an intake passage 10b (see FIG. 2). The low-pressure fuel flow path 10a is provided with a pressure pulsation reduction mechanism 9. When the fuel that has flowed into the pressurized chamber 11 passes through the electromagnetic intake valve mechanism 3, which is in an open state, again and is returned to the intake passage 10b (see FIG. 2), pressure pulsation is generated in the low-pressure fuel chamber 10. The pressure pulsation reduction mechanism 9 reduces the pressure pulsation generated in the high-pressure fuel pump 100 from spreading to the low-pressure piping 104.

[0042] The pressure pulsation reduction mechanism 9 is formed of a metal diaphragm damper made by bonding two corrugated disk-shaped metal plates together at their peripheries and injecting an inert gas such as argon into the interior. The metal diaphragm damper of the pressure pulsation reduction mechanism 9 absorbs or reduces pressure pulsations by expanding and contracting.

[0043] The suction passage 10b communicates with the suction port 31b (see FIG. 2) of the electromagnetic intake valve mechanism 3, and the fuel that has passed through the low-pressure fuel passage 10a reaches the suction port 31b of the electromagnetic intake valve mechanism 3 via the suction passage 10b.

[0044] 2 and 4, the electromagnetic intake valve mechanism 3 is inserted into an intake valve chamber 30 formed in the pump body 1. The intake valve chamber 30 is provided on the upstream side (the intake passage 10b side) of the pressurizing chamber 11, and is formed as a horizontal hole extending in the horizontal direction. The electromagnetic intake valve mechanism 3 has an intake valve seat 31 press-fitted into the intake valve chamber 30, a valve portion 32, a rod 33, a rod biasing spring 34, an electromagnetic coil 35, an anchor 36, a stopper 37, and an intake valve biasing spring 38.

[0045] The suction valve seat 31 is formed in a cylindrical shape, and a seating portion 31a is provided on the inner periphery. The suction valve seat 31 is also formed with a suction port 31b that reaches from the outer periphery to the inner periphery. The suction port 31b is connected to the suction passage 10b in the low-pressure fuel chamber 10 described above.

[0046] A stopper 37 is disposed in the suction valve chamber 30, facing the seating portion 31a of the suction valve seat 31. The valve portion 32 is disposed between the stopper 37 and the seating portion 31a. A suction valve biasing spring 38 is disposed between the stopper 37 and the valve portion 32. The suction valve biasing spring 38 biases the valve portion 32 toward the seating portion 31a.

[0047] The valve portion 32 comes into contact with the seat portion 31a to close the communication portion between the suction port 31b and the pressurizing chamber 11. When the valve portion 32 closes the communication portion between the suction port 31b and the pressurizing chamber 11, the electromagnetic suction valve mechanism 3 is in a closed state. On the other hand, the valve portion 32 comes into contact with the stopper 37 to open the communication portion between the suction port 31b and the pressurizing chamber 11. When the valve portion 32 opens the communication portion between the suction port 31b and the pressurizing chamber 11, the electromagnetic suction valve mechanism 3 is in an open state.

[0048] The rod 33 passes through a cylindrical hole in the suction valve seat 31. One end of the rod 33 abuts against the valve portion 32. The rod biasing spring 34 biases the valve portion 32 in the valve opening direction, that is, toward the stopper 37, via the rod 33. One end of the rod biasing spring 34 engages with a flange portion provided on the outer periphery of the rod 33. The other end of the rod biasing spring 34 engages with a magnetic core 39 arranged to surround the rod biasing spring 34.

[0049] The anchor 36 faces the end face of the magnetic core 39. The anchor 36 engages with a flange portion provided on the outer periphery of the rod 33. The electromagnetic coil 35 is disposed so as to go around the magnetic core 39. A terminal member 40 is electrically connected to the electromagnetic coil 35, and a current flows through the terminal member 40.

