JP7769587B2 - fuel pump - Google Patents

Description

The present invention relates to a fuel pump that supplies fuel at high pressure to an engine.

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. A cylinder is attached to the housing. The housing and cylinder form a pressure chamber that pressurizes the fuel. A plunger is engaged with the cylinder so that it can reciprocate. As the plunger reciprocates, the volume of the pressure chamber changes.

The intake valve has an electromagnetic solenoid. When current is supplied to the electromagnetic solenoid, the intake valve opens. When the intake valve opens, fuel is drawn into the pressurization chamber. The discharge valve opens when the fuel pressure in the pressurization chamber reaches a predetermined value or higher. When the discharge valve opens, the fuel is pressurized and sent to the common rail. The relief valve opens when the pressure of the fuel on the common rail side reaches a specific pressure or higher. When the relief valve opens, the fuel on the common rail side returns to the pressurization chamber.

A flange is welded to the housing. The flange is fastened to the engine with mounting bolts. This secures the fuel pump to the engine.

JP 2011-1865 A

However, in the high-pressure fuel supply pump described in Patent Document 1, excessive stress is generated at the weld between the housing and flange and in the vicinity thereof due to the high-pressure fuel in the pressurized chamber. As a result, there is a problem in that the weld between the housing and flange or the vicinity thereof can suffer fatigue failure.

In order to increase the rigidity near the weld, it is possible to increase the flange thickness and length of the weld. However, increasing the weld length increases the area that becomes hotter due to welding. As a result, there is a risk that the housing will experience thermal deformation beyond the allowable limit.

Furthermore, increasing the weld length increases the amount of spatter, making it more difficult to remove. If the spatter is not removed, it will get in the way when attaching other components such as cylinders. Therefore, it is not advisable to increase the flange thickness and lengthen the weld length.

The object of the present invention is to take into consideration the above-mentioned problems and to provide a fuel pump that can suppress fatigue failure at the joint between the housing (body) and the flange and in the vicinity thereof.

To solve the above problems and achieve the object of the present invention, a fuel pump of the present invention includes a body that defines a pressurizing chamber and a flange joined to the body. The flange is fixed to a pump mounting portion of an engine. The flange is formed in an annular shape with an inner periphery that is joined to the body. The flange has a step on the inner periphery that is convex toward the opposite side from the pump mounting portion. The thickness of the inner periphery of the flange is thinner than the thickness of the outer periphery of the flange.

According to the fuel pump having the above configuration, fatigue failure can be suppressed at the joint between the body and the flange and in the vicinity thereof.
Problems, configurations, and effects other than those described above will become clear from the following description of the embodiments.

1 is an overall configuration diagram 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 an embodiment of the present invention. FIG. 3 is a vertical cross-sectional view of the high-pressure fuel supply pump according to the embodiment of the present invention, as viewed from a direction different from that of FIG. 2 . 1 is a horizontal cross-sectional view of a high-pressure fuel supply pump according to an embodiment of the present invention, as viewed from above. FIG. FIG. 5 is a cross-sectional view taken along line AA shown in FIG. 4. FIG. 4 is an explanatory diagram showing an enlarged view of a joint portion between a body and a flange according to an embodiment of the present invention.

1. Embodiment A high-pressure fuel supply pump according to an embodiment of the present invention will be described below. Note that common members in the various drawings are designated by the same reference numerals.

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

As shown in FIG. 1, the fuel supply system includes a high-pressure fuel supply pump (fuel pump) 100, an ECU (Engine Control Unit) 101, a fuel tank 103, a common rail 106, and multiple injectors 107. The components of the high-pressure fuel supply pump 100 are integrally incorporated into a pump body 1 (hereinafter referred to as "body 1").

Fuel is pumped up from the fuel tank 103 by a feed pump 102, which is driven based on a signal from the ECU 101. The pumped fuel is pressurized to an appropriate pressure by a pressure regulator (not shown) and sent to the low-pressure fuel intake port 51 of the high-pressure fuel supply pump 100 through a low-pressure pipe 104.

The high-pressure fuel supply pump 100 pressurizes fuel supplied from the fuel tank 103 and sends it to the common rail 106. The common rail 106 is equipped with multiple injectors 107 and a fuel pressure sensor 105.

