Pulsation damper and fuel pump device

Abstract

Pulsation dampener (50), comprising: a housing (51) in which a fuel chamber (51a) is defined; and a damper unit (60, 600, 601, 602, 603, 604) arranged in the fuel chamber (51a) to dampen pressure pulsation of fuel, the damper unit (60, 600, 601, 602, 603, 604) comprises: a membrane (61) which is elastically deformed by absorbing fuel pressure, and a plate (62, 620, 621, 622) with a higher stiffness than that of the membrane (61), wherein a gas chamber (61a) is defined between the membrane (61) and the plate (62, 620, 621, 622), which are connected to each other, wherein the plate (62, 620, 621, 622) has a projecting portion (620a, 622a, 621a) that protrudes to enlarge or reduce the gas chamber (61a); and wherein the damper unit (60, 600, 601, 602, 603, 604) corresponds to one of a plurality of damper units arranged in a predetermined direction in the fuel chamber (51a), and wherein the pulsation damper (50) further comprises: a spacer (63, 630, 631) which defines a length of space between adjacent membranes (61) in the predetermined direction, characterized by the fact that the spacer (63, 630, 631) has a regulating part (630e, 631e) in contact with the projection part (620a, 622a, 621a) to restrict the damping unit (60, 600, 601, 602, 603, 604) from moving in a direction perpendicular to the predetermined direction.

Description

Technical field

[0001] The present disclosure relates to a pulsation damper and a fuel pump device. background

[0002] JP 2013-60945 A describes a pulsation dampener that reduces or dampens pressure pulsations of fuel generated in a fuel pump to decrease noise, wear, or failure of line components caused by these pressure pulsations. The pulsation dampener has a housing containing a defined fuel chamber and two diaphragms arranged within the fuel chamber. The two diaphragms are connected to form an internal gas chamber, which is elastically deformed by the fuel pressure to dampen the pressure pulsations.

[0003] Furthermore, EP 2 625 419 B1 discloses a pressure damper arrangement for a fuel inlet channel in a single-piston high-pressure fuel pump, comprising: an inlet fitting;a cover attached to the fitting and having a substantially cylindrical side wall defining a damping chamber designed for fluidic connection with a fuel inlet channel of the pump, and a bottom for sealing attachment to the pump, at least one diaphragm arrangement supported in the damping chamber, each diaphragm arrangement comprising a first and a second metal diaphragm, the diaphragm edges being sealed to a first and second side of an unperforated middle plate, respectively, and convex middle regions spaced apart from the unperforated middle plate, thereby defining a first and a second independent closed gas volume radially inward of a surrounding diaphragm arrangement edge;the unperforated middle plate and the metal diaphragms are circular and have the same radius, defining the circumference of the metal diaphragm and the unperforated plate; and the edge of each metal diaphragm is welded to the unperforated middle plate at the circumference of the metal diaphragm, the fuel supplied to the pump through the inlet fitting flowing through the damping chamber at a pressure acting on the first and second metal diaphragms of each diaphragm assembly before entering the inlet channel of the pump, the circumference of each metal diaphragm being welded to the unperforated middle plate at the circumference by a common weld that seals the first metal diaphragm against the unperforated middle plate and the second metal diaphragm against the unperforated middle plate, so that the first and second independent closed gas volumes do not communicate;A holder arrangement supports an upper and lower membrane arrangement in the cover, comprising a first holder with a projection that abuts and pre-tensions an upper portion of the common weld; a second holder with a projection that abuts and pre-tensions a lower portion of the common weld on the lower membrane arrangement; a spacer with an upper projection that abuts and pre-tensions a lower portion of the common weld of the upper membrane arrangement, and a lower projection that abuts and pre-tensions the upper portion of the common weld of the lower membrane arrangement; wherein the pre-tensioning of the common welds holds the membrane arrangements in position in the holder arrangement;and an upper part of the cover, as attached to the pump, rests axially against the first holder and the second holder is axially fixed by a pump housing, wherein the projections on the holders are spring-loaded against the projections of the spacer when inwardly extending parts of the projections on the holders slide with interference along the projections of the spacer. Summary

[0004] The damping performance, used to reduce or attenuate pressure pulsation, can be increased by enlarging the diaphragm. If the damping performance is too high, the diaphragm size is reduced. However, controlling the damping performance by adjusting the size and shape of the diaphragm in this way reduces the manufacturing efficiency of the pulsation dampers, as it becomes necessary to prepare diaphragms of different sizes to vary the damping performance of the pulsation damper.

[0005] It is an objective of the present disclosure to provide a pulsation damper and a fuel pump device in which a damping performance can be precisely controlled.

[0006] The above problem is solved by the subject matter of claims 1 and 5. Advantageous embodiments of the invention are the subject matter of the dependent claims that follow.