[0050] In a non-energized state where no current flows through the electromagnetic coil 35, the rod 33 is urged in the valve-opening direction by the urging force of the rod-urging spring 34, pressing the valve portion 32 in the valve-opening direction. As a result, the valve portion 32 moves away from the seating portion 31a and abuts against the stopper 37, and the electromagnetic intake valve mechanism 3 is in an open state. In other words, the electromagnetic intake valve mechanism 3 is of a normally open type, which opens in a non-energized state.

[0051] When the electromagnetic intake valve mechanism 3 is in an open state, fuel in the intake port 31b passes between the valve portion 32 and the seat portion 31a, and flows through a plurality of fuel passage holes (not shown) in the stopper 37 and the supply communication hole 1g into the pressurization chamber 11. When the electromagnetic intake valve mechanism 3 is in an open state, the valve portion 32 comes into contact with the stopper 37, so that the position of the valve portion 32 in the valve opening direction is restricted. When the electromagnetic intake valve mechanism 3 is in an open state, the gap between the valve portion 32 and the seat portion 31a is the movable range of the valve portion 32, which is the valve opening stroke.

[0052] When a control signal from ECU 101 is applied to the electromagnetic intake valve mechanism 3, a current flows through the electromagnetic coil 35 via the terminal member 40. When a current flows through the electromagnetic coil 35, the anchor 36 is attracted in the valve closing direction on the magnetic attraction surface by the magnetic attraction force of the magnetic core 39. As a result, the anchor 36 moves against the biasing force of the rod biasing spring 34 and comes into contact with the magnetic core 39.

[0053] When the anchor 36 is attracted to the magnetic core 39 and moves, the rod 33 moves together with the anchor 36 in the valve closing direction. As a result, the valve portion 32 is released from the biasing force in the valve opening direction and moves in the valve closing direction due to the biasing force of the valve biasing spring 38. Then, when the valve portion 32 comes into contact with the seating portion 31a of the suction valve seat 31, the electromagnetic suction valve mechanism 3 is brought into the valve closed state.

[0054] 4 and 5, the discharge valve mechanism 8 is disposed in a discharge valve chamber 80 provided on the outlet side (downstream side) of the pressurizing chamber 11. The discharge valve mechanism 8 includes a discharge valve seat member 81 communicating with the pressurizing chamber 11, and a discharge valve 82 moving toward and away from the discharge valve seat member 81. The discharge valve mechanism 8 also includes a discharge valve spring 83 that biases the discharge valve 82 toward the discharge valve seat member 81, and a discharge valve stopper 84 that determines the stroke (movement distance) of the discharge valve 82. The discharge valve mechanism 8 also has a plug 85 that blocks leakage of fuel to the outside.

[0055] The discharge valve stopper 84 is press-fitted into a plug 85. The plug 85 is joined to the pump body 1 by welding at a welded portion 86. The discharge valve chamber 80 is opened and closed by a discharge valve 82. The discharge valve chamber 80 communicates with a discharge valve chamber passage 87. The discharge valve chamber passage 87 is formed in the pump body 1.

[0056] The pump body 1 is provided with a horizontal hole that communicates with the second chamber 1b (relief valve chamber) shown in Fig. 2. A discharge joint 12 is inserted into this horizontal hole. The discharge joint 12 has the above-mentioned discharge passage 12a that communicates with the horizontal hole of the pump body 1 and the discharge valve chamber passage 87, and a fuel discharge port 12b that is one end of the discharge passage 12a. The fuel discharge port 12b of the discharge joint 12 communicates with a common rail 106. The discharge joint 12 is fixed to the pump body 1 by welding at a welded portion 12c.

[0057] When there is no difference in fuel pressure between the pressurizing chamber 11 and the discharge valve chamber 80 and the discharge valve chamber passage 87, i.e., when there is no so-called fuel differential pressure, the discharge valve 82 is pressed against the discharge valve seat member 81 by the differential pressure acting on the discharge valve 82 and the biasing force of the discharge valve spring 83. As a result, the discharge valve mechanism 8 is in a closed state. On the other hand, when the fuel pressure in the pressurizing chamber 11 becomes greater than the fuel pressure in the discharge valve chamber 80 and the discharge valve chamber passage 87 and the differential pressure acting on the discharge valve 82 becomes greater than the biasing force of the discharge valve spring 83, the discharge valve 82 moves away from the discharge valve seat member 81 against the biasing force of the discharge valve spring 83. As a result, the discharge valve mechanism 8 is in an open state.

