High-pressure fuel supply pump and manufacturing process for it

Abstract

High-pressure fuel supply pump a pump body (1a) in which a pressurization chamber (11) is formed, and a cylinder (6) which is inserted into a cylinder fitting hole (6f) which is formed in the pump body (1a) and has a cylindrical shape, comprising the high-pressure fuel supply pump: a projection (1f) which is arranged on an end section (1k) of the pump body (1a) which is opposite the pressurization chamber (11), wherein this projection is formed from an outer circumferential side to an inner circumferential side with respect to an inner circumferential surface opposite to an outer circumferential surface of the cylinder (6) and projects in the axial direction of the cylinder (6), wherein the projection (1f) is designed such that it protrudes in the direction of the side opposite the pressurization chamber (11) with respect to a flat section of the end section (1k) of the pump body (1a), and the projection (1f) is designed in such a way that it supports the cylinder (6) from one side opposite the pressurization chamber (11).

Description

Technical field

[0001] The present invention relates to a high-pressure fuel supply pump and a manufacturing method therefor according to claims 1, 5 and 11 respectively. State of the art

[0002] In internal combustion engines, such as those in automobiles, high-pressure fuel supply pumps are frequently used to increase fuel pressure in a type of direct injection of fuel into a combustion chamber.

[0003] JP 5178676 A of PTL 1 discloses a high-pressure fuel supply pump with a mounting structure in which an outer circumference of a cylinder is held by a cylindrical fitting section of a cylinder holder, and a screw which is screwed to the outer circumference of the cylinder holder is turned into a screw which is screwed to a pump body such that one end face of the cylinder is brought into close contact with the pump body and the other end face of the cylinder is brought into close contact with the cylinder holder.

[0004] PTL 2 discloses a hydraulic pump of a hydraulic unit for a brake device, in which a liner is fitted into a cylinder bore formed in a housing, a liner is brought into metal-to-metal contact with the housing by a caulking load at the time of caulking of a circumference of a plug that closes and opens the cylinder bore, and an internal seal is formed between the housing and the liner to seal a suction side and a pressure side of the pump. PTL 3 shows a high-pressure fuel pump for an internal combustion engine comprising a housing, a piston, and a piston bushing attached to the housing with an axial through-hole in which the piston is guided. The piston bushing is radially held on the housing in at least two axially opposed radial support areas and secured by caulking.PTL 4 shows a fuel pump for the fuel system of an internal combustion engine, comprising a housing and a piston driven by means of a drive mechanism. The piston is guided in an insert which is received in an inwardly directed recess in the housing. The recess has an obliquely sloping annular shoulder against which a complementary shoulder of the insert rests. Plastic deformation of the housing holds the insert with the shoulder in contact with the annular shoulder. An end face of the insert is sized and oriented such that, during operation, the resulting hydraulic force forces the insert axially inward with the shoulder against the annular shoulder, and the plastic deformation acts only axially inward on the insert, thus being relieved by the hydraulic force. List of references Patent literature PTL 1: JP 5178676 A PTL 2: JP 2002-337683 A PTL 3: DE 10 2004 063 074 A1 PTL 4: DE 101 34 069 A1 Brief description of the invention Technical problem

[0005] Recently, in one type of direct injection system for directly injecting fuel into a combustion chamber in an automotive internal combustion engine, the need to increase fuel pressure has grown, particularly from the perspective of complying with environmental regulations. Furthermore, to increase fuel pressure, high-strength materials (materials with high hardness) exhibiting high deformation resistance have been applied to the materials of components.

[0006] To handle the higher fuel pressure, the axial tightening force of the screw in PTL1 must be increased, and the cylinder must be attached to the pump body. This results in a larger screw size, a larger pump body, higher manufacturing costs, and greater limitations in mounting to the internal combustion engine. Therefore, there are concerns that marketability could be negatively impacted.

[0007] Furthermore, as a method for sealing the cylinder and the pump body, the cylinder end face is brought into close contact with the pump body by the axial force of the screw. However, with this method, depending on the surface roughness of the contact area, deformation is only possible with close contact, and there is a risk that a small gap will remain. Additionally, there is a risk that, due to geometric tolerances such as the rectangularity of the components and vibration of the screw part, the contact area will experience partial contact, and the sealing properties will therefore not be maintained.

[0008] On the other hand, a method using a riveting connection is also provided as an example of a compact cylinder fastening. In PTL 2, which is an example of a riveting connection, when riveting the circumference of the plug that closes and opens the opening of the cylinder hole provided in the housing, the housing material flows plastically towards the inner diameter side (the middle side of the cylinder hole) and towards the stepped section of the plug's outer circumference by locally applying pressure to the flat section of the cylinder hole opening with the stepped annular section at the tip of the rivet.

[0009] Since the caulking load tends to concentrate on the stepped section of the ram's tip, and furthermore, since the material flows plastically towards the inner diameter side of the plug (the middle side of the plug) during the caulking process, a bending force caused by the friction of this plastic flow is exerted on the pressurized surface of the ram, which serves as the contact surface between the ram and the housing, and the ram can easily break off from the stepped section. In particular, if a high-strength material is used as the housing material, exhibiting a tensile strength of, for example, 1,000 MPa to withstand the high pressure of the fuel, the service life of the ram can be considerably reduced, even if a ram made of die-cast steel or the like is used.

[0010] Since the casing is pressurized to be sheared in the axial direction of the cylinder bore and thus undergoes plastic flow, this plastic flow can also cause local displacement from the corner section on the outer diameter side of the pressurized section of the punch towards the center side. The riveted section can then crack due to reduced expansion resulting from the high strength of the material. Furthermore, in materials such as aluminum die-casting materials, which have low strength but low expansion, local displacement can easily lead to cracking, and the riveted section can break.

