JP5910143B2 - Fuel pump structure - Google Patents

Description

  The present invention relates to a fuel pump structure, and more particularly to a fuel pump structure in which a fuel passage is formed using a plurality of cylindrical parts coupled to each other and a valve holding mechanism is configured.

  Some internal combustion engines for vehicles directly inject high-pressure fuel into cylinders. However, in such an internal combustion engine, it is necessary to pressurize the fuel to a high pressure and supply it to a fuel injection valve (injector). A fuel supply system that pressurizes fuel supplied from a low-pressure fuel pump to a high pressure by a high-pressure fuel pump is often used.

  In such a fuel supply system, compactness and reliability are required, and in order to downsize the high-pressure fuel pump, at least a suction valve and a discharge valve having a check valve function are mounted and held in a compact manner. Is required.

  Therefore, conventionally, for example, a pump housing (pump body) of a high-pressure fuel pump and a discharge valve housing that houses the discharge valve are configured separately, and the pressure in the fuel pressure accumulator on the injector side can be controlled to a set pressure. A pressure relief valve is mounted in the discharge valve housing and assembled to the pump housing together with the discharge valve (for example, see Patent Document 1).

  Further, the cylinder and the pump housing on which the plunger is slidably supported are formed of different metals, and the pressurizing chamber formed between the pump housing and the cylinder is sealed with the mutual pressure contact surface. What provided the press mechanism which presses a pump housing relatively is known (for example, refer to patent documents 2).

JP 2004-218547 A JP 2007-146862 A

  However, in the conventional fuel supply system as described above, in order to miniaturize the high-pressure fuel pump, valves and sliding parts are arranged with high density and assembly parts such as a housing member for housing them are provided. A fuel pump structure that is coupled and fixed to the pump body main body portion by screw coupling or press fitting has been employed. For this reason, the sealing performance of the valve and the sliding performance of the sliding parts may be deteriorated due to distortion of the housing member, particularly in the fixed portion of the housing member on the discharge side where the fuel is at a high pressure. The fuel pressurization performance and durability were reduced.

  In addition, if a discharge valve housing is configured by press-fitting a plurality of cylindrical parts or screwed together, it is considered that the discharge valve housing can be configured compactly even if a relief valve is mounted in the discharge valve housing. In such a case, a plurality of coupling parts such as a screw coupling part, a press-fitting fitting part, or a welding part come close to each other. Therefore, the dimensional change in the radial direction of the assembly part such as the housing member is increased due to mutual interference between the plurality of coupling portions, and there is a concern that the sealing performance of the valve and the sliding performance of the sliding part may be deteriorated.

  That is, in the conventional fuel pump structure, the pump performance is improved by suppressing the mutual interference of the plurality of coupling portions, and the request for downsizing of the pump size is met as a mounting form in which the plurality of coupling portions are close to each other. However, it was difficult to make these requirements compatible.

  Therefore, the present invention can suppress the dimensional change of the assembly parts due to their mutual interference even if a plurality of coupling parts are close to the fixed part of the assembly parts such as the housing member, and requires miniaturization and performance. A fuel pump structure capable of achieving both of the above is provided.

  In order to solve the above problems, the present invention provides (1) a fuel passage and a fuel pressurization chamber connected to the fuel passage, and a fuel pressurization mechanism for pressurizing fuel in the fuel pressurization chamber is mounted. A fuel pump structure including a pump body and a housing member that houses a movable part and is assembled to the pump body, wherein the housing members are at least partially overlapped with each other in the radial direction. The plurality of cylindrical parts have a plurality of coupling portions for mutual coupling and coupling to the pump body, and among the plurality of cylindrical parts, a specific cylindrical part is the plurality of the plurality of coupling parts. And the first and second coupling portions are located on both sides of the inner and outer peripheral walls of the specific cylindrical part, the coupling position in the axial direction of the specific cylindrical part being different. And second At least one of the first and second coupling regions in the axial direction of the specific cylindrical part in which the coupling part is formed is formed with either one of the first and second coupling parts. The inner and outer peripheral walls are opposite to one side and are fitted into a gap with other adjacent cylindrical parts.

  With this configuration, the specific cylindrical component is coupled to the other cylindrical components inside and outside by the first and second coupling portions having different axial positions on both sides of the inner and outer peripheral walls. In at least one of the second coupling regions, one of the first and second coupling portions is formed on one side of the inner and outer peripheral walls, and the other one side (opposite side) of the inner and outer peripheral walls is The gap is fitted to other adjacent cylindrical parts. Therefore, in addition to eliminating mutual interference due to the radial overlap between the first and second coupling portions, distortion in one of the first and second coupling portions is a gap fitting portion. Therefore, the dimensional change in the radial direction of the housing member composed of a plurality of cylindrical parts is suppressed. As a result, even if a plurality of joints are close to the fixed part of an assembly part such as a housing member, the dimensional change of the assembly part due to their mutual interference and the resulting deterioration in sealing performance and slidability are suppressed. Thus, a fuel pump structure that can satisfy both the demand for miniaturization and the performance requirement of the fuel pump is obtained. In addition, it is desirable that any one of the coupling portions mentioned here is one that requires particularly relaxation of the strain among the first and second coupling portions. Moreover, you may provide the gap | interval fitting part which the position of an axial direction and a radial direction reverses these so that the distortion of both the 1st and 2nd coupling | bond part may be relieve | moderated.

  In the fuel pump structure of the present invention, preferably, (2) the number of the coupling portions is three or more, and an arbitrary pair of coupling portions adjacent in the radial direction among the three or more coupling portions is the The axial positions are different from each other.

Therefore, the axial position of each pair of coupling portions adjacent in the radial direction is not the same,
It is possible to prevent the distortion at each coupling portion from interfering with each other.

