High-pressure fuel pump

Abstract

High-pressure fuel pump, which includes: a stationary core (39) made of a ferritic metal of the precipitation-hardening type; a ferritic metal armature (36) of the precipitation-hardening type, which is attracted by a magnetic attraction force of the stationary core (39); an outer core (38) with an inner circumferential surface on which an outer circumferential surface of the anchor (36) slides; and a sealing ring (48) formed from a material with a lower hardness than the stationary core (39) and the anchor (36), wherein the sealing ring (48) connects the stationary core (39) and the outer core (38), and wherein the high-pressure fuel pump is characterized in that the sealing ring (48) has a cylindrical shape, the stationary core (39) and the outer core (38) each have an insertion section that is to be inserted into the sealing ring (48), and the stationary core (39) and the outer core (38) have an outer circumferential surface which, in a state in which they are inserted into the sealing ring (48), is flush with an outer circumferential surface of the sealing ring (48).

Description

Technical area

[0001] The present invention relates to a high pressure fuel pump. State of the art

[0002] There is a conventional technique of the high-pressure fuel pump of the present invention, as described in PTL 1. PTL 1 discloses in paragraph 0058 that "the armature and the second core are made of stainless magnetic steel to form a magnetic circuit, and the impact surface of both the armature and the second core is subjected to a surface treatment to improve hardness," and that "the surface treatment includes hard Cr plating."

[0003] As a conventional technology for a magnetic material product, although not a high-pressure fuel pump, PTL 2, a prior art publication, discloses in paragraph 0035 that "the fixed core, the movable core, and the magnetic cylinder are all made of a high-hardness ferritic magnetic material." Furthermore, PTL 2 discloses in paragraph 0004 that "the high-hardness ferritic magnetic material is subjected to precipitation hardening, thermal hardening, and heat treatment." Furthermore, WO 2017 / 056681 A1 (cf. PTL 3) describes a high-pressure fuel pump for internal combustion engines that ensures fast and efficient closure of the suction valve even under increased pressure or capacity. The pump includes a rod that pushes the suction valve in the opening direction, a mover that moves the rod in the closing direction, and a solenoid that generates a magnetic attraction force.This configuration allows the responsiveness of the suction valve to be maintained and the discharge capacity to be maximized. The special arrangement and control of the components improves fuel delivery efficiency and reduces noise. Finally, (see PTL 4) discloses an electromagnetic valve structure for fuel injection systems, in which the electromagnet cores consist of 10 to 20 wt. percent chromium (Cr), 0.1 wt. percent silicon (Si), 1.15 to 6 wt. percent aluminum (Al) and nickel (Ni), as well as ferritic iron (Fe) and impurities. This leads to a reduction in manufacturing costs and an improvement in the performance and durability of the electromagnetic valves. List of citationsPatent literature PTL 1: JP 2016-94913 A PTL 2: JP 2004-300540 A, PTL 3: WO 2017 / 056 681 A1, PTL 4: JP 2002-4 013 A Summary of the inventionTechnical problem

[0004] However, in the structure of PTL 1, hard chromium plating is applied to the impact surface, increasing the number of components and the number of steps, thereby increasing costs. When the high-hardness ferritic magnet material described in PTL 2 is applied, there is a possibility that the plating treatment can be omitted due to its high hardness and wear resistance. However, precipitation-hardening stainless steel generally has low toughness, requiring anti-cracking treatment.

[0005] An object of the present invention is to provide a high pressure fuel pump capable of ensuring good magnetic properties and reliability against cracking. Solution to the problem

[0006] The problem is solved by the features of claim 1. Particular embodiments are described in the dependent claims. Advantageous effects of the invention

[0007] According to the present invention, it is possible to ensure good magnetic properties and reliability against cracking. Problems, configurations, and effects other than those described above will be clarified from the following description of embodiments. Brief description of the drawings Fig. 1 illustrates a configuration diagram of an engine system to which a high-pressure fuel pump of the present embodiment is applied. Fig. 2 is a longitudinal cross-sectional view of the high-pressure fuel pump of the present embodiment. Fig. 3 is a horizontal cross-sectional view of the high-pressure fuel pump of the present embodiment as seen from above. Fig. 4 is a longitudinal cross-sectional view of the high-pressure fuel pump of the present embodiment as seen from a direction other than that in Fig. 2 seen. Fig. 5 is an enlarged longitudinal cross-sectional view of an electromagnetic valve mechanism of the high-pressure fuel pump of the present embodiment, illustrating a state in which the electromagnetic valve mechanism is in a valve-opening state. Fig. 6 is an enlarged longitudinal cross-sectional view of an electromagnetic valve mechanism of a high-pressure fuel pump of another embodiment. Description of embodiments