[0011] One object of the present invention is to provide a high-pressure fuel supply pump which, with a simple structure, can attach a cylinder to a pump body with excellent sealing properties even at high fuel pressure. Problem solving

[0012] To solve the problem described above, the present invention comprises a high-pressure fuel supply pump comprising a pump body in which a pressurization chamber is formed and a cylinder which is inserted into a hole formed in the pump body and which has a cylindrical shape, a projection arranged on an end section of the pump body opposite the pressurization chamber, wherein this projection is formed from an outer circumferential side to an inner circumferential side with respect to an inner circumferential surface opposite to an outer circumferential surface of the cylinder and projects towards the cylinder, wherein the projection is configured to project towards a side opposite the pressurization chamber with respect to a flat section of the end section of the pump body, and the projection is configuredthat he carries the cylinder from one side opposite the pressurization chamber." Advantageous effects of the invention

[0013] According to the present invention, a high-pressure fuel supply pump can be provided which, with a simple structure, can attach a cylinder to a pump body with excellent sealing properties, even at high fuel pressure. Other features, operating modes, and effects of the present invention are described in detail in the following embodiments. Brief description of the drawings

[0014] They show: [ Fig. 1] Fig. 1 A general view of a longitudinal section through a high-pressure fuel supply pump according to a first embodiment in which the present invention is implemented. [ Fig. 2] Fig. 2 a general view of a longitudinal section through another angle of the high-pressure fuel supply pump of the first embodiment in which the present invention is implemented, and represents a section through the center of a suction connection axis. [ Fig. 3] Fig. 3 shows an overall view of a cross-section through the high-pressure fuel supply pump according to the first embodiment in which the present invention is implemented, and represents a section through the center of an outlet axis of aspirated fuel. [ Fig. 4] Fig. 4. A complete diagram of the configuration of a system. [ Fig. 5] Fig. 5 a form of a convex section having three interrupted sections. [ Fig. 6] Fig. 6 another form of the convex section. [ Fig. 7] Fig. 7 a state before a cylinder is riveted to a pump body. [ Fig. 8] Fig. 8 a condition after a cylinder has been riveted to a pump body. [ Fig. 9] Fig. 9 a detailed shape of a ring-shaped protrusion. [ Fig. 10] Fig. 10 a detailed form of a cylindrical shoulder section. [ Fig. 11] Fig. 11 a state before caulking another cylindrical shape. [ Fig. 12] Fig. 12 a state after caulking a different cylindrical shape. [ Fig. 13] Fig. 13 a ratio between a load, a cylinder joint strength and a permanent deformation. Description of the embodiments

[0015] The embodiments according to the present invention are described below. Design 1

[0016] The structure and operation of a system are discussed with reference to Fig. 1, Fig. 3 and Fig. 4 described. Fig. Figure 4 illustrates an overall diagram of a configuration of a high-pressure fuel supply system to which a high-pressure fuel supply pump of the existing embodiment is applied. Fig. 4 The section surrounded by a dashed line represents a high-pressure pump body, and mechanisms and parts shown in this dashed line are integrated into the high-pressure pump body 1.

[0017] Fuel in a fuel tank 20 is pumped upwards by a feed pump 21 in response to a signal from an engine control unit 27 (hereinafter referred to as MSE). This fuel is brought to a suitable supply pressure and directed through a suction pipe 28 to a low-pressure fuel intake port 10a of the high-pressure fuel supply pump.

[0018] The fuel, which has passed through a suction connection 51, reaches from the low-pressure fuel intake port 10a an intake port 31b of an electromagnetic intake valve mechanism 300, which forms a capacity variable mechanism by means of a pressure pulsation reduction mechanism 9 and an intake channel 10d.

[0019] The fuel flowing into the electromagnetic intake valve mechanism 300 passes through an intake valve 30 and flows into a pressurization chamber 11. A piston 2 receives lifting force from a cam 93 of an engine (see Fig. 1) Due to the reciprocating motion of the piston 2, fuel is drawn in through the intake valve 30 during the downstroke of the piston 2 and pressurized during the upstroke. The fuel is fed under pressure through an exhaust valve mechanism 8 to a common rail 23, to which a pressure sensor 26 is attached. An injector 24 injects the fuel into the engine based on a signal from the MSE 27.

[0020] The high-pressure fuel supply pump outputs a fuel flow rate of a desired supply fuel to the electromagnetic intake valve mechanism 300 based on a signal from the MSE 27.

[0021] In this way, a necessary quantity of fuel, which is led to the suction connection 51, is brought to a high pressure by the back-and-forth movement of the piston 2 in the pressurization chamber 11 of the pump body 1 and fed under pressure from a fuel outlet port 12c to the common rail 23.

[0022] A direct injection injector 24 (so-called direct injection injector) and the pressure sensor 26 are attached to the common rail 23. The direct injection injector 24 is positioned according to the number of cylinders of an internal combustion engine and is opened and closed according to a control signal from the MSE 27 to inject the fuel into the cylinder.

[0023] If an abnormally high pressure in the common rail 23 or the like is caused by failure of the direct injection injector 24 or the like, a relief valve 101 is opened when a pressure difference between the fuel outlet port 12c and the pressurization chamber 11 is equal to or greater than a valve opening pressure of a relief valve mechanism 100, and the fuel, which was subject to an abnormally high pressure, passes through the interior of the relief valve mechanism and is returned to the pressurization chamber 11 by a relief channel 100a, so that the lines of the high-pressure section such as the common rail 23 are protected.

[0024] The present embodiment is the high-pressure fuel supply pump, which is applied to a so-called direct injection engine system in which the injector 24 injects the fuel directly into the cylinder of the engine.

[0025] The pump's structure and function are explained using the following examples: Fig. 1 to 3 described. Fig. Figure 1 is an overall view of a longitudinal section through the high-pressure fuel supply pump of the present embodiment, and Fig. Figure 2 is an overall view of a longitudinal section through another angle of the high-pressure fuel supply pump of the present embodiment and represents a section through the center of a suction connection axis. Furthermore, Fig. 3 shows an overall view of a cross-section through the high-pressure fuel supply pump of the present embodiment and represents a section through the center of an outlet axis of aspirated fuel. <Aufbau und Funktion>

[0026] The high-pressure fuel supply pump of the present embodiment is brought into close contact with a mounting section 90 of the internal combustion engine for the high-pressure fuel supply pump, using a mounting flange 1e which is provided in the pump body 1a, and is fastened by means of several bolts.

[0027] An O-ring 61 is fitted into the pump body 1a to seal between the mounting section 90 of the high-pressure fuel supply pump and the pump body 1a, thus preventing engine oil from escaping to the outside.

[0028] A cylinder 6 for guiding the reciprocating movement of the piston 2 and forming the pressurization chamber 11, together with the pump body 1a, is attached to the pump body 1a. Furthermore, the electromagnetic intake valve mechanism 300 for supplying the fuel to the pressurization chamber 11 and the exhaust valve mechanism 8 for releasing the fuel from the pressurization chamber 11 to the exhaust port are provided.