  In the fuel pump structure having the configuration of (2) above, (3) the coupling portion includes the first coupling portion and the second coupling portion that are adjacent in the radial direction, and the second coupling portion. And a third coupling portion disposed on the opposite side of the first coupling portion in the radial direction, wherein the third coupling portion is more in the axial direction than the second coupling portion. It is desirable that it is disposed near the joint portion.

  In this case, the three or more coupling portions are alternately arranged at different positions in the axial direction, and the housing member can be configured compactly even when the number of coupling portions overlapping in the radial direction increases. it can. In addition, the joint distortion of multiple joints that overlap in the radial direction within the joint region where the gap fitting part is formed is alleviated by the gap fitting part, and the thickness of each cylindrical part can be reduced. Therefore, it becomes effective for minimizing the physique when multiple coupling is used.

  In the fuel pump structure having the configuration of (3) above, (4) it is more preferable that the third coupling portion is disposed in the first coupling region in the axial direction.

  In this case, the three or more coupling portions are alternately arranged at two positions in the axial direction, and the housing member can be configured more compactly.

  In the fuel pump structure of the present invention, (5) at least one of the first coupling portion and the second coupling portion is preferably a press-fitting fitting portion.

  In this case, at least the distortion due to the press-fitting on one side of the inner and outer circumferences of the specific cylindrical part can be reduced on the opposite side of the inner and outer circumferences of the specific cylindrical part, and the diameter dimension of the specific cylindrical part can be reduced. It is possible to prevent changes due to the influence of coupling distortion with other cylindrical parts.

  In the fuel pump structure of the present invention, (6) it is preferable that at least one of the first coupling portion and the second coupling portion is a screw coupling portion.

  In this case, distortion due to screw connection on one side of the inner and outer circumferences of at least a specific cylindrical part can be reduced on the opposite side of the inner and outer circumferences of the specific cylindrical part. It is possible to prevent the change due to the influence of the coupling distortion with the cylindrical part.

  In the fuel pump structure according to the present invention, (7) a discharge valve body in which the movable part allows discharge of fuel from the fuel pressurization chamber while preventing backflow of the fuel to the fuel pressurization chamber. It is preferable that a discharge valve seat on which the discharge valve body can be seated is formed on the specific cylindrical component among the plurality of cylindrical components.

  In this case, the housing member that houses the discharge valve can be made compact.

  In the fuel pump structure having the configuration described in (7) above, (8) the movable part includes a relief valve body that is displaced according to the pressure of fuel downstream from the discharge valve body, and the plurality of cylinders It is more preferable that a relief valve seat on which the relief valve body can be seated is formed on the specific cylindrical part among the cylindrical parts.

  In this case, the housing member that houses the discharge valve and the relief valve can be made compact.

  In the fuel pump structure having the configuration described in (7) or (8) above, (9) it is preferable that the valve seat surface of the discharge valve seat is orthogonal to the axial direction.

  In this case, distortion caused by coupling such as press fitting or screw coupling hardly affects the valve seat surface of the discharge valve, and the sealing performance of the discharge valve during the non-discharge period can be improved.

  According to the present invention, the strain in one coupling portion is alleviated at the gap fitting portion in the same region in the axial direction while avoiding the overlap in the radial direction between the first and second coupling portions. Even if a plurality of coupling parts come close to the fixed part of an assembly part such as a housing member, the dimension of the assembly part due to mutual interference is suppressed even if the dimensional change in the radial direction of the housing member made of the cylindrical part is suppressed. It is possible to provide a fuel pump structure that can suppress the change and can satisfy both the miniaturization requirement and the performance requirement.

It is sectional drawing of the fuel pump which shows the fuel pump structure which concerns on one Embodiment of this invention. It is a principal part expanded sectional view which expands and shows the characteristic part of the fuel pump structure which concerns on one Embodiment of this invention. It is explanatory drawing of the arrangement | positioning state of the some coupling | bond part in the characteristic part of the fuel pump structure which concerns on one Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(One embodiment)
1 to 3 show a high-pressure fuel pump for an internal combustion engine having a fuel pump structure according to an embodiment of the present invention. The high-pressure fuel pump 10 of this embodiment is mounted on an internal combustion engine mounted on a vehicle, for example, a cylinder injection or dual injection multi-cylinder gasoline engine (hereinafter simply referred to as an engine), and the fuel of the engine. Is a plunger pump type that pressurizes and discharges at a high pressure.

  The high-pressure fuel pump 10 of the present embodiment shown in FIG. 1 is connected to a low-pressure fuel pump (feed pump) (not shown) on the suction side, and sucks fuel pumped up from the fuel tank by the low-pressure fuel pump. It is like that. The low-pressure fuel pump is constituted by, for example, an electric Wesco pump in which a pump impeller is rotationally driven by a drive motor, and the discharge amount and discharge pressure per unit time can be changed.

  The high-pressure fuel pump 10 is connected to a plurality of in-cylinder injectors via delivery pipes on the discharge side, and pumps high-pressure fuel to the delivery pipes. The delivery pipe stores and accumulates high-pressure fuel discharged from the high-pressure fuel pump 10, and distributes and supplies high-pressure fuel to the injector when the in-cylinder injector for each cylinder is opened. It has become.

  As shown in FIG. 1, the high-pressure fuel pump 10 includes a pump body 11 and a substantially cylindrical plunger 12 (pressurizing member) provided so as to be reciprocally displaceable in the axial direction with respect to the pump body 11. Yes.

  The pump body 11 includes a suction passage 11a (low pressure side fuel passage) for sucking fuel from the low pressure fuel pump, and a discharge passage 11b (high pressure side fuel passage) for discharging fuel pressurized inside to the delivery pipe side. Is formed.