Multiple injectors 107 are installed in accordance with the number of cylinders (combustion chambers). The multiple injectors 107 inject fuel in accordance with the drive current output from the ECU 101. The fuel supply system of this embodiment is a so-called direct injection engine system in which the injectors 107 inject fuel directly into the engine cylinders.

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

The ECU 101 controls the operation of the high-pressure fuel supply pump 100 and multiple injectors 107 based on the calculation results of the fuel pressure (target fuel pressure), etc. In other words, the ECU 101 has a pump control unit that controls the high-pressure fuel supply pump 100 and an injector control unit that controls the injectors 107.

The high-pressure fuel supply pump 100 has a pressure pulsation reduction mechanism 9, a variable displacement electromagnetic intake valve mechanism (solenoid valve mechanism) 3, a relief valve mechanism 4 (see Figure 2), and a discharge valve mechanism 8. Fuel flowing in from the low-pressure fuel intake port 51 reaches the intake port 31b of the electromagnetic intake valve mechanism 3 via the pressure pulsation reduction mechanism 9 and the intake passage 10b.

Fuel that flows into the electromagnetic intake valve mechanism 3 passes through the intake valve 32, flows through the intake passage 1d formed in the body 1, and then flows into the pressurized chamber 11. A plunger 2 is slidably held in the pressurized chamber 11. The plunger 2 reciprocates when power is transmitted by the engine cam 91 (see Figure 2).

In the pressurization chamber 11, fuel is drawn in through the electromagnetic intake valve mechanism 3 during the downward stroke of the plunger 2, and is pressurized during the upward stroke. When the fuel pressure in the pressurization chamber 11 exceeds a predetermined value, the discharge valve mechanism 8 opens, and high-pressure fuel is pumped through the fuel discharge port 12a to the common rail 106. Fuel discharge by the high-pressure fuel supply 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.

[High-pressure fuel supply pump]
Next, the configuration of the high-pressure fuel supply pump 100 will be described with reference to FIGS.
Fig. 2 is a vertical cross-sectional view of the high-pressure fuel supply pump 100. Fig. 3 is a vertical cross-sectional view of the high-pressure fuel supply pump 100 as seen from a direction different from that of Fig. 2. Fig. 4 is a horizontal cross-sectional view of the high-pressure fuel supply pump 100 as seen from a cross section perpendicular to the vertical direction.

As shown in Figures 2 to 4, the pump body 1 of the high-pressure fuel supply pump 100 is formed in a generally cylindrical shape. As shown in Figures 2 and 3, the pump body 1 is provided with a first chamber 1a, a second chamber 1b, a third chamber 1c, and an intake passage 1d inside.

The first chamber 1a is a cylindrical space provided in the pump body 1. The center line 1A of the first chamber 1a coincides with the center line of the pump body 1. One end of the plunger 2 is inserted into the first chamber 1a. The plunger 2 reciprocates within the first chamber 1a. The first chamber 1a and one end of the plunger 2 form a pressurization chamber 11.

The intake passage 1d is connected to the pressurized chamber 11. Fuel that passes through the electromagnetic intake valve mechanism 3 is drawn into the pressurized chamber 11 through the intake passage 1d.

The second chamber 1b is a cylindrical space provided in the pump body 1. The center line of the second chamber 1b is perpendicular to the center line of the pump body 1 (first chamber 1a). The second chamber 1b forms a relief valve chamber in which the relief valve mechanism 4 is located. The second chamber 1b is located above the first chamber 1a. The second chamber 1b is connected to one end (upper end) of the first chamber 1a. The diameter of the second chamber 1b (relief valve chamber) is smaller than the diameter of the first chamber 1a.

The third chamber 1c is a cylindrical space provided in the pump body 1. It is continuous with the other end (lower 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. 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 located in the third chamber 1c.

The cylinder 6 is cylindrical. The outer periphery of the cylinder 6 is press-fit into the third chamber 1c of the body 1. The end face of the cylinder 6 abuts against the step between the first chamber 1a and the third chamber 1c. This prevents the cylinder 6 from shifting toward the first chamber 1a. The cylinder 6 guides the reciprocating motion of the plunger 2.