[0029] A tappet 92 for converting the rotary motion of a cam 93, which is attached to a camshaft of the internal combustion engine, into an up and down motion and transmitting the up and down motion to the piston 2 is provided at the lower end of the piston 2. The piston 2 is press-fitted to the tappet 92 by a spring 4 via a bracket 15. Therefore, the piston 2 can move up and down along the rotary motion of the cam 93.

[0030] Furthermore, a piston seal 13, held at a lower end section of an inner circumference of a seal holder 7, is mounted in a state of sliding contact with an outer circumference of the piston 2. Therefore, as the piston 2 slides, fuel is sealed in a partial chamber 7a and prevented from flowing into the internal combustion engine. Simultaneously, lubricating oil (including engine oil) that lubricates a sliding section in the internal combustion engine is prevented from flowing into the pump body 1a.

[0031] The suction connection 51 is attached to a side surface section of the pump body 1a of the high-pressure fuel supply pump. The suction connection 51 is connected to a low-pressure line that supplies fuel from the vehicle's fuel tank 20, and the fuel is supplied by the suction connection 51 to the interior of the high-pressure fuel supply pump. A suction filter 52 in the suction connection 51 serves to prevent foreign material present between the fuel tank 20 and the low-pressure fuel intake port 10a from entering the high-pressure fuel supply pump via the fuel flow.

[0032] The fuel that has entered through the low-pressure fuel intake port 10a reaches the intake port 31b of the electromagnetic intake valve mechanism 300 through the pressure pulsation reduction mechanism 9 and the low-pressure fuel flow channel 10d.

[0033] The exhaust valve mechanism 8, provided at an outlet of the pressurization chamber 11, comprises an exhaust valve seat 8a, an exhaust valve 8b that contacts and separates from the exhaust valve seat 8a, an exhaust valve spring 8c that forces the exhaust valve 8b towards the exhaust valve seat 8a, a stop 8d that determines a stroke (distance of movement) of the exhaust valve 8b, and an exhaust valve pin 8e that is attached to an inner circumferential surface of a hole provided in the stop 8d. The exhaust valve stop 8d and the pump body 1a are welded and joined at an adjoining section 8f to exclude fuel from the outside.

[0034] If there is no fuel pressure difference between the pressurization chamber 11 and the exhaust valve chamber 12a, the exhaust valve 8b is held against the exhaust valve seat 8a by pressure due to the preload force of the exhaust valve spring 8c and is in a closed position. Only when the fuel pressure in the pressurization chamber 11 becomes greater than the fuel pressure in the exhaust valve chamber 12a does the exhaust valve 8b open against the exhaust valve spring 8c. The high-pressure fuel in the pressurization chamber 11 is supplied to the common rail 23 via the exhaust valve chamber 12a, the fuel outlet channel 12b, and the fuel outlet port 12c. When the exhaust valve 8b opens, it comes into contact with the exhaust valve stop 8d, limiting its stroke. Therefore, the stroke of the exhaust valve 8b is appropriately determined by the exhaust valve stop 8d.When the exhaust valve 8b repeats the opening and closing motion, it is also guided on the outer circumferential surface of the exhaust valve pin 8e, so that it moves only in the stroke direction. With the configuration described above, the exhaust valve mechanism 8 becomes a check valve, restricting the direction of fuel flow.

[0035] As described above, the pressurization chamber 11 comprises the pump body 1a, the electromagnetic intake valve mechanism 300, the piston 2, the cylinder 6 and the exhaust valve mechanism 8. <ansaugvorgang>

[0036] When piston 2 moves towards cam 93 by rotating cam 93 and is in the intake stroke state, the volume of pressurization chamber 11 increases and the fuel pressure in pressurization chamber 11 decreases. During this process, intake valve 30 is in the open position when the fuel pressure in pressurization chamber 11 is lower than the pressure at intake port 31b. Fuel enters through an opening 30e of intake valve 30 and flows into pressurization chamber 11. <Rückhubvorgang>

[0037] After piston 2 completes its intake stroke, it moves upwards, entering a compression stroke. During this stroke, the electromagnetic coil 43 is held in a de-energized state, and no magnetic preload force acts on the rod 35. A spring 40, which preloads the rod 35, is adjusted to provide a preload force sufficient to keep the intake valve 30 open and in a de-energized state. The volume of the pressurization chamber 11 decreases with the compression stroke of piston 2. However, the pressure in the pressurization chamber never increases during this phase because the fuel drawn into the pressurization chamber 11 is returned to the intake port 10d through the opening 30e of the intake valve 30 when the valve is open. This process is called the return stroke. <Ausstoßvorgang>

[0038] In this state, a current flows through a terminal 46 to the electromagnetic coil 43 when a control signal from the MSE 27 is applied to the electromagnetic intake valve mechanism 300. The magnetic preload then overcomes the preload force of the spring 40 that preloads the rod, and the rod 35 moves away from the intake valve 30. Therefore, the intake valve 30 is closed by the preload force of the intake valve's preload spring 33 and the fluid force caused by the fuel flowing into the intake port 10d. After the valve closes, the fuel pressure in the pressurization chamber 11 rises along with the upward movement of the piston 2, and when the pressure becomes equal to or greater than the pressure in the fuel outlet port 12c, the high-pressure fuel is discharged through the outlet valve mechanism 8 and delivered to the common rail 23. This process is called the exhaust stroke. <Kapazitätssteuerung>

[0039] As described above, the compression stroke (upward stroke between a lower starting point and an upper starting point) of piston 2 consists of the return stroke and the exhaust stroke. The amount of high-pressure fuel to be exhausted can be controlled by adjusting the power supply timing of the coil 43 of the electromagnetic intake valve mechanism 300. When the power supply timing of the electromagnetic coil 43 is advanced, the return stroke rate during the compression stroke is small and the exhaust stroke rate is large. This means that the amount of fuel returned to the intake port 10d is small and the amount of fuel to be exhausted is large. Conversely, when the power supply timing is retarded, the return stroke rate during the compression stroke is large and the exhaust stroke rate is small.This means that the amount of fuel returned to intake port 10d is large, and the amount of fuel expelled at high pressure is small. The energy supply timing of the electromagnetic coil 43 is controlled by a command from the MSE 27.