  The plunger 12 is slidably inserted into the pump body 11 at its inner end 12a (upper end in FIG. 1). A fuel pressurizing chamber 13 connected to the suction passage 11a and the discharge passage 11b is defined inside the pump body 11 in which the plunger 12 is inserted. The fuel pressurizing chamber 13 can suck and discharge fuel by changing (increasing or decreasing) the volume of the fuel pressurizing chamber 13 according to the axial displacement of the plunger 12.

  On the suction passage 11 a of the pump body 11, there is a check valve function that allows the fuel to be sucked into the fuel pressurizing chamber 13 while preventing the reverse flow of the fuel from the fuel pressurizing chamber 13 to the upstream side. A suction valve 14 is provided. A check valve function is provided on the discharge passage 11b of the pump body 11 to allow the fuel to be discharged from the fuel pressurizing chamber 13 while preventing the backflow of fuel from the downstream side to the fuel pressurizing chamber 13. And when the fuel pressure from the downstream side of the discharge valve 15 reaches the upper limit of the allowable pressure range, the downstream fuel is allowed to flow back to the fuel pressurizing chamber 13 bypassing the discharge valve 15. And a relief valve 16 for avoiding an abnormal increase in pressure.

  A part of the suction passage 11a of the pump body 11 is a suction gallery chamber 11g (fuel storage chamber) having a predetermined volume capable of storing fuel from the low-pressure fuel pump. The fuel introduced into the suction passage 11a is this The fuel is first stored in the suction gallery chamber 11 g and then sucked into the fuel pressurizing chamber 13.

  The plunger 12 is engaged with a driving cam (not shown) via a rocker arm with a roller (not shown) on the lower end 12b side in FIG. This drive cam has a cam profile (for example, an elliptical or a polygonal cam profile with rounded corners) whose radius (lift amount) is larger than the radius of the other part at least at one place in the circumferential direction. Are known ones. For example, the drive cam is integrally mounted on an exhaust camshaft (not shown in detail) of the engine and is driven by the power of the engine.

  On the base end side of the pump body 11, a plurality of flange portions 11 f (only one is shown in FIG. 1) each formed with a bolt hole 11 c and a fitting portion that is fitted into a pump mounting hole portion such as a head cover (not shown). 11h, and the pump body 11 is fastened to the pump mounting case by a plurality of bolts (not shown) inserted into the plurality of bolt holes 11c.

  A spring receiving portion 12c is mounted in the vicinity of the other end portion 12b of the plunger 12, and a compression coil spring 19 (elastic member) is incorporated in a compressed state between the spring receiving portion 12c and the pump body 11. It is. The compression coil spring 19 is an elastic member that urges the plunger 12 toward the side approaching the drive cam 21, and the plunger 12 increases the volume of the pressurizing chamber 13 by the compression coil spring 19 (FIG. 1). It is always energized in the downward direction. Therefore, when the drive cam is rotationally driven, the plunger 12 is reciprocally displaced in the axial direction in accordance with the rotation of the drive cam.

  The plunger 12 inserted into the pump body 11 constitutes a fuel pressurization mechanism 17 that pressurizes the fuel in the fuel pressurization chamber 13 together with the drive cam, the compression coil spring 18, the oil seal holder 19 and the like. The high-pressure fuel pump 10 has a pump body 20 in which the fuel pressurizing mechanism 17 is attached to the pump body 11.

  The pump body 20 is assembled with a cylindrical suction side housing member 21 and a cylindrical discharge side housing member 22 so as to protrude outward.

  Specifically, the pump body 11 includes a main cylindrical member 31, a cylindrical cylinder member 32 that holds the plunger 12 slidably in the axial direction, and is press-fitted into the center of the main cylindrical member 31; The flange portion 11f and the fitting portion 11h are integrally mounted, and include a main cylindrical member 31 and an attachment member 33 that supports the cylinder member 32.

  The main cylindrical member 31 and the cylinder member 32 form the suction passage 11 a together with the suction side housing member 21, and form the discharge passage 11 b together with the discharge side housing member 22. The suction valve 14 is held at the center of the main cylindrical member 31 with the suction-side housing member 21 screwed to the left end portion of the main cylindrical member 31 in FIG. Further, the discharge valve 15 and the relief valve 16 are held inside the discharge-side housing member 22 screwed to the right end portion of the main cylindrical member 31 in FIG.

  The intake valve 14 allows the introduction of fuel into the intake passage 11a, while restricting the backflow of the fuel introduced into the intake passage 11a, and normally urges the intake valve body 14a in the valve closing direction. Thus, the suction valve spring 14b for defining the valve opening pressure of the suction valve 14 and the suction valve seat 14c on which the suction valve body 14a receiving the biasing force from the suction valve spring 14b is seated and engaged are configured. Yes. The suction valve 14 can be opened when a predetermined valve opening differential pressure is generated before and after that.

  The suction side housing member 21 is equipped with an electromagnetic operation unit 40 that can close the suction valve body 14a of the suction valve 14.

  The electromagnetic operation unit 40 includes an operation member 41 connected to the intake valve body 14a, and an intake valve of the intake valve 14 with an urging force in the valve opening direction larger than the urging force of the intake valve spring 14b in the valve closing direction. A compression coil spring 42 that urges the body 14a in the valve opening direction, a movable core 43 that is fixed to the upper end of the operating member 41 in FIG. 1, a fixed core 44 that faces the movable core 43, and a fixed core 44 An electromagnetic force that is provided so as to surround the outer periphery and generates an electromagnetic force that attracts the movable core 43 by the fixed core 44 when excited by energization, and closes the suction valve body 14a of the suction valve 14 via the operation member 41. And a coil 45.

