JP4597576B2 - Pulsating diaphragm fuel pump - Google Patents

Description

  The present invention relates to a pulsating diaphragm fuel pump which is driven by a pulsating pressure generated in a crankcase or an intake pipe as the engine is operated to supply fuel to be supplied to the engine.

  As a means for transporting fuel supplied to a two-cycle or four-cycle small gasoline engine, a pulsating diaphragm fuel pump having an advantage of being simple in structure and capable of being driven without mechanical loss is widely used.

  FIG. 1A is a longitudinal sectional view showing an example of a pulsating diaphragm fuel pump that has been conventionally known and to which the present invention is applied. A pump diaphragm 2 and a diaphragm cover are provided on one surface of the pump body 1. The space on the pump body 1 side and the space on the diaphragm cover body 3 side form a pump chamber 4 and a pulse pressure chamber 5, respectively. The pulse pressure chamber 5 is provided in the crankcase or intake pipe of the engine. The connected pulse pressure inlet 6 is opened. A pulsator diaphragm 7 and a cap body 8 are overlaid on the other surface of the pump body 1, and two recesses provided in the pump body 1 and covered with the pulsator diaphragm 7 define a suction chamber 9 and a discharge chamber 10. Two recesses formed respectively on the cap body 8 so as to face the suction chamber 9 and the discharge chamber 10 form air chambers 11 and 12. In addition, a suction valve 14 and a discharge valve 15 are provided in a partition wall 13 formed in the pump body 1 and dividing the pump chamber 4 from the suction chamber 9 and the discharge chamber 10.

  A pulsation pressure generated in the crankcase or the intake pipe, generally in the crankcase as the engine is operated, is introduced into the pulsation pressure chamber 5 to reciprocate the pump diaphragm 2, and fuel in a fuel tank (not shown) is supplied to the fuel inlet 16. From the suction chamber 9, the suction valve 14, the pump chamber 4, the discharge valve 15, and the discharge chamber 10, the fuel is sent to the fuel outlet 17 and supplied to the engine by a vaporizer (not shown).

  In the fuel pump, the pump body 1, the diaphragm cover body 3, and the cap body 8 which are structural parts thereof are made of a thermoplastic resin to avoid a concern that a paper lock is caused by the influence of engine heat, and the assembly is subjected to creep. Many are performed by welding such as ultrasonic welding without worrying to generate.

  Further, as shown in FIGS. 1A and 1B, the pump diaphragm 2 has a peripheral bead 2A, and the pulsator diaphragm 7 has a peripheral bead 7A and a central bead 7B. These beads 2A and 7A 7B is fitted into the pump body 1 or a groove provided in the diaphragm cover body 3 and the cap body 8 in addition to this, the mating surface of the pump body 1 and the diaphragm cover body 3, and the mating surface of the pump body 1 and the cap body 8 Are joined and assembled by overlapping and welding the beads 2A, 7A and 7B in a compressed state.

  A fuel pump similar to that shown in FIG. 1 is described in Japanese Patent Application Laid-Open No. 9-217662, and a technique for welding the mating surfaces of the two members by compressing the peripheral beat of the diaphragm in the groove is actually disclosed in Japanese Utility Model Laid-Open No. 57-57. No. 53175, Japanese Utility Model Laid-Open No. 57-61285, Japanese Utility Model Laid-Open No. 57-61286, and so on.

Here, the pulsator diaphragm 7 and the air chambers 11 and 12 absorb the pressure pulsations in the suction chamber 9 and the discharge chamber 10, and the fuel flows from the suction chamber 9 to the pump chamber 4 and from the pump chamber 4 to the discharge chamber 10. Works to smooth out. However, as described above, when the peripheral bead 7A and the central bead 7B are respectively compressed in the grooves, the pulsator diaphragm 7 is pushed inwardly toward the inner side of the peripheral bead 7A and pressed toward both sides of the central bead 7B. The suction chamber 9 and the discharge chamber 10 are partitioned from the air chambers 11 and 12 in a state of being loosened by the expanded amount. For this reason, the pulsator diaphragm 7 may be displaced more than necessary, and the volume change of the suction chamber 9 and the discharge chamber 10 may be increased to reduce the fuel flow rate, and there may be a case where fuel at the required engine flow rate cannot be supplied.
Japanese Patent Laid-Open No. 9-217662 Japanese Utility Model Publication No. 57-53175 Japanese Utility Model Publication No. 57-61285 Japanese Utility Model Publication No. 57-61286