[0058] When the discharge valve mechanism 8 is in an open state, the high-pressure fuel in the pressurizing chamber 11 passes through the discharge valve mechanism 8 and reaches the discharge valve chamber 80 and the discharge valve chamber passage 87. The fuel that has reached the discharge valve chamber passage 87 is then discharged into the common rail 106 (see FIG. 1) through the fuel discharge port 12b of the discharge joint 12. With the above-mentioned configuration, the discharge valve mechanism 8 functions as a check valve that limits the flow direction of the fuel.

[0059] 2 and 6 is a valve that is configured to operate when some problem occurs in the common rail 106 or a component beyond it, causing the common rail 106 to exceed a predetermined pressure, and to return fuel in the discharge passage 12a to the pressurizing chamber 11. The discharge passage 12a communicates with the discharge valve chamber 80 via a discharge valve chamber passage 87. Therefore, the pressure in the discharge passage 12a is equal to the pressure in the discharge valve chamber 80.

[0060] The relief valve mechanism 4 opens when the difference between the pressure in the discharge valve chamber 80 (discharge valve chamber passage 87) and the pressure in the second chamber 1b (relief valve chamber) exceeds a set value. The relief valve mechanism 4 is disposed at a higher position in the direction in which the plunger 2 reciprocates (up and down direction) than the discharge valve mechanism 8 (see FIG. 5).

[0061] The relief valve mechanism 4 has a relief spring 41, a relief valve holder 42, a spherical relief valve 43, and a seat member 44. This relief valve mechanism 4 is inserted from the discharge joint 12, and disposed in the second chamber 1b (relief valve chamber).

[0062] The relief spring 41 is a coil spring, and one end of the relief spring 41 abuts against the pump body 1 (one end of the second chamber 1b). The other end of the relief spring 41 abuts against a relief valve holder 42. The relief valve holder 42 engages with a relief valve 43, and the urging force of the relief spring 41 acts on the relief valve 43 via the relief valve holder 42.

[0063] The relief valve holder 42 has a contact portion 42a and an insertion portion 42b that is continuous with the contact portion 42a. The contact portion 42a is formed in a disk shape having an appropriate thickness. An engagement groove with which the relief valve 43 is engaged is formed on one flat surface of the contact portion 42a. The insertion portion 42b protrudes from the other flat surface of the contact portion 42a and the other end of the relief spring 41 abuts against the other flat surface.

[0064] The insertion portion 42b is formed in a cylindrical shape and is inserted into the radially inner side of the relief spring 41. The tip of the insertion portion 42b opposite the abutment portion 42a is formed in a circular flat surface and is disposed near the seat surface of the relief spring 41, which is one end of the relief spring 41. The one end of the relief spring 41 is an end opposite to the insertion side (other end) into which the insertion portion 42b of the relief spring 41 is inserted. The insertion portion 42b has a tapered portion 42c whose outer diameter becomes smaller toward the tip. The tapered portion 42c starts from the relief valve 43 side relative to the portion where a gap is formed between adjacent rings of the relief spring 41.

[0065] Furthermore, the tip end of the insertion portion 42b, where the tapered portion 42c is provided, faces the blocking wall 1d that separates the suction valve chamber 30 and the second chamber 1b. The insertion portion 42b and the blocking wall 1d form a movement restriction portion for the relief valve holder 42. When the relief valve mechanism 4 is in the closed state, a gap S is formed between the tip end of the insertion portion 42b and the blocking wall 1d.

[0066] In a compressed state, the relief spring 41 is interposed between the blocking wall 1d, which separates the second chamber 1b from the suction valve chamber 30, and the contact portion 42a of the relief valve holder 42. When compressed, the relief spring 41 urges the relief valve holder 42 and the relief valve 43 toward the seat member 44. Therefore, it is considered that adjacent rings come into contact with each other at both ends of the relief spring 41. Even if the tapered portion 42c is disposed at the portion where the adjacent rings come into contact with each other, the fuel between the relief spring 41 and the tapered portion 42c is prevented from advancing radially outward from the relief spring 41.

