JP4027496B2 - Fuel pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel pump used in an internal combustion engine or the like.
[0002]
[Prior art]
4 and 5A to 5C show a conventional fuel pump of this type, which shows the structure of a plunger drive type. FIG. 4 is a longitudinal sectional view of the conventional fuel pump, and FIG. FIG. 5A is a plan view of a pump housing in a conventional fuel pump, FIG. 5B is a plan view of a valve seat used in a conventional fuel pump, and FIG. 5C is a seat used in a conventional fuel pump. It is a bottom view of a holding plate.
[0003]
This fuel pump includes a pump housing 1 made of a metal such as an aluminum casting or a synthetic resin. The pump housing 1 is provided with an opening 2 on one side, and a pump chamber 3 having a circular cross section is formed. . A rubber diaphragm 4 is disposed on the end surface of the pump housing 1 on the opening 2 side so as to close the opening 2 in a liquid-tight manner. The peripheral edge of the diaphragm 4 is held by the peripheral edge of the cap-shaped pump lid 5, and the opening 2 of the pump housing 1 is formed by tightening fastening means such as a screw for fastening the pump lid 5 to the pump housing 1. 4 is liquid-tightly closed. Similarly to the pump housing 1, the pump lid 5 is also made of a metal such as an aluminum casting or a synthetic resin.
[0004]
A boss portion 5 a protrudes outward from the central portion of the outer surface of the pump lid 5, and a plunger guide hole 6 is provided in the boss portion 5 a in a direction orthogonal to the diaphragm 4. A plunger 7 is slidably fitted in the plunger guide hole 6. The inner end of the plunger 7 is fixed in a liquid-tight manner to the central portion of the diaphragm 4 with a fixture 8. The outer end of the plunger 7 is periodically pressed by a cam attached to a crankshaft of an internal combustion engine (not shown), so that the diaphragm 4 is displaced inward. A spring 9 for biasing the plunger 7 outward is incorporated in the boss portion 5a so that the plunger 7 is returned to the standby position when the plunger 7 is not pressed by the cam. A stopper 5b is projected on the inner surface of the pump lid 5 so that the plunger 7 stops at the standby position.
[0005]
A fuel inlet chamber 10 and a fuel outlet chamber are formed on one inner wall 1a of the pump housing 1 parallel to the diaphragm 4 by opening the pump chamber 3 at a different position in the radial direction of the pump chamber 3 having a circular cross section. 11 is provided. The pump housing 1 is provided with a fuel inlet 12 for supplying fuel to the fuel inlet chamber 10 and a fuel outlet 13 for delivering fuel from the fuel outlet chamber 11. A cylindrical hose joint 14 is provided on the outer surface of the pump housing 1 so as to surround the fuel inlet 12, and a cylindrical hose joint 15 is provided on the outer surface of the pump housing 1 so as to surround the fuel outlet 13. Yes.
[0006]
A valve seat 16 made of a disc-like rubber thin film is disposed on the inner wall 1a of the pump housing 1 so as to close the fuel inlet chamber 10 and the fuel outlet chamber 11 that open to the pump chamber 3. As shown in FIG. 5B, the valve seat 16 is formed by punching the periphery of the valve bodies 16a and 16b into a cantilevered shape so that the fuel inlet chamber 10 and the fuel outlet chamber 11 can be opened and closed. ing. That is, the valve seat 16 has an annular seal ring portion 16c around it, a bridge portion 16d exists across the center of the seal ring portion 16c, and valve bodies 16a and 16b are formed on both sides of the center of the bridge portion 16d. Is formed by removing unnecessary portions so as to be supported in a cantilever manner in the opposite direction.
[0007]
A sheet pressing plate 17 is fixed to the inner wall 1 a of the pump housing 1 with a fixing screw 18 so as to press the valve seat 16. That is, the fixing screw 18 is passed from the seat pressing plate 17 side to the screw through hole 19 provided in the bridge portion 16 d of the seat pressing plate 17 and the valve seat 16, and the tip of the fixing screw 18 is passed through the inner wall 1 a of the pump housing 1. The sheet pressing plate 17 is fixed to the inner wall 1 a of the pump housing 1 by being screwed into the provided screw hole 20.
[0008]
The sheet pressing plate 17 is provided with through holes 21 and 22 corresponding to the fuel inlet chamber 10 and the fuel outlet chamber 11. Corresponding to the valve body 16a on the fuel inlet chamber 10 side, the seat pressing plate 17 is provided with a valve body escape recess 23 for allowing the valve body 16a to escape to the open side. On the other hand, on the inner wall 1a of the pump housing 1 corresponding to the valve body 16b on the fuel outlet chamber 11 side, a valve body relief recess 24 for allowing the valve body 16b to open to the open side is provided.