  Therefore, the electromagnetic operation unit 40 can variably control the pressurization period of the fuel in the fuel pressurization chamber 13 by the plunger 12 by controlling the period during which the intake valve 14 is forcibly closed. In the intake valve 14, the fuel pressure in the fuel pressurizing chamber 13 becomes smaller than the fuel pressure in the intake gallery chamber 11g by a predetermined intake valve opening differential pressure, for example, a differential pressure of several tens of kPa. It can be opened when

  As shown in FIGS. 2 and 3, the discharge valve 15 includes a discharge valve body 15a that opens and closes the discharge passage 11b, an annular discharge valve seat 15b, a predetermined discharge pressure (a predetermined discharge pressure is determined based on the fuel pressure in the delivery pipe). It is constituted by a discharge valve spring 15c (elastic member) that keeps the valve closed state in which the discharge valve body 15a is brought into contact with the discharge valve seat 15b until the pressure reaches a pressure higher by the valve opening differential pressure. Here, the valve seat surface 15s of the discharge valve seat 15b with which the discharge valve body 15a contacts has an annular shape orthogonal to the axial direction (center axis direction) of the intermediate cylindrical part 52.

  The discharge valve 15 has a discharge valve opening differential pressure (for example, several tens of kPa) set in advance with respect to the pressure (delivery pressure) of the fuel in the fuel pressurizing chamber 13 downstream of the discharge valve body 15a. The valve can be opened when the pressure becomes high. That is, when the plunger 12 is displaced upward in FIG. 1 so as to decrease the volume of the fuel pressurizing chamber 13, the fuel in the fuel pressurizing chamber 13 is pressurized and its pressure rises, and the discharge valve 15 When a differential pressure equal to or greater than the discharge valve opening differential pressure is generated before and after, the discharge valve 15 can be opened while the suction valve 14 is closed.

  The relief valve 16 includes a spherical relief valve body 16a provided on a bypass passage 22w (details will be described later) formed so as to bypass the discharge valve 15 in the discharge-side housing member 22, and the relief valve body 16a. An annular relief valve seat 16b that can be closed by the above and a relief valve spring 16c that urges the relief valve body 16a toward the relief valve seat 16b.

  The relief valve 16 is always in the discharge direction from the fuel pressurizing chamber 13 to the downstream side inside the pump body 11 and on the bypass passage 22w that bypasses the discharge valve 15 on the discharge side of the fuel pressurizing chamber 13. The valve is closed and can be opened in the backward flow direction from the downstream side to the fuel pressurizing chamber 13 side. That is, the relief valve 16 has a predetermined relief in which the fuel pressure in the discharge passage 11b downstream of the discharge valve 15 is sufficiently larger than the predetermined discharge valve opening differential pressure with respect to the fuel pressure in the fuel pressurizing chamber 13. The valve is opened when the valve opening differential pressure is exceeded (for example, a pressure difference several MPa higher than the maximum discharge pressure). Here, the expression “sufficiently larger than the discharge valve opening differential pressure” means that the relief valve 16 is not opened when the fuel pressure in the delivery pipe pulsates. The valve differential pressure is set within a range that can guarantee the piping limit pressure of each component after the delivery pipe.

  Returning to FIG. 1, when the drive cam is driven by the power of the engine and the lift amount of the plunger 12 periodically changes, the electromagnetic operation unit 40 is energized by an electronic control unit (ECU) (not shown). To be controlled. When the actual fuel pressure in the delivery pipe falls below a preset delivery pressure due to fuel injection from the injector, the lift amount of the plunger 12 increases based on the detection information of the fuel pressure sensor for detecting the actual fuel pressure by the ECU. During this period (a predetermined crank angle period during which fuel can be pressurized), the electromagnetic coil 45 of the electromagnetic operation unit 40 is energized, the intake valve 14 is closed, and the pressure from the fuel pressurizing chamber 13 into the delivery pipe is increased. Fuel is pumped.

  During the period when the intake valve 14 is open, the lift amount of the plunger 12 increases with the rotation of the drive cam, and the fuel in the fuel pressurizing chamber 13 decreases when the volume of the fuel pressurizing chamber 13 decreases. Leaks to the suction passage 11a, so that the fuel in the fuel pressurizing chamber 13 is not pressurized to a high fuel pressure level (non-pressurized state).

  As described above, the high-pressure fuel pump 10 of the present embodiment includes the fuel pressurizing mechanism 17 in the pump body 11 in which the suction passage 11a and the discharge passage 11b, which are fuel passages, and the fuel pressurization chamber 13 connected thereto are formed. The pump body 20 to which is mounted, the suction valve 14, the discharge valve 15 and the relief valve 16 which are movable parts are housed, and the suction side housing member 21 and the discharge side housing member 22 (assembly parts) assembled to the pump body 20 And a fuel pump structure.

  Here, as shown in FIG. 2, the discharge-side housing member 22 stores and holds the discharge valve 15 and the relief valve 16 by a plurality of cylindrical parts 51, 52, 53 that are at least partially overlapped with each other in the radial direction. A valve holding mechanism is configured.

  The inner cylindrical part 51 located in the main cylindrical member 31 includes an inner peripheral wall 51a that forms the upstream end portion of the discharge passage 11b, and a proximal inner peripheral wall 52a of the intermediate cylindrical part 52 that is adjacent in the radial direction. An outer peripheral wall 51b that is press-fitted into the inner peripheral wall, a spring receiving portion 51c that supports one end of the valve spring 16c of the relief valve 16 on the upstream end side of the inner peripheral wall 51a, and a plurality of radial communication composing a part of the discharge passage 11b. And has a hole 51d.