[0067] In contrast, in this embodiment, the tapered portion 42c is disposed in a portion where a gap is formed between adjacent rings of the relief spring 41. This makes it easier for the fuel present between the relief spring 41 and the tapered portion 42c to move from between the adjacent rings of the relief spring 41 to the radially outer side of the relief spring 41. As a result, the fuel can be efficiently sucked into the pressurized chamber 11.

[0068] The relief valve 43 is formed, for example, in a spherical shape having a diameter T. The relief valve 43 is pressed by the biasing force of the leaf spring 41 to block the fuel passage of the seat member 44. The movement direction of the relief valve 43 (relief valve holder 42) is perpendicular to the direction in which the plunger 2 reciprocates, and is the same as the movement direction of the valve portion (suction valve) 32 in the electromagnetic intake valve mechanism 3. The center line of the relief valve mechanism 4 (the center line of the relief valve holder 42) is perpendicular to the center line of the plunger 2.

[0069] The seat member 44 has a fuel passage 44a facing the relief valve 43, and the side of the fuel passage 44a opposite to the relief valve 43 communicates with the discharge passage 12a. The movement of fuel between the pressurizing chamber 11 (upstream side) and the seat member 44 (downstream side) is blocked when the relief valve 43 comes into contact (closes) with the seat member 44 to block the fuel passage 44a.

[0070] Moreover, the seat member 44 faces a contact portion 42a that engages with the relief valve 43 of the relief valve holder 42. A gap H is formed between the seat member 44 and the contact portion 42a of the relief valve holder 42.

[0071] Here, the distance S between the tip of the insertion portion 42b of the relief valve holder 42 and the blocking wall 1d is set to be smaller than the length obtained by subtracting the gap H between the seat member 44 and the abutment portion 42a of the relief valve holder 42 from the diameter T of the relief valve 43.

[0072] When the pressure in the discharge valve chamber 80 (discharge valve chamber passage 87) and the common rail 106 and the components beyond them increases, the difference with the pressure in the second chamber 1b (relief valve chamber) exceeds a set value. As a result, the fuel on the seat member 44 side presses the relief valve 43, moving the relief valve 43 against the biasing force of the relief spring 41. As a result, the relief valve 43 opens, and the fuel in the discharge passage 12a returns to the pressurizing chamber 11 through the fuel passage 44a of the seat member 44. Therefore, the pressure that opens the relief valve 43 is determined by the biasing force of the relief spring 41.

[0073] The movement direction of the relief valve 43 and the relief valve holder 42 in the relief valve mechanism 4 is different from the movement direction of the discharge valve 82 in the above-mentioned discharge valve mechanism 8. That is, the movement direction of the discharge valve 82 in the discharge valve mechanism 8 is a first radial direction of the pump body 1, and the movement direction of the relief valve 43 in the relief valve mechanism 4 is a second radial direction different from the first radial direction of the pump body 1. This allows the discharge valve mechanism 8 and the relief valve mechanism 4 to be disposed in positions where they do not overlap each other in the up-down direction, and the internal space of the pump body 1 can be effectively utilized to reduce the size of the pump body 1.

[0074] As described above, the second chamber 1b, which is the relief valve chamber, is provided with the blocking wall 1d. The blocking wall 1d is disposed between the suction valve chamber 30 and the second chamber 1b in the pump body 1. In this example, the blocking wall 1d is configured as a wall that forms the second chamber 1b, i.e., a wall that separates the suction valve chamber 30 and the second chamber 1b. This blocking wall 1d prevents fuel from passing directly between the second chamber 1b, which is the relief valve chamber, and the suction valve chamber 30.