[0007] According to one aspect of the present disclosure, a pulsation damper comprises: a housing in which a fuel chamber is defined; and a damper unit arranged in the fuel chamber to dampen pressure pulsations of the fuel. The damper unit has a diaphragm which is elastically deformed by absorbing fuel pressure, and a plate with a higher stiffness than that of the diaphragm. A gas chamber is defined between the diaphragm and the plate, which are connected to each other.

[0008] According to one aspect of the present disclosure, a fuel pump device comprises: a fuel pump which compresses and delivers a fuel flowing in a fuel passage defined in a pump body; and a pulsation dampener to reduce pressure pulsation of the fuel in the fuel passage. The pulsation dampener comprises a housing in which a fuel chamber is defined, and a damper unit arranged in the fuel chamber to dampen pressure pulsation of the fuel. The damper unit has a diaphragm which is elastically deformed by absorbing fuel pressure, and a plate with a higher stiffness than that of the diaphragm. A gas chamber is defined between the diaphragm and the plate, which are connected to each other.

[0009] Accordingly, the diaphragm in the damper unit is connected to the high-stiffness plate, and the gas chamber is formed between the diaphragm and the plate. Therefore, one damper unit comprises one diaphragm. The damping performance is controlled by adjusting the number of damper units. The number of diaphragms can be increased or decreased in proportion to the number of damper units. Therefore, the damping performance of the pulsation damper can be precisely controlled. Brief description of the illustrations

[0010] The foregoing and further tasks, features, and advantages of the present disclosure will become more apparent from the following detailed description, which is given with reference to the accompanying illustrations. The illustrations show: Fig. 1 a sectional view showing a fuel pump device according to a first embodiment, installed on a machine; Fig. 2 a sectional view showing a pulsation damper in Fig. 1 represents; Fig. 3 a sectional view showing a damper unit and an elastic support object according to a second embodiment; Fig. 4 a sectional view showing a damper unit and an elastic support object according to a third embodiment; Fig. 5 a sectional view showing damper units and an elastic support object according to a fourth embodiment; Fig. 6 a sectional view showing damper units and a housing according to a fifth embodiment; and Fig. Figure 7 shows a sectional view, which depicts a damper unit and an elastic support object according to a sixth embodiment. Detailed description

[0011] Embodiments of the present disclosure are described below with reference to the figures. In these embodiments, a part corresponding to an item described in a preceding embodiment may be assigned the same reference numeral, and a redundant explanation for the part may be omitted. If only one part of a configuration is described in one embodiment, a further preceding embodiment may be applied to the other parts of the configuration. The parts may be combined, even if it is not explicitly stated that the parts may be combined. The embodiments may be partially combined, even if it is not explicitly stated that the embodiments may be combined, provided that there is no disadvantage to the combination. (First embodiment)

[0012] One in Fig. The fuel pump device shown in Figure 1 is applied to an internal combustion engine (engine E) for a vehicle and comprises a fuel pump P and a pulsation dampener 50. The fuel pump P compresses fuel for the engine E and delivers it. The engine E is a compression-ignition type, and the fuel compressed and delivered by the fuel pump device is light oil. The fuel pump P has a pump body 10, a piston 20, and a control valve unit 30. The pulsation dampener 50 is attached to the pump body 10.

[0013] Within the pump body 10, a fuel passage 10a is formed. The fuel passage 10a comprises a first low-pressure passage L1, a second low-pressure passage L2, a third low-pressure passage L3, a compression chamber H1, and a high-pressure passage H2. Fuel flowing from a fuel tank (not shown) into the fuel pump P flows through the first low-pressure passage L1, the second low-pressure passage L2, the pulsation damper 50, and the third low-pressure passage L3 in that order, and flows into the compression chamber H1 to be compressed by the piston 20. The high-pressure fuel compressed by the piston 20 is discharged to the outside through the high-pressure passage H2 and directed to a common rail (not shown). The high-pressure fuel directed to the common rail is injected by a fuel injector into the combustion chamber of the engine E.

[0014] The pump body 10 is made of metal and is formed, for example, by punching holes into a forged product. The pump body 10 has a high-pressure port 11, a damper mounting 12, a control valve mounting 13, and a cylinder 15.

[0015] The high-pressure port H2 is defined in the high-pressure port 11, and a high-pressure line (not shown) is connected to the high-pressure port 11. A pressure relief valve 21 is installed in the high-pressure port H2. When the pressure of the pressurized fuel in the compression chamber H1 becomes higher than or equal to a predetermined pressure, the pressure relief valve 21 opens, and high-pressure fuel is discharged from the high-pressure port 11. The high-pressure port 11 is configured to extend in a direction perpendicular to the axial direction of the piston 20. The axial direction represents a reciprocating direction for the piston 20, that is, along the axis C1 of the piston 20.

[0016] The control valve mounting 13 projects axially from the piston 20. A mounting hole 13a is formed within the control valve mounting 13, and the control valve unit 30 is installed in the mounting hole 13a.