[0008] A high-pressure fuel supply pump (hereinafter referred to as a high-pressure fuel pump) according to an embodiment of the present invention will be described in detail with reference to the drawings. Although partially overlapping with the above-described object of the invention, an object of the present embodiment is to provide an electromagnetic valve that achieves both reliability and manufacturing cost without deteriorating magnetic properties, and a high-pressure fuel pump equipped with the electromagnetic valve.

[0009] Fig. 1 illustrates an overall configuration diagram of an engine system. The portion surrounded by a dashed line indicates a main body of the high-pressure fuel pump, indicating that the mechanism and components shown in the dashed line are integrally integrated into a pump body 1. Fig. 1 is a diagram schematically illustrating the operation of the engine system, with a part of the detailed configuration of the high pressure fuel pump configuration in Fig. 2 and in the following figures. Fig. 2 is a longitudinal cross-sectional view of the high-pressure fuel pump of the present embodiment, and Fig. 3 is a horizontal cross-sectional view of the high pressure fuel pump as seen from above. Fig. 4 is a longitudinal cross-sectional view of the high pressure fuel pump, from a direction other than Fig. 2 seen. Fig. 5 is an enlarged view of an electromagnetic valve mechanism 300 (electromagnetic suction valve).

[0010] Fuel in a fuel tank 20 is pumped up by a feed pump 21 based on a signal from an engine control unit 27 (hereinafter referred to as ECU). This fuel is pressurized to a suitable discharge pressure and sent through a suction pipe 28 to a low-pressure fuel suction port 10a of the high-pressure fuel pump.

[0011] The fuel supplied from the low-pressure fuel suction port 10a through a suction connection 51 ( Fig. 3), reaches a suction port 31b of the electromagnetic valve mechanism 300, which forms a variable capacity mechanism, via damper chambers (10b and 10c) in which a pressure pulsation reducing mechanism 9 is arranged. More specifically, the electromagnetic valve mechanism 300 forms an electromagnetic suction valve mechanism.

[0012] The fuel that has flowed into the electromagnetic valve mechanism 300 passes through a suction port opened and closed by a suction valve 30 and flows into a pressurization chamber 11. Power for the reciprocating movement is supplied to a piston 2 through a cam 93 (cam mechanism) of the engine. Due to the reciprocating movement of the piston 2, the fuel is sucked by the suction valve 30 during a downward stroke of the piston 2, and the fuel is pressurized during an upward stroke. The pressurized fuel is supplied under pressure via a discharge valve mechanism 8 to a common fuel rail 23 on which a pressure sensor 26 is mounted.

[0013] An injector 24 then injects fuel into the engine based on a signal from the ECU 27.

[0014] The present embodiment is directed to a high-pressure fuel pump applied to a so-called direct-injection engine system in which the injector 24 injects fuel directly into a cylinder of the engine. The high-pressure fuel pump discharges a fuel flow rate of a desired fuel supply to the electromagnetic valve mechanism 300 through a signal from the ECU 27.

[0015] As in Fig. 2 and Fig. 3, the high-pressure fuel pump of the present embodiment is mounted in close contact with a high-pressure fuel pump mounting portion 90 of an internal combustion engine. As shown in Fig. 3, a bolt hole 1b is formed in a mounting flange 1a provided in the pump body 1, and a plurality of bolts (not shown) are inserted into the bolt hole 1b. In this way, the mounting flange 1a comes into close contact with and is fixed to the high-pressure fuel pump mounting portion 90 of the internal combustion engine. An O-ring 61 is fitted into the pump body 1 to seal between the high-pressure fuel pump mounting portion 90 and the pump body 1, thereby preventing engine oil from leaking to the outside.

