JP4324906B2 - Pulsating diaphragm fuel pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pulsating diaphragm fuel pump that transports fuel to be supplied to an engine driven by pulsating pressure generated in a crankcase or an intake pipe as the engine is operated.
[0002]
[Prior art]
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.
[0003]
FIG. 1 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 body 3 are formed on one surface of a 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 has a pulse pressure inlet 6 connected to the crankcase or intake pipe of the engine.
[0004]
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. Each is formed, and the inside of the cap body 8 forms an air chamber 11. In addition, a suction valve 13 and a discharge valve 14 are provided in a partition wall 12 that partitions the pump chamber 4, the suction chamber 9, and the discharge chamber 10 formed in the pump body 1.
[0005]
The pulsation pressure generated in the crankcase and the intake pipe as the engine is operated, generally, the pulsation pressure in the crankcase is introduced into the pulsation pressure chamber 5 to reciprocate the pump diaphragm 2, and the fuel in a fuel tank (not shown) is supplied. The fuel is supplied from the fuel inlet 15 to the fuel outlet 16 through the suction chamber 9, the suction valve 13, the pump chamber 4, the discharge valve 14, and the discharge chamber 10, and is supplied to the engine by a carburetor (not shown).
[0006]
The pump body 1, the diaphragm cover body 3 and the cap body 8 which are the structural parts of the pump are generally made of metal. However, since they are liable to cause a vapor lock due to the influence of engine heat, they have excellent formability to avoid the concern. It is known that the assembly using the thermoplastic resin and the assembly using the screw are welded and assembled to each other by, for example, ultrasonic welding in order to eliminate the fear of generating creep.
[0007]
FIGS. 8 and 9 show that the peripheral portion of the diaphragm 52 is sandwiched between the first housing 51 as a pump body and the second housing 53 as a diaphragm cover body when a structural portion such as the fuel pump is made of a thermoplastic resin. FIG. 2 is a diagram for explaining a conventional method of welding by using a diaphragm 52 having gas / liquid tightness holding gaskets, ribs that act as stoppers for preventing displacement movement, and bead portions 52A and 52B, also called locking edges, on the outer periphery. Have.
[0008]
The diaphragm 52 shown in FIGS. 8A and 8B has a bead portion 52A protruding toward the first housing 51, and the first housing 51 has a groove 54 for receiving the bead portion 52A opened upward. ing. Then, the bead portion 52A is fitted in the groove 54, the lower surface 53a of the second housing 53 is pressed against the upper surface 52a of the peripheral portion of the diaphragm 52 to compress the bead portion 52A, and in this state, the rising inward surface 51a of the first housing 51 The outer surface 53b of the second housing 53 facing this is welded. As a result, the first housing 51 and the second housing 53 are assembled and joined together by the welding surface 55 perpendicular to the surface of the diaphragm 52. Such assembling is described in Japanese Utility Model Laid-Open Nos. 57-53175, 57-61285, and 57-61286.
[0009]
The diaphragm 52 shown in FIGS. 9A and 9B has a bead portion 52B protruding from both surfaces, and the first housing 51 and the second housing 53 have a groove 56 for receiving one-half of the bead portion 52B. , 57 facing each other. Then, the bead portion 52B is fitted into the grooves 56, 57, and the upper surface 51A of the first housing 51 and the lower surface 53A of the second housing 53 that open the grooves 56, 57 are overlapped on the outer side of the bead portion 52B. The bead portion 52B is compressed, and the upper portion 51A and the lower surface 53A are welded in this state. Thus, the first housing 51 and the second housing 53 are assembled and assembled with each other by the welding surface 58 parallel to the surface of the diaphragm 52. Such assembling is described in Japanese Patent Laid-Open No. 9-217662.
[0010]
[Problems to be solved by the invention]
According to the above assembly, the bead portions 52A and 52B are flattened outwardly and inwardly when compressed, and the inner regions of the bead portions 52A and 52B of the diaphragm 52 are only expanded inwardly. It becomes a small diameter, and it will be in the state which has looseness as exaggeratedly shown in FIG.8 (B) and FIG.9 (B). In a pulsating diaphragm fuel pump, the pump diaphragm is required to react sharply and faithfully to the pulsating pressure to reciprocate and give a predetermined fuel discharge amount. Can be satisfied.
[0011]
However, in a pump of a type in which a diaphragm spring does not act on the pump diaphragm, there is a concern that the discharge amount may be reduced due to the above-described loosening and fuel at the required flow rate of the engine may not be supplied.