The body 1 is provided with a fixing portion 1e that engages with the axial center of the cylinder 6. The fixing portion 1e of the body 1 presses the cylinder 6 upward (upward in Figure 2). This prevents fuel pressurized in the compression chamber 11 from leaking between the upper end surface of the cylinder 6 and the body 1.

As shown in Figure 3, a mounting flange 21 is joined to the body 1. The mounting flange 21 is in close contact with the fuel pump mounting portion 90 of the engine (internal combustion engine). The mounting flange 21 is attached to the fuel pump mounting portion 90 using two bolts (screws) 22. In other words, the high-pressure fuel supply pump 100 is fixed to the fuel pump mounting portion 90 by the mounting flange 21. The mounting flange 21 will be described later with reference to Figures 5 and 6.

As shown in Figures 2 and 3, an O-ring 93, which is a specific example of a seat member, is interposed between the fuel pump mounting portion 90 and the body 1. This O-ring 93 prevents engine oil from passing between the fuel pump mounting portion 90 and the body 1 and leaking outside the engine (internal combustion engine).

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 engine's camshaft 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. As a result, the lower end of the plunger 2 is pressed against the tappet 92. The tappet 92 reciprocates as the cam 91 rotates. The plunger 2 reciprocates together with the tappet 92, changing the volume of the pressurized chamber 11.

A seal holder 17 is positioned between the cylinder 6 and the retainer 15. The seal holder 17 is cylindrically shaped and the plunger 2 is inserted into it. A sub-chamber 17a is formed between the top of the seal holder 17 and the pump body 1. The seal holder 17 also holds a plunger seal 18 at its lower end, which faces the retainer 15.

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 off the fuel in the auxiliary chamber 17a, preventing the fuel from flowing into the engine. The plunger seal 18 also prevents lubricating oil (including engine oil) that lubricates the sliding parts inside the engine from flowing into the body 1.

In Figure 2, the plunger 2 reciprocates up and down. When the plunger 2 descends, the volume of the pressurized chamber 11 expands, and when the plunger 2 ascends, the volume of the pressurized chamber 11 decreases. In other words, the plunger 2 is positioned to reciprocate in directions that expand and contract the volume of the pressurized chamber 11.

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 or decreases as the plunger 2 reciprocates.

The auxiliary chamber 17a is connected to the low-pressure fuel chamber 10 via the fuel passage 10c (see Figure 4). When the plunger 2 descends, fuel flows from the auxiliary chamber 17a to the low-pressure fuel chamber 10. When the plunger 2 ascends, fuel flows from the low-pressure fuel chamber 10 to the auxiliary chamber 17a. This reduces the amount of fuel flowing into and out of the high-pressure fuel supply pump 100 during the intake stroke or return stroke. As a result, pressure pulsations generated inside the high-pressure fuel supply pump 100 can be reduced.

As shown in Figure 3, a low-pressure fuel chamber 10 is provided at the top of the pump body 1 of the high-pressure fuel supply pump 100. An intake joint 5 is attached to the side of the low-pressure fuel chamber 10. The intake joint 5 is connected to a low-pressure pipe 104 that carries fuel supplied from a fuel tank 103 (see Figure 1). The fuel in the fuel tank 103 is supplied from the intake joint 5 to the inside of the pump body 1.

The intake joint 5 has a low-pressure fuel intake port 51 connected to the low-pressure pipe 104, and an intake passage 52 that communicates with the low-pressure fuel intake port 51. An intake filter 53 is arranged in the intake passage 52. Fuel that enters the intake passage 52 from the low-pressure fuel intake port 51 passes through the intake filter 53 and is supplied to the low-pressure fuel chamber 10. The intake filter 53 removes foreign matter from the fuel, preventing it from entering the high-pressure fuel supply pump 100.

The low-pressure fuel chamber 10 is covered by a damper cover 14. The low-pressure fuel chamber 10 is provided with a low-pressure fuel flow path 10a and an intake passage 10b. The intake passage 10b is connected to the intake port 31b (see Figure 2) of the electromagnetic intake valve mechanism 3. The fuel that passes through the low-pressure fuel flow path 10a reaches the intake port 31b of the electromagnetic intake valve mechanism 3 via the intake passage 10b.