[0016] As in Fig. 2 and Fig. As shown in Figure 4, a cylinder 6 is attached to the pump body 1, which guides the reciprocating movement of the piston 2 and, together with the pump body 1, forms the pressurizing chamber 11. That is, the piston 2 changes the volume of the pressurizing chamber through the reciprocating movement within the cylinder. The electromagnetic valve mechanism 300 for supplying fuel to the pressurizing chamber 11 and the discharge valve mechanism 8 for discharging fuel from the pressurizing chamber 11 to a discharge passage are provided.

[0017] The cylinder 6 is press-fitted into the pump body 1 on its outer peripheral side. An insertion hole is formed in the pump body 1 for inserting the cylinder 6 from below, and an inner peripheral protrusion portion is formed, which is deformed toward the inner peripheral side so as to contact the lower surface of a stationary portion 6a of the cylinder 6 at the lower end of the insertion hole. The upper surface of the inner peripheral protrusion portion of the pump body 1 pressurizes the stationary portion 6a of the cylinder 6 upward in the figure and seals the upper end surface of the cylinder 6, so that the fuel pressurized in the pressurizing chamber 11 does not leak to the low-pressure side.

[0018] The lower end of piston 2 is provided with a tappet 92, which converts the rotational movement of cam 93, attached to a camshaft of the internal combustion engine, into a vertical movement and transmits the vertical movement to piston 2. Piston 2 is compressed to tappet 92 by a spring 4 via a retainer 15. This allows piston 2 to reciprocate vertically with the rotational movement of cam 93.

[0019] Furthermore, at the lower portion of the cylinder 6 in the figure, a piston seal 13 held at the lower end portion of the inner periphery of a seal holder 7 is installed in a state of slidably contacting the outer periphery of the piston 2. Thus, the fuel is sealed in an auxiliary chamber 7a to prevent the fuel from flowing into the internal combustion engine when the piston 2 slides. At the same time, lubricating oil (including engine oil) that lubricates a sliding portion in the internal combustion engine is prevented from flowing into the interior of the pump body 1.

[0020] As in Fig. 3 and Fig. As shown in Fig. 4, the suction joint 51 is attached to a side surface portion of the pump body 1 of the high-pressure fuel pump. The suction joint 51 is connected to a low-pressure pipe through which fuel is supplied from the fuel tank 20 of the vehicle, and the fuel is supplied from the suction joint 51 to the interior of the high-pressure fuel pump. A suction filter 52 plays a role in preventing foreign matter present between the fuel tank 20 and the low-pressure fuel suction port 10a from being absorbed by the flow of fuel into the high-pressure fuel pump.

[0021] The fuel that has passed through the low-pressure fuel suction port 10a is discharged through a low-pressure fuel suction passage connected to the Fig. 4, to the pressure pulsation reducing mechanism 9. The pressure pulsation reducing mechanism 9 is arranged in the damper chambers (10b and 10c) between a damper cover 14 and the upper end surface of the pump body 1, and is supported from below by a holding member 9a arranged on the upper end surface of the pump body 1. More specifically, the pressure pulsation reducing mechanism 9 is a metal damper configured by stacking two metal diaphragms. A gas of 0.3 MPa to 0.6 MPa is sealed inside the pressure pulsation reducing mechanism 9, and the outer peripheral edge portion is fixed by welding. For this purpose, the pressure pulsation reducing mechanism 9 is configured to have a thin outer peripheral edge portion that becomes thicker toward the inner peripheral side.

[0022] As in Fig. 2, a protrusion portion is formed on the upper surface of the support member 9a for securing the outer peripheral edge portion of the pressure pulsation reducing mechanism 9 from below. On the other hand, a protrusion portion is formed on the lower surface of the damper cover 14 for securing the outer peripheral edge portion of the pressure pulsation reducing mechanism 9 from above. These protrusion portions are formed in a circular shape, and the pressure pulsation reducing mechanism 9 is secured by being sandwiched between these protrusion portions. The damper portion 14 is press-fitted into and secured to the outer peripheral portion of the pump body 1, and at the same time, the support member 9a is elastically deformed to support the pressure pulsation reducing mechanism 9.

[0023] In this way, damper chambers (10b and 10c) are formed on the upper and lower surfaces of the pressure pulsation reducing mechanism 9, which communicate with the low-pressure fuel suction port 10a and the low-pressure fuel suction passage. Although not shown in the drawings, a passage is formed in the support member 9a through which the upper and lower surfaces of the pressure pulsation reducing mechanism 9 communicate with each other, thereby forming damper chambers (10b and 10c) on the upper and lower surfaces of the pressure pulsation reducing mechanism 9.