[0017] The control valve unit 30 comprises a control valve 31, an electromagnetic coil 33, a fixed core 34, a movable core 35, and a spring 36. The control valve 31 controls the amount of fuel to be compressed by opening and closing an inlet port 32 of the compression chamber H1. The control valve 31 is mounted on the control valve unit 30 in such a way that it can move in both directions. The control valve unit 30 is attached to the control valve mounting 13 in such a way that the direction of movement of the control valve 31, i.e., the axis of the control valve 31, coincides with the axis C1 of the piston 20.

[0018] When the electromagnetic coil 33 is energized, a magnetic flux occurs between the fixed core 34 and the movable core 35. The fixed core 34 and the movable core 35 form a magnetic circuit, and the movable core 35 is attracted to the fixed core 34 by the magnetic force. The movable core 35, attracted in this way, moves with the control valve 31, and the spring 36 biases the movable core 35 and the control valve 31 in a direction opposite to that of the magnetic force. Therefore, when the electromagnetic coil 33 is energized, the movable core 35 and the control valve 31 move to one side due to the magnetic force against the elastic force or spring force. When the energization of the electromagnetic coil 33 is stopped, the movable core 35 and the control valve 31 move to the other side due to the spring force.The control valve 31 corresponds in particular to a normally open type valve which is closed by the application of current. The control valve 31 is opened by stopping the current. The current to the electromagnetic coil 33 is controlled by a control device (not shown).

[0019] The fuel pump assembly is mounted on a predetermined part of machine E. For example, the fuel pump assembly is attached to a crankcase E1, which receives and supports a crankshaft of machine E. In this state, the driving force of machine E is transmitted via a cam (not shown) to the piston 20, and the piston 20 moves back and forth inside the cylinder 15 while machine E is in operation.

[0020] The damper mounting 12 projects in a direction perpendicular to the axial direction of the piston 20. The end of the first low-pressure passage L1 and the end of the second low-pressure passage L2 are open at the projecting end surface of the damper mounting 12.

[0021] The pulsation damper 50 comprises a housing 51, an elastic support object 52, and several damper units 60. The housing 51 is made of metal and has a cylindrical shape with a base or bottom. It is attached to the damper mounting 12 to form a fuel chamber 51a inside. The housing 51 is attached to the damper mounting 12 by welding or bolting. The fuel chamber 51a is filled with low-pressure fuel, which flows from the first low-pressure passage L1 and the second low-pressure passage L2.

[0022] The elastic support object 52 and the damper units 60 are in the predetermined direction (the left and right direction of Fig. 2) arranged in the fuel chamber 51a. The elastic support object 52 is made of metal or rubber and is fixed to the bottom surface of the housing 51. The damper units 60 are inserted and supported between the elastic support object 52 and the damper mounting 12. In this embodiment, the damper units 60 are supported between the elastic support object 52 and the damper mounting 12 without being fixed to one another. The damper units 60 can be fixed to one another by welding.

[0023] As in Fig. As shown in Figure 2, each of the damper units 60 has a diaphragm 61, a plate 62 and a spacer or distance piece 63. The configuration and shape are the same for the damper units 60.

[0024] The diaphragm 61 has a cup shape, produced by compression molding a thin metal plate, which is elastically deformed by absorbing the pressure of the fuel flowing into the fuel chamber 51a. The plate 62 corresponds to a metal plate or wall and is connected to the diaphragm 61, so that a gas chamber 61a is formed between the diaphragm 61 and the plate 62. The gas chamber 61a is filled with high-pressure gas, which has a higher pressure than atmospheric pressure. More precisely, the diaphragm 61 and the plate 62 have a round shape when viewed from a direction perpendicular to the wall surface of the plate 62. The cup-shaped diaphragm 61 has an opening, and this opening is covered and sealed by the plate 62. The outer circumferential edge (flange part) of the diaphragm 61 is welded to the plate 62, and the inner space defined by the diaphragm 61 and the plate 62 corresponds to the gas chamber 61a.

[0025] Plate 62 has a higher stiffness than membrane 61. In particular, the thickness of plate 62 is greater than the thickness of membrane 61. The bending stiffness of plate 62 is higher than the bending stiffness of membrane 61.

[0026] The spacer 63 is a metal cylinder, and one end surface of the spacer 63 is connected to the flange portion of the diaphragm 61. Therefore, the diaphragm 61, the plate 62, and the spacer 63 are welded together to form the damper unit 60. The other end surface of the spacer 63 is in contact with the adjacent plate 62 of the adjacent damper unit 60, thus defining a space between the adjacent diaphragms 61 in the predetermined direction. The inner circumferential surface of the spacer 63 faces the diaphragm 61.

[0027] Of the several damper units 60, the damper unit 60 opposite the damper mounting 12 (upstream damper unit) forms a damper chamber 63b, which is surrounded by the end surface of the damper mounting 12, the inner circumferential surface of the spacer 63 and the diaphragm 61 (referring to Fig. 1) The spacer 63 has several through-holes 63a which penetrate it radially and are arranged circumferentially. Therefore, the fuel in the fuel chamber 51a flows through the through-hole 63a into and out of the damper chamber 63b. Of the several damper units 60, those damper units 60 that differ from the upstream damper unit 60 form the damper chamber 63b, which is surrounded by the plate 62 of the adjacent damper unit 60, the inner circumferential surface of the spacer 63, and the diaphragm 61.