A pressure pulsation reduction mechanism 9 is provided in the low-pressure fuel flow path 10a. When fuel that has flowed into the pressurized chamber 11 passes through the open electromagnetic intake valve mechanism 3 and is returned to the intake passage 10b (see Figure 2), pressure pulsations occur in the low-pressure fuel chamber 10. The pressure pulsation reduction mechanism 9 reduces the spread of pressure pulsations generated within the high-pressure fuel supply pump 100 to the low-pressure piping 104.

The pressure pulsation reduction mechanism 9 has a metal diaphragm damper made of two corrugated, disk-shaped metal plates bonded together at their outer peripheries. An inert gas such as argon is injected inside the metal diaphragm damper. The metal diaphragm damper absorbs or reduces pressure pulsations by expanding and contracting.

As shown in Figures 2 and 4, the electromagnetic intake valve mechanism 3 is inserted into a horizontal hole formed in the body 1. The horizontal hole is located upstream of the pressurizing chamber 11 (on the intake passage 10b side). The electromagnetic intake valve mechanism 3 includes an intake valve seat 31 press-fitted into the horizontal hole formed in the body 1, an intake valve 32, an intake valve biasing spring 34, an electromagnetic coil 35, and an anchor 36.

The intake valve seat 31 is cylindrical. A seat 31a is provided on the inner periphery of the intake valve seat 31. An intake port 31b is formed in the intake valve seat 31, reaching from the outer periphery to the inner periphery. The intake port 31b is connected to the intake passage 10b in the low-pressure fuel chamber 10 described above.

The suction valve 32 has a rod portion 32a and a valve portion 32b. The rod portion 32a is cylindrical. One end of the rod portion 32a is provided with the valve portion 32b. The other end of the rod portion 32a faces the anchor 36. The valve portion 32b faces the seat portion 31a of the suction valve seat 31.

The intake valve seat 31 has a rod guide 31c through which the rod portion 32a passes. The rod guide 31c is cylindrical. In addition to the cylindrical bore through which the rod portion 32a passes, the rod guide 31c also has a communication passage that passes through it in the axial direction. This prevents the movement of fuel within the electromagnetic intake valve mechanism 3 from being impeded when the anchor 36 moves axially.

A stopper 37 is positioned in a horizontal hole formed in the body 1, facing the seating portion 31a of the suction valve seat 31. The valve portion 32b of the suction valve 32 is positioned between the stopper 37 and the seating portion 31a.

When the valve portion 32b abuts against the seat portion 31a, it closes the communication between the suction port 31b and the pressurizing chamber 11. As a result, the electromagnetic suction valve mechanism 3 is in a closed state. On the other hand, when the valve portion 32b abuts against the stopper 37, it opens the communication between the suction port 31b and the pressurizing chamber 11. As a result, the electromagnetic suction valve mechanism 3 is in an open state.

One end of the suction valve biasing spring 34 abuts against a flange provided on the rod portion 32a of the suction valve 32. The other end of the suction valve biasing spring 34 abuts against the rod guide 31c of the suction valve seat 31. The suction valve biasing spring 34 biases the suction valve 32 in a direction in which the valve portion 32b approaches the seating portion 31a of the suction valve seat 31. Hereinafter, the direction in which the valve portion 32b approaches the seating portion 31a will be referred to as the valve closing direction.

The anchor 36 is formed in a substantially cylindrical shape. One axial end of the anchor 36 abuts against the rod portion 32a of the suction valve 32. The other axial end of the anchor 36 faces the fixed core 39. The fixed core 39 is formed in a cylindrical shape. One axial end of the fixed core 39 faces the other axial end of the anchor 36.

An anchor guide 33 is fitted to the other axial end of the fixed core 39. The anchor guide 33 is cylindrical. The anchor guide 33 has a large diameter portion that fits into the inner periphery of the fixed core 39 and a small diameter portion that is smaller than the large diameter portion. The small diameter portion of the anchor guide 33 protrudes from one axial end of the fixed core 39. An anchor 36 is slidably fitted into the small diameter portion of the anchor guide 33.

An anchor biasing spring 40 is fitted around the outer periphery of the small diameter portion of the anchor guide 33. One end of the anchor biasing spring 40 abuts against the other axial end of the anchor 36. The other end of the anchor biasing spring 40 abuts against the large diameter portion of the anchor guide 33.