[0075] Further, the blocking wall 1d faces the tip of the insertion portion 42b of the relief valve holder 42. The other end of the relief spring 41 opposite to the one end that abuts against the abutment portion 42a of the relief valve holder 42 abuts against the blocking wall 1d. That is, the blocking wall 1d is disposed downstream in the moving direction of the relief valve holder 42 when the relief valve mechanism 4 is released.

[0076] The first chamber 1a constituting the pressurizing chamber 11 and the suction valve chamber 30 are in communication with each other through a supply hole 1g. The supply hole 1g extends in a direction perpendicular to the center line of the first chamber 1a. The supply hole 1g is formed closer to the plunger 2 side than the communication hole 1e that communicates the first chamber 1a and the second chamber 1b. The supply hole 1g is connected to the side surface of the first chamber 1a.

[0077] Furthermore, the open ends of the supply communication holes 1g are located closer to the second chamber 1b than the end of the plunger 2, i.e., upstream in the movement direction of the plunger 2, at the upper start point of the plunger 2 where the volume of the pressurizing chamber 11 is at its smallest. In other words, at the upper start point of the plunger 2 where the volume of the pressurizing chamber 11 is at its smallest, the two supply communication holes 1g are formed at positions that are not blocked by the side peripheral surface of the plunger 2.

[0078] Furthermore, as the plunger 2 moves toward the lower starting point where the volume of the pressurizing chamber 11 is maximized, the area of ​​the supply communication hole 1g communicating with the pressurizing chamber increases. This allows the pressurizing chamber 11 to communicate with the suction valve chamber 30 via the supply communication hole 1g regardless of the position of the plunger 2. As a result, a sufficient flow rate of fuel can be ensured from the suction valve chamber 30 to the pressurizing chamber 11, or from the pressurizing chamber 11 to the suction valve chamber 30.

[0079] In addition, when the plunger 2 moves downward and draws fuel from the suction valve chamber 30 into the pressurizing chamber 11, there is a large pressure loss, and if the fuel pressure becomes lower than the saturated vapor pressure, some of the fuel vaporizes and the pressurizing chamber 11 is not completely filled with liquid, resulting in a decrease in volumetric efficiency. Volumetric efficiency is the ratio of the amount of fuel discharged from the discharge valve mechanism 8 to the moving distance from the lower starting point of the plunger 2, where the volume of the pressurizing chamber 11 is most expanded, to the upper starting point of the plunger 2, where the volume of the pressurizing chamber 11 is most reduced.

[0080] In response to this, as described above, the supply communication hole 1g ensures a sufficient flow rate of fuel from the suction valve chamber 30 to the pressurized chamber 11, or from the pressurized chamber 11 to the suction valve chamber 30, thereby reducing pressure loss.

[0081] 1-2.Fuel pump operation Next, the operation of the high-pressure fuel pump 100 according to this embodiment will be described. When the plunger 2 shown in Fig. 1 descends, if the electromagnetic intake valve mechanism 3 is open, fuel flows into the pressurized chamber 11 from the supply communication hole 1g. Hereinafter, the stroke in which the plunger 2 descends will be referred to as the intake stroke. On the other hand, when the plunger 2 ascends, if the electromagnetic intake valve mechanism 3 is closed, the fuel in the pressurized chamber 11 is pressurized and is pumped through the discharge valve mechanism 8 to the common rail 106 (see Fig. 1). Hereinafter, the process in which the plunger 2 ascends will be referred to as the up stroke.

[0082] As described above, if the electromagnetic intake valve mechanism 3 is closed during the upward stroke, the fuel sucked into the pressurization chamber 11 during the intake stroke is pressurized and discharged toward the common rail 106. On the other hand, if the electromagnetic intake valve mechanism 3 is open during the upward stroke, the fuel in the pressurization chamber 11 is pushed back toward the supply passage 1g and is not discharged toward the common rail 106. In this way, the discharge of fuel by the high-pressure fuel pump 100 is controlled by opening and closing the electromagnetic intake valve mechanism 3. The opening and closing of the electromagnetic intake valve mechanism 3 is controlled by the ECU 101.

