JP2019112945A - Pulsation damper and fuel supply system - Google Patents

Abstract

To provide a pulsation damper capable of suitably suppressing the resonance of a diaphragm, and to provide a fuel supply system.SOLUTION: A pulsation damper (40), which is applied to a fuel supply system (10) including a fuel pump (20) for periodically sucking/discharging fuel, and provided in a communication passage branching from a supply passage for supplying low-pressure fuel to the fuel pump, includes a casing (50) having an internal space communicated with the communication passage, a diaphragm part (60) including a diaphragm (62) for partitioning the internal space into a first region on the communication passage side and a second region on the opposite side to the communication passage, and a state switch part (70) arranged in the first region for switching between a first state that the low-pressure fuel is supplied to the diaphragm and a second state that the low-pressure fuel is not supplied to the diaphragm.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pulsation damper capable of suppressing resonance of a diaphragm in a fuel supply system including a pulsation damper, and a fuel supply system.

  Conventionally, a fuel pump is known which changes the volume of a pressure chamber by reciprocating movement of a plunger and periodically sucks and discharges fuel. The high pressure pump disclosed in Patent Document 1 includes a pulsation damper provided branched to a supply path for supplying low pressure fuel to the high pressure pump. The pulsation damper includes a diaphragm that reduces pressure pulsations of the low pressure fuel by deforming in response to pressure fluctuations of the low pressure fuel.

  When the pressure pulsation frequency of low-pressure fuel matches the natural frequency of the diaphragm, the phenomenon that the amplitude of the diaphragm becomes large, that is, resonance occurs. When diaphragm resonance occurs, the amplitude of pressure pulsation of low pressure fuel (hereinafter referred to as pulsation amplitude) increases. In Patent Document 1, by providing an elastic member in contact with both metal plates in a shielding space defined by two metal plates constituting the diaphragm, pulsation amplitude of low-pressure fuel when the diaphragm resonates can be obtained. It is suppressing the increase.

JP, 2013-213488, A

  In the low pressure fuel supply path, pressure pulsation of the low pressure fuel occurs because the suction of the low pressure fuel is periodically performed as the plunger reciprocates. Therefore, the diaphragm resonates when the rotational speed of the high-pressure pump, which indicates the number of times of reciprocating movement of the plunger per unit time, becomes the natural rotation speed corresponding to the natural frequency of the diaphragm. In the above pulsation damper, even when the diaphragm resonates, the low pressure fuel is supplied to the diaphragm, so the resonance of the diaphragm can not be suppressed.

  An object of the present invention is to provide a pulsation damper and a fuel supply system capable of suitably suppressing the resonance of a diaphragm in view of the above-mentioned situation.

  The present invention is applied to a fuel supply system including a fuel pump that periodically sucks and discharges fuel, and the pulsation damper is provided in a communication path that branches from a supply path that supplies low-pressure fuel to the fuel pump. A diaphragm portion that includes a casing having an internal space communicating with the communication path, and a diaphragm, and divides the internal space into a first area on the communication path side and a second area on the opposite side to the communication path. And a state switching unit disposed in the first region to switch between a first state in which the low pressure fuel is supplied to the diaphragm and a second state in which the low pressure fuel is not supplied to the diaphragm.

  The pulsation damper of the present invention includes a state switching unit that switches between a first state in which low pressure fuel is supplied to the diaphragm and a second state in which low pressure fuel is not supplied to the diaphragm. Therefore, when the diaphragm resonates when low-pressure fuel is supplied to the diaphragm, the state switching unit switches from the first state to the second state so that the diaphragm is not deformed, whereby the resonance of the diaphragm is suitably suppressed. can do.

  The present invention also provides a fuel supply system including the pulsation damper described above. The fuel supply system according to the present invention is provided in a fuel pump that periodically sucks and discharges fuel, and in a communication path that branches from a supply path that supplies low-pressure fuel to the fuel pump, integrally with the fuel pump or And the above-mentioned pulsation damper provided separately from the fuel pump.