The anchor biasing spring 40 biases the anchor 36 in a direction away from the fixed core 39. Hereinafter, the direction in which the anchor 36 moves away from the fixed core 39 will be referred to as the valve closing direction. Note that the biasing force of the anchor biasing spring 40 is greater than the biasing force of the suction valve biasing spring 34.

The electromagnetic coil 35 is arranged so as to wrap around the fixed core 39. The electromagnetic coil 35 is made of copper wire wound multiple times around a bobbin. The terminal member 30 is electrically connected to the electromagnetic coil 35. Current flows through the electromagnetic coil 35 via the terminal member 30.

In the de-energized state where no current flows through the electromagnetic coil 35, the anchor 36 is biased in the valve-open direction by the biasing force of the anchor biasing spring 40. As a result, the anchor 36 presses the suction valve 32 in the valve-open direction. As a result, the valve portion 32b of the suction valve 32 moves away from the seating portion 31a and abuts against the stopper 37. Therefore, the electromagnetic suction valve mechanism 3 is in an open state. In other words, the electromagnetic suction valve mechanism 3 is a normally open type that opens in the de-energized state.

When the electromagnetic intake valve mechanism 3 is in an open state, fuel in the intake port 31b passes between the intake valve 32 and the seat 31a, through multiple fuel passage holes (not shown) in the stopper 37, and through the intake passage 1d and into the pressurized chamber 11. When the electromagnetic intake valve mechanism 3 is in an open state, the valve portion 32b of the intake valve 32 comes into contact with the stopper 37, restricting the position of the intake valve 32 in the valve opening direction. When the electromagnetic intake valve mechanism 3 is in an open state, the gap between the valve portion 32b of the intake valve 32 and the seat 31a is the distance the intake valve 32 can move, which is the valve opening stroke.

When current flows through the electromagnetic coil 35, magnetic flux is generated. The generated magnetic flux passes through the fixed core 39, anchor 36, etc. as a magnetic path. A magnetic attraction force is then exerted on the magnetically attractive surfaces (facing surfaces) of the anchor 36 and fixed core 39. As a result, the anchor 36 moves against the biasing force of the anchor biasing spring 40 and comes into contact with the fixed core 39.

When the anchor 36 moves in the valve-closing direction, toward the fixed core 39, the intake valve 32 is released from the valve-opening biasing force of the anchor biasing spring 40. The intake valve 32 then moves in the valve-closing direction due to the biasing force of the intake valve biasing spring 34 and the fluid force generated by fuel flowing into the intake passage 10b. This causes the valve portion 32b of the intake valve 32 to come into contact with the seat portion 31a of the intake valve seat 31. As a result, the electromagnetic intake valve mechanism 3 enters a closed state.

As shown in Figure 4, the discharge valve mechanism 8 is connected to the outlet side of the pressurizing chamber 11. The discharge valve mechanism 8 is housed in a discharge valve chamber 80 formed in the body 1. The discharge valve mechanism 8 includes a discharge valve seat member 81 and a discharge valve 82 that moves 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 lift amount (travel distance) of the discharge valve 82.

The discharge valve mechanism 8 also has a plug 85 that prevents fuel from leaking to the outside. The discharge valve stopper 84 is press-fit into the plug 85. The plug 85 is joined to the body 1 by welding at a weld 86.

The discharge valve chamber 80 is a generally cylindrical space extending horizontally. One end of the discharge valve chamber 80 is connected to the pressurizing chamber 11. The other end of the discharge valve chamber 80 opens to the side of the body 1. The opening at the other end of the discharge valve chamber 80 is sealed by a discharge valve stopper 84.

A discharge joint 12 is joined to the body 1 by a welded portion 12b. The discharge joint 12 has a fuel discharge port 12a. The fuel discharge port 12a is connected to the discharge valve chamber 80 via a discharge passage 87. The discharge passage 87 extends horizontally inside the body 1. The fuel discharge port 12a is connected to a common rail 106 (see Figure 1).

When the fuel pressure in the pressurization chamber 11 is lower than the fuel pressure in the discharge valve chamber 80, the differential pressure acting on the discharge valve 82 and the biasing force of the discharge valve spring 83 press the discharge valve 82 against the discharge valve seat member 81. As a result, the discharge valve mechanism 8 is in a closed state. On the other hand, when the fuel pressure in the pressurization chamber 11 exceeds the fuel pressure in the discharge valve chamber 80 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. As a result, the discharge valve mechanism 8 is in an open state.