  An intermediate cylindrical part 52 located between the inner and outer cylindrical parts 51 and 53 in the radial direction is composed of two bottomed segments 54 and 55 that are press-fitted and joined.

  As shown in FIGS. 2 and 3, the proximal segment 54 includes a proximal recess 54 a having a proximal inner wall 52 a and relief valves 16 formed in the inner depth of the proximal recess 54 a. The relief valve seat 16b communicates with the relief valve seat 16b around the relief valve seat 16b in the proximal recess 54a and extends in the axial direction of the segment 54 so as to open inward of the annular discharge valve seat 15b of the discharge valve 15. A discharge-side inner passage 54b. The proximal segment 54 has an intermediate outer peripheral surface 54c that opposes the proximal inner peripheral wall 53a of the outer cylindrical part 53 with a predetermined annular gap therebetween, and an intermediate outer peripheral surface that opens into the relief valve seat 16b. 54f is press-fitted and fitted within a partial axial range (coupling region Z2 in FIG. 3) with respect to the relief-side inner passage 54d that opens on 54c and the base-end-side inner peripheral wall 53a of the outer cylindrical part 53, A proximal end outer peripheral wall 54e that is fitted in a gap within the range of the remaining portion in the axial direction.

  The distal end side segment 55 is opposed to the inner peripheral wall 55a that forms the intermediate portion of the discharge passage 11b that houses the discharge valve body 15a and the discharge valve spring 15c of the discharge valve 15, and the intermediate inner peripheral surface 53b of the outer cylindrical part 53. An intermediate outer peripheral surface 55b opposed to each other with a predetermined annular gap therebetween, and an annular inner projecting spring receiving portion 55c that supports one end of the discharge valve spring 15c of the discharge valve 15 on the downstream end side of the inner peripheral wall 55a. Yes. Further, an annular gap 56 a between the intermediate outer peripheral surface 54 c of the base end side segment 54 and the base end side inner peripheral wall 53 a of the outer cylindrical part 53 is provided in the distal end side segment 55, and the discharge valve body of the discharge valve 15. A plurality of notches 55e are formed to communicate with the discharge passage 11b downstream of 15a. The discharge passage 11b on the downstream side of the discharge valve body 15a of the discharge valve 15 here is an intermediate portion of the discharge passage 11b formed by the inner peripheral wall 55a, an intermediate outer peripheral surface 55b of the distal end side segment 55, and an outer cylindrical part. 53, and an annular gap 56b between the intermediate inner peripheral surface 53b of 53. The notches 55e have a plurality of elongated holes that penetrate the distal end side segment 55 inward and outward in the vicinity of the proximal end enlarged diameter portion 55f.

  The outer cylindrical part 53 has a stepped shape in which the base end side inner peripheral wall 53a and the intermediate inner peripheral surface 53b have different inner diameters, and is screwed to the main cylindrical member 31 at the base end side outer peripheral part. It has a possible proximal end side threaded portion 53c. Further, on the outer peripheral portion of the outer cylindrical part 53, for example, a hexagonal enlarged portion 53hx for rotating operation at the time of screw connection is integrally provided. Note that the outer cylindrical part 53 may also have a connecting thread portion for pipe connection to the delivery pipe on the outer peripheral portion on the distal end side (right end side in FIG. 2).

  On the other hand, as shown in FIGS. 2 and 3, the plurality of cylindrical parts 51 to 53 include a plurality of coupling portions 61 and 62 for coupling to each other and an outer coupling portion for coupling to the pump body 20. 63. In addition, in this embodiment, although the number of the some connection parts 61-63 is three, of course, three or more may be sufficient.

  Among the plurality of cylindrical parts 51 to 53, a specific cylindrical part, for example, an intermediate cylindrical part 52 positioned between the inner and outer cylindrical parts 51 and 53 in the radial direction, is a part of the plurality of coupling parts 61 to 63. It has an inner coupling portion 61 and an intermediate coupling portion 62 that serve as first and second coupling portions. The inner and intermediate coupling portions 61 and 62 are different from each other in the coupling position in the axial direction of the specific cylindrical part 52 and are located on both sides of the inner and outer peripheral walls on the left end side in FIG. ing. These specific cylindrical parts 52 have two coupling regions Z1 and Z2 in which inner and intermediate coupling parts 61 and 62 are formed at different positions in the axial direction.

  A coupling region Z1 (first coupling region) in which at least one of the two coupling regions Z1 and Z2, for example, the inner coupling portion 61 (one of the inner and middle coupling portions 61 and 62) is formed is The range of the remaining portion in the axial direction of the base end side outer peripheral wall 54e of the base end side segment 54 on the side opposite to the inner peripheral wall (one of the inner and outer peripheral walls) side where the inner coupling portion 61 is formed (FIG. 3). In the inner coupling region Z1), the gap is fitted to the outer cylindrical part 53 which is another adjacent cylindrical part. Hereinafter, a portion in which the base end side outer peripheral wall 54e of the base end side segment 54 is gap-fitted with the base end side inner peripheral wall 53a of the outer cylindrical part 53 is referred to as a gap fitting portion Fc.

  In addition, the plurality of coupling portions 61 to 63 include the inner coupling portion 61 and the intermediate coupling portion 62 adjacent to each other in the radial direction of the specific cylindrical component 52, and the specific cylindrical component 52 with respect to the intermediate coupling portion 62. And an outer coupling portion 63 (third coupling portion) disposed on the outer side opposite to the inner coupling portion 61 in the radial direction.