[0012]
The present invention has a structure in which a pump body of a thermoplastic resin and a diaphragm cover body are assembled by sandwiching and welding the bead portion of the pump diaphragm to their mating surfaces in a compressed state. The purpose of the present invention is to solve the above-mentioned problem of reducing the amount of the pump, and the pump diaphragm can be installed without loosening, so that the predetermined pump performance can be exhibited. And
[0013]
[Means for Solving the Problems]
The pump body and diaphragm cover body are made of thermoplastic resin, and these are pulsating type that are assembled by sandwiching the bead part of the outer periphery of the pump diaphragm at the overlapped part and welding together For diaphragm fuel pumps, a push-bending edge is provided in the overlapping part of the pump body and the diaphragm cover body, and this pushing-bending edge bends the adjacent part inside the compressed bead portion in the thickness direction to keep the pump diaphragm in tension. It was the first means to solve the problem that it was stretched.
[0014]
Further, in the pulsating diaphragm fuel pump, the pressing surfaces which are provided facing each other at the overlapping portion of the pump main body and the diaphragm cover body and compress the sandwiched bead portion gradually increase toward the outside. The second means for solving the problem is to form the pump diaphragm in a tensioned state by compressing the pressing surface while pressing the bead portion outward.
[0015]
In the first means, the inner part of the bead part due to compression is pushed and bent at the bending edge, and in the second part, the inner part of the bead part due to compression is not caused to be inward. It is possible to achieve the purpose of installing in a state and giving a required discharge pressure and discharge amount, and thus exhibiting a predetermined pump performance for those that do not use a diaphragm spring.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIGS. 2, 3, and 4 show different actual states of the first means of the present invention described in claims 1, 2, 3, and 4, respectively. FIG. 5, FIG. 6 and FIG. 7 are diagrams showing different embodiments of the second means of the present invention as set forth in claims 5, 6, 7 and 8. The part shown by the code | symbol A of this is expanded.
[0017]
FIGS. 2A and 2B show a pump diaphragm 2 having a bead portion 2A protruding toward the pump body 1 and is opened to the upper surface 1A of the portion of the pump body 1 that is overlapped with the diaphragm cover body 3 to bead portion 2A. And a push-bending edge 22 protruding upward from the upper surface 1A along the inner peripheral edge of the groove 21 is provided in the pump body 1 by integral molding. The lower surface of the portion of the diaphragm cover 3 overlapped with the pump main body 1 cooperates with the bottom surface of the groove 21 so as to sandwich and compress the bead portion 2A, and the lower surface and the bottom surface are parallel to each other pressing surfaces 23A, 21A. Form. Further, a stepped notch 3B is provided on the inner peripheral side of the pressing surface 23A.
[0018]
The bead portion 2A is loosely fitted into the groove 21, and when the diaphragm cover body 3 is pressed against the pump body 1, the bead portion 2A is compressed and expanded outward and inward, and the pressing surface 23A is formed on the upper surface 1A. When closely contacted, the portion adjacent to the inside of the bead portion 2A of the diaphragm 2 is bent upward by a push-bending edge 22 as indicated by reference numeral 2C, and the diaphragm 2 passes through the inside of the notch 3B and passes through the pump chamber 4 of FIG. And the pulse pressure chamber 5 are separated. In this state, it is assumed that the upper surface 1A and the pressing surface 23A are welded in the outer region of the bead portion 2A, and the pump body 1 and the diaphragm cover body 3 are joined by the welded portion 24.
[0019]
3A and 3B, as in FIG. 2, the pump diaphragm 2 in which the bead portion 2A is protruded toward the pump main body 1 is formed on the upper surface 1A of the portion of the pump main body 1 that is overlapped with the diaphragm cover body 3. While providing the groove | channel 21 which open | releases and receives the bead part 2A, the notch step part 1B was formed along the outer periphery of the groove | channel 21. FIG. The lower surface of the portion of the diaphragm cover 3 that is overlapped with the pump body 1 forms a pressing surface 23A that compresses the bead portion 2A in cooperation with the pressing surface 21A that is the bottom surface of the groove 21, and is pushed and bent along the inner periphery. The edge 26 is formed to project downward, and a wall 3 </ b> C that forms the outer peripheral surface of the groove 21 on the outer peripheral edge projects downward.
[0020]
When the bead portion 2A is fitted into the groove 21 and the diaphragm cover body 3 is pressed against the pump main body 1, the bead portion 2A is sandwiched between the pressing surfaces 21A and 23A parallel to each other and compressed to be expanded outward and inward. When the pressing surface 23A is in close contact with the upper surface 1A across the diaphragm 2, the portion adjacent to the inside of the bead portion 2A of the diaphragm 2 is bent downward by the pressing and bending edge 26 as indicated by reference numeral 2D. 1 pump chamber 4 and pulse pressure chamber 5 are partitioned and stretched. In this state, it is assumed that the outer side surface of the notched step portion 1B and the inner side surface of the wall body 3C fitted therein are welded, and the pump body 1 and the diaphragm cover body 3 are joined by the welded portion 27.