Schematic which shows a fuel supply system. The figure which shows the damper which concerns on 1st Embodiment. A figure explaining state change operation of a damper. The graph which shows the relationship between pump rotational speed R and the pressure peak value P. FIG. The figure which shows the state switch part of the damper which concerns on 2nd Embodiment. The figure which shows the state switch part of the damper which concerns on 3rd Embodiment. The figure which shows the through-hole formed in an opening-and-closing member.

First Embodiment
Hereinafter, a fuel supply system 10 to which a pulsation damper (hereinafter, simply referred to as a damper) according to the first embodiment is applied will be described with reference to the drawings. The fuel supply system 10 is a fuel supply system applied to a diesel engine (hereinafter referred to as an engine).

  As shown in FIG. 1, the fuel supply system 10 according to the present embodiment includes a fuel tank 11, a low pressure pump 12, a low pressure pipe 13, a fuel filter 14, a connector 15, a high pressure pump 20, and a high pressure pipe. 30, a recovery pipe 31, and a controller 32.

  The low pressure pump 12 is an electric pump and is disposed inside the fuel tank 11. The low pressure pump 12 sucks the fuel (light oil) stored in the fuel tank 11 and discharges the low pressure fuel to the low pressure pipe 13. The low pressure pipe 13 is a metal pipe connecting the low pressure pump 12 and the high pressure pump 20, and forms a supply path for supplying the low pressure fuel discharged from the low pressure pump 12 to the high pressure pump 20. The fuel filter 14 is a filter disposed at an intermediate position between the low pressure pump 12 and the high pressure pump 20 in the low pressure pipe 13 and filters the low pressure fuel conveyed in the low pressure pipe 13. The connection connector 15 is a plastic connector, and connects the high pressure pump 20 and the low pressure pipe 13. The connector 15 is lower in strength than the low pressure pipe 13 made of metal, and the peak value of the limit of the pressure of the low pressure fuel is set to the limit pressure Pg (see FIG. 4).

  The high pressure pump 20 is a pump that periodically sucks and discharges fuel as the engine rotates. The high pressure pump 20 includes a cylinder body 21, a suction valve 23, a supply valve 24, a plunger 25, a spring 26, a discharge valve 27, a cam 28, a rotary shaft 29, and a damper 40. . The high pressure pump 20 is an example of a fuel pump.

  A pressure chamber 22 is formed in the cylinder body 21. The low pressure fuel supplied to the high pressure pump 20 by the low pressure pipe 13 is supplied to the pressurizing chamber 22 through the supply passage 21 a formed in the cylinder body 21. The suction valve 23 is an electromagnetic valve that opens and closes the supply path 21 a and adjusts the amount of low pressure fuel supplied to the pressurizing chamber 22. The supply valve 24 is an elastic valve disposed in the pressure chamber 22 and prevents backflow of low pressure fuel from the pressure chamber 22 to the low pressure pipe 13.

  The plunger 25 is reciprocally supported by the cylinder body 21. The plunger 25 is driven by a cam 28 which rotates around a rotation axis 29 by the rotation of the engine. Further, the movement of the plunger 25 is restricted by the elastic force of the spring 26 that interferes with the expanded portion 25 a of the plunger 25. The plunger 25 reciprocates by the driving force of the cam 28 and the elastic force of the spring 26. When the volume of the pressure chamber 22 is increased by the reciprocation of the plunger 25, the low pressure fuel is sucked into the pressure chamber 22 from the low pressure pipe 13. Further, when the volume of the pressure chamber 22 decreases due to the reciprocation of the plunger 25, the low pressure fuel in the pressure chamber 22 is pressurized. The fuel pressurized in the pressurizing chamber 22 is discharged to the high pressure pipe 30 and supplied to the engine through the high pressure pipe 30. The discharge valve 27 is an elastic valve disposed in the pressure chamber 22 and prevents backflow of fuel from the high pressure pipe 30 to the pressure chamber 22. The recovery pipe 31 is a pipe for recovering the remaining fuel of the supply path remaining in the low pressure pipe 13 and the pressurizing chamber 22 when the engine is stopped into the fuel tank 11.