  Among a plurality of coupling portions 61 to 63, any pair of coupling portions adjacent in the radial direction, for example, the inner coupling portion 61 and the middle coupling portion 62, are coupled in the axial direction of the specific cylindrical component 52. Arranged so that more than half (preferably 2/3) of the length region of each coupling portion 61, 62 does not overlap with the coupling portions 62, 63 adjacent in the radial direction. Yes. Further, the outer coupling portion 63 is disposed near the inner coupling portion 61 with respect to the intermediate coupling portion 62 in the axial direction of the specific cylindrical part 52. For example, the coupling region Z3 (see FIG. 3) of the outer tubular part 53 to the pump body 20 by the outer coupling part 63 is separated from the coupling region Z2 outside the specific tubular part 52 in the axial direction. It arrange | positions so that it may overlap with the joint area | region Z1 inside the specific cylindrical component 52 partially.

  That is, an arbitrary pair of connecting portions adjacent in the radial direction among the plurality of connecting portions 61 to 63, for example, the intermediate connecting portion 62 and the outer connecting portion 63 are different from each other in their axial positions. More than half of the length regions of the portions 62 and 63 do not overlap with the coupling portions 62 and 61 adjacent in the radial direction. Therefore, the some coupling | bond parts 61-63 which overlap in a radial direction are the arrangement | positioning forms which back and forth alternately in an axial direction.

  Here, at least one of a pair of arbitrary coupling portions having different axial positions and adjacent in the radial direction, for example, both the inner coupling portion 61 and the middle coupling portion 62 are press-fitting fitting portions.

  In addition, an arbitrary pair of coupling portions having different coupling positions in the axial direction and adjacent to each other in the radial direction, for example, an intermediate coupling portion 62 and an outer coupling portion 63 having different axial positions, one outer coupling portion 63 is a screw. It is a connecting part. Each of the pair of coupling portions 61, 62 or 62, 63 corresponds to the first and second coupling portions according to the present invention, and the remaining coupling portions 63 or 61 among the plurality of coupling portions 61-63. Corresponds to the third coupling portion referred to in the present invention. Most of the proximal-side threaded portion 53c of the outer cylindrical part 53 constitutes the outer coupling part 63, but the outer cylindrical part 53 has an axis that overlaps with the formation region Z2 of the intermediate coupling part 62. You may have another screw part out of the direction range.

  As described above, the discharge side housing member 22 assembled to the pump body 20 houses the discharge valve body 15a of the discharge valve 15 and the relief valve body 16a of the relief valve 16 which are movable parts. And the discharge valve seat 15b in which the discharge valve body 15a can be seated is formed in the intermediate | middle specific cylindrical part 52 among several cylindrical parts 51-53, and the relief valve in which the relief valve body 16a can be seated is formed. A seat 16b is formed.

  In addition, a relief valve spring 16c that urges the relief valve body 16a to the relief valve seat 16b is held by an inner cylindrical part 51 that is press-fitted to the proximal end side of the specific cylindrical part 52, and a discharge valve. A discharge valve spring 15 c that urges the body 15 a toward the discharge valve seat 15 b is held by a distal end side segment 55 of a specific cylindrical part 52. Therefore, the intermediate cylindrical part 52 can be press-fitted into the outer cylindrical part 53 in a state in which the discharge valve 15 is assembled to the intermediate cylindrical part 52 in advance, and both the discharge valve 15 and the relief valve 16 are intermediate. It is also possible to press-fit the intermediate cylindrical part 52 into the outer cylindrical part 53 in a state in which the cylindrical part 52 is assembled in advance.

  A dotted line L1 in FIG. 2 indicates the flow path of the pressurized fuel along the discharge passage 11b in the discharge-side housing member 22. In this case, the fuel that has entered the proximal-side concave portion 54a of the proximal-side segment 54 through the inside of the inner cylindrical component 51 from the radial communication hole 51d of the inner cylindrical component 51 is the proximal-side concave portion. 54 a enters the inside of the annular discharge valve seat 15 b of the discharge valve 15 through the discharge side inner passage 54 b on the inner side of the inner side 54 a, and when the discharge valve 15 is opened, the notch 55 e and the annular gap of the distal end side segment 55 It is discharged to the delivery pipe side through 56b. 2 indicates a fuel pressure release path when the delivery pipe side is abnormally raised and the relief valve 16 is opened. The release path includes a bypass path 22w. Yes. Here, the bypass passage 22w includes an annular gap 56b around the distal end side segment 55, an annular gap 56a around the distal end side segment 55, and a relief side communicating from the gap 56a to the inside of the relief valve seat 16b. The inner passage 54d functions as a bypass passage when the relief valve 16 opens when the discharge valve 15 is closed.

  Next, the operation will be described.

  In the fuel pump structure of the present embodiment configured as described above, the intermediate cylindrical part 52 has other inner and outer coupling portions 61 and 62 that are different in axial direction on both sides of the inner and outer peripheral walls. It couple | bonds with the cylindrical components 51 and 53. FIG.

  In this state, the first coupling portion 61 is formed on the inner peripheral wall side of at least one coupling region, for example, one coupling region Z1 of the two coupling regions Z1, Z2 of the intermediate cylindrical part 52, On the opposite outer peripheral wall side, a gap is fitted to the adjacent outer cylindrical part 53.

  Therefore, in addition to no adverse effect due to the radial overlap of the inner and intermediate coupling portions 61, 62, the coupling distortion due to the press-fitting in the inner coupling portion 61 is caused by the proximal segment of the intermediate cylindrical part 52. It is relieved by a gap fitting portion Fc between the base end side outer peripheral wall 54e of 54 and the base end side inner peripheral wall 53a of the outer cylindrical part 53. Further, the coupling distortion in the outer coupling portion 63 that overlaps in the radial direction within the same coupling region Z1 in the axial direction with the inner coupling portion 61 is also reduced by the gap fitting portion Fc in the coupling region Z1. Thereby, it is possible to reliably avoid the adverse effects of the multiple coupling portions 61 to 63 using the gap fitting portion Fc as a buffer region, and the coupling portions 61 to 63 in the discharge-side housing member 22 including the plurality of cylindrical parts 51 to 53. Therefore, the dimensional change in the radial direction can be suppressed. In addition, since the thickness of the cylindrical parts 51 to 53 on the proximal end side can be reduced, it is effective for minimizing the size of the discharge-side housing member 22 in the case of a multiple coupling structure.