[0040] By controlling the energy supply timing of the electromagnetic coil 43 as described above, the amount of fuel to be expelled at high pressure can be controlled to the amount required by the internal combustion engine. <Reduzieren der Druckpulsation>

[0041] A low-pressure fuel chamber 10 is provided with a mechanism for reducing pressure pulsation 9, which reduces pressure pulsation generated in the high-pressure fuel supply pump from propagation to the fuel line 28. Once the fuel that has flowed into the pressurization chamber 11 has been returned to the intake port 10d through the intake valve 30, which is in the open position for capacity control, pressure pulsation occurs in the low-pressure fuel chamber 10 due to the fuel returned to the intake port 10d.However, the mechanism for reducing pressure pulsation 9, which is provided in the low-pressure fuel chamber 10, is formed by a metal diaphragm damper in which two disc-shaped metal plates are laminated in a ribbed form on its outer circumference, and an inert gas such as argon is injected into the interior, and the pressure pulsation is absorbed by the expansion and contraction of the metal damper.

[0042] The piston 2 has a large-diameter section 2a and a small-diameter section 2b, and the volume of a sub-chamber 7a is increased or decreased by the reciprocating movement of the piston. Sub-chamber 7a is connected to the low-pressure fuel chamber 10e via the fuel channel 10e. When the piston 2 moves downwards, fuel flow is generated from sub-chamber 7a to the low-pressure fuel chamber 10, and when the piston 2 moves upwards, fuel flow is generated from the low-pressure fuel chamber 10 to sub-chamber 7a.

[0043] Therefore, a mode of operation is possible in which the fuel flow into the interior and exterior of the pump is reduced during the suction stroke or the return stroke of the pump, and the pressure pulsation generated in the high-pressure fuel supply pump is reduced.

[0044] The operation of the relief valve mechanism is described in detail. The relief valve mechanism 100, for limiting the fuel flow in the relief channel 100a in only one direction from the fuel outlet port 12c to the pressurization chamber 11, is provided in the pump body 1. As shown, the relief valve mechanism 100 comprises the relief valve 101, a relief valve holder 102, a relief valve seat 103, a relief spring stop 104, and a relief spring 105. After the relief valve 101 has been inserted into the relief valve seat 103, the relief valve 101 is held by the relief valve holder 102, the position of the relief spring stop 104 is adjusted so that the relief spring 105 has a desired load, and the relief valve 101 is secured to the relief valve seat 103 by pressing or the like.The opening pressure of the relief valve 101 is regulated by a pressure force of the relief spring 105. If a pressure difference between the interior of the pressurization chamber 11 and the interior of the relief channel 100a becomes equal to or greater than a predetermined pressure, the relief valve 101 is separated from the relief valve seat 103 and opened.

[0045] The relief valve mechanism 100, assembled as described above, is secured by fitting the relief valve seat 103 into an inner circumferential wall of a cylindrical through hole 1c provided in the pump body 1. The fuel outlet port 12c is then attached so that the cylindrical through hole 1c of the pump body 1 is closed to prevent fuel from escaping the high-pressure pump and to allow connection to the common rail.

[0046] As the volume of the pressurization chamber 11 begins to decrease due to the movement of the piston 2, the pressure in the pressurization chamber increases with the decreasing volume. When the pressure in the pressurization chamber 11 finally becomes greater than the pressure in the outlet channel 12b, the outlet valve mechanism 8 opens the valve and the fuel is released from the pressurization chamber 11 into the outlet channel 12b. Immediately thereafter, from the moment the outlet valve mechanism 8 opens the valve, the pressure in the pressurization chamber rises sharply to a very high pressure. This high pressure also propagates into the outlet channel 12b, and the pressure in the outlet channel 12b also rises sharply at the same time.

[0047] When the outlet of the relief valve mechanism 100 is connected to an intake flow channel 10b, the pressure difference between the inlet and outlet of the relief valve 101 becomes greater than the valve opening pressure of the relief valve mechanism 100 due to the excess pressure in the outflow channel 12b, and the relief valve opens. Since the outlet of the relief valve mechanism 100 is connected to the pressurization chamber 11, in this embodiment, the pressure in the pressurization chamber 11 acts on the outlet of the relief valve mechanism 100, and the pressure in the outflow channel 12b acts on the inlet of the relief valve mechanism 100. Because the excess pressure occurs simultaneously in the pressurization chamber 11 and the outflow channel 12b, the pressure difference between the inlet and outlet of the relief valve is not equal to or greater than the valve opening pressure of the relief valve.This means that the pressure relief valve does not open.

[0048] The cylindrical structure of the present embodiment is described in detail with reference to Fig. 1 and Fig. 7 described.

[0049] The pump body 1 is provided with the pump body 1a, in which the pressurization chamber 11 is formed, and the cylinder 6, which is inserted into a cylinder bore 6f formed in the pump body 1a and is cylindrical in shape. Furthermore, the fuel in the pressurization chamber 11 is pressurized during the upward stroke of the piston 2. At this point, the pressure generated in the pressurization chamber 11 is approximately 70 MPa at instantaneous pressure. A downward force, as shown in the drawing, acts on the pressurized fuel in the cylinder end face 6d of the large-diameter section 6b of the cylinder 6, and as a result, the pump body 1a and the cylinder end face 6d of the cylinder 6 separate from each other, and the fuel exits into the sub-chamber 7a formed by the seal holder 7 and the lower end of the cylinder.Therefore, the connection strength in the axial direction of the cylinder 6 is set higher than a force that is generated during an upward movement process and acts downwards in the drawing.

[0050] Details of the sealing section are given with reference to Fig. Described in sections 7 to 9.

[0051] Fig. Figure 7 illustrates a state in which the cylinder 6 is attached to the pump body 1a. When it is as in Fig. As shown in Figure 7, the side of the pump body 1a with the pressurization chamber 11 is oriented downwards, so that it corresponds to the illustration in Figure 7. Fig. The cylinder 6 is opposite to the cylinder 6, and the cylinder fitting hole 6f is arranged so that it opens upwards. The cylinder fitting hole 6f, into which the cylinder 6 is inserted, is formed in the pump body 1a. It can be said that the cylinder fitting hole 6f and a cylinder side surface 6j are fitted together. Furthermore, a stepped section is formed on the side of the pressurization chamber 11 of the pump body 1a, and a cylinder fitting hole underside 6h is formed, which is held in contact with the cylinder end surface 6d at the tip of the cylinder 6 on the side of the pressurization chamber 11. A projection 6e, which extends from the cylinder 6 towards the cylinder fitting hole underside 6h, is formed locally on the cylinder end surface 6d. Since the projection 6e is formed in an annular shape along the circumferential shape of the cylinder, the projection 6e in this embodiment is referred to as an annular projection 6e.