  The control device 32 is an electronic control unit (ECU) that controls the amount of low pressure fuel drawn into the high pressure pump 20, and is configured by a microcomputer including a CPU, a ROM, a RAM, an input / output interface and the like. The control device 32 acquires the rotational speed R of the high-pressure pump 20 (hereinafter referred to as a pump rotational speed) by measuring the rotational speed per unit time of the cam 28, and opens and closes the suction valve 23 by the acquired pump rotational speed R. Control.

  The damper 40 reduces the pressure pulsation of the low pressure fuel supplied to the high pressure pump 20. The damper 40 is provided at one end of the communication path 21b branched from the supply path 21a. The communication passage 21 b is formed in the cylinder body 21 and branches from the supply passage 21 a at a branch point B located upstream of the suction valve 23.

  As illustrated in FIG. 2A, the damper 40 includes a casing 50, a diaphragm unit 60, and a state switching unit 70.

  First, the casing 50 will be described. The casing 50 has a substantially cylindrical shape, and an internal space 51 communicating with the supply passage 21 a via the communication passage 21 b is formed in the casing 50. A connecting portion 53 for connecting to the communication path 21 b is provided on one end surface 52 in the axial direction (hereinafter simply referred to as the axial direction) X of the casing 50. The connecting portion 53 has a hollow cylindrical shape, and extends in the axial direction X from the approximate center of the end face 52. The connecting portion 53 is formed with a thread (not shown) for connecting to the communication path 21b.

  Next, the diaphragm unit 60 will be described. The diaphragm portion 60 is provided in the internal space 51, and the internal space 51 is formed on the communication path 21b side, that is, a first area R1 on the connection portion 53 side, and a second area R2 on the opposite side to the communication path 21b. It is divided into. The diaphragm unit 60 includes a base plate 61 and a diaphragm 62. The base plate 61 is a circular metal flat plate and is disposed in a direction orthogonal to the axial direction X. The outer edge 61 a of the base plate 61 is fixed to the casing 50 along the entire circumference.

  The diaphragm 62 is disposed on the side of the communication path 21 b of the base plate 61. The diaphragm 62 is a thin plate made of metal, and has a plate-like shape with a central portion 62a protruding toward the communication path 21b. The outer edge 62 b of the diaphragm 62 is fixed to the base plate 61 over the entire circumference. Thus, a shielding space 63 isolated from the internal space 51 is defined in the diaphragm 60. In addition, the inert gas of predetermined pressure is enclosed by the shielding space 63. As shown in FIG.

  The diaphragm 62 is disposed substantially at the center of the base plate 61 in the axial direction X. A plurality of through holes 64 are formed in an outer peripheral portion 61 b located outside the diaphragm 62 of the base plate 61. The through holes 64 communicate the first region R <b> 1 and the second region R <b> 2 and are arranged at equal intervals in the circumferential direction of the casing 50.

  As shown in FIG. 3, the diaphragm 62 can be elastically deformed (hereinafter simply referred to as deformation) according to the pressure in the first region R1. For example, as shown in FIG. 3C, when the pressure in the first region R1 becomes larger than the pressure of the inert gas in the shielding space 63, the central portion 62a of the diaphragm 62 is deformed toward the base plate 61. As a result, when the volume of the shielded space 63 decreases, the volume of low pressure fuel that can be accommodated in the internal space 51 increases, and the increase in pressure of the low pressure fuel is suppressed.

  Further, as shown in FIGS. 3A and 3B, when the pressure in the first region R1 becomes smaller than the pressure of the inert gas in the shielding space 63, the central portion 62a of the diaphragm 62 is opposite to the base plate 61. Transform into As a result, when the volume of the shielded space 63 increases, the volume of low pressure fuel that can be accommodated in the internal space 51 decreases, and a drop in pressure of the low pressure fuel is suppressed. This reduces the pressure pulsation of the low pressure fuel.