[0028] The spacer 63 of the upstream damper unit defines a length of space between the damper mounting 12 and the diaphragm 61. In this case, a counterpart component opposite the upstream damper unit corresponds to the damper mounting 12 of the pump body 50. The spacer 63 of the other damper units defines a length of space between the plate 62 of the adjacent damper unit 60 and the diaphragm 61. In this case, a counterpart component opposite the other damper unit corresponds to the plate 62 of the adjacent damper unit 60.

[0029] The fuel pressure in the damper chamber 63b fluctuates. In particular, the fuel pressure changes with a predetermined cycle. In a pressure waveform, which represents a change in pressure relative to an elapsed time, waveforms of several frequency components overlap. The diaphragm 61 is elastically deformed in the predetermined direction according to such a pulsation of the fuel pressure, and the pulsation of the fuel pressure is absorbed and reduced by the diaphragm 61. The elastic deformation of the plate 62 is so small compared to the elastic deformation of the diaphragm 61 that it can be neglected and does not contribute to the reduction of the fuel pressure pulsation.

[0030] The operation of fuel pump P is explained below.

[0031] A control device (not shown) controls the electrical power supply to the electromagnetic coil 33 and opens the control valve 31 for the duration of the downward movement of the piston 20. This draws the low-pressure fuel, flowing in that order through the first low-pressure passage L1, the fuel chamber 51a including the damper chamber 63b, the second low-pressure passage L2 and the third low-pressure passage L3, through the inlet opening 32 into the compression chamber H1.

[0032] The control device then opens the control valve 31 until a desired control period has elapsed after the piston 20 begins its upward movement. During this control period, in which the flow rate is controlled, the low-pressure fuel from the compression chamber H1 flows out of the inlet opening 32 and is pushed back towards the third low-pressure port L3, the second low-pressure port L2, the fuel chamber 51a, and the first low-pressure port L1. Therefore, the pressure of the fuel flowing back in this manner is varied or fluctuates. The pressure pulsation is distributed, or propagated, in the order of the fuel from the third low-pressure port L3, the fuel from the second low-pressure port L2, and the fuel from the fuel chamber 51a.The pulsation of the fuel pressure propagating towards the fuel in fuel chamber 51a is absorbed and reduced by the diaphragm 61. This reduces noise, breakage, and wear in line components caused by the fuel pressure pulsation.

[0033] Then, during the upward movement (compression phase) of piston 20, the control device closes the control valve 31 after the control period has elapsed. This compresses the fuel in the compression chamber H1 during the compression phase, and the pressure increases. When the pressure exceeds or equals a predetermined pressure, the pressure relief valve 21 opens, and the high-pressure fuel is expelled through the high-pressure passage H2. Therefore, the control period is controlled by adjusting the closing time of the control valve 31, thus controlling the amount of fuel compressed during the compression phase.

[0034] As explained above, the pulsation damper 50 of this embodiment comprises the damper unit 60 arranged in the fuel chamber 51a of the housing 51 to attenuate or dampen pressure pulsations of the fuel. The damper unit 60 has the diaphragm 61 and the plate 62. The plate 62, designed as a panel or wall, has a stiffness greater than that of the diaphragm 61, and the gas chamber 61a is defined between the diaphragm 61 and the plate 62, which are connected to each other.

[0035] Accordingly, the damping performance of the pulsation damper 50 can be adjusted by changing the number of damper units 60 arranged in the fuel chamber 51a, without altering the size and shape of the diaphragm 61. Since one diaphragm 61 is contained within one damper unit 60, the number of diaphragms 61 is increased or decreased by the same number of damper units 60 when the number of damper units 60 is changed to control the damping performance. Therefore, according to this embodiment, the damping performance of the pulsation damper 50 can be adjusted more precisely compared to a case in which two diaphragms 61 are contained within one damper unit 60.

[0036] In a comparative example, a damper unit comprises two diaphragms, and the multiple damper units are arranged in a fuel chamber. Since the damping performance can be adjusted by changing the number of damper units, it is not necessary to prepare diaphragms of varying sizes, and the manufacturing efficiency of the pulsation damper can be improved.

[0037] Since the two diaphragms in the comparison example are contained within a single damper unit, the number of diaphragms is increased or decreased by twice the number of damper units. Therefore, fine-tuning the damping performance is difficult due to the low adjustment resolution. Furthermore, positioning the damper units based on the diaphragm arrangement and considering the directions of elastic deformation can be challenging.

[0038] Furthermore, according to this embodiment, the spacer 63 specifies the length of a space between the counter-component and the diaphragm 61 in the predetermined direction. The spacer 63 is integrally fixed with the damper unit 60. Therefore, it is not necessary to insert the spacer 63 and the damper unit 60 separately into the housing 51 when the pulsation damper 50 is mounted.