[0083] During the intake stroke, the volume of the pressurized chamber 11 increases, and the fuel pressure in the pressurized chamber 11 decreases. During this intake stroke, the fluid pressure difference between the pressurized chamber 11 and the intake port 31b (see FIG. 2) decreases. When the biasing force of the rod biasing spring 34 becomes greater than the fluid pressure difference across the valve portion 32, the rod 33 moves in the valve opening direction, the valve portion 32 separates from the seat portion 31a of the intake valve seat 31, and the electromagnetic intake valve mechanism 3 enters an open state.

[0084] When the electromagnetic intake valve mechanism 3 is in an open state, fuel in the intake port 31b passes between the valve portion 32 and the seat portion 31a, passes through multiple fuel passage holes (not shown) in the stopper 37, and flows into the pressurizing chamber 11 from the supply communication hole 1g. When the electromagnetic intake valve mechanism 3 is in an open state, the valve portion 32 comes into contact with the stopper 37, so that the position of the valve portion 32 in the valve opening direction is restricted. The gap between the valve portion 32 and the seat portion 31a when the electromagnetic intake valve mechanism 3 is in an open state is the movable range of the valve portion 32, which is the valve opening stroke.

[0085] After the intake stroke is completed, the valve moves to the upstroke. At this time, the electromagnetic coil 35 remains in a non-energized state, and no magnetic attraction force acts between the anchor 36 and the magnetic core 39. The valve portion 32 is subjected to a biasing force in the valve opening direction corresponding to the difference between the biasing forces of the rod biasing spring 34 and the valve biasing spring 38, and a force pressing in the valve closing direction due to a fluid force generated when fuel flows back from the pressurizing chamber 11 to the low-pressure fuel flow path 10a.

[0086] In this state, in order to maintain the electromagnetic intake valve mechanism 3 in an open state, the difference in the biasing force between the rod biasing spring 34 and the valve biasing spring 38 is set to be larger than the fluid force. The volume of the pressurization chamber 11 decreases as the plunger 2 rises. Therefore, the fuel that was sucked into the pressurization chamber 11 passes between the valve portion 32 and the seat portion 31a again and is returned to the intake port 31b, and the pressure inside the pressurization chamber 11 does not increase. This stroke is called the return stroke.

[0087] In the return stroke, when a control signal from ECU 101 (see FIG. 1) is applied to the electromagnetic intake valve mechanism 3, a current flows through the electromagnetic coil 35 via the terminal member 40. When a current flows through the electromagnetic coil 35, a magnetic attraction force acts between the magnetic core 39 and the anchor 36, and the anchor 36 (rod 33) is attracted to the magnetic core 39. As a result, the anchor 36 (rod 33) moves in the valve closing direction (direction away from the valve portion 32) against the biasing force of the rod biasing spring 34.

[0088] When the anchor 36 (rod 33) moves in the valve closing direction, the valve portion 32 is released from the biasing force in the valve opening direction, and moves in the valve closing direction due to the biasing force of the valve biasing spring 38 and the fluid force caused by the fuel flowing into the intake passage 10b. Then, when the valve portion 32 comes into contact with the seating portion 31a of the intake valve seat 31 (the valve portion 32 seats on the seating portion 31a), the electromagnetic intake valve mechanism 3 is brought into a valve closed state.

[0089] After the electromagnetic intake valve mechanism 3 is closed, the fuel in the pressurizing chamber 11 is pressurized as the plunger 2 rises, and when the pressure of the fuel reaches a predetermined level or higher, it passes through the discharge valve mechanism 8 and is discharged into the common rail 106 (see FIG. 1). This stroke is called the discharge stroke. In other words, the upward stroke of the plunger 2 from the bottom dead center to the top dead center consists of a return stroke and a discharge stroke. The amount of high-pressure fuel discharged can be controlled by controlling the timing of energization of the electromagnetic coil 35 of the electromagnetic intake valve mechanism 3.