  On the other hand, the diaphragm 62 has a natural frequency, and when the frequency of pressure pulsation of low pressure fuel matches the natural frequency of the diaphragm 62, a phenomenon that the width of vibration of the diaphragm 62 becomes large, that is, resonance occurs. In the low pressure fuel supply path 21a, pressure pulsation of the low pressure fuel occurs because the suction of the low pressure fuel to the high pressure pump 20 is periodically performed as the plunger 25 reciprocates. Therefore, when the pump rotation speed R becomes equal to the natural rotation speed Rc (see FIG. 4) corresponding to the natural frequency of the diaphragm 62, the diaphragm 62 resonates. When the diaphragm 62 resonates, the pulsation amplitude of the low pressure fuel increases. Thereby, when the peak value (hereinafter referred to as a pressure peak value) P of the pressure of the low pressure piping 13 exceeds the limit pressure Pg of the connection connector 15, there is a concern that a problem may occur in the connection connector 15.

  The damper 40 of the present embodiment includes the state switching unit 70 in order to solve the above-described problem. The state switching unit 70 switches between a first state in which the low pressure fuel is supplied to the diaphragm 62 and a second state in which the low pressure fuel is not supplied to the diaphragm 62. In the damper 40 of the present embodiment, the pressure peak value P can be controlled so as not to exceed the limit pressure Pg of the connection connector 15 by the state switching unit 70 switching between the first state and the second state. . The principle will be described below.

  FIG. 4 is a graph F1 (broken line) showing the relationship between the pump rotational speed R and the pressure peak value P when the damper 40 is not used, and the pump rotational speed R and the pressure peak value P when the damper 40 is used. A graph F2 (one-dot chain line) showing the relationship is shown. The graph F1 and the graph F2 intersect at the intersection point M. Hereinafter, the pressure peak value P at the intersection point M is referred to as a reference pressure value Pm, and the pump rotational speed R at the intersection point M is referred to as a reference rotational speed Rm. Further, a region where the pump rotational speed R is equal to or less than the reference rotational speed Rm is referred to as a low rotational speed region Rd, and a region where the pump rotational speed R is equal to or higher than the reference rotational speed Rm is referred to as a high rotational speed region Ru. In the present embodiment, the reference rotational speed Rm is about 2000 rpm. Therefore, the low rotational speed region Rd corresponds to the rotational speed region at the time of idling, and the high rotational speed region Ru corresponds to the rotational speed region at the time of traveling.

  In the graph F1 in the state where the damper 40 is not used, the pressure peak value P increases as the pump rotational speed R increases. Therefore, the pressure peak value P does not exceed the limit pressure Pg in the low rotational speed region Rd. On the other hand, the pressure peak value P may exceed the limit pressure Pg in the high rotational speed region Ru.

  On the other hand, in graph F2 in the state where damper 40 is used, pressure peak value P in high rotational speed region Ru is suppressed by damper 40, and pressure peak value P is prevented from exceeding limit pressure Pg in high rotational speed region Ru. Be done. On the other hand, because the natural rotation speed Rc corresponding to the natural frequency of the diaphragm 62 is smaller than the reference rotation speed Rm, the pressure peak value P may exceed the limit pressure Pg in the low rotation speed region Rd due to the resonance of the diaphragm 62 is there.

  The inventor has noticed that in the graph F1 and the graph F2, the regions where the pressure peak value P exceeds the limit pressure Pg are different from each other. The state switching unit 70 switches between the state using the damper 40 and the state not using the damper 40 based on this finding, and is configured to suppress the pressure peak value P from exceeding the limit pressure Pg. is there. Specifically, the state switching unit 70 realizes the state in which the damper 40 is used by the first state in which the low pressure fuel is supplied to the diaphragm 62. Further, the state switching unit 70 realizes the state in which the damper 40 is not used by the second state in which the low pressure fuel is not supplied to the diaphragm 62. Then, by switching between the first state and the second state, it becomes possible to suppress that the pressure peak value P exceeds the limit pressure Pg regardless of the pump rotational speed R.