When the discharge valve mechanism 8 is in an open state, fuel in the pressurized chamber 11 is discharged into the common rail 106 (see Figure 1) via the discharge valve chamber 80, the discharge passage 87, and the fuel discharge port 12a of the discharge joint 12. With this configuration, the discharge valve mechanism 8 functions as a check valve that restricts the direction of fuel flow.

As shown in FIG. 2, a relief valve mechanism 4 is disposed in the second chamber 1b of the body 1. The relief valve mechanism 4 includes a relief spring 41, a relief valve holder 42, a relief valve 43, and a seat member 44.

The seat member 44 is formed in a cylindrical shape with a bottom. The outer periphery of the seat member 44 is fixed to the inner wall surface of the second chamber 1b. The relief spring 41, relief valve holder 42, and relief valve 43 are disposed between the bottom of the seat member 44 and the bottom of the second chamber 1b. A through hole that serves as a fuel passage is formed in the bottom of the seat member 44.

One end of the relief spring 41 abuts against the bottom of the second chamber 1b. The other end of the relief spring 41 abuts against the relief valve holder 42. The relief spring 41 biases the relief valve holder 42 toward the bottom of the seat member 44. The relief valve 43 is disposed between the relief valve holder 42 and the bottom of the seat member 44.

The relief valve 43 engages with the relief valve holder 42. The relief valve 43 is biased toward the bottom of the seat member 44 together with the relief valve holder 42. As a result, the relief valve 43 blocks the fuel passage of the seat member 44. The fuel passage of the seat member 44 communicates with the discharge passage 87 (see Figure 4). The movement of fuel between the pressurization chamber 11 (upstream side) and the seat member 44 (downstream side) is blocked by the relief valve 43 coming into contact (close contact) with the seat member 44.

When the pressure of fuel in the common rail 106 and the components beyond it increases, the fuel on the seat member 44 side presses against the relief valve 43. This causes the relief valve 43 to move against the biasing force of the relief spring 41. As a result, the relief valve mechanism 4 opens, and fuel in the discharge passage 87 returns to the pressurized chamber 11 through the fuel passage 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.

In this embodiment, the relief valve mechanism 4 is connected to the pressurized chamber 11, but this is not limited to this. The relief valve mechanism according to the present invention may also be connected to a low-pressure passage (such as the low-pressure fuel intake port 51 or intake passage 10b), for example.

[Mounting flange]
Next, the mounting flange 21 will be described with reference to FIGS.
Fig. 5 is a cross-sectional view taken along line AA shown in Fig. 4. Fig. 6 is an enlarged explanatory view of the joint between the body 1 and the mounting flange 21.

As shown in Figure 4, the mounting flange 21 consists of a substantially annular plate. The mounting flange 21 is formed by processing sheet metal. The inner periphery of the mounting flange 21 is joined to the outer periphery of the body 1. The mounting flange 21 has a fixing portion 211 that protrudes radially.

As shown in FIG. 5 , the fixing portion 211 has a threaded through-hole 212 through which a bolt (screw) 22 passes. The bolt 22 is threaded into the fuel pump mounting portion 90. The mounting flange 21 is fixed to the fuel pump mounting portion 90 by the bolt 22. The lower surface of the mounting flange 21 abuts against the upper surface of the fuel pump mounting portion 90.

As shown in FIG. 6 , the mounting flange 21 has a step 213. The step 213 is formed so that its inner circumferential side is convex upward. In other words, the step 213 is formed so that its inner circumferential side is convex on the side opposite the fuel pump mounting portion 90. The upper surface of the step 213 is higher than the upper surface of the fixing portion 211. The lower surface of the step 213 is higher than the lower surface of the fixing portion 211. A gap is formed between the lower surface of the step 213 and the fuel pump mounting portion 90.

The step 213 is formed by plastically deforming the inner periphery of the mounting flange 21. As a result, work hardening occurs in the step 213. The thickness t1 of the inner periphery of the mounting flange 21 is thinner than the thickness t2 of the outer periphery of the mounting flange 21.