[0090] If the timing of energizing the electromagnetic coil 35 is advanced, the proportion of the return stroke during the upward stroke becomes smaller and the proportion of the discharge stroke becomes larger. As a result, less fuel is returned to the intake passage 10b and more fuel is discharged at high pressure. On the other hand, if the timing of energizing the electromagnetic coil 35 is delayed, the proportion of the return stroke during the upward stroke becomes larger and the proportion of the discharge stroke becomes smaller. As a result, more fuel is returned to the intake passage 10b and less fuel is discharged at high pressure. In this way, by controlling the timing of energizing the electromagnetic coil 35, the amount of fuel discharged at high pressure can be controlled to the amount required by the engine (internal combustion engine).

[0091] 2. Example of relief valve mechanism operation Next, a state in which the relief valve mechanism 4 having the above-mentioned configuration is in operation will be described with reference to FIG. FIG. 7 is a cross-sectional view showing a state in which the relief valve mechanism is in operation (opened).

[0092] When the pressure in the discharge valve chamber 80 (discharge valve chamber passage 87), the common rail 106, and the components beyond them increases, the difference with the pressure in the second chamber 1b (relief valve chamber) exceeds a set value. As a result, the fuel on the seat member 44 side presses the relief valve 43, moving the relief valve 43 against the biasing force of the relief spring 41. Then, as shown in FIG. 7, the fuel passage 44a of the seat member 44 that had been blocked by the relief valve 43 is opened. As a result, the fuel in the discharge passage 12a returns to the pressurizing chamber 11 through the fuel passage 44a of the seat member 44.

[0093] At this time, the relief valve holder 42 moves in the valve opening direction (direction approaching the blocking wall 1d) together with the relief valve 43. Then, when the relief valve holder 42 and the relief valve 43 move in the valve opening direction, the tip of the insertion portion 42b of the relief valve holder 42 abuts against the blocking wall 1d, as shown in Fig. 7. This restricts the movement of the relief valve holder 42 and the relief valve 43 in the valve opening direction. Therefore, it is possible to prevent the relief valve 43 from falling out from between the relief valve holder 42 and the seat member 44.

[0094] Furthermore, when the pressure in the discharge valve chamber 80 (discharge valve chamber passage 87), the common rail 106, and the components beyond them decreases and the difference with the pressure in the second chamber 1b (relief valve chamber) falls below a set value, the relief valve holder 42 and the relief valve 43 are moved in the valve closing direction, i.e., in the direction approaching the seat member 44, by the urging force of the relief spring 41. As described above, even in the open state, the relief valve 43 is disposed between the relief valve holder 42 and the seat member 44. Therefore, the fuel passage 44a of the seat member 44 is blocked by the relief valve 43. In this way, according to the fuel pump 100 of this embodiment, it is possible to easily return to the closed valve state after the relief valve mechanism 4 is released.

[0095] Further, a distance S between the tip of the insertion portion 42b of the relief valve holder 42 and the blocking wall 1d is the amount of movement of the relief valve holder 42 and the relief valve 43 in the valve opening direction. This distance S is set to be smaller than a length obtained by subtracting a gap H between the seat member 44 and the abutting portion 42a of the relief valve holder 42 from a diameter T of the relief valve 43. As a result, even if the relief valve holder 42 and the relief valve 43 move significantly in the valve opening direction, the relief valve 43 continues to be reliably present between the relief valve holder 42 and the seat member 44. As a result, the reliability of the fuel pump 100 can be improved.

[0096] The fuel pump of the present invention has been described above with reference to the embodiment, including its operation and effect. However, the fuel pump of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention as set forth in the claims. Furthermore, the above embodiment has been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to the embodiment having all of the configurations described.

[0097] In the above-described embodiment, the restricting portion that restricts the amount of movement of the relief valve holder 42 and the relief valve 43 in the opening operation is configured by the tip of the insertion portion 42b of the relief valve holder 42 and the blocking wall 1d, but the present invention is not limited to this. For example, a protrusion that protrudes from the blocking wall 1d toward the tip of the insertion portion 42b may be used as the restricting portion. Alternatively, a new member that restricts the amount of movement of the relief valve holder 42 may be provided between the insertion portion 42b of the relief valve holder 42 and the blocking wall 1d. In this way, the restricting portion that restricts the amount of movement of the relief valve holder 42 and the relief valve 43 in the opening operation is not limited to the above-described example, and various other mechanisms may be applied.