[0039] Furthermore, in this embodiment, the multiple damper units 60 are arranged inside the fuel chamber 51a in a predetermined direction. The damper units 60 are identical in configuration and shape. Therefore, the manufacturing efficiency of the pulsation dampers 50 can be improved, as it is not necessary to prepare damper units 60 that differ in shape.

[0040] Furthermore, according to this embodiment, the pulsation damper 50 is arranged relative to the fuel pump assembly such that the predetermined direction in which the diaphragm 61 is elastically deformed intersects the axis C1 of the piston 20. Therefore, the control valve 31 can be arranged on the axis C1 of the piston 20, thus reducing the volume of high-pressure fuel remaining after fuel delivery compared to a case where the control valve 31 is arranged to intersect the axis C1. In recent years, there has been a trend toward increased pressure in the fuel pump P. When the pressure in the compression chamber H1 is higher, it is necessary to reduce the loss by decreasing the volume. Therefore, according to this embodiment, in which the control valve 31 is arranged on the axis C1 of the piston 20, the volume can be reduced to minimize the loss.

[0041] Furthermore, in this embodiment, the high-stiffness plate 62 has a function for being attached to the adjacent damper unit 60 when multiple damper units 60 are arranged. Specifically, the plate 62 is mounted to the damper unit 60 by connecting it to the spacer 63. Therefore, the damper units 60 can be installed without a component dedicated solely to fastening or mounting, thus simplifying installation. In addition, the high-stiffness plate 62 also has a function for forming the fuel chamber 51a, whereby the size of the pulsation damper 50 can be limited. (Second embodiment)

[0042] The plate 62 of the first embodiment has a flat wall shape without a projection or a depression. In a second embodiment, the plate 620 of the damper unit 600 has a projecting portion (enlargement projection portion 620a) that protrudes to enlarge the gas chamber 61a (referring to Fig. 3) The plate 620 with the enlargement projection 620a is produced, in particular, by pressing a metal plate of uniform thickness. The volume of the gas chamber 61a is increased by a volume surrounded by the inner wall surface 620b of the enlargement projection 620a.

[0043] The enlargement projection 620a, viewed from a direction perpendicular to the wall surface of the plate 620, has a ring shape that surrounds the center line C2 of the plate 620. Therefore, a section of the gas chamber 61a, in which the volume is increased, extends in a ring shape around the center line C2 of the plate 620.

[0044] In Fig. Figure 3 omits the illustration of the housing 51. The pulsation damper of this embodiment has the damper unit 600 and the elastic support object 520 instead of the damper unit 60 and the elastic support object 52 of the first embodiment.

[0045] The elastic support object 52 of the first embodiment is arranged to overlap a central region of the plate 62. In contrast, the elastic support object 520 of this embodiment is arranged in a region outside the enlarging projection part 620a in the radial direction, that is, outside the central line C2 of the plate 620. Furthermore, the elastic support object 520 of this embodiment corresponds to a coil spring. The elastic support object 520 can be a spring disc or an annular plate made of rubber.

[0046] According to the present embodiment, the plate 620 of the pulsation damper has an enlargement projection 620a, which protrudes to increase the volume of the gas chamber 61a. Therefore, the volume of the gas chamber 61a is adjusted by modifying the shape and size of the enlargement projection 620a, thus allowing the damping performance of the pulsation damper to be adjusted. Consequently, the damping performance of the pulsation damper can be adjusted without changing the size and shape of the diaphragm 61. For example, the volume of the gas chamber 61a can be increased by enlarging the enlargement projection 620a. Therefore, when pressure pulsation is detected, the rate of increase of the internal gas pressure can be reduced by increasing the volume. This increases the degree of deformation of the diaphragm 61, thereby improving the damping performance.In return, however, the strength required for the membrane 61 relative to the cyclic stress becomes large.

[0047] Furthermore, the damping performance can be adjusted between the damper unit 600 with the plate 620 with the enlarging projection 620a and a damper unit using the plate 62, which does not have the enlarging projection 620a. Therefore, the damping performance of the pulsation damper can be adjusted without changing the size and shape of the diaphragm 61 of the damper unit.

[0048] Furthermore, since the enlargement projection 620a of this embodiment is designed to have a ring shape that surrounds the center line C2 of the plate 620, the enlargement projection 620a acts as a rib that increases the stiffness of the plate 620 relative to bending deformation. Therefore, the variation in damping performance caused by the bending deformation of the plate 620 can be reduced. (Third embodiment)

[0049] The plate 620 of the second embodiment has the enlargement projection 620a, which projects to enlarge the gas chamber 61a. In contrast, the plate 621 of the damper unit 601 of this embodiment has a projection (reduction projection 621a) that projects to reduce the size of the gas chamber 61a (referring to Fig. 4) The plate 621 with the reducing projection part 621a is produced, in particular, by pressing a metal plate with a uniform plate thickness. The volume of the gas chamber 61a is reduced by reducing the volume of the reducing projection part 621a.

