JPH1162771A - Diaphragm type damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm type damper which prevents a diaphragm from deforming plastically. SOLUTION: This diaphragm type damper 39 is formed so that the outer peripheral part 55 of a metal diaphragm 43 is fixed to the fixed surface 51 of a case 48 so as to partition the case into a back pressure chamber 41 in which gas is sealed and a pressure receiving chamber 49 receiving fluid pressure, and the area near the boundary 53 of the fixed surface 51 and a supporting surface 50 of the case is formed in a continuous curved shape. By this, even if the diaphragm 43 is deformed according to the profile of the supporting surface 50, no deflection angle is formed on the outer peripheral part of the diaphragm 43. Thus the outer peripheral part of the diaphragm 43 can be prevented from deforming plastically.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm type damper in which gas is sealed in a back pressure chamber and pressure pulsation in a pressure receiving chamber is reduced by gas pressure.

[0002]

2. Description of the Related Art For example, in a high-pressure pump used in a fuel injection device for directly injecting gasoline fuel into an internal combustion engine, a high-pressure pulsation reduction damper (or accumulator) for reducing pulsation of fuel pumped from the high-pressure pump to a common rail is known. It is. This high-pressure pulsation reducing damper converts intermittent oil supply from a high-pressure pump into constant-pressure oil supply. Generally, as shown in FIG. In this configuration, the pressure pulsation received in the pressure receiving chamber 105 is absorbed and discharged by the displacement of the thin diaphragm 107, which is divided into two sections, to maintain the common rail pressure. The back pressure chamber 103 is sealed by sealing a high-pressure gas. When the pressure in the back pressure chamber 103 becomes excessively large compared to the pressure in the pressure receiving chamber 105, the back pressure chamber 103 is displaced (deformed) toward the pressure receiving chamber 105. The deformed surface of the diaphragm 107 is received by the support surface 109 to prevent excessive deformation of the diaphragm 107.

On the other hand, Japanese Patent Laying-Open No. 62-206265 discloses a configuration in which a diaphragm is arranged on a fuel rail (common rail) to reduce pressure fluctuation in the fuel rail.

[0004]

However, in the former diaphragm type damper, the high pressure gas is sealed in the back pressure chamber, but the fuel pressure is not applied to the pressure receiving chamber. When the high-pressure pump stops,
Since there is little or no pressure in the pressure receiving chamber,
The differential pressure between the gas pressure in the back pressure chamber and the pressure in the pressure receiving chamber becomes excessive, and the diaphragm 107 deforms largely following the support surface 109. On the other hand, as shown in an enlarged manner in FIG. 6, a fixing surface 111 for fixing the diaphragm is a flat surface, and a corner 113 near a boundary 113 with the concave supporting surface 109 is provided.
5 are formed. This angle 115 forms the deflection angle θ. Therefore, when the pressure in the back pressure chamber 103 is larger than the pressure in the pressure receiving chamber 105, the diaphragm 107 is greatly deformed along the support surface 109,
Fixing surface 111 for fixing diaphragm 107 and support surface 1
In the vicinity 113 of the boundary with 09, the deflection angle θ is formed in the diaphragm 107. Thus, the diaphragm 1
07 forms a deflection angle θ and deforms.
07 has an inconvenience that its outer peripheral portion is plastically deformed and its function is reduced or breakage occurs.

On the other hand, in the latter technology disclosed in the above-mentioned publication, since the gas-filled damper is not used, a large pressure difference occurs in the pressure receiving chamber as described above, and the diaphragm is extremely deformed (displaced). It is unlikely that if such extreme deformation occurs, there is no direct bending angle in the vicinity of the fixed surface of the diaphragm, and there is no continuous supporting surface that regulates the deformation of the diaphragm. Since the diaphragm is greatly deformed, the inside of the fixed surface is deformed substantially with a deflection angle, and the diaphragm is disadvantageously plastically deformed.

Accordingly, an object of the present invention is to provide a diaphragm type damper which prevents plastic deformation of the diaphragm.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, the outer periphery of a metal diaphragm is fixed to a fixing surface of a case, and a gas is sealed in the case. In a diaphragm-type damper in which a pressure chamber and a pressure receiving chamber receiving fluid pressure are partitioned and a deformed surface of the diaphragm is supported by a support surface of the pressure receiving chamber when the diaphragm is deformed, the diaphragm-type damper includes a fixing surface of the case and a supporting surface. The vicinity of the boundary is characterized by a continuous curved surface shape.

According to the first aspect of the present invention, at the time of assembling the damper for filling the high-pressure gas into the back pressure chamber or at the time of using the assembled damper, the back pressure chamber side is compared with the pressure receiving chamber. When the pressure difference becomes extremely large, the diaphragm is deformed and supported along the support surface of the pressure receiving chamber. In this case, near the boundary between the fixed surface of the diaphragm and the support surface,
Since it has a continuous curved surface shape, even if the diaphragm is largely deformed, a bending angle is not formed in the diaphragm. Thus, plastic deformation of the outer peripheral portion of the diaphragm is prevented.