  Next, the state switching unit 70 will be described. As shown in FIG. 2, the state switching unit 70 is provided in the first region R1, and the first region R1 is divided into a third region R3 on the communication path 21b side and a fourth region R4 on the diaphragm portion 60 side. It is divided into and. The state switching unit 70 includes a first member 71 and a second member 72. The state switching unit 70 is an example of a partition unit.

  As shown in FIGS. 2A and 2B, the first member 71 is an annular metal flat plate, and is disposed in a direction orthogonal to the axial direction X. The plate thickness of the first member 71 is thicker than the plate thickness of the diaphragm 62, and deformation according to the pressure in the third region R3 is suppressed. The outer edge portion 71 a of the first member 71 is fixed to the casing 50 over the entire circumference. In the first member 71, a through hole 73 communicating the third region R3 and the fourth region R4 is formed. The through hole 73 is disposed substantially at the center of the first member 71, and is disposed at a position facing the communication path 21b. The through hole 73 is an example of a first through hole.

  The second member 72 opens and closes the through hole 73. As shown in FIGS. 2 (a) and 2 (c), the second member 72 is a circular thin plate made of metal, and its central portion 72a has a plate shape protruding toward the first member 71 side. The central portion 72a is disposed in a direction perpendicular to the axial direction X, and has a circular shape. The outer diameter of the central portion 72 a is smaller than the diameter of the through hole 73, and the central portion 72 a is provided in a size that allows the through hole 73 to be inserted. As the diameter is expanded in the radial direction of the casing 50, an inclined portion 72b which is inclined to the side opposite to the first member 71 is provided around the central portion 72a. Further, an outer peripheral portion 72c disposed in a direction orthogonal to the axial direction X is provided around the inclined portion 72b.

  The central portion 72 a and the inclined portion 72 b of the second member 72 are disposed at a position facing the through hole 73, and are disposed at a position facing the communication path 21 b via the through hole 73. Further, the central portion 72a and the inclined portion 72b of the second member 72 project toward the first member 71 side, that is, the communication path 21b side, as compared with the outer peripheral portion 72c. The outer edge portion 72 d of the outer circumferential portion 72 c is fixed to the casing 50 over the entire circumference on the diaphragm portion 60 side of the first member 71. By fixing the first member 71 and the second member 72 to the casing 50, the state switching unit 70 is fixed to the casing 50. A plurality of through holes 74 are formed in the outer peripheral portion 72 c of the second member 72. The through holes 74 are arranged at equal intervals in the circumferential direction of the casing 50, and communicate the third region R3 and the fourth region R4. The through hole 74 is an example of a second through hole.

  As shown in FIG. 3, the second member 72 is deformable by the pressure of the third region R3. For example, as shown in FIG. 3C, when the pressure in the third region R3 is equal to or higher than a predetermined pressure described later, the central portion 72a of the second member 72 is deformed to the opposite side to the first member 71. As a result, the second member 72 is in the open state separated from the first member 71. When the second member 72 is in the open state, the third region R3 and the fourth region R4 are in communication with each other, and the first state in which the low pressure fuel is supplied to the diaphragm 62 is realized.

  When the second member 72 is in the open state, low pressure fuel is supplied to the diaphragm 62. Therefore, when the second member 72 is in the open state, the pressure pulsation of the low pressure fuel is reduced by the diaphragm 62.

  Further, as shown in FIGS. 3A and 3B, when the pressure in the third region R3 becomes smaller than the predetermined pressure, the central portion 72a of the second member 72 deforms to the first member 71 side. As a result, the central portion 72a of the second member 72 protrudes toward the communication path 21b more than the first member 71, and the inclined portion 72b of the second member 72 contacts the side surface around the through hole 73 of the first member 71. The through hole 73 is closed by the central portion 72a and the inclined portion 72b. That is, the second member 72 comes in contact with the first member 71 to close the through hole 73. When the second member 72 is in the closed state, the third region R3 and the fourth region R4 are shut off, and the second state in which the low pressure fuel is not supplied to the diaphragm 62 is realized. The central portion 72a and the inclined portion 72b are an example of a movable portion and a projecting portion, and the outer peripheral portion 72c is an example of a fixed portion.