[0052] When the end face 6d of the cylinder 6 is press-fitted with the lower surface 6h of the cylinder bore, the annular projection 6e is press-fitted to the lower surface 6h of the cylinder bore and brought into close contact with it, so that the pressurized fuel in the pressurization chamber 11 is sealed and does not escape to the low-pressure side. It can be said that the annular projection 6e bites into the lower surface 6h of the cylinder bore.

[0053] To support the reciprocating motion of the piston 2, the material of the cylinder 6 is selected to have a material hardness equal to or greater than that of the pump body 1a. This further improves the sealing function of the cylinder end face 6d, as the annular projection 6e bites into the pump body 1a, causing plastic deformation of the pump body 1a. In the present embodiment, the annular projection 6e has a triangular cross-section; however, the same effect can be expected with a convex shape, a curved shape, or the like.

[0054] A method for plastically joining the pump body 1a and the cylinder 6 is described with reference to Fig. Sections 7 to 10 and 13 are described in more detail.

[0055] Fig. Figure 7 illustrates a state in which the cylinder 6 is installed in the cylinder fitting hole 6f of the pump body 6, and 200 is a punch upon which a load is exerted by a pressurizing device such as a press. A convex section 1f, which is convex on the side opposite the insertion direction of the cylinder 6 (hereinafter simply referred to as the "insertion direction"), is formed on the end section 1k of the pump body 1a on the side opposite the pressurizing chamber 11. The insertion direction of the cylinder 6 runs in Fig. 7 from top to bottom and in Fig. 1. From bottom to top. The convex section 1f is compressed in the axial direction of the cylinder 6 by the pressurized surface 200a of the plunger in the same direction as the insertion direction and begins to undergo plastic deformation. As the plunger 200 moves downwards, the convex section 1f is deformed towards the inner circumferential side of the cylinder 6. The direction towards the central axis of the piston 2 with respect to the cylinder 6 is called the inner circumferential side, and the opposite direction is called the outer circumferential side.

[0056] An inner circumferential end face of the convex section 1f, prior to deformation, is arranged on the outer circumferential side of the cylinder side surface 6j such that the cylinder 6 can be inserted into the cylinder fitting hole 6f of the pump body 1a. Fig. 7 The cylindrical cylinder 6 comprises a large-diameter section 6b on the side of the pressurization chamber and a small-diameter section 6c on the side opposite the pressurization chamber. In other words, the small-diameter section 6c and the large-diameter section 6b are arranged one after the other in the insertion direction of the cylinder 6.

[0057] Since the pressurized ram 200 can only apply pressure and plastically deform the convex section 1f of the pump body 1a with a portion of the flat surface of the ram 200, the stiffness of the ram 200 can be increased. Therefore, a high-strength material with a tensile strength of approximately 1,000 MPa can be pressurized and plastically bonded, and breakage of the ram 200 can be prevented, even when a heat-treated die steel is used as the material for the ram 200.

[0058] Most of the convex section 1f of the pump body 1a deforms plastically. However, since the pressurized surface 200a of the piston is subjected to pressure in the same axial direction as the insertion direction of the cylinder 6, a compressive load is exerted on the entire convex section 1f, and the convex section 1f is deformed. At this point, the outer circumferential surface of the convex section 1f, before deformation, is an inclined surface 1g that spreads out in the direction of pressure (insertion direction of the cylinder 6) towards the outer circumferential surface. That is, the inclined surface 1g widens in the direction of pressure.

[0059] Therefore, if the convex section 1f is subjected to pressure by the pressurizing surface 200a of the punch, the convex section 1f can hardly be deformed in the outer circumferential direction, so that the convex section 1f is plastically deformed in the direction of the inner circumference while compressive loading is applied. Since the convex section 1f and the area surrounding the lower part of the convex section 1f can be plastically deformed as a whole without causing local displacement under compressive loading, plastic joining can also be achieved even with a material that has an elongation of 10% or less (for example, die-cast aluminum material) without cracking occurring.

[0060] After the large-diameter section 6b of the cylinder 6 was inserted into the cylinder fitting hole 6f and the convex section 1f was deformed, the convex section 1f was deformed such that the end face of the inner circumferential side of the deformed convex section 1f is located on the inner circumferential side with respect to the cylinder side face 6j. If the end section of the outer circumferential side of the large-diameter section 6b of the cylinder 6 and the end section on the side opposite the insertion direction are designated as the cylinder shoulder section 6g, then the deformed convex section 1f is finally plastically deformed so that it forms the cylinder shoulder section 6g as shown in Fig. 8 and Fig. 10 shown covered.

[0061] As described above, a projection (convex section 1f after deformation) is provided on the end section 1k of the pump body 1a, which is opposite the pressurization chamber 11. This projection extends from the outer circumferential side to the inner circumferential side with respect to the inner circumferential surface that is opposite the outer circumferential surface (cylinder side surface 6j) of the cylinder 6 (the inner circumferential surface of the cylinder fitting hole 6f). As in Fig. Figure 8 also shows the projection (convex section 1f after deformation) such that it protrudes from the cylinder side surface 6j in the direction of the inner circumferential side of the cylinder 6. Furthermore, the projection (convex section 1f after deformation) is designed such that it protrudes in the direction of the side opposite the pressurization chamber 11 with respect to the flat section of the end section 1k of the pump body 1a, and the cylinder 6 is supported from the side opposite the pressurization chamber 11.