[0021]
4 (A) and 4 (B) show a groove for receiving a half of the bead portion 2B in the overlap portion of the pump body 1 and the diaphragm cover body 3 with respect to the pump diaphragm 2 having the bead portion 2B protruding from both surfaces. 28 and 29 are provided facing each other, and the bottom surface of the groove 28 opened to the top surface 1A of the pump body 1 forms a pressing surface 28A. The bottom surface of the groove 29 opened on the lower surface 3A of the diaphragm cover 3 forms a pressing surface 29A parallel to the pressing surface 28, and a relief groove 30 is provided along the inner peripheral surface of the groove 29. Further, the relief groove 30 is provided. A press-bending edge 31 is formed so as to protrude downward from the lower surface 3A along the inner peripheral surface of.
[0022]
When the bead portion 2B is fitted into the grooves 28 and 29 and the diaphragm cover 3 is pressed against the pump body 1, the bead portion 2B is compressed and expanded outward and inward, and the lower surface 3A is in close contact with the upper surface 1A. When the portion of the diaphragm 2 adjacent to the bead portion 2B passes through the relief groove 30, it is then bent downward by a pushing / bending edge 31 as indicated by reference numeral 2E, and the diaphragm 2 has the pump chamber 4 and the pulse pressure chamber of FIG. 5 and is stretched. In this state, it is assumed that the upper surface 1A and the lower surface 3A that are overlapped on the outer side of the bead portion 2B are welded, and the pump body 1 and the diaphragm cover body 3 are joined by the welded portion 32.
[0023]
According to the embodiment shown in FIGS. 2, 3 and 4, the slack caused by expanding the bead portions 2A and 2B inward is bent in the thickness direction by the push bending edges 22, 26 and 31. Thus, the diaphragm 2 can be installed in a moderate tension state.
[0024]
5A and 5B show the diaphragm 2 with the bead portion 2A projecting toward the pump main body 1 side, and the bead portion 2A is opened to the upper surface 1A of the portion of the pump main body 1 that is overlapped with the diaphragm cover body 3. The receiving groove 35 is provided, and the bottom surface thereof is inclined so that the groove 35 gradually becomes deeper toward the outer side to form a pressing surface 35A, and is pressed against the lower surface 3A of the portion of the diaphragm cover 3 that is overlapped with the pump body 1 A pressing surface 36A is provided which is inclined in the same direction with respect to the surface 35A and the surface of the pump diaphragm 2 and gradually increases in distance from the pressing surface 35A toward the outer side. That is, the pressing surface 35A of the pump main body 1 has a larger inclination angle than the pressing surface 36A of the diaphragm cover body 3, and the distance between them gradually increases outward.
[0025]
When the bead portion 2A is fitted into the groove 35 and the diaphragm cover 3 is pressed against the pump body 1, the inner peripheral edge of the bead portion 2A is first sandwiched between the pressing surfaces 35A and 36A and then compressed. The area extending toward the outer peripheral edge expands. When the lower surface 3A is in close contact with the upper surface 1A, this portion is welded, and the pump main body 1 and the diaphragm cover body 3 are joined by the welded portion 37.
[0026]
FIGS. 6 (A) and 6 (B) show a groove for receiving one-half of the bead portion 2B in the overlapping portion of the pump body 1 and the diaphragm cover body 3 with respect to the pump diaphragm 2 with the bead portion 2B protruding from both surfaces. 38 and 39 are provided so as to face each other, and the bottom surface of the groove 38 opened on the upper surface 1A of the pump body 1 is inclined so that the groove 38 becomes deeper toward the outer side to form a pressing surface 38A. The bottom surface of the groove 39 opened to the lower surface 3A of the diaphragm cover body 3 is also inclined so that the groove 39 gradually becomes deeper toward the outer side to form a pressing surface 39A. That is, the two pressing surfaces 38A and 39A are inclined in directions opposite to each other with respect to the surface of the pump diaphragm 2, so that the distance between them gradually increases outward.
[0027]
When the bead portion 2B is fitted into the grooves 38 and 39 and the diaphragm cover body 3 is pressed against the pump body 1, the inner peripheral edge portion of the bead portion 2B is first sandwiched between the pressing surfaces 38A and 39A, and then compression is started. The area to be compressed expands towards the outer periphery. When the lower surface 3A is in close contact with the upper surface 1A, this portion is welded, and the pump main body 1 and the diaphragm cover body 3 are joined by the welded portion 40.