[0050] The reduction projection section 621a is designed such that, viewed from a perpendicular direction to the wall surface of the plate 621, it has a ring shape that surrounds the center line C2 of the plate 621. Therefore, a section of the gas chamber 61a, in which the volume is reduced, has a ring-shaped form that surrounds the center line C2 of the plate 621.

[0051] The plate 621 of the pulsation damper of this embodiment has the reduction projection 621a, which protrudes to reduce the size of the gas chamber 61a. Therefore, the capacity of the gas chamber 61a is adjusted by modifying the shape and size of the reduction projection 621a, thus allowing the damping performance of the pulsation damper to be adjusted. Therefore, the damping performance of a pulsation damper can be adjusted without changing the size and shape of the diaphragm 61. For example, the volume of the gas chamber 61a is reduced by increasing the size of the reduction projection 621a. Consequently, the amount of deformation of the diaphragm 61 is reduced by the reduction in volume, thus decreasing the damping performance. However, the stiffness required for the diaphragm 61 relative to a cyclic stress can also be reduced.

[0052] Furthermore, the damping performance can be varied between the damper unit 601 with the plate 621 with the reduction projection 621a and a damper unit using the plate 62, which does not have the reduction projection 621a. Therefore, the damping performance of the pulsation damper can be adjusted without changing the size and shape of the diaphragm 61 of the damper unit.

[0053] Furthermore, since the reduction projection section 621a of this embodiment is designed to have a ring shape that surrounds the center line C2 of the plate 621, the reduction projection section 621a acts as a rib that increases the stiffness of the plate 621 relative to bending deformation. Therefore, the variation in damping performance caused by the bending deformation of the plate 621 can be reduced. (Fourth embodiment)

[0054] The pulsation dampener of this embodiment has, instead of the one in Fig. 3 spacer shown 63 one in Fig. The spacer 630 shown in Figure 5 is designed such that it has a cylindrical part 630c, a flanged part 630d and a regulating part 630e formed by pressing a metal plate with a uniform plate thickness.

[0055] The cylinder part 630c has a cylindrical shape extending in the predetermined direction, and the length of the space between the membranes 61, which are adjacent to each other in the predetermined direction, is specified by the length of the cylinder part 630c in the axial direction. The flange part 630d has a ring shape that projects outwards in the radial direction from the end of the cylinder part 630c, and it is connected to the flange section 61b of the membrane 61 or the plate 620.

[0056] The regulating part 630e has a ring shape that extends radially inwards from the other end of the cylindrical part 630c, and it is in contact with a section of the plate 620 of the adjacent damper unit 603, which is arranged on the outer circumferential side of the enlarger projection part 620a. A through-hole 630f is formed in the central section of the regulating part 630e, and the enlarger projection part 620a of the adjacent damper unit 603 is inserted into the through-hole 630f. Thus, the enlarger projection part 620a is inserted and fitted into the through-hole 630f, so that the outer circumferential side of the enlarger projection part 620a and the inner circumferential side of the regulating part 630e are in contact with each other.This allows the regulating part 630e to regulate the adjacent damper unit 603 to move in the radial direction perpendicular to the predetermined direction relative to each other.

[0057] Of the multiple damping units 603, the damping unit 603 adjacent to the elastic support object 520 is in contact with the elastic support object 520 at the surface located on the radially outer side of the enlargement projection part 620a. Since the elastic support object 520 is fixed to the housing 51, the damping unit 603 is regulated such that it moves in the radial direction relative to the housing 51. The multiple damping units 603 are pressed in the predetermined direction by the elastic force or spring force of the elastic support object 520 and are supported between the damper mounting 12 and the housing 51.

[0058] According to the present embodiment, the distance between the membranes 61 adjacent in the predetermined direction is defined by the spacer 630. The spacer 630 has the regulating element 630e, which regulates the damper unit 603 by contact with the enlarging projection 620a to move in the direction perpendicular to the predetermined direction. Therefore, the damper unit 603 can be positioned radially on the plate 620 using the enlarging projection 620a. (Fifth embodiment)

[0059] In the fourth embodiment, the enlargement projection 620a is inserted into the through-hole 630f of the spacer 630, so that the spacer 630 and the enlargement projection 620a are in contact with each other. In a fifth embodiment, the pulsation damper has, instead of the spacer 630 and the plate 620, as shown in Fig. Figure 5 shows the spacer 631 and the plate 622, which are in Fig. 6 are shown.

[0060] The spacer 631 is formed by pressing a metal plate with a uniform wall or plate thickness such that it has a cylindrical part 631c, a flanged part 631d, and a regulating part 631e. The cylindrical part 631c has a cylindrical shape extending in the predetermined direction, and the length of the space between the membranes 61 adjacent in the predetermined direction is specified by the length of the cylindrical part 631c in the axial direction. The flanged part 631d has a ring shape that projects outwards in the radial direction from the end of the cylindrical part 631c, and it is connected to the flanged section 61b of the membrane 61 or the plate 622.