  As a result, even if a plurality of coupling portions 61 to 63 are close to the fixed portion of the discharge-side housing member 22, dimensional changes due to mutual interference can be suppressed, and the sealing performance of the discharge valve 15 and the relief valve 16 is reduced. Or the fall of the sliding performance of the valve bodies 15a and 16a and other sliding parts can be prevented. Therefore, the fuel pressure structure and the performance requirement of the high-pressure fuel pump 10 can be made compatible with each other without deteriorating the fuel pressurization performance and durability of the high-pressure fuel pump 10.

  Moreover, in this embodiment, arbitrary pair of coupling parts 61, 62 or 62, 63 adjacent in the radial direction among three or more coupling parts have their axial positions different from each other. Therefore, the axial positions of the pair of coupling portions 61, 62 or 62, 63 adjacent in the radial direction are not the same, and the distortions in the coupling portions 61 to 63 are prevented from interfering with each other. .

  Further, in the present embodiment, the plurality of coupling portions 61 to 63 include an inner coupling portion 61 and an intermediate coupling portion 62 that are adjacent in the radial direction, and an inner coupling portion 61 in the radial direction with respect to the intermediate coupling portion 62. Includes an outer coupling portion 63 disposed on the opposite side, and the outer coupling portion 63 is disposed closer to the inner coupling portion 61 than the intermediate coupling portion 62 in the axial direction. Accordingly, the three or more coupling parts 61 to 63 are arranged so that the positions in the axial direction are alternately different, and even if the number of the coupling parts 61 to 63 overlapping in the radial direction increases, the discharge side housing Assembly parts, such as the member 22, etc. can be comprised compactly.

  In particular, in the present embodiment, since the outer coupling portion 63 is disposed in the coupling region Z1 in which the inner coupling portion 61 is formed in the axial direction, the three or more coupling portions 61 to 63 are alternately arranged on the shaft. It will be arrange | positioned at two positions of a direction, and the discharge side housing member 22 can be comprised more compactly.

  In addition, since both the inner and intermediate coupling portions 61 and 62 are press-fitting fitting portions and the outer coupling portion 63 is a screw coupling portion, at least the inner circumferential press-fitting fitting of the intermediate cylindrical part 52 is performed. Can be relieved on the outer peripheral side of the intermediate cylindrical part 52, and the diameter of the press-fitting fitting portion with the inner cylindrical part 51 (or the outer cylindrical part 53) of the specific cylindrical part 52. It is possible to prevent the size from changing due to the influence of the coupling distortion with the other cylindrical part 53 on the outside (or the other cylindrical part 51 on the inside).

  This can also be said for the outer cylindrical part 53. That is, the intermediate and outer coupling portions 62 and 63 are press-fit fitting portions and screw coupling portions, and the outer coupling portion 63 is within the coupling region Z2 of the intermediate cylindrical part 52 corresponding to the intermediate coupling portion 62. Therefore, the outer cylindrical part 53 has a low coupling strength on the outer peripheral side, and therefore the outer cylindrical part 53 has a distortion caused by press fitting on the inner peripheral side and screw connection on the outer peripheral side. Can be relaxed on the inner peripheral side of the outer cylindrical part 53, and the diameter dimension of the screw coupling portion 63 with the pump body 20 of the outer cylindrical part 53 is press-fitted with the other cylindrical part 52 on the inner side. It is possible to prevent the change due to the coupling distortion caused by the fitting.

  Further, in the present embodiment, the discharge valve seat 15b in which the discharge valve body 15a can be seated and the relief valve seat in which the relief valve body 16a can be seated on a specific cylindrical part 52 among the plurality of cylindrical parts 51 to 53. 16b are formed, so that the discharge-side housing member 22 that houses the discharge valve 15 and the relief valve 16 can be made compact.

  Further, in the present embodiment, the valve seat surface 15s of the discharge valve seat 15b is orthogonal to the axial direction of the intermediate cylindrical part 52. The distortion due to the screw connection of the cylindrical part 53 hardly affects the valve seat surface 15s of the discharge valve 15, and the sealing performance of the discharge valve 15 in the non-discharge period can be sufficiently improved.

  As described above, in the present embodiment, the coupling distortion in the inner and outer coupling portions 61 and 63 that overlap in the radial direction within the same coupling region Z1 in the axial direction can be relaxed by the gap fitting portion Fc. The dimensional change of the discharge side housing member 22 having the multiple coupling portions of the plurality of cylindrical parts 51 to 53 is suppressed, and the plurality of coupling portions 61 to 63 are close to the fixed portion of the discharge side housing member 22. However, it is possible to prevent the deterioration of the performance of the seal and sliding parts by suppressing the dimensional change of the assembly parts due to the mutual interference, and provide the fuel pump structure that can satisfy both the demands for miniaturization and performance can do.

  Such an effect of the present invention is effective when the number of coupling portions overlapping in the radial direction in the same coupling region in the axial direction is increased, and a compact pump structure can be obtained.

  In the above-described embodiment, the plurality of cylindrical parts 51 to 53 have the annular coupling portions 61 to 63. However, the radial coupling portions are doubled or quadruple or more. Even in this case, the present invention can be applied.