[0028]
7A and 7B show a pump diaphragm 2 having a bead portion 2A protruding toward the pump main body 1 and is opened to the upper surface 1A of the portion of the pump main body 1 that is overlapped with the diaphragm cover body 3 to bead portion 2A. Groove 41 is provided, and the bottom surface thereof is inclined so that the groove 41 gradually becomes deeper toward the outer side to form a pressing surface 41A, and the bottom surface 3A of the portion of the diaphragm cover 3 that is overlapped with the pump body 1 is formed. The portion facing the pressing surface 41A is directly used as the pressing surface 42A. That is, one pressing surface 41A is inclined with respect to the surface of the pump diaphragm 2, and the other pressing surface 42A is parallel to the surface of the pump diaphragm 2, so that these intervals gradually increase outward. It is getting bigger.
[0029]
When the bead portion 2A is fitted into the groove 41 and the diaphragm cover 3 is pressed against the pump body 1, the inner peripheral edge portion of the bead portion 2A is first sandwiched between the pressing surfaces 41A and 42A, and then compression is started. The area extending toward the outer peripheral edge expands. When the lower surface 3A is in close contact with the upper side, this portion is welded, and the pump main body 1 and the diaphragm cover body 3 are joined by the welded portion 43.
[0030]
In the embodiment shown in FIGS. 2, 3 and 4, the pressing surfaces 21A and 23A, 28A and 29A which face each other are parallel to each other, so that the bead portions 2A and 2B are evenly compressed to the inner side and On the other hand, in the embodiment shown in FIGS. 5, 6, and 7, the bead portions 2 </ b> A and 2 </ b> B are first compressed at the inner peripheral edge and then moved to the outer peripheral edge. The compression area is expanded toward the front. At this time, the inner peripheral edge is compressed most and the amount of compression gradually decreases outward, and the pressing surfaces 35A and 36A, 38A and 39A, 41A and 42A facing each other have a wedge action. Thus, the bead portions 2A and 2B receive a force pushed outward while being compressed, and are expanded only outward.
[0031]
Therefore, according to the embodiment shown in FIGS. 5, 6 and 7, the bead portions 2A and 2B are fitted into the grooves 35, 38, 39 and 41 in a state in which the pump diaphragm 2 is not loosened, and the pump body 1 and the diaphragm cover. The body 3 can be installed in an appropriate tension state by overlapping and bonding.
[0032]
【The invention's effect】
As described above, according to the present invention, the pump diaphragm is installed in an appropriate tension state by a very simple means of slightly adding or changing the overlapped portion of the pump body and the diaphragm cover body for compressing and fixing the bead portion. Therefore, it is possible to obtain a fuel pump that exhibits a predetermined performance by reacting sharply and faithfully to the pulsation pressure.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an example of a fuel pump to which the present invention is applied.
FIG. 2 is a partial longitudinal sectional view showing a first embodiment of the present invention.
FIG. 3 is a partial longitudinal sectional view showing a second embodiment of the present invention.
FIG. 4 is a partial longitudinal sectional view showing a third embodiment of the present invention.
FIG. 5 is a partial longitudinal sectional view showing a fourth embodiment of the present invention.
FIG. 6 is a partial longitudinal sectional view showing a fifth embodiment of the present invention.
FIG. 7 is a partial longitudinal sectional view showing a sixth embodiment of the present invention.
FIG. 8 is a partial longitudinal sectional view showing a conventional example.
FIG. 9 is a longitudinal sectional partial view showing a different conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pump main body, 1A upper surface, 2 Pump diaphragm, 2A, 2B bead part, 3 Diaphragm cover body, 3A lower surface, 21, 28, 29, 35, 41 Groove, 21A, 23A, 28A, 29A, 35A, 36A, 38A, 39A, 41A, 42A Press surface, 22, 26, 31 Press bending edge, 24, 27, 32, 37, 40, 43 Welded part

Claims (1)

The pump body and the diaphragm cover body is made of a thermoplastic resin, they are bonded to assemble et been by being welded together to sandwich the bead portion of the diaphragm outer periphery in a compressed state by a pump at a portion superposed, the A push-bending edge is provided at the overlapping portion of the pump body and the diaphragm cover body, and the push-bending edge bends the adjacent portion inside the compressed bead portion in the thickness direction to tension the pump diaphragm. in pulsatile diaphragm fuel pump in that not allowed stretched, which the pump diaphragm has to project to one surface of the beat section, is one groove for the bead portion received in the pump body and the diaphragm cover body together provided, wherein the press bending edge is provided to the other Doshiki diaphragm fuel pump.

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