[0061] The regulating part 631e has a ring shape that projects inwards in the radial direction from the other end of the cylinder part 631c, and this is in contact with a section of the plate 622 of the adjacent damper unit 604, which is arranged on the radially outer side of the enlargement projection part 622a.

[0062] The enlargement projection 622a of the adjacent damper unit 604 is inserted into a concave section 631g. Therefore, an outer circumferential surface (contact side 622t) of the enlargement projection 622a and a circumferential wall surface (contact side 631t) of the concave section 631g are in contact with each other due to the insertion of the enlargement projection 622a into the concave section 631g. The contact sides 622t and 631t have a conical shape, respectively, inclined in the same direction to the predetermined direction, and are designed such that they extend in a ring shape around the center line C2 of the spacer 631 and the plate 622.Therefore, the contact side 622t of the plate 622 and the contact side 631t of the spacer 631 are in contact with each other, so that the adjacent damper unit 604 is regulated by the regulating part 631e such that they are displaced in the radial direction perpendicular to the predetermined direction relative to each other.

[0063] Of the multiple damper units 604, the damper unit 604 adjacent to the elastic support object 520 has the magnifying projection 622a, and the contact side 622t of the magnifying projection 622a is in contact with the elastic support object 520. Since the elastic support object 520 is fixed to the housing 51, the damper unit 604 is regulated to move radially relative to the housing 51. The multiple damper units 604 are pressed in the predetermined direction by the elastic force of the elastic support object 520 and are supported between the damper mounting 12 and the housing 51.

[0064] According to this embodiment, a space between the membranes 61 adjacent in the predetermined direction is defined by the spacer 631. The spacer 631 has the regulating part 631e, which is in contact with the enlarging projection part 622a to restrict the movement of the damper unit 604 in the direction perpendicular to the predetermined direction. Therefore, the positioning of the damper unit 604 in the radial direction can be determined using the enlarging projection part 622a of the plate 622.

[0065] Furthermore, in this embodiment, the contact side 631t of the regulating part 631e, which is in contact with the enlargement projection part 622a, has a conical shape inclined in the predetermined direction. Therefore, the processability can be improved, as explained below, if the damper units 604 are arranged in the predetermined position in the housing 51. That is, as shown in Fig. As shown in Figure 6, the damper units 604 can be coaxially aligned if the damper unit 604 is in the state in the predetermined direction (the left and right directions of Fig. 6) is pressed, in which the center lines C2 of the damper units 604 differ from each other, as indicated by the arrow directions in Fig. Figure 6 shows that the contact surfaces 622t and 631t with the conical shape are pressed together, causing the damper unit 604 to move radially to align the center lines C2. Therefore, the damper units 604 can be coaxially aligned using the enlarging projection portion 622a of the plate 622 when the damper units 604 are arranged to improve processability for the assembly. (Sixth embodiment)

[0066] The damper unit 602 of this embodiment has an elastic body 64, as shown in Fig. Figure 7 shows that the elastic body 64 is a product made of rubber or resin foam and has a shape that extends annularly around the center line C2 of the membrane 61. The damper unit 602 of this embodiment is identical to the damper unit 60 of the first embodiment in terms of structure, shape, and size, except that it includes the elastic body 64. The elastic body 64 is supported between the membrane 61 and the plate 62.

[0067] According to this embodiment, the elastic body 64 is in the Fig. The damper unit 60 shown in the diagram is arranged to provide the damper unit 602, which differs in its damping performance. Therefore, the damping performance of the pulsation damper 50 can be adjusted without changing the size and shape of the diaphragm 61 of the damper unit 60, 602. (Further embodiment)

[0068] It should be recognized that the present disclosure is not limited to the embodiments described above and may be suitably modified within the scope of protection of the appended claims. The aforementioned embodiments are not insignificant in relation to one another and may be suitably combined, provided that such a combination is not obviously impossible.

[0069] The pulsation dampener 50 is applied to the fuel pump P in which the control valve 31 is located directly above the piston 20. The pulsation dampener 50 can be applied to a fuel pump in which the control valve 31 is positioned such that its axis intersects the axis C1 of the piston 20 (for example, perpendicularly). Alternatively, the pulsation dampener 50 can be applied to a fuel pump in which the control valve 31 is positioned such that its axis deviates from the axis C1 of the piston 20.

[0070] In each embodiment, the pulsation dampener 50 is attached to the pump body 10 in such a way that the centerline C2 of the diaphragm 61 (the predetermined direction in which the diaphragm 61 is elastically deformed) intersects the axis C1 of the piston 20 (for example, perpendicularly). Alternatively, the pulsation dampener 50 can be attached to the pump body 10 in such a way that the predetermined direction in which the diaphragm 61 is elastically deformed is parallel to the axis C1 of the piston 20.