  In addition, the coupling portion is a press-fitting fitting portion and a screw coupling portion in the above-described embodiment. However, the coupling portion may be a coupling portion that can cause distortion due to coupling, such as a coupling portion by welding or a tightening coupling portion by a band or the like. , It may have a coupling portion by a different coupling method. Therefore, the gap fitting portion does not need to have a uniform gap like the gap fitting, and other than the outer coupling portion 63 as long as it is an effective form for relaxing the strain due to the coupling of adjacent coupling portions. It may be a gap formed in a screw groove or the like in a screw coupling portion such as the screw portion 53c. In the case of serration fitting, etc., the gap fitting portion has a sufficiently small fitting margin (for example, about one-fifth or less) compared to the first and second coupling portions that are firmly joined by press-fitting serration fitting. It only has to be. In other words, when the coupling portion has such a coupling portion that the dimensional change (deformation amount) for coupling increases as the coupling strength increases, the coupling strength of the first and second coupling portions is relatively sufficiently large, and the gap The fitting portion has a relatively sufficiently low bond strength. The coupling strength here is, for example, the removal force, but is, for example, the escape torque in the case of screw coupling.

  Further, the distal end side segment 55 of the intermediate cylindrical part 52 may be configured as an integral part integrated with the outer cylindrical part 53, and a part of the bypass passage 22w replacing the gap 56b may be formed in the integral part. .

  As described above, in the fuel pump structure according to the present invention, strain at a plurality of coupling portions adjacent to each other in the radial direction of a plurality of cylindrical parts is relieved at a gap fitting portion where they overlap in the radial direction in the same axial region. To be. Therefore, the dimensional change in the radial direction of the housing member made up of a plurality of cylindrical parts is suppressed, and the dimensional change of the assembled parts due to their mutual interference even if a plurality of coupling parts come close to the fixed part of the assembled parts. Therefore, it is possible to provide a fuel pump structure that can be reduced and can satisfy both a demand for miniaturization and a demand for performance. The present invention as described above is useful for all fuel pump structures in which a fuel passage is formed using a plurality of cylindrical parts coupled to each other and a valve holding mechanism is configured.

10 High-pressure fuel pump (fuel pump)
DESCRIPTION OF SYMBOLS 11 Pump body 11a Suction passage 11b Discharge passage 11g Suction gallery chamber 12 Plunger 13 Fuel pressurization chamber 14 Suction valve 15 Discharge valve 15b Discharge valve seat 15s Valve seat surface 16 Relief valve 16b Relief valve seat 17 Fuel pressurization mechanism 20 Pump main body 21 Suction side housing member 22 Discharge side housing member 31 Main cylindrical member 32 Cylinder member 33 Mounting member 40 Electromagnetic operation unit 51 Cylindrical parts (first cylindrical part, third cylindrical part)
51a Inner peripheral wall 51b Outer peripheral wall 52 Cylindrical component (specific cylindrical component, second cylindrical component)
52a, 53a Proximal inner wall 52b Outer wall 53 Cylindrical parts (third cylindrical part, first cylindrical part, other cylindrical parts)
53b Middle inner peripheral surface 61 Inner coupling portion (first coupling portion)
62 Middle coupling part (second coupling part)
63 Outer coupling part (third coupling part)
Z1, Z2 bonding region (first and second bonding regions)

Claims (6)

A pump main body having a fuel passage and a fuel pressurizing chamber connected to the fuel passage and having a fuel pressurizing mechanism for pressurizing fuel in the fuel pressurizing chamber; A fuel pump structure comprising a housing member assembled to
The housing member is composed of a plurality of cylindrical parts that are at least partially overlapped with each other in the radial direction,
The plurality of cylindrical parts have a plurality of coupling portions for mutual coupling and coupling to the pump body,
Among the plurality of cylindrical parts, the specific cylindrical part is different in the coupling position in the axial direction of the specific cylindrical part among the plurality of coupling parts, and is on both sides of the inner and outer peripheral walls of the specific cylindrical part. Having first and second coupling portions located;
At least one of the first and second coupling regions in the axial direction of the specific cylindrical part in which the first and second coupling parts are formed is any of the first and second coupling parts. On the side opposite to one side of the inner and outer peripheral walls where one of the two is formed, a gap is fitted to another adjacent cylindrical part ,
The plurality of coupling portions are disposed on a side opposite to the first coupling portion with respect to the second coupling portion in the radial direction, while the first coupling portion is disposed in the axial direction from the second coupling portion. Including a third coupling portion disposed near the coupling portion;
The specific tubular component and the other tubular component are placed over the entire overlapping region in the first coupling region where the third coupling portion overlaps the first coupling portion in the radial direction. A fuel pump structure characterized in that a gap is formed in the radial direction . 2. The fuel pump structure according to claim 1, wherein at least one of the first coupling portion and the second coupling portion is a press-fitting fitting portion. The fuel pump structure according to claim 1, wherein the third coupling portion is a screw coupling portion. The movable part includes a discharge valve body that allows the fuel to be discharged from the fuel pressurizing chamber while preventing a reverse flow of the fuel to the fuel pressurizing chamber, and among the plurality of cylindrical parts The fuel pump structure according to any one of claims 1 to 3, wherein a discharge valve seat on which the discharge valve body can be seated is formed on the specific cylindrical part. . The movable part includes a relief valve body that is displaced in accordance with the pressure of fuel downstream from the discharge valve body in the fuel discharge direction from the fuel pressurizing chamber, and the specific part among the plurality of cylindrical parts The fuel pump structure according to claim 4, wherein a relief valve seat on which the relief valve body can be seated is formed on the cylindrical part. The fuel pump structure according to claim 4 or 5, wherein a valve seat surface of the discharge valve seat is orthogonal to the axial direction.

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