[0024] The fuel that has passed through the damper chambers (10b and 10c) then reaches the suction port 31b of the electromagnetic valve mechanism 300 via a suction passage 10d (low-pressure fuel suction passage) formed in vertical communication with the pump body. The suction port 31b is formed in vertical communication with a suction valve seat member 31 forming a suction valve seat 31a.

[0025] The electromagnetic valve mechanism 300 (the electromagnetic suction valve) is controlled by Fig. 5 in detail. There is a coil 43 (an electromagnetic coil) in which a copper wire is wound several times on a coil body 45 and both ends of the copper wire of the coil are energizable with respective ends of the two terminals 46 (in Fig. 2). The terminal 46 is integral with a connector 47 (shown in Fig. 2) and the other end may be connected to the side of the engine control unit.

[0026] The components surrounding the outer periphery of the coil 43 include a first yoke 42, a second yoke 44, and an outer core 38. The first yoke 42 and the second yoke 44 are arranged to surround the coil 43 and are integrally molded and fixed with a connector that is a resin member. The outer core 38 is press-fitted into a hole portion in a central portion of the first hole 42 and fixed therein. The outer core 38 is fixed to the pump body 1 by welding or the like.

[0027] The inner diameter side of the second yoke 44 is configured to contact a stationary core 39 or with a slight gap near the stationary core 39. The outer diameter side of the second yoke 44 is configured to contact the inner circumference of the first yoke 42 or with a slight gap near the inner circumference of the first yoke 42. A fixing pin 832 is fixed to the stationary core 39, and a preload force is generated to press the second yoke 44 against the stationary core 39. The fixing pin 832 may engage the stationary core 39 at a corner portion on the inner circumference side or may be fixed by welding or the like.

[0028] To form a magnetic circuit and to ensure corrosion resistance, both the first yoke 42 and the second yoke 44 are made of a magnetic stainless material. A high-strength heat-resistant resin is used for the coil body 45 and the connector 47, taking into account strength and heat resistance properties.

[0029] A seal ring 48 is welded and fixed to the outer core 38 on the inner circumference of the coil 43, and is welded and fixed to the stationary core 39 at the opposite end thereof. On the inner circumference of the seal ring 48 or the outer core 38, there are an armature 36 (a moving device) and a rod 35, which are movable portions, a rod guide 37, which is a fixed portion, a rod preload spring 40, and an armature spring preload spring 41. The rod 35 is axially slidably supported on the inner circumference of the rod guide 37 and slidably supports the armature 36.

[0030] When a current flows through the coil 43, the armature 36 is attracted to the stationary core 39 by the generated magnetic attraction force. To move axially freely and smoothly in the fuel, the armature 36 has one or more through holes 36a penetrating it in a component axial direction, thereby eliminating as much as possible the restriction of movement due to a pressure difference between the front and back of the armature.

[0031] The rod guide 37 is radially inserted into an inner peripheral side of a hole into which the suction valve of the pump body 1 is inserted, and the rod guide 37 abuts against an end portion of the suction valve seat. The rod guide 37 is configured to be interposed between the outer core 38, which is welded and fixed to an insertion hole of the pump body 1, and the pump body 1. Similar to the armature 36, the rod guide 37 is also provided with an axially penetrating through hole 37a, and is thereby configured not to obstruct the movement of the internal fuel when the armature moves axially.

[0032] The outer core 38 is fixed to the pump body 1 by welding or the like, the seal ring 48 is fixed to the other end, which is welded to the pump body 1 as described above, and further, the stationary core 39 is fixed to the outer end. The rod preload spring 40 is arranged on the inner peripheral side of the stationary core 39, with the small-diameter portion of the rod 35 facing the guide, and preloads the rod 35 to the right in the figure. The rod 35 is engaged with the armature 36 via a flange portion 35a. At the same time, the rod 35 is engaged with the suction valve 30 at the distal end and exerts a preload force in a direction in which the suction valve 30 is separated from the suction valve seat 31a, that is, in a valve-opening direction of the suction valve.

[0033] The armature preload spring 41 is arranged to apply a preload force to the armature 36 toward the flange portion 35a (left in the figure) while coaxially holding the armature by inserting one end of it into a cylindrical center support portion 37b provided on the center side of the rod guide 37. A movement amount 36e of the armature 36 is set larger than a movement amount 30e of the suction valve 30, thereby preventing the suction valve 30 from interfering at the time of valve closing.