  When the second member 72 is in the closed state, the low pressure fuel is not supplied to the diaphragm 62, and the low pressure fuel is supplied to the third region R3. The low pressure fuel is supplied from the supply passage 21a to the third region R3 having a larger cross-sectional area than the supply passage 21a, whereby the pressure pulsation is reduced. Therefore, when the second member 72 is in the closed state, the pressure pulsation of the low pressure fuel is reduced by the third region R3. The pulsation reduction effect of the low pressure fuel by the third region R3 is smaller than the pulsation reduction effect of the low pressure fuel by the diaphragm 62.

  That is, the second member 72 opens and closes the through hole 73 by the pressure in the third region R3 and thereby switches between the open state and the closed state. In the state switching unit 70 of the present embodiment, the predetermined pressure for switching between the open state and the closed state is set to be equal to the reference pressure value Pm (see FIG. 4). Accordingly, when the pump rotational speed R becomes equal to or higher than the reference rotational speed Rm and the pressure peak value P becomes equal to or higher than the reference pressure value Pm, the second member 72 is opened, thereby switching the damper 40 to the first state. Therefore, as shown in FIG. 4, the graph F3 (solid line) showing the relationship between the pump rotational speed R and the pressure peak value P in the present embodiment is equal to the graph F2 in the high rotational speed region Ru. Thereby, it is possible to suppress that the pressure peak value P exceeds the limit pressure Pg in the high rotation speed region Ru. The second member 72 is an example of an opening and closing unit.

  On the other hand, when the pump rotational speed R is smaller than the reference rotational speed Rm and the pressure peak value P becomes smaller than the reference pressure value Pm, the second member 72 is closed, whereby the damper 40 is switched to the second state. Therefore, as shown in FIG. 4, the graph F3 (solid line) showing the relationship between the pump rotational speed R and the pressure peak value P in the present embodiment becomes equal to the graph F1 in the low rotational speed region Rd. As a result, it is possible to suppress that the pressure peak value P exceeds the limit pressure Pg in the low rotation speed region Rd.

  That is, according to the damper 40 of the present embodiment, it is possible to suppress that the pressure peak value P exceeds the limit pressure Pg at all the pump rotational speeds R. The predetermined pressure for switching between the open state and the closed state is adjusted to be equal to the reference pressure value Pm by a plurality of parameters including the opening area of the through hole 73 and the material of the second member 72.

  According to the embodiment described above, the following effects can be obtained.

  The damper 40 includes a state switching unit 70 that switches between the first state and the second state. Therefore, when the diaphragm 62 resonates when low-pressure fuel is supplied to the diaphragm 62, the state switching unit 70 switches from the first state to the second state so that the diaphragm 62 is not deformed. Resonance can be suitably suppressed.

  Further, when the low pressure fuel is not supplied to the diaphragm 62, the damper 40 causes the state switching unit 70 to switch from the second state to the first state to deform the diaphragm 62 when the pulsation amplitude of the low pressure fuel increases. Thus, the increase in pulsation amplitude of the low pressure fuel can be suitably suppressed.

  The state switching unit 70 includes the second member 72 that switches between the open state and the closed state, switches to the first state by the second member 72 being open, and the second member 72 changes to the closed state. Switch to 2 states. Therefore, by switching the state of the second member 72, it is possible to switch between the first state and the second state.

  The second member 72 switches between the open state and the closed state by the pressure of the third region R3. Therefore, it is not necessary to provide an actuator for switching the state of the second member 72, and the configuration of the damper 40 can be simplified.

  Specifically, the second member 72 is open when the pressure in the third region R3 is equal to or higher than the reference pressure value Pm and the pump rotational speed R of the high pressure pump 20 is equal to or higher than the reference rotational speed Rm. It becomes. The second member 72 is closed when the pressure in the third region R3 is smaller than the reference pressure value Pm and the pump rotational speed R of the high-pressure pump 20 is smaller than the reference rotational speed Rm. . That is, the damper 40 switches to the first state when the pump rotational speed R of the high pressure pump 20 becomes equal to or higher than the reference rotational speed Rm, and the second when the pump rotational speed R of the high pressure pump 20 is smaller than the reference rotational speed Rm. Switch to the state. The reference rotational speed Rm is set to a pump rotational speed R which is larger than the inherent rotational speed Rc of the diaphragm 62. Therefore, since the second state is established when the pump rotational speed R is equal to the specific rotational speed Rc, resonance of the diaphragm 62 can be suppressed.