The inner periphery of the mounting flange 21 and the outer periphery of the body 1 are joined by welding. The welding is, for example, laser welding. The laser is applied from the underside of the mounting flange 21 and the body 1. As a result, the vertical cross section of the weld 214 is formed into an approximately triangular shape that narrows toward the top surface of the mounting flange 21.

When the fuel pressure in the pressurization chamber 11 of the high-pressure fuel supply pump 100 becomes high, a force is applied to the body 1 that pulls it upward. This generates stress in the weld 214. At this time, the stress is distributed not only to the weld 214, which is the joint, but also to the step 213. Note that while stress is more likely to be distributed to the step 213, it is also distributed around the step 213. This prevents stress from concentrating on the weld 214 and its vicinity without changing the weld length. As a result, damage to the body 1 and mounting flange 21 can be suppressed or prevented.

[Operation of high-pressure fuel supply pump]
Next, the operation of the high-pressure fuel supply pump 100 will be described with reference to FIG.

In Figure 2, when the plunger 2 descends, if the electromagnetic intake valve mechanism 3 is open, fuel flows from the intake passage 1d into the pressurization chamber 11. 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 pressurization chamber 11 is pressurized. As a result, the fuel in the pressurization chamber 11 passes through the discharge valve mechanism 8 (see Figure 4) and is pressure-fed to the common rail 106 (see Figure 1). Hereinafter, the stroke in which the plunger 2 ascends will be referred to as the compression stroke.

If the electromagnetic intake valve mechanism 3 is closed during the compression stroke, the fuel drawn 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 compression stroke, the fuel in the pressurization chamber 11 is pushed back toward the intake passage 1d and is not discharged toward the common rail 106. In this way, the discharge of fuel by the high-pressure fuel supply pump 100 is controlled by the opening and closing of the electromagnetic intake valve mechanism 3. The opening and closing of the electromagnetic intake valve mechanism 3 is controlled by the ECU 101.

During the intake stroke, the volume of the pressurized chamber 11 increases, causing the fuel pressure within the pressurized chamber 11 to decrease. This causes the fuel pressure in the pressurized chamber 11 to decrease below the fuel pressure in the intake port 31b. When the biasing force due to the pressure difference between the two exceeds the biasing force of the valve biasing spring 38, the intake valve 32 moves away from the seat 31a. This causes the electromagnetic intake valve mechanism 3 to enter an open state. As a result, fuel on the intake port 31b side flows between the intake valve 32 and the seat 31a and through multiple holes in the stopper 37 into the pressurized chamber 11.

After the intake stroke is completed, the compression stroke begins. At this time, the electromagnetic coil 35 remains de-energized, and no magnetic attraction force acts between the anchor 36 and the fixed core 39. A biasing force in the valve-opening direction is applied to the intake valve 32 according to the difference in biasing force between the anchor biasing spring 40 and the rod biasing spring 34. Furthermore, a fluid force (a pushing force in the valve-closing direction) is applied to the intake valve 32 when fuel flows back from the pressurization chamber 11 to the low-pressure fuel flow path 10a.

In this state, to maintain the electromagnetic intake valve mechanism 3 in an open state, the difference in the biasing forces of the anchor biasing spring 40 and the rod biasing spring 34 is set greater 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 intake valve 32 and the intake valve seat 31 and is returned to the intake port 31b. Therefore, the fuel pressure inside the pressurization chamber 11 does not increase. This stroke is called the return stroke.

During the return stroke, when a control signal from the ECU 101 (see Figure 1) is applied to the electromagnetic intake valve mechanism 3, current flows through the electromagnetic coil 35 via the terminal member 30. When current flows through the electromagnetic coil 35, a magnetic attraction force acts on the magnetic attraction surfaces of the fixed core 39 and anchor 36, attracting the anchor 36 to the fixed core 39.

When the magnetic attractive force becomes greater than the biasing force of the anchor biasing spring 40, the anchor 36 moves toward the fixed core 39 (in the valve closing direction) against the biasing force of the anchor biasing spring 40. This causes the anchor 36 to move away from the intake valve 32. As a result, the biasing force of the intake valve biasing spring 34 and the fluid force caused by the fuel flowing into the intake passage 10b cause the valve portion 32b of the intake valve 32 to seat on the seating portion 31a. When the intake valve 32 seats on the seating portion 31a, the electromagnetic intake valve mechanism 3 enters a closed state.