[0034] The outer core 38, the first yoke 42, the second yoke 44, the stationary core 39, and the armature 36 form a magnetic circuit around the coil 43. When a current is applied to the coil 43, a magnetic attraction force is generated between the stationary core 39 and the armature 36. Since the armature 36 and the stationary core 39 form a magnetic attraction surface, it is desirable to use a material with good magnetic properties in terms of behavior. At the same time, it must be hard enough to withstand impact. As a material that satisfies these requirements, precipitation hardening type ferritic stainless steel is used.

[0035] To allow magnetic flux to flow between the armature 36 and the stationary core 39, it is desirable that the seal ring 48 be a non-magnetic material. To absorb the shock at the time of impact, it is also desirable to use a thin stainless material with a high elongation. Specifically, austenitic stainless steel is used.

[0036] As in Fig. As shown in Fig. 3, the discharge valve mechanism 8 provided at the outlet of the pressurizing chamber 11 is constituted by a discharge valve seat 8a, a discharge valve 8b in contact with and separated from the discharge valve seat 8a, a discharge valve spring 8c that biases the discharge valve 8b toward the discharge valve seat 8a, and a discharge valve stopper 8d that determines the stroke (movement distance) of the discharge valve 8b. The discharge valve stopper 8e and the pump body 1 are joined by welding at an abutting portion 8d, thereby blocking the fuel from the outside.

[0037] When there is no fuel pressure difference between the pressurizing chamber 11 and a discharge valve chamber 12a, the discharge valve 8b is squeezed against the discharge valve seat 8a by the biasing force of the discharge valve spring 8c and is in a valve-closing state. Only when the fuel pressure in the pressurizing chamber 11 is higher than the fuel pressure in the discharge valve chamber 12a does the discharge valve 8b open against the discharge valve spring 8c. Then, the high-pressure fuel in the pressurizing chamber 11 is discharged through the discharge valve chamber 12a, through a fuel discharge passage 12b, and through a fuel discharge port 12 to the common fuel rail 23.

[0038] When it opens, the discharge valve 8b comes into contact with the discharge valve stopper 8d, which thereby restricts the stroke. Accordingly, the stroke of the discharge valve 8b is appropriately determined by the discharge valve stopper 8d. This can prevent the fuel that has been discharged at high pressure to the discharge valve chamber 12a from flowing back into the pressurizing chamber 11 due to the delay in closing the discharge valve 8b caused by a stroke that is too large, and can suppress the efficiency of the high-pressure fuel pump from decreasing. The discharge valve 8b is guided by the outer peripheral surface of the discharge valve stopper 8d to move only in one stroke direction when the discharge valve 8b repeats the valve opening and closing motion. As described above, the discharge valve mechanism 8 serves as a check valve that restricts a distribution direction of the fuel.

[0039] One in Fig. The relief valve mechanism 200 shown in Figure 3 includes a relief body 201, a relief valve 202, a relief valve retainer 203, a relief spring 204, and a spring stopper 205. The relief body 201 is provided with a seat portion. The relief valve 202 is biased by the load of the relief spring 204 through the relief valve retainer 203, which is pressed onto the seat portion of the relief body 201, and blocks the fuel in cooperation with the seat portion. The valve opening pressure of the relief valve 202 is determined by the load of the relief spring 204. The spring stopper 205 is press-fitted and fixed into the relief body 201, and the load of the relief spring 204 is adjusted according to the press-fit and fixed position.

[0040] When the pressure at the fuel discharge port 12 becomes abnormally high due to a malfunction of the electromagnetic valve mechanism 300 of the high-pressure fuel pump or the like and becomes greater than the target pressure of the relief valve mechanism 200, the fuel under abnormally high pressure is relieved to the pressurizing chamber 11 via a relief passage.

[0041] As described above, the pressurizing chamber 11 is formed by the pump body 1, the electromagnetic valve mechanism 300, the piston 2, the cylinder 6, and the discharge valve mechanism 8.