  The central portion 72a and the inclined portion 72b of the second member 72 are disposed to face the communication path 21b. The state of the second member 72 is switched by the pressure of the third region R3, and the pressure of the third region R3 fluctuates by the pressure of the low pressure fuel supplied to the third region R3 via the communication path 21b. Therefore, the central portion 72a and the sloped portion 72b of the second member 72 are disposed to face the communication path 21b, according to the pressure fluctuation of the third region R3 as compared to the case where they are not disposed to face each other. It is possible to switch the state accurately.

  In the second member 72, a through hole 74 is formed in the outer peripheral portion 72c. Therefore, in the first state, low pressure fuel can be supplied to the diaphragm 62 through the through holes 73 and the through holes 74.

Second Embodiment
Next, a damper according to a second embodiment will be described with reference to FIG. The damper according to the second embodiment differs from the damper 40 according to the first embodiment in the configuration of the state switching unit. Therefore, hereinafter, the state switching unit 170 of the damper according to the second embodiment will be described.

  As shown in FIG. 5, the state switching unit 170 includes a first member 71 and a second member 172. The second member 172 differs from the second member 72 of the first embodiment in that the outer diameter of the central portion 172a is larger than the diameter of the through hole 73, and the connecting portion 172b is provided instead of the inclined portion 72b. It is a point that In FIG. 5, the same components as those shown in FIG. 2 are denoted by the same reference numerals for convenience, and the description thereof is omitted.

  In the second member 172 of the present embodiment, since the outer diameter of the central portion 172a is larger than the diameter of the through hole 73, the through hole 73 can be closed only by the central portion 172a. In the present embodiment, the central portion 172a and the connection portion 172b are an example of the movable portion.

  Further, in the second member 172, a connection portion 172b is provided instead of the inclined portion 72b. The connection portion 172b is disposed between the central portion 172a and the outer peripheral portion 72c, and connects the central portion 172a and the outer peripheral portion 72c. The connection portion 172 b is in the shape of a bellows that is folded a plurality of times in the direction intersecting the axial direction X, and is formed so as to be elastically deformable in the axial direction X. Therefore, in the second member 172 of the present embodiment, by elastically deforming the connection portion 172b in the axial direction X, it is possible to easily switch between the first state and the second state.

Third Embodiment
Next, a damper according to a third embodiment will be described with reference to FIG. The damper according to the third embodiment differs from the damper 40 according to the first embodiment in the configuration of the state switching unit. Therefore, hereinafter, the state switching unit 270 of the damper according to the third embodiment will be described.

  As shown in FIG. 6, the state switching unit 270 includes a first member 71 and an opening / closing member 272. The opening / closing member 272 is different from the second member 72 of the first embodiment in that the outer diameter of the central portion 272a is larger than the diameter of the through hole 73, and the through hole 274 is formed in the inclined portion 272b. is there. In FIG. 6, the same components as those shown in FIG. 2 are designated by the same reference numerals for convenience, and the description thereof is omitted.

  In the second member 172 of the present embodiment, since the outer diameter of the central portion 172a is larger than the diameter of the through hole 73, the through hole 73 can be closed only by the central portion 172a. In the present embodiment, the central portion 272a is an example of the movable portion, and the inclined portion 272b and the outer peripheral portion 72c are an example of the fixed portion.

  In the opening / closing member 272 of the present embodiment, the through hole 274 is formed in the inclined portion 272 b. By forming the through holes 274 in the inclined portion 272b, the strength of the inclined portion 272b can be weakened. Therefore, in the opening and closing member 272 of the present embodiment, the first state and the second state can be easily switched by deforming the inclined portion 272b in the axial direction X.