  The present invention has a structure in which a pump body made of a thermoplastic resin and a cap body are assembled by sandwiching and welding a pulsator diaphragm bead to a mating surface thereof in a compressed state, and a fuel flow rate is generated by loosening the pulsator diaphragm. The pulsator diaphragm is installed without loosening, so that the predetermined pump performance can be exhibited. And

  In the present invention, the pump body and the cap body are made of a thermoplastic resin, and the pulsator diaphragm is sandwiched between the mating surfaces and the beads are compressed and welded to each other at the overlapping portion of the outer peripheral edge portion. The above-mentioned problems of the pulsating diaphragm fuel pump combined and assembled by the above are solved as follows.

  That is, the groove and the press-bending edge and the presser edge are provided facing each other on the mating surface of the pump body and the cap body, and the bead is fitted into the groove to be compressed by the presser edge, and the pulsator diaphragm is thickened by the press-bend edge. The first means for solving the problem is to be in a state of tension that is bent in the vertical direction.

  In addition, the pulsator diaphragm has a bead only at the periphery without having a bead in the center, and a groove, a push-bend edge and a press edge are provided facing each other on the mating surface of the pump body and the cap body. The center part is overlapped with the presser edge across the groove and the bead is fitted into the groove to be compressed by the presser edge, and the pulsator diaphragm is bent in the thickness direction by the push-bending edge to be in a tension state. As a second means for.

  The loosening of the pulsator diaphragm caused by compressing and expanding the bead is eliminated by bending at the bending edge, and the pulsator diaphragm is installed in a tensioned state with appropriate tension in the suction chamber and the discharge chamber. . The first means can correspond to a conventional pulsator diaphragm having a bead at the center, and the pulsator diaphragm having a bead only at the periphery of the second means has no directionality and is easy to assemble, and the pump diaphragm There is an advantage that it can be shared.

  According to the present invention, the pulsator diaphragm can be installed in a moderate tension state, so that the fuel flow rate can be increased and the fuel required for the engine flow rate can be reliably supplied without unnecessarily changing the volume of the suction chamber and the discharge chamber. Is something that can be done.

  Embodiments of the present invention will be described below with reference to the drawings. 2, 3 and 4 show different embodiments, (A) before assembly and (B) after assembly. Moreover, in each embodiment, the pulsator diaphragm 7 has a bead 7A only at the periphery without having a bead in the center.

  In each of the embodiments of FIGS. 2, 3 and 4, wall portions forming the peripheral side walls 18 of the suction chamber 9, the discharge chamber 10, and the air chambers 11 and 12 are formed at the peripheral portions of the pump body 1 and the cap body 8. 18A and 18B face each other and protrude. A groove 19 for receiving the bead 7A is provided on the end face of the wall portion 18A on the pump main body 1 side, the inner side wall forms a push-bending edge 20, and the outer side wall 21 protrudes larger than that. A pressing edge 22 projects from the end face of the wall portion 18B on the cap body 8 side so as to face the groove 19, and a notch 23 is provided along the outer peripheral edge of the wall portion 18B.

  When the bead 7A is fitted in the groove 19 and the cap body 8 is pressed against the pump body 1, the bead 7A is compressed by the presser edge 22 and is expanded both inward and outward, and the portion adjacent to the bead 7A of the pulsator diaphragm 7 Is bent by the push-bending edge 20. On the other hand, the notch step 23 is fitted to the outer wall 21 so that the side surface and the end surface are brought into close contact with each other, and the pump body 1 and the cap body 8 are joined and assembled by welding the contact portions. Become.

  Next, wall portions 25 </ b> A and 25 </ b> B that form a partition wall 25 that partitions the suction chamber 9 and the discharge chamber 10 and the two air chambers 11 and 12 face each other and protrude from the pump body 1 and the cap body 8. The end face of the wall portion 25A on the pump body 1 side is provided with a groove 26 and a push-bending edge 27 as a side wall thereof, and the end face of the wall portion 25B on the cap body 8 side is opposed to the groove 26 with a press edge 28. Protrusions are formed.