[0062] As in Fig. As shown in Figure 8, the inclined surface 1g is also configured such that it inclines in a direction opposite to the pressurization chamber 11 (opposite the insertion direction) by the outer circumferential section of the projection (convex section 1f after deformation) moving from the flat section of the end section 1k of the pump body 1a towards the inner circumferential side. Furthermore, the inner circumferential section of the projection (convex section 1f after deformation) is configured such that it is inclined inwards from the inner circumferential surface (inner circumferential surface of the cylinder fitting hole 6f), which is opposite the outer circumferential surface (cylinder side surface 6j) of the cylinder 6, towards the side opposite to the pressurization chamber 11 (opposite the insertion direction). The cylinder 6 is then supported by the side surface of the pressurization chamber on the inner circumferential section of the projection (convex section 1f after deformation).Furthermore, the projection (convex section 1f after deformation) comes into contact with a side surface (cylinder shoulder section 6g of cylinder 6) of a counter-pressure chamber (sub-chamber 7a) when pressure is exerted on the projection (convex section 1f before deformation) of the pump body 1a in the insertion direction from the side opposite the pressure chamber 11.

[0063] In the large-diameter cylinder shoulder section 6g of the cylinder 6, a tapered section 6i is formed such that it inclines towards the inner circumferential side in a direction opposite to the cylinder insertion direction. Therefore, prior to the deformation of the convex section 1f, a wedge-shaped gap is formed between the cylinder side surface 6j and the cylinder insertion hole 6f, and at the interface between the cylinder side surface 6j and the cylinder shoulder section 6g. This enhances cold forming and allows for an increased material thickness, as the amount of plastic deformation of the pump body 1a is increased. Furthermore, internal stress can be increased because the material flow is restricted by the tapered section 6i.On the other hand, the material that flows plastically through the tapered section 6i is wedge-shaped when a pull-out force is applied to the cylinder 6 in the axial direction, and thus a reaction force can also be generated in the pull-out direction from the outer circumferential direction. As described above, the pull-out direction and the remaining deformation of the cylinder 6 can be increased by the tapered surface 6i.

[0064] At this point, the load of the pressurizing device is also transmitted in the axial direction of the cylinder 6 via plastic deformation. The projection 6e, which is provided on the cylinder end face 6d, is plastically deformed and bites into the cylinder mounting hole underside 6h, and the cylinder end face 6d and the cylinder mounting hole underside 6h are press-fitted. Regarding the sealing properties between the pump body 1a and the cylinder 6, the cylinder mounting hole underside 6h and the cylinder end face 6d are press-fitted, and the projection 6e is plastically deformed and bites into the cylinder mounting hole underside 6h.Therefore, the surface roughness of the projection 6e is transferred to the surface roughness of the cylinder fitting hole under surface 6h, the projection 6e and the cylinder fitting hole under surface 6h are brought into sufficient contact to seal the fluid without being affected by the surface roughness of the cylinder fitting hole under surface 6h and the component accuracy such as the right angle between the pump body 1a and the cylinder 6, and it is possible to considerably improve the sealing properties for the fuel.

[0065] Fig. Figure 13 illustrates a relationship between the load, the connection strength of cylinder 6, and the permanent deformation. Regarding the connection strength, the load is almost constant between 160 and 220, but the residual stress increases with the load. This is considered a difference in cold forming due to the plastic deformation of the pump body 1a, and in particular, it is considered that the yield stress of the pump body material 1a increases with the cold forming of the section that is to be press-fitted to the tapered surface 6i.

[0066] As described above, the material of the pump body 1a covers the cylinder shoulder section 6g through plastic bonding and is press-fitted to the cylinder shoulder section 6g, the tapered surface 6i of the cylinder 6 and the cylinder side surface 6j by residual stress, and furthermore the axial direction of the cylinder 6 is maintained while it is press-fitted through the plastic bonding section 1h and the cylinder fitting hole under surface 6h, and is firmly attached to the cylinder 6 (cf. Fig. 8 and Fig. 10).

[0067] Fig. 11 and Fig. Figure 12 illustrates another embodiment of the cylinder.

[0068] In Fig. 11 forms, in contrast to Fig. 7, in the cylindrically shaped cylinder 6, a section 6c with a small diameter forms a pressurization chamber side, and a section 6b with a large diameter forms a pressurization chamber opposite side. In Fig. 6 The inner diameter of the cylinder fitting hole 6f is designed such that it is essentially the same as that of the large-diameter section 6b, and the inner circumferential surface of the inner diameter passes through the stepped section (cylinder fitting hole underside 6h) and is configured to communicate with the pressurization chamber 11. On the other hand, in Fig. 11. The point that the inner diameter of the cylinder fitting hole 6f is designed such that it is essentially the same as that of the large-diameter section 6b, the same as in Fig. 7, however, an inner circumferential surface with a smaller diameter than the inner diameter of the cylinder fitting hole 6f is formed on the side of the pressurization chamber 11. That is, the cylinder fitting hole 6f is formed by connecting a first inner circumferential surface with a large inner diameter on one half of the pressurization chamber and a second inner circumferential surface with a small inner diameter on the side of the pressurization chamber. The second inner circumferential surface is configured such that it is in contact with the pressurization chamber 11.

[0069] The cylinder 6 is inserted into the pump body 1a, and the cylinder fitting hole 6f is formed in the pump body 1a. Specifically, the small-diameter section 6c of the cylinder 6 is fitted and inserted into the second inner circumferential surface, and the large-diameter section 6b is fitted and inserted into the first inner circumferential surface. The convex section 1f (projection), which was previously provided on the circumference of the inlet of the cylinder fitting hole 6f of the pump body 1a, is subjected to pressure in the insertion direction of the cylinder and thus deformed by compression. At this point, the materials of the convex section 1f and its surroundings are plastically deformed in the direction of the cylinder 6. In particular, the materials of the convex section 1f and its surroundings are plastically deformed in the direction of the inner circumferential surface.Therefore, the convex section 1f is plastically connected and fastened to press-fit and cover the cylinder shoulder section 6g and the cylinder side surface 6j.

[0070] As in Fig. 7. Before deformation, the outer circumferential side of the convex section 1f is an inclined surface 1g that extends towards the outer circumferential side in the direction of pressurization (insertion direction of the cylinder 6). This means that the inclined surface 1g widens in the direction of pressurization. Even after deformation, the inclined surface 1g, which extends towards the outer circumferential side, is still formed on the outer circumferential side of the convex section 1f in the direction of pressurization (insertion direction of the cylinder 6). Before and after deformation, the convex section 1f (projection) is formed in an annular shape on the circumference of the pump body 1a. Furthermore, the same reference numerical values ​​as those in Fig. 7 have the same functions, and a description of them is omitted.