[0042] Based on Fig. 5 describes a detailed operation of the electromagnetic valve mechanism 300. When the piston 2 moves in the direction of the cam 93 by rotation of the cam 93 and is in a suction stroke state, the volume of the pressurizing chamber 11 increases, and the fuel pressure in the pressurizing chamber 11 decreases. When the fuel pressure in the pressurizing chamber 11 becomes lower than the pressure at the suction port 31b during this stroke, the suction valve 30 enters a valve-opening state. 30e denotes a maximum opening, and at the same time, the suction valve 30 comes into contact with a stopper 32. By opening the suction valve 30, an opening portion 31c formed in the suction valve seat member 31 opens. The fuel passes through the opening portion 31c and flows into the pressurizing chamber 11 in a lateral direction via a hole 1c formed in the pump body 1. The hole 1c also forms a part of the pressurizing chamber 11.

[0043] After the piston 2 completes the suction stroke, the piston 2 transitions to an upward movement and moves to an upward stroke. The coil 43 remains in a de-energized state, and the magnetic preload force is not applied. The rod preload spring 40 is set to preload the flange portion 35a (rod protrusion portion) projecting toward the outer diameter side of the rod 35, which has a preload force necessary and sufficient to maintain the opening of the suction valve 30 in the de-energized state. The volume of the pressurizing chamber 11 decreases with the upward movement of the piston 2, but in this state, the fuel once sucked into the pressurizing chamber 11 is returned to the suction passage 10d through the opening portion 31c of the suction valve 30 in the valve-opening state, so that the pressure in the pressurizing chamber does not increase.This stroke is called a return stroke.

[0044] In this state, when a control signal from the ECU 27 is applied to the electromagnetic valve mechanism 300, a current flows through the terminal 46 through the coil 43. A magnetic attraction force acts between the stationary core 39 and the armature 36, and the stationary core 39 and the armature 36 collide with each other at a magnetic attraction surface S. The magnetic attraction force overcomes the biasing force of the rod biasing spring 40 to bias the armature 36, and the armature 36 engages the flange portion 35a to move the rod in a direction away from the suction valve 30.

[0045] At the same time, the suction valve 30 is closed by the biasing force of a suction valve biasing spring 33 and the fluid force caused by the fuel flowing in the suction passage 10d. After the valve is closed, the fuel pressure in the pressurizing chamber 11 increases with the upward movement of the piston 2, and when the fuel pressure becomes equal to or greater than the pressure of the fuel discharge port 12, the high-pressure fuel is discharged via the discharge valve mechanism 8 and supplied to the common rail 23. This stroke is called a discharge stroke.

[0046] That is, the upward stroke from the lower starting point to the upper starting point of the piston 2 includes a return stroke and an exhaust stroke. The amount of high-pressure fuel to be exhausted can then be controlled by controlling the energization timing of the coil 43 of the electromagnetic valve mechanism 300. If the energization timing of the coil 43 is earlier, the ratio of the return stroke to the compression stroke is small and the ratio of the exhaust stroke is large. That is, less fuel is returned to the suction passage 10d, and more fuel is exhausted at high pressure. On the other hand, if the energization timing is delayed, the ratio of the return stroke is large and the ratio of the exhaust stroke to the compression stroke is small. That is, more fuel is returned to the suction passage 10d, and less fuel is exhausted at high pressure. The energization timing of the coil 43 is controlled by a command from the ECU 27.

[0047] By controlling the timing of energization of the coil 43 as described above, the amount of high-pressure fuel discharged can be controlled to an amount required by the internal combustion engine.

[0048] The following is based on Fig. 5 describes a characteristic configuration of the high-pressure fuel pump according to the present embodiment. The stationary core 39 is made of precipitation-hardening ferritic stainless steel (a ferritic precipitation-hardening metal). The armature 36 is made of precipitation-hardening ferritic stainless steel, which is attracted by the magnetic attraction force of the stationary core 39. This can ensure wear resistance and magnetic properties.

[0049] The outer core 38 has an inner peripheral surface on which the outer peripheral surface of the armature 36 slides. The seal ring 48 is formed of a material with a lower hardness than the stationary core 39 and the armature 36, and connects the stationary core 39 and the outer core 38. In other words, the seal ring 48 is formed of a material (e.g., austenitic stainless steel) with a lower hardness than the ferritic precipitation hardening metal. As described later, this can mitigate the impact load.