  In the embodiment shown in FIG. 2, both side walls of one groove 26 are pressed and bent edges 27, and when the cap body 8 is repeatedly pressed against the pump body 1, both sides of the pulsator diaphragm 7 overlapping the presser edge 28 are adjacent to each other. The part is bent by the push-bending edge 27. As a result, the pulsator diaphragm 7 is installed in a tensioned state in the suction chamber 9 and the discharge chamber 10. In this embodiment, a pulsator diaphragm having a bead at the center can be used.

  In the embodiment shown in FIG. 3, two grooves 26 are provided in parallel to each other, and the outer wall and the partition wall are formed as a bending edge 27, and two pressing edges 28 are provided facing each of the grooves 26. It is a thing. When the cap body 8 is pressed against the pump body 1, the pulsator diaphragm 7 overlapping the two presser edges 28 is bent between the presser edges 28 and on both outer sides by the press bending edge 27. As a result, the pulsator diaphragm 7 is installed in a tension state having a higher tension than that of the configuration shown in FIG.

  In the embodiment shown in FIG. 4, the side wall on the suction chamber 9 side of the groove 26 is removed and the side wall on the discharge chamber 10 side is formed as a bending edge 27, and the cap body 8 is pressed against the pump body 1 repeatedly. A portion adjacent to one side of the pulsator diaphragm 7 that overlaps the presser edge 28 is bent by the press bending edge 27. In this embodiment, the tension is lower than that of the embodiment shown in FIG. 2, but a tension state capable of achieving the object of the present invention can be obtained.

  In each of the above embodiments, the tension of the pulsator diaphragm 7 can be arbitrarily set by appropriately selecting the depth of the groove 26 and the height relationship between the push-bending edge 27 and the presser edge 28. Accordingly, it is possible to provide a product having an appropriate pumping capacity. In addition, the use of a pulsator diaphragm 7 having a bead 7A only at the periphery makes it easy to assemble because it can be installed without considering directionality, and can be shared with the pump diaphragm, so that parts can be managed. This is advantageous in terms of

  The pushing and bending edge 27 that bends the central portion of the pulsator diaphragm 7 presses the pulsator diaphragm 7 against the end face of the wall portion 25B of the partition wall 25, so that the liquid tightness between the suction chamber 9 and the discharge chamber 10, and two airs The airtightness of the chambers 11 and 12 is maintained.

The longitudinal cross-sectional view which shows an example of the fuel pump with which this invention is applied. BRIEF DESCRIPTION OF THE DRAWINGS The longitudinal cross-section fragmentary figure which shows 1st embodiment of this invention. The fragmentary longitudinal cross-section which shows 2nd embodiment of this invention. The fragmentary longitudinal cross-section which shows 3rd embodiment of this invention.

Explanation of symbols

1 pump body, 7 pulsator diaphragm, 7A bead, 8 cap body, 9 suction chamber, 10 discharge chamber, 11, 12 air chamber, 18 peripheral side wall, 18A, 18B, 25A, 25B wall portion, 19, 26 groove, 20, 27 Bending edge, 22, 28 Pressing edge, 25 Dividing wall

Claims (3)

The pump body and the cap body are made of thermoplastic resin, and these are joined and assembled by sandwiching the pulsator diaphragm between the mating surfaces and welding the beads together at the overlapping part of the outer peripheral edge. ing
The pulsator diaphragm has no bead in the center and has a bead only at the periphery, and a groove, a push-bend edge and a press edge are provided facing each other on the mating surface of the pump body and the cap body. In the pulsating diaphragm fuel pump, the pulsating diaphragm fuel pump is characterized in that a groove and a press-bending edge and a pressing edge on both sides of the pulsator diaphragm face each other so as to sandwich the central portion of the pulsator diaphragm .   2. The pulsating diaphragm fuel pump according to claim 1, wherein two grooves, two outer sides thereof, and a press-bending edge and two presser edges in between are provided facing each other on a mating surface sandwiching the central portion of the pulsator diaphragm. 2. The pulsating diaphragm according to claim 1, wherein a groove having one side wall removed from a mating surface sandwiching the central portion of the pulsator diaphragm, and a pressing bending edge on one side thereof and a pressing edge are provided facing each other. Fuel pump.

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