[0009]
In such a fuel pump, when the outer end of the plunger 7 is pressed by a cam attached to a crankshaft of an internal combustion engine (not shown), the diaphragm 4 is displaced inward, whereby the fuel in the pump chamber 3 is discharged. The valve body 16b is pushed toward the valve body escape recess 24 side of the fuel outlet chamber 11 by the pressure and is separated from the valve seat 25b on the seat presser plate 17 side, and the fuel in the pump chamber 3 is fueled in the fuel outlet chamber 11 And is discharged to the outside and supplied to the internal combustion engine. When the plunger 7 is pressed by the cam, the spring 9 is compressed and stored.
[0010]
When the pressing by the cam disappears, the plunger 7 is returned to the standby position by the repulsive force of the spring 9. With this operation, the diaphragm 4 is displaced outward, whereby the inside of the pump chamber 3 is depressurized, and the valve body 16a of the fuel inlet chamber 10 is separated from the valve seat 25a on the inner wall 1a side of the pump housing 1 and fuel is discharged. Fuel is supplied from the inlet chamber 10 to the pump chamber 3.
[0011]
Such an operation is repeated as the crankshaft of the internal combustion engine rotates, and fuel is supplied to the internal combustion engine.
[0012]
[Problems to be solved by the invention]
However, in such a conventional fuel pump, the valve bodies 16a and 16b are composed only of a rubber thin film, so that the follow-up to the operation of the diaphragm 4 is insufficient, or permanent deformation occurs. As a result, the valve action is reduced, and the pump performance is lowered.
[0013]
In order to solve this problem, there is an example in which the valve seat 16 is made of a stainless steel plate or a synthetic resin thin plate instead of rubber. However, in a valve body made of such an elastic metal thin plate such as stainless steel or an elastic synthetic resin thin plate, There was a problem that the sealing performance against the seat was insufficient.
[0014]
An object of the present invention is to provide a fuel pump having a valve body that can sufficiently obtain a sealing performance against a valve seat and that can sufficiently follow the operation of a diaphragm.
[0015]
[Means for Solving the Problems]
According to the present invention , a pump chamber is formed by partitioning a diaphragm within a pump housing, and a fuel inlet chamber and a fuel outlet chamber are provided at different positions on the inner wall of the pump housing by opening the pump chamber. A fuel inlet for supplying fuel to the fuel inlet chamber and a fuel outlet for sending fuel from the fuel outlet chamber are provided on the inner wall, and the inner wall of the pump housing is closed so as to close the fuel inlet chamber and the fuel outlet chamber that open to the pump chamber. A valve seat is arranged, and a valve body corresponding to the fuel inlet chamber and a valve body corresponding to the fuel outlet chamber are formed in a cantilever shape in a size that can open and close the fuel inlet chamber and the fuel outlet chamber, respectively. The seat pressing plate is fixed to the pump housing so as to press the valve seat, and the seat pressing plate is provided with through holes corresponding to the fuel inlet chamber and the fuel outlet chamber. Corresponding to the valve body on the fuel inlet chamber side, the seat retainer plate is provided with a valve body relief recess for releasing the valve body to the open side, and on the inner wall of the pump housing corresponding to the valve body on the fuel outlet chamber side A valve body relief recess is provided to release the valve body to the open side, and when the diaphragm is displaced outward, the valve body corresponding to the fuel inlet chamber is separated from the valve seat on the inner wall side of the pump housing, and the pump chamber is separated from the fuel inlet chamber. The fuel is put into the valve, and when the diaphragm is displaced inward, the valve body corresponding to the fuel outlet chamber is separated from the valve seat on the seat pressing plate side, and the fuel in the pump chamber is discharged outside through the fuel outlet chamber. It is intended to improve the fuel pump.
[0016]
In the present invention, two valve seats are provided as the valve seat, a valve seat having a valve body corresponding to the fuel inlet chamber and a valve seat having a valve body corresponding to the fuel outlet chamber. These two valve seats are overlapped with a backup sheet so as to exist at least in the valve body corresponding to the fuel inlet chamber and the valve body corresponding to the fuel outlet chamber. This backup sheet is overlaid on the two valve seats so that the two valve seats are present on both sides thereof.
[0017]
In this way, when the valve seat is backed up by overlapping the backup seat on the valve seat at least in the valve body portion, the valve seat is sufficiently sealed, and the valve body sufficiently follows the operation of the diaphragm. A fuel pump with good durability performance can be obtained.