[0050] The impact of the stationary core 39 and the armature 36 on the magnetic attraction surface S will be described in detail below. Immediately after the armature 36 impacts the stationary core 39, an impact stress is generated near the contact portion. Due to the elastic deformation of the seal ring 48 during the impact stress generation period, the stationary core 39, the first yoke 42, the second yoke 44, and the fixing pin 832 move in the direction receiving the impact force (in Fig. 5 to the left), and the impact load generated in the stationary core 39 and in the armature 36 is mitigated.

[0051] The material of the stationary core 39 and the armature 36 is precipitation-hardening ferritic stainless steel, which has similar magnetic properties to ferritic stainless steel, but also has a hardness similar to precipitation-hardening stainless steel (HV 300 or higher depending on the manufacturing process). Thus, it can withstand a certain level of stress. Furthermore, the impact stress can be reduced by the mitigating effect described above, ensuring the durability of the impact surface.

[0052] It is important that the sealing ring 48 is thin and capable of large deformation (= large elongation). Here, the sealing ring 48 exhibits greater elongation than the stationary core 39 and the armature 36.

[0053] The sealing ring 48 has an elongation rate, for example, of 35% or more. Furthermore, the sealing ring 48 is required to be non-magnetic (a non-magnetic body) in terms of magnetic behavior, and it is specifically desired that it be formed of austenitic stainless steel. Generally, austenitic stainless steel is non-magnetic and has an elongation rate of 35 to 45% or more.

[0054] The seal ring 48 has a cylindrical shape. The stationary core 39 and the outer core 38 have insertion portions 39ins and 38ins, respectively, which are to be inserted into the seal ring 48. The stationary core 39 and the outer core 38 have an outer peripheral surface that, when inserted into the seal ring 48, is flush with an outer peripheral surface CS of the seal ring 48. This facilitates the attachment of other components such as the coil body 45.

[0055] Precipitation-hardening ferritic stainless steel is specifically composed of the following elements: Cr: 13 to 15%, Ni: about 3%, Cu: 2% or less, C: 0.05% or less, S: 0.05% or less, and Mo: 4% or less. By subjecting this metal to solution treatment and aging, it is possible to achieve a hardness of nearly 370 HV. Generally, precipitation-hardening stainless steel has a small elongation (5% or less), but the precipitation-hardening ferrite type with good magnetic properties has an even smaller elongation (about 1%). To compensate for this low elongation, the seal ring 48 is thin and mitigates the impact load by deforming.

[0056] Fig.6 illustrates another embodiment. In the present embodiment, a cylindrical groove 39c is formed in the stationary core 39, and an annular member 50 is inserted or press-fitted therein. An elastic material 53 is provided between the annular member 50 and the second yoke 44 to absorb play due to a gap created between the annular member 50 and the second yoke 44 and to exert an axial preload force. With this configuration, the annular member 50 can generate a larger fastening force than the fastening pin 832 depending on the depth design of the groove 39c. As a result, the fastening force of the stationary core 39 and the second yoke 44 can be enhanced, allowing them to follow even greater impact vibration without separation.

[0057] As described above, according to the present embodiment, it is possible to provide an electromagnetic valve that achieves both movement device reliability and manufacturing cost without deterioration of magnetic properties, and a high-pressure fuel pump equipped with the electromagnetic valve.

[0058] In particular, the use of a ferritic precipitation hardening metal for the stationary core 39 and the armature 36 ensures good magnetic properties. Furthermore, the use of the sealing ring 48, which is formed from a material with lower hardness than the ferritic precipitation hardening metal, ensures reliability against cracking.

[0059] As an example, the sealing ring 48 in the above embodiment is formed of austenitic stainless steel, but it is not limited thereto and does not have to be formed of a metal.

[0060] The embodiment of the present invention may have the following aspects.

[0061] (1) A high-pressure fuel pump including an electromagnetic suction valve having a precipitation hardening type metal magnetic core and a seal ring disposed radially outside the magnetic core, the magnetic core being fixed to the seal ring, the seal ring being formed of a metal having a lower hardness than the magnetic core.

[0062] (2) High pressure fuel pump according to (1), in which the magnetic core is welded to the sealing ring and fixed thereto.

[0063] (3) The high-pressure fuel pump according to (2), in which the seal ring is arranged between the magnetic core and a stationary core in a valve body axial direction and is welded and fixed to the stationary core.

[0064] (4) High-pressure fuel pump according to (1), in which the magnetic core is made of SUS630 (17Cr-4Ni-4Cu-Nb).