[0071] Furthermore, the cylinder fitting hole 6f of the pump body 1a has the cylinder fitting hole undersurface 6h, the cylinder end surface 6j, which comes into contact with the cylinder fitting hole undersurface 6h, is press-fitted to the cylinder fitting hole undersurface 6h by pressurization, and the local annular projection 6e, which is provided on the stepped section between the large-diameter section 6b and the small-diameter section 6c of the cylinder 6 (cf. Fig. 9), is pressed and thus brought into close contact with the cylinder fitting hole underside 6h, so that the pressurized fuel is sealed in the pressurization chamber 11 and does not escape onto the low-pressure side.

[0072] Another form of the convex section 1f of the present embodiment is described with reference to Fig. 5 and Fig. 6 described.

[0073] In the convex section 1f of the present embodiment, the convex section 1f of the pump body 1a has a ring shape; however, the same effect can be expected for the convex section 1f that has one or more interrupted sections 1j. That is, the projection (convex section 1f) is designed to protrude towards the side opposite the pressurization chamber 11 relative to the flat section of the end section 1k of the pump body 1a, but can be configured so that only a portion protrudes, even if it does not protrude over the entire circumference. By forming the interrupted section, the amount of plastic deformation can be reduced, thus reducing the load to be deformed, and consequently, the effect of displacing the deformation of the pump body 1a to other sections can be expected.The same effect can be expected even if the inclined surface 1g is a vertical surface 1i. Fig. Figure 5 represents an example of the convex section 1f, which has three interrupted sections 1j.

[0074] As described above, in the manufacturing process of the high-pressure fuel supply pump according to the present embodiment, the cylinder 6 is fitted into the cylinder bore 6f, which has the cylinder bore underside 1h of the pump body 1a. The convex section 1f, which was previously provided on the circumferential section of the inlet of the cylinder bore 6f of the pump body 1a, loads the pressurized surface 200a of the piston 200. Furthermore, a portion of the piston end face is deformed compressively, separately from the side face of the piston 200, by being subjected to pressure in a substantially axial direction of the cylinder (insertion direction). The materials of the convex section 1f and the surrounding area of ​​the convex section 1f are plastically deformed in the direction of the cylinder (inner circumferential side). Therefore, it is press-fitted and plastically bonded to the cylinder shoulder section and the cylinder side face 6j to cover it.The cylinder end surface 6d, which is in contact with the cylinder fitting hole under surface 6h of the cylinder 6 (see . . Fig. 9), is press-fitted to the cylinder fitting hole under surface 6h by applying pressure, and the local projection 6e, which is provided on the cylinder end surface 6d, plastically deforms the cylinder fitting hole under surface 6h and bites into the cylinder fitting hole under surface 6h, so that the biting section is press-fitted and thus brought into close contact to perform the sealing.

[0075] The preceding description describes the method of inserting the cylinder 6 into the cylinder fitting hole 6f of the pump body 1a and securing the cylinder 6. However, the objective of the present embodiment is to provide a method for joining two elements in which no cracks occur in the riveted section, even when a high-strength material exhibiting high tensile strength and low expansion, or a material with low tensile strength but low expansion, is used, and furthermore, when a plastic joining process (e.g., riveting) is carried out to prevent the breakage of the pressurizing device (piston) when high-strength material exhibiting high tensile strength is riveted together, which is likely to cause a pressurizing device (piston) to breakage.

[0076] Therefore, the joining and fastening method of the present embodiment is not necessarily limited to the high-pressure fuel supply pump and can also be used in the case of joining two other elements. That is to say, in the method for joining two elements, a fitting section is a cylindrical fitting part that is fitted into a body having a hole with a bottom, and a fitting section that is fitted into the hole with a bottom, and a convex section that is pre-provided on the circumferential section of the inlet of the hole with a bottom of the body, is subjected to pressure in the substantially axial direction (insertion direction) of the fitting part.Therefore, the convex section is deformed by compression, and the materials of the convex section and its surroundings are plastically deformed in the direction of the mating part. The convex section is thus fixed and connected, covering the shoulder section and side surface of the mating part during the press fit. Furthermore, it is desirable that the outer circumferential surface of the convex section be a surface that deviates from the direction of compression. It is also desirable that the convex section is subjected to compression in the substantially axial direction (insertion direction) of the mating part, with a portion of the die end surface, which is the pressure-bearing surface of the die, and further away from the side surface of the die.

[0077] According to the embodiment described above, even with a material exhibiting small dimensions, cracks hardly occur in the plastic connection section, since the cylinder and the body can be plastically joined by compressive deformation, which is not subjected to shear stress in the convex section and its surroundings. Furthermore, the deformation strength of the plastic connection can be reduced because the stiffness of the plastically deformed section is utilized by employing the plastically deformed section of the body as the convex section.

[0078] On the other hand, with a die to be subjected to pressure, it is not necessary to make only the pressure-bearing section locally convex, as with the die in PTL 2, so that only the convex section of a portion of the die's flat surface is subjected to pressure. Since the die's stiffness can be increased, breakage of the die can consequently be prevented, even when the high-strength material is subjected to pressure.

[0079] Regarding the sealing properties between the body and the cylinder, the cylinder bore underside and the cylinder end face are press-fitted, and the protrusion is plastically deformed and bites into the cylinder bore underside. Therefore, the surface roughness of the protrusion is transferred to the surface roughness of the cylinder bore underside. The protrusion and the cylinder bore underside can be brought into sufficiently close contact to seal the fluid, without being affected by component accuracy such as the surface roughness of the cylinder bore underside or the right angle between the body and the cylinder. Therefore, it is possible to significantly improve the fuel sealing properties.

[0080] As described above, a high-pressure fuel supply pump can be provided which can make the connection structure of the cylinder and the body compact with excellent sealing properties through plastic joining, and which can make the pump body smaller, more cost-effective and highly reliable.