[0018]
In addition, as described above, the structure in which the valve seats are overlapped on both sides of the backup sheet, the valve seat is on the opposite side of the backup sheet on the fuel inlet chamber side and the fuel outlet chamber side. This fuel pump can be sufficiently adapted.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2A and 2B show a first example of an embodiment of a fuel pump according to the present invention. FIG. 1 is a longitudinal sectional view of the fuel pump of this example, and FIG. (B) is a plan view of two valve seats used in this example. Note that portions corresponding to those in FIGS. 4 and 5A and 5B described above are denoted by the same reference numerals.
[0020]
In this fuel pump, two valve seats 16A and 16B shown in FIGS. 2A and 2B having the same dimensions as those of the valve seat 16 shown in FIG. 5B are used.
[0021]
The valve seat 16A has an annular seal ring portion 16Ac around it, a bridge portion 16Ad exists across the center of the seal ring portion 16Ac, and corresponds to the fuel inlet chamber 10 only on one central side of the bridge portion 16Ad. The valve body 16Aa that is to be supported is cantilevered and is formed by removing unnecessary portions. The bridge portion 16Ad is provided with a screw through hole 19A.
[0022]
The valve seat 16B has an annular seal ring portion 16Bc around it, a bridge portion 16Bd exists across the center of the seal ring portion 16Bc, and corresponds to the fuel outlet chamber 11 only on one side of the center of the bridge portion 16Bd. The valve body 16Ba to be formed is cantilevered and is formed by removing unnecessary portions. The bridge portion 16Bd is provided with a screw through hole 19B corresponding to the screw through hole 19A.
[0023]
In this example, a backup sheet 26 having the same shape as the valve seat 16 shown in FIG. Valve sheets 16A and 16B shown in FIGS. 2A and 2B are positioned and overlapped on both surfaces of the backup sheet 26 so that the valve bodies 16Aa and 16Ba exist in opposite directions.
[0024]
In such a superposed body of the valve seats 16A, 16B and the valve seat 16, the valve body 16Aa faces the valve seat 25a on the inner wall 1a side of the pump housing 1, and the valve body 16Ba is a valve seat on the seat presser plate 17 side. It is sandwiched between the inner wall 1a of the pump housing 1 and the sheet pressing plate 17 so as to face 25b, and is attached to the inner wall 1a of the pump housing 1 by a fixing screw 18.
[0025]
Thus, when the backup sheet 26 is overlaid on the sheet-like valve bodies 16Aa and 16Bb for backup, the sealing performance for the valve seats 25a and 25b is sufficiently obtained, and the valve bodies 16Aa and 16Bb are sufficient for the operation of the diaphragm 4. A fuel pump having good durability performance can be obtained. As in this example, when the backup seat 26 is entirely overlapped on the valve seats 16A and 16B and the valve seats 16A and 16B are backed up, the whole including the valve bodies 16Aa and 16Bb can be backed up. Further, if the valve seats 16A and 16B exist on both sides of the backup sheet 26, the valve seats 25a and 25b are opposite to the backup sheet 26 on the fuel inlet chamber 10 side and the fuel outlet chamber 11 side. This fuel pump having the structure described in FIG.
[0026]
FIG. 3 is a longitudinal sectional view showing a reference configuration example of the fuel pump according to the present invention. Note that portions corresponding to those in FIGS. 1 and 2A and 2B described above are denoted by the same reference numerals.
[0027]
This fuel pump has a structure in which the valve seat 16B is superimposed on one side of the backup sheet 26, that is, the side of the backup sheet 26 facing the sheet pressing plate 17 side. In other words, the backup seat 26 is superposed on the valve seat 16B on the side corresponding to the valve seat 25b. Other configurations are the same as those in the first example.
[0028]
Thus, even if the backup seat 26 has a simple structure in which one side is exposed and overlapped with the valve seat 16B, the valve body 16Bb formed by the valve seat 16B is placed on the valve seat 25b on the seat presser plate 17 side. Since it is arranged in the abutting direction, the sealing performance between the valve seat 25b and the valve body 16Bb on the side of the fuel outlet chamber 11 that requires a sufficient seal can be improved, and the cost increase is minimized. The present invention can be implemented.
[0029]
In the above example, the entire valve seats 16A and 16B are backed up by the backup seat 26. However, the present invention is not limited to this, and at least the valve bodies 16Aa and 16Bb and the fixing screws 18 on the base side thereof. It is only necessary that the part fixed on the side is backed up by the backup sheet 26.