After the electromagnetic intake valve mechanism 3 closes, the fuel in the pressurization chamber 11 is pressurized as the plunger 2 rises. When the fuel in the pressurization chamber 11 reaches a predetermined pressure or higher, it passes through the discharge valve mechanism 8 (see Figure 4) and is discharged into the common rail 106 (see Figure 1). This stroke is called the discharge stroke. In other words, the compression stroke from the lower starting point of the plunger 2 to the upper starting point 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.

If the timing at which current is applied to the electromagnetic coil 35 is advanced, the proportion of the return stroke during the compression stroke decreases and the proportion of the discharge stroke increases. 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 at which current is applied to the electromagnetic coil 35 is delayed, the proportion of the return stroke during the compression stroke increases and the proportion of the discharge stroke decreases. 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 at which current is applied to 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).

2. Summary As described above, the above-described high-pressure fuel supply pump 100 (fuel pump) includes the body 1 that defines the pressurizing chamber 11, and the mounting flange 21 (flange) that is joined to the body 1. The mounting flange 21 is fixed to the fuel pump mounting portion 90 (pump mounting portion) of the engine. The mounting flange 21 is formed in an annular shape with an inner periphery that is joined to the body 1. The mounting flange 21 has a step 213 on the inner periphery that is convex on the side opposite the fuel pump mounting portion 90.
As a result, when stress is generated due to the application of a force that pulls the body 1 upward, the stress can be distributed not only to the welded portion 214, which is the joint between the body 1 and the mounting flange 21, but also to the step portion 213. As a result, stress can be prevented from concentrating on the welded portion 214 and its vicinity, without changing the weld length.

The body 1 and the mounting flange 21 (flange) in the above-described high-pressure fuel supply pump 100 (fuel pump) are joined by welding.
This allows for a strong connection between the body 1 and the mounting flange 21. The connection between the body 1 and the mounting flange 21 is not limited to welding, and may be achieved by, for example, adhesion using an adhesive, soldering, press-fitting, caulking, or the like.

The thickness of the mounting flange 21 (flange) on the inner periphery side of the high-pressure fuel supply pump 100 (fuel pump) described above is thinner than the thickness of the mounting flange 21 on the outer periphery side.
This allows work hardening to occur in the step portion 213 provided on the inner peripheral side, thereby preventing or suppressing damage to the step portion 213 when stress is distributed.

The mounting flange 21 (flange) of the above-described high-pressure fuel supply pump 100 (fuel pump) is formed by processing (processing that causes plastic deformation) that causes work hardening in the step portion 213 .
This makes it possible to prevent or suppress damage to the step portion 213 when stress is distributed.

The above describes an embodiment of the fuel pump of the present invention, including its effects. However, the fuel pump of the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the invention as set forth in the claims.

The above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the configurations described. It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

1...Body, 2...Plunger, 3...Electromagnetic intake valve mechanism, 4...Relief valve mechanism, 5...Intake joint, 6...Cylinder, 8...Discharge valve mechanism, 9...Pressure pulsation reduction mechanism, 10...Low-pressure fuel chamber, 11...Pressure chamber, 12...Discharge joint, 14...Damper cover, 15...Retainer, 17...Seal holder, 17a...Sub-chamber, 18...Plunger seal, 21...Mounting flange, 22...Bolt, 90...Fuel pump mounting portion, 100...High-pressure fuel supply pump, 101...ECU, 102...Feed pump, 103...Fuel tank, 104...Low-pressure piping, 105...Fuel pressure sensor, 106...Common rail, 107...Injector, 211...Fixed portion, 212...Threaded through-hole, 213...Step portion, 214...Welded portion

Claims (3)

A fuel pump comprising: a body that defines a pressurizing chamber; and a flange that is joined to the body, the flange being fixed to a pump mounting portion of an engine,
the flange is formed in an annular shape having an inner circumferential portion to be joined to the body, and the inner circumferential portion has a step portion that is convex on the side opposite to the pump mounting portion,
The thickness of the flange on the inner periphery side is thinner than the thickness of the flange on the outer periphery side.
Fuel pump. The fuel pump according to claim 1, wherein the body and the flange are joined by welding. The fuel pump according to claim 1 or 2 , wherein the flange is formed by processing that causes work hardening to appear in the stepped portion.