[0081] Furthermore, this joining method can be widely applied as a method for joining two elements without being limited to a high-pressure fuel supply pump, and in particular, it is extremely effective for plastic joining of low-expansion materials or plastic joining of high-strength materials. List of reference symbols 1 High-pressure pump body 1a Pump body 1c Cylindrical through hole 1e Flange 1f convex section 1g inclined surface 1h plastic connection section 1i vertical surface 1j interrupted section 6 cylinders 6b Large diameter section 6c small diameter section 6e ring-shaped protrusion 6d Cylinder end surface 6f Cylinder fitting hole 6g cylinder shoulder section 6h Cylinder fitting hole underside 6i tapered surface 6j cylinder side surface 7 Seal holder 7a Subchapter 8 Exhaust valve mechanism 9 Mechanism for reducing pressure pulsation 10 Low-pressure fuel chamber 11 Pressurization chamber 12 Outlet connection 13 Piston seal 15 bracket 20 Fuel tank 21 Feed pump 23 Common Rail 24 injectors 26 Pressure sensor 27 Engine control unit 28 Intake manifold 30 Intake valve 33 Intake valve preload spring 35 bars 40 Rod preload spring 43 electromagnetic coil 51 Suction connection 52 Intake filters 61 O-ring 92 pestles 93 cams 100 Relief valve mechanism 200 stamps 200a pressure-bearing surface of the stamp 300 electromagnetic intake valve mechanism< / ansaugvorgang>

Claims

[1] High-pressure fuel supply pump comprising a pump body (1a) in which a pressurization chamber (11) is formed, and a cylinder (6) which is inserted into a cylinder fitting hole (6f) which is formed in the pump body (1a) and has a cylindrical shape, comprising the high-pressure fuel supply pump: a projection (1f) which is arranged on an end section (1k) of the pump body (1a) which is opposite the pressurization chamber (11), wherein this projection is formed from an outer circumferential side to an inner circumferential side with respect to an inner circumferential surface opposite to an outer circumferential surface of the cylinder (6) and projects in the axial direction of the cylinder (6), wherein the projection (1f) is designed such that it protrudes in the direction of the side opposite the pressurization chamber (11) with respect to a flat section of the end section (1k) of the pump body (1a), and the projection (1f) is designed in such a way that it supports the cylinder (6) from one side opposite the pressurization chamber (11). [2] High-pressure fuel supply pump according to claim 1, wherein an inner circumferential section of the projection (1f) is designed such that it is inclined towards the inner circumferential side from the inner circumferential surface which is facing the outer circumferential surface of the cylinder (6) to the side which is opposite the pressurization chamber (11). [3] High-pressure fuel supply pump according to claim 1, wherein an inner circumferential section of the projection (1f) is designed such that it is inclined towards the inner circumferential side from the inner circumferential surface facing the outer circumferential surface of the cylinder (6) to the side opposite the pressurization chamber (11), and the cylinder (6) is supported by a side surface of the pressurization chamber (11) from the inner circumferential section of the projection (1f). [4] High-pressure fuel supply pump according to one of the preceding claims, wherein pressure is applied to the projection (1f) of the pump body (1a) from the side opposite the pressurization chamber (11), so that the projection (1f) comes into contact with a side surface (6g) of a counter-pressurization chamber (7a) of the cylinder (6). [5] High-pressure fuel supply pump comprising a pump body (1a) in which a pressurization chamber (11) is formed, and a cylinder (6) which is inserted into a cylinder fitting hole (6f) which is formed in the pump body (1a) and is cylindrical in shape, wherein the cylinder (6) is fitted into the cylinder fitting hole (6f) of the pump body (1a) and a projection (1f) which was previously provided on a circumferential section of an inlet of the cylinder fitting hole (6f) of the pump body (1a) is plastically deformed by compression towards the inner circumferential side by applying pressure in the insertion direction of the cylinder (6), and is connected and fastened to press-fit and cover a cylinder shoulder section (6g) and a cylinder side surface (6j) of the cylinder, wherein the cylinder (6) comprises a first section (6b) and a second section (6c), the first section (6b) having a larger diameter than the second section (6c), and the cylinder shoulder section (6g) is arranged at an end section of the second section (6b) which is opposite to the insertion direction of the cylinder,and wherein in the cylinder shoulder section (6g) a tapered section (6i) is formed such that it inclines towards the inner circumferential side in a direction opposite to an insertion direction of the cylinder (6). [6] High-pressure fuel supply pump according to one of the preceding claims, wherein an outer circumferential section of the projection (1f) is designed such that it inclines from the flat section of the end section of the pump body to an inner circumferential side in the direction of a side opposite the pressurization chamber. [7] High-pressure fuel supply pump according to one of the preceding claims, wherein the projection has a ring shape. [8] High-pressure fuel supply pump according to one of the preceding claims, wherein the convex section has a ring shape with one or more interrupted sections. [9] High-pressure fuel supply pump according to one of the preceding claims, wherein a cylinder fitting hole under surface is formed in the pump body, an annular projection is formed locally from the cylinder towards the cylinder fitting hole under surface on a cylinder end surface, and the annular projection bites into the cylinder fitting hole under surface, so that sealing is effected. [10] High-pressure fuel supply pump according to one of the preceding claims, wherein the elastic pressure deformation in the direction of the cylinder axis remains between an outer circumferential end section of the cylinder and the cylinder end surface and the elastic pressure deformation is maintained between the connection fastening section of the pump body and the cylinder fitting hole under surface. [11] Method for manufacturing a high-pressure fuel supply pump, wherein a cylinder (6) is fitted into a cylinder bore (6f) of a pump body (1a) having a cylinder bore underside (6h), and a convex section, which is provided in advance at a circumferential section of the inlet of the cylinder bore (6f) of the pump body, is compressed in a cylinder insertion direction by a portion of an end face (200a) of a punch (200) such that the convex section is plastically deformed in the direction of an inner circumferential side, and plastic joining is carried out such that a cylinder shoulder section (6g) and a cylinder side face (6f) of the cylinder (6) are covered while being press-fitted, wherein the cylinder (6) comprises a first section (6b) and a second section (6c), the first section (6b) having a larger diameter than the second section (6c),and the cylinder shoulder section (6g) is arranged at an end section of the second section (6b) which is opposite to an insertion direction of the cylinder (6), and wherein in the cylinder shoulder section (6g) a tapered section (6i) is formed such that it inclines towards the inner circumferential side in a direction opposite to an insertion direction of the cylinder (6). [12] Method for manufacturing a high-pressure fuel supply pump according to claim 11, wherein a cylinder end surface (6d) which comes into contact with the cylinder fitting hole under surface (6h) of the cylinder (6) is press-fitted to the cylinder fitting hole under surface (6h) by applying pressure, in that a local projection provided on the cylinder end surface (6d) plastically deforms the cylinder fitting hole under surface (6h) and bites into it.

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