[0030]
In the above example, the present invention is applied to a fuel pump of the type in which the diaphragm 4 is driven by the plunger 7. However, the present invention is not limited to this, and there is no plunger 7 in FIG. Instead of the plunger guide hole 6, a communication hole that communicates with the crankcase of the internal combustion engine is provided at the center of the lid 5, and the pressure change due to the reciprocating motion of the piston of the internal combustion engine is transmitted to the right chamber of the diaphragm 4 through this communication hole. The present invention can be similarly applied to a fuel pump of a type that drives the diaphragm 4.
[0031]
In each of the above examples, an example in which the backup seat is simply superimposed on the valve seat has been described. However, such a simple overlapping structure has an advantage of preventing an increase in cost.
[0032]
However, it is needless to say that the valve seat and the backup seat may be integrated by bonding or the like if necessary in an overlapped state. When the valve seat or valve body and the backup seat are integrated in this way, the elasticity of the valve seat or valve body is enhanced, and the performance of the valve seat or valve body can be further improved.
[0033]
【The invention's effect】
In the fuel pump according to the present invention, since the seat-like valve body is backed up by the backup seat, a sufficient sealing performance for the valve seat can be obtained, and the valve body can sufficiently follow the operation of the diaphragm. A fuel pump with good durability performance can be obtained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a first example of an embodiment of a fuel pump according to the present invention.
FIGS. 2A and 2B are plan views of two valve seats used in this example.
FIG. 3 is a longitudinal sectional view showing a reference configuration example of a fuel pump according to the present invention.
FIG. 4 is a longitudinal sectional view of a conventional fuel pump.
5A is a plan view of a pump housing in a conventional fuel pump, FIG. 5B is a plan view of a valve seat used in a conventional fuel pump, and FIG. 5C is a seat used in a conventional fuel pump. It is a bottom view of a holding plate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pump housing 1a Inner wall 2 Opening part 3 Pump chamber 4 Diaphragm 5 Pump lid 5a Boss part 5b Stopper 6 Plunger guide hole 7 Plunger 8 Mounting tool 9 Spring 10 Fuel inlet chamber 11 Fuel outlet chamber 12 Fuel inlet 13 Fuel outlet 14 Hose joint 15 Hose joint 16, 16A, 16B Valve seat 16a, 16b, 16Aa, 16Bb Valve body 16c, 16Ac, 16Bc Seal ring portion 16d, 16Ad, 16Bd Bridge portion 17 Sheet pressing plate 18 Fixing screw 19, 19A, 19B Screw through hole 20 Screw Holes 21 and 22 Through-hole 23 Valve body escape recess 24 Valve body escape recess 25a, 25b Valve seat 26 Backup sheet

Claims (1)

A pump chamber is formed by being partitioned by a diaphragm in the pump housing, and a fuel inlet chamber and a fuel outlet chamber are provided at different positions on the inner wall of the pump housing by opening to the pump chamber, and the inner wall of the pump housing Is provided with a fuel inlet for supplying fuel to the fuel inlet chamber and a fuel outlet for sending the fuel from the fuel outlet chamber, and the fuel inlet chamber and the fuel outlet chamber open to the pump chamber are closed. A valve seat is disposed on the inner wall of the pump housing, and the valve seat has a size capable of opening and closing the fuel inlet chamber and the fuel outlet chamber, respectively, and a valve body corresponding to the fuel inlet chamber and a valve body corresponding to the fuel outlet chamber. Is formed in the shape of a cantilever support, and a sheet pressing plate is fixed to the pump housing so as to press the valve seat, and the sheet pressing plate Has a through-hole corresponding to the fuel inlet chamber and the fuel outlet chamber, and the valve body escapes the valve body to the open side corresponding to the valve body on the fuel inlet chamber side. A recess is provided, and a valve body escape recess is provided on the inner wall of the pump housing corresponding to the valve body on the fuel outlet chamber side so as to release the valve body to the open side. The valve body corresponding to the fuel inlet chamber is separated from the valve seat on the inner wall side of the pump housing to inject fuel into the pump chamber from the fuel inlet chamber, and into the fuel outlet chamber when the diaphragm is displaced inward. In the fuel pump configured to discharge the fuel in the pump chamber to the outside through the fuel outlet chamber by separating the corresponding valve body from the valve seat on the seat pressing plate side,
  As the valve seat, there are provided two valve seats, a valve seat having a valve body corresponding to the fuel inlet chamber and a valve seat having a valve body corresponding to the fuel outlet chamber, A backup seat is superimposed on the valve seat so as to exist at least in the valve body corresponding to the fuel inlet chamber and the valve body corresponding to the fuel outlet chamber,
  The fuel pump according to claim 1, wherein the backup sheet is superposed on the two valve seats so that the two valve seats are present on both sides of the backup sheet.

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