[0098] In the above embodiment, the second chamber 1b, which is the relief valve chamber, and the suction valve chamber 30 are adjacent to each other, and the center line of the second chamber 1b and the center line of the suction valve chamber 30 are arranged on the same plane. However, the present invention is not limited to this. The second chamber 1b, which is the relief valve chamber, and the suction valve chamber 30 may be on different planes. For example, the center line of the second chamber 1b and the center line of the suction valve chamber 30 may not be parallel but may have an angle therebetween. The center lines of the second chamber 1b and the suction valve chamber 30 may be parallel but offset from each other, or the center lines of the second chamber 1b and the suction valve chamber 30 may be offset from each other and may not be parallel but may have an angle therebetween.

[0099] In this specification, the words "parallel" and "orthogonal" are used, but these do not mean only "parallel" and "orthogonal" in the strict sense, but may also mean a "substantially parallel" or "substantially orthogonal" state that includes "parallel" and "orthogonal" and is within a range in which the respective functions can be exerted. [Explanation of symbols]

[0100] 1...pump body, 1a...first chamber, 1b...second chamber (relief valve chamber), 1c...third chamber, 1d...blocking wall (wall surface portion), 1e...communication hole, 1f...tapered surface, 1g...supply communication hole, 2...plunger, 3...electromagnetic suction valve mechanism, 4...relief valve mechanism, 5...suction joint, 6...cylinder, 8...discharge valve mechanism, 9...pressure pulsation reduction mechanism (damper), 10...low-pressure fuel chamber, 10a...low-pressure fuel flow path, 10b...suction passage, 10c...fuel passage, 11...pressurizing chamber, 12...discharge joint, 30...suction valve chamber, 41...relief spring, 42...relief valve holder, 42a...contact portion, 42b...insertion portion, 42c...tapered portion, 43...relief valve, 44...seat member, 44a...fuel passage, 51...low pressure fuel intake port, 52...intake passage, 53...intake filter, 80...discharge valve chamber, 87...discharge valve chamber passage, 100...high pressure fuel pump, 101...ECU, 102...feed pump, 103...fuel tank, 104...low pressure piping, 105...fuel pressure sensor, 106...common rail, 107...injector

Claims

1. A suction valve chamber; a pressurizing chamber formed downstream of the suction valve chamber; a relief valve chamber formed downstream of the pressurizing chamber; a relief valve mechanism disposed in the relief valve chamber, The relief valve mechanism includes: a relief valve holder disposed in the relief valve chamber; a relief valve engaged with the relief valve holder; a coil-shaped relief spring that biases the relief valve and the relief valve holder in a valve closing direction; a restriction portion that restricts the amount of movement of the relief valve and the relief valve holder in a valve opening direction; Equipped with The relief valve holder includes a contact portion against which the relief spring contacts; a through-portion that is continuous with the abutment portion and is inserted into a radially inner side of the relief spring; The insertion portion has a tapered portion whose outer diameter decreases toward the tip, The tapered portion is formed on the relief valve side from a portion where a gap is formed between adjacent rings of the relief spring. Fuel pump.

2. The amount of movement restricted by the restricting portion is set to be smaller than the diameter of the relief valve.

2. The fuel pump of claim 1.

3. The relief valve mechanism includes: a seat member disposed opposite the relief valve holder, with the relief valve interposed between the seat member and the relief valve holder, The amount of movement restricted by the restriction portion is set to be smaller than the length obtained by subtracting the gap between the seat member and the relief valve holder from the diameter of the relief valve.

3. The fuel pump of claim 2.

4. The restriction portion is formed by a tip portion of the relief valve holder in a valve opening direction and a wall portion of the relief valve chamber that faces the tip portion of the relief valve holder.

2. The fuel pump of claim 1.

5. The wall portion is a wall that separates the relief valve chamber and the suction valve chamber.

5. A fuel pump according to claim 4.

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