(Other embodiments)
Although the through-hole 74 formed in the outer peripheral part 72c was illustrated in FIG.2 (c), it is not limited to this. For example, the shape illustrated in FIG. 7 may be used. The same applies to the through holes 274 formed in the inclined portion 272b.

  Although the shape of the diaphragm 62 is illustrated in FIG. 2, the present invention is not limited to this and can be applied to diaphragms of known shapes. The same applies to the shape of the casing 50.

  Although the damper 40 is disposed inside the high pressure pump 20 and is integrally formed with the high pressure pump 20, the invention is not limited thereto, and the damper 40 is disposed outside the high pressure pump 20. And may be formed separately.

  DESCRIPTION OF SYMBOLS 10 ... Fuel supply system, 21a ... Supply path, 21b ... Communication path, 23 ... Suction valve, 32 ... Control apparatus, 40 ... Damper, 50 ... Casing, 51 ... Internal space, 60 ... Diaphragm part, 62 ... Diaphragm, 64 ... Through hole 70 70 state switching unit 71 first member 72 second member 73 through hole 74 through hole P pressure peak value Pg limit pressure Pm reference pressure value R Pump rotational speed, Rc: Specific rotational speed, Rm: Reference rotational speed.

Claims (8)

It is applied to a fuel supply system (10) including a fuel pump (20) for periodically sucking and discharging fuel, and a pulsation damper (40) is provided in a communication path branched from a supply path for supplying low pressure fuel to the fuel pump. ) And
A casing (50) having an internal space communicating with the communication path;
A diaphragm portion (60) which includes a diaphragm (62) and divides the internal space into a first area on the communication path side and a second area on the opposite side to the communication path;
A state switching unit (70) arranged in the first region to switch between a first state in which the low pressure fuel is supplied to the diaphragm, and a second state in which the low pressure fuel is not supplied to the diaphragm;
Pulsation damper with. The state switching unit is
A partition (70) fixed to the casing and partitioning the first area into a third area on the communication path side and a fourth area on the diaphragm side;
The partition part has an open / close part (72) that switches between an open state and a closed state,
The first state is a state in which the third area and the fourth area are communicated with each other by the opening / closing unit being in an open state,
2. The pulsation damper according to claim 1, wherein the second state is a state in which the third area and the fourth area are shut off by the opening / closing part being closed. The partition part is
A first member (71) having a through hole (73) communicating the third region and the fourth region;
A second member (72) provided as the open / close unit, and switching between the open state and the closed state by opening and closing the through hole;
Have
The pulsation damper according to claim 2, wherein the second member switches between the open state and the closed state according to the pressure in the third region. The second member has a movable portion (72a, 72b) that opens and closes the through hole by the pressure of the third region,
The pulsation damper according to claim 3, wherein the movable portion is disposed to face the communication path. The second member has a fixed portion (72c) disposed around the movable portion and fixed to the casing,
The through hole is a first through hole,
The pulsation damper according to claim 4, wherein a second through hole (74) communicating the third area and the fourth area is formed in the fixing portion.   The movable portion protrudes toward the first member more than the fixed portion, and closes the first through hole by the protruding portion, and is elastic in a direction in which the first member and the second member are arranged. The pulsation damper according to claim 5, which is formed to be deformable. A fuel pump (20) for periodically sucking and discharging fuel;
The fuel pump according to any one of claims 1 to 6, provided in a communication passage branched from a supply passage for supplying low-pressure fuel to the fuel pump, and integrally provided with the fuel pump or separately from the fuel pump. A pulsation damper (40) according to any one of
A fuel supply system comprising: The state switching unit (70) switches to the first state when the rotational speed of the fuel pump is equal to or higher than a predetermined reference rotational speed (Rm), and the rotational speed of the fuel pump is smaller than the reference rotational speed. Switch to the second state,
The fuel supply system according to claim 7, wherein the reference rotational speed is set to a rotational speed larger than a natural rotational speed (Rc) corresponding to a natural frequency of the diaphragm.

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