[0065] In other words, the high-pressure fuel pump includes an electromagnetic suction valve having a precipitation hardening type metal magnetic core and a thin seal ring disposed radially outside the magnetic core, the seal ring to which the magnetic core is attached, in which the seal ring is formed of a metal having a larger elongation than the magnetic core.

[0066] In addition, the electromagnetic suction valve includes an armature that drives the valve body and is configured so that the armature impacts the magnetic core by energizing the electromagnet.

[0067] Furthermore, the electromagnetic suction valve is configured such that the magnetic core is welded and fixed to the seal ring. Furthermore, in the electromagnetic suction valve, the seal ring is arranged between the magnetic core and the stationary core in the valve body axial direction and is welded and fixed to the stationary core.

[0068] This reduces the impact force by stretching the thin sealing ring that holds the magnetic core when the armature impacts the magnetic core. Furthermore, due to the high-hardness material properties of the magnetic core, it is possible to withstand the impact stress until the effect of reducing the impact force is exerted.

[0069] By utilizing the formability of the seal ring in the elastic axial direction, it is possible to (A) "absorb and mitigate the shock at the time of impact of the armature" and (B) "prevent a welded portion from breaking due to stress concentration caused by thermal stress in a portion (welded portion) attached to a non-magnetic material". List of reference symbols 1 pump body 1a flange 1b hole 1c hole 2 pistons 4 springs 6 cylinders 6a paved section 7 Seal holder 7a Additional Chamber 8 discharge valve mechanism 8a Exhaust valve seat 8b discharge valve 8c exhaust valve spring 8d exhaust valve stop 8e adjacent section 9 Pressure pulsation reduction mechanism 9a Holding element 10a Low-pressure fuel suction opening 10b, 10c Damper chambers 10d suction passage 11 Pressurization chamber 12 Fuel discharge opening 12a discharge valve chamber 12b Power output outlet 13 Piston seal 14 Damper cover 15 holders 20 Fuel tank 21 Feed pump 23 common fuel line 24 Injection device 26 Pressure sensor 27 Engine control unit 28 intake manifold 30 Suction valve 30e movement amount 31 Suction valve seat element 31a Suction valve seat 31b Suction opening 31c Opening section 32 stops 33 Suction valve preload spring 35 bars 35a Flange section 36 anchors 36a Through hole 36e movement amount 37 Staff guidance 37a Through hole 37b middle storage section 38 Outer core 39 solid core 39c groove 40 rod preload spring 42 first yoke 43 coil 44 second yoke 45 coil bodies 46 connection 47 connectors 48 Sealing ring 50 ring-shaped element 51 Suction connection 52 suction filters 53 elastic material 61 O-ring 90 High-pressure fuel pump assembly section 92 tappets 93 cams 200 relief valve mechanism 201 relief body 202 relief valve 203 relief valve holder 205 stop 300 electromagnetic valve mechanism 832 fixing pin

Claims

[1] High pressure fuel pump, which includes: a stationary core (39) made of a ferritic metal of the precipitation hardening type; a precipitation hardening type ferritic metal armature (36) attracted by a magnetic attraction force of the stationary core (39); an outer core (38) having an inner peripheral surface on which an outer peripheral surface of the armature (36) slides; and a sealing ring (48) formed from a material having a lower hardness than the stationary core (39) and the armature (36), wherein the sealing ring (48) connects the stationary core (39) and the outer core (38), and wherein the high-pressure fuel pump characterized by is that the sealing ring (48) has a cylindrical shape, the stationary core (39) and the outer core (38) each have an insertion section which is to be inserted into the sealing ring (48), and the stationary core (39) and the outer core (38) have an outer peripheral surface which, in a state in which they are inserted into the sealing ring (48), is flush with an outer peripheral surface of the sealing ring (48). [2] High pressure fuel pump according to claim 1, wherein the sealing ring (48) has a greater elongation than the stationary core (39) and the armature (36). [3] High pressure fuel pump according to claim 1, wherein the sealing ring (48) has an elongation rate of 35% or more. [4] High pressure fuel pump according to claim 1, wherein the sealing ring (48) is a non-magnetic body. [5] A high-pressure fuel pump according to claim 1, wherein the ferritic precipitation hardening type metal is a ferritic precipitation hardening type stainless steel.

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