[0071] The pulsation dampener is used in each embodiment of the fuel pump P, which compresses and delivers fuel. The pulsation dampener can be applied at a point in a fuel line extending from a fuel tank to the fuel pump P, or in a fuel line extending from the fuel pump P to a fuel injector. The pulsation dampener can be used in a common rail or a supply line, which will be explained later. The common rail and the supply line correspond to a pressure reservoir that absorbs or collects the pressure of the fuel discharged by the fuel pump P and distributes the fuel to the fuel injectors in each cylinder of the internal combustion engine.

[0072] In each embodiment, the multiple damper units are arranged in the fuel chamber 51a; however, only one damper unit may be arranged in the fuel chamber 51a. When the multiple damper units are arranged, the shape of the plate or spacer between the damper units may differ, while the diaphragm 61 has the same shape. For example, the volume increased by the enlarging projection 620a may be the same or different, and the volume reduced by the reducing projection 621a may be the same or different. The plates 62, 620, 621, and 622 can be used in combination to form a pulsation damper.

[0073] In each embodiment, the damper unit is arranged such that the diaphragm 61 is positioned between the plate and the second low-pressure passage L2. Alternatively, the damper unit can be arranged such that the plate is positioned between the diaphragm 61 and the second low-pressure passage L2.

[0074] In each embodiment, the spacer is fixed to the diaphragm 61 or the plate to be integrally formed with the damper unit. Alternatively, the spacer can be manufactured separately from the damper unit. In this case, the damper unit and the spacer are inserted separately into the fuel chamber 51a.

[0075] Such changes and modifications shall be understood as falling within the scope of protection of the present disclosure as defined by the attached claims.

Claims

[1] Pulsation dampener (50), comprising: a housing (51) in which a fuel chamber (51a) is defined; and a damper unit (60, 600, 601, 602, 603, 604) arranged in the fuel chamber (51a) to dampen pressure pulsation of fuel, the damper unit (60, 600, 601, 602, 603, 604) comprises: a membrane (61) which is elastically deformed by absorbing fuel pressure, and a plate (62, 620, 621, 622) with a higher stiffness than that of the membrane (61), wherein a gas chamber (61a) is defined between the membrane (61) and the plate (62, 620, 621, 622), which are connected to each other, wherein the plate (62, 620, 621, 622) has a projecting portion (620a, 622a, 621a) that protrudes to enlarge or reduce the gas chamber (61a); and wherein the damper unit (60, 600, 601, 602, 603, 604) corresponds to one of a plurality of damper units arranged in a predetermined direction in the fuel chamber (51a), and wherein the pulsation damper (50) further comprises: a spacer (63, 630, 631) which defines a length of space between adjacent membranes (61) in the predetermined direction, characterized by , that the spacer (63, 630, 631) has a regulating part (630e, 631e) in contact with the projection part (620a, 622a, 621a) to restrict the damping unit (60, 600, 601, 602, 603, 604) from moving in a direction perpendicular to the predetermined direction. [2] Pulsation damper according to claim 1, wherein the regulating part (631e) has a contact surface (631t) in contact with the projection part (622a) and wherein the contact surface (631t) has a conical shape inclined to the predetermined direction. [3] Pulsation damper according to claim 1 or 2, wherein the projection part (620a) has an annular shape surrounding a center of the plate (620). [4] Pulsation damper according to any one of claims 1 to 3, wherein the damper unit (60, 600, 601, 602, 603, 604) corresponds to one of a plurality of damper units arranged in the fuel chamber (51a). [5] Fuel pump device comprising: a fuel pump (P) which compresses and delivers a fuel which flows in a fuel passage (10a) defined in a pump body (10); and a pulsation damper (50) which reduces pressure pulsation of the fuel in the fuel passage (10a), the pulsation dampener (50) comprises: a housing (51) in which a fuel chamber (51a) is defined, and a damper unit (60, 600, 601, 602, 603, 604) arranged in the fuel chamber (51a) to dampen pressure pulsation of fuel, the damper unit (60, 600, 601, 602, 603, 604) comprises: a membrane (61) which is elastically deformed by absorbing fuel pressure, and a plate (62, 620, 621, 622) with a higher stiffness than that of the membrane (61), wherein a gas chamber (61a) is defined between the membrane (61) and the plate (62, 620, 621, 622), which are connected to each other, wherein the plate (62, 620, 621, 622) has a projecting portion (620a, 622a, 621a) that protrudes to enlarge or reduce the gas chamber (61a); and wherein the damper unit (60, 600, 601, 602, 603, 604) corresponds to one of a plurality of damper units arranged in a predetermined direction in the fuel chamber (51a), and wherein the pulsation damper further comprises: a spacer (63, 630, 631) which defines a length of space between adjacent membranes (61) in the predetermined direction, characterized by , that the spacer (63, 630, 631) has a regulating part (630e, 631e) in contact with the projection part (620a, 622a, 621a) to restrict the damping unit (60, 600, 601, 602, 603, 604) from moving in a direction perpendicular to the predetermined direction.

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