According to a second aspect of the present invention, in the first aspect of the present invention, the support surface is formed with a concave curved surface that is continuous over the entire surface on the pressure receiving chamber side. Is what you do.

According to the second aspect of the present invention, not only the vicinity of the fixed surface to which the diaphragm is fixed but also the entire supporting surface has a curved shape, so that the diaphragm undergoes plastic deformation even on the supporting surface. It can prevent plastic deformation from occurring at all parts where the diaphragm functions.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG.
An embodiment of the present invention will be described in detail with reference to FIG.
FIG. 1 is a cross-sectional view of a fuel supply pump equipped with a diaphragm type damper according to an embodiment of the present invention, cut from the front side, FIG. 2 is a cross-sectional view of the diaphragm type damper shown in FIG. 1, and FIG. FIG. 4 is an enlarged sectional view showing the fixing surface and the supporting surface, and FIG. 4 is a sectional view of the deformed diaphragm.

The fuel supply pump 3 according to the present embodiment
Injects gasoline directly into the combustion chamber of a gasoline engine, and is used in a fuel supply system referred to as a so-called direct injection gasoline engine to pump high-pressure gasoline.

The fuel supply pump 3 includes a plunger 5
And a plunger 5
And a lower main body 10 in which a cam 9 for driving the main body is housed. The cam 9 is connected to a shaft 8 driven by an engine (not shown). When the engine 9 is driven, the cam 9 rotates, and the cam 9 comes into circumferential contact with a cam contact shoe 11 disposed at the lower end of the plunger 5. Are driven up and down.

The pump housing 7 has a suction port 13 to which low-pressure fuel is supplied and a fuel tank 4 for leaking fuel.
A tank port 15 for returning the pressure to 0 and a discharge port 17 for discharging the fuel pressurized by the plunger 5 are provided.

The suction port 13 communicates with a pump chamber (fuel compression chamber) 21 through a fuel supply passage 19 formed in the pump housing 7, and the discharge port 17 communicates with the pump chamber 21 through a fuel discharge passage 23. When the valve opens and closes, the fuel compressed in the pump chamber 21 is discharged to the discharge port 17.
Is discharged from.

A fixed member 29 is screwed into a large-diameter hole formed in the pump housing 7, and a plunger barrel 33 for guiding the sliding of the plunger 5 is fixed inside the fixed member 29. ing.

On the other hand, a push rod 24 is interposed between the plunger 5 and the above-mentioned cam contact shoe 11, and the plunger 5 is pressed through the push rod 24 to slide into the plunger barrel 33. Let me. In the present embodiment, the push rod 24 is provided separately from the plunger 5, but contacts the lower end of the plunger 5 and reciprocates integrally with the plunger 5. One thing. The plunger 5 slides up and down along the plunger barrel 33. The lower end of the spring 35 is in contact with the plunger 5. The spring 35 constantly urges the plunger 5 downward, and the upper end of the spring 35 is supported by the lower surface of the fixed face member 37. The pump chamber 21 for pressurizing the fuel is formed between the lower surface of the fixed surface member 37 and the plunger 5.

The plunger barrel 33 has a plunger 5
At the lower end (opposite the pump chamber) of the plunger 5
Pulsation reducing space 26 defined by the push rod 24
Are formed. The pulsation reducing space 26 communicates with the fuel suction port 13 via the first low-pressure passage 28 so as to reduce pulsation on the low-pressure side generated by the reciprocating operation of the pump chamber 21. That is, the pulsation reduction space 2
6 is formed below the plunger 5, and when the plunger 5 descends, the fuel in the pulsation reduction space 26 is returned to the fuel suction passage 19 via the first low-pressure passage 28,
When the plunger 5 rises, fuel is sucked into the pulsation reduction space 26 from the fuel supply port 13 through the fuel supply passage 19. In the present embodiment, the pulsation reduction space 26
The volume change ratio between the pump chamber 21 and the pump chamber 21 is, for example, 1: 2, and the suction amount at the fuel supply port 13 is equal to the volume change ratio 2 of the fuel sucked into the pump chamber 21 when the plunger 5 is lowered. On the other hand, the amount of return from the pulsation reducing space 26 becomes 1, and when the plunger 5 rises, the fuel supply passage 1
Since fuel is supplied only to the pulsation reduction space 26 from 9,
The amount returned to the fuel supply port 13 becomes -1. Therefore,
When the plunger 5 descends and ascends, the volume change ratio of the fuel sucked from the fuel supply port 13 becomes 1 as a whole in each case. This eliminates intermittent pulsation of suction.

An elastic seal member 30 for sealing between the push rod 24 and the plunger barrel 33 is provided below the push rod 24, and seals between the push rod 24 and the plunger barrel 33.

In the plunger barrel 33, a second low-pressure passage 32 is formed between the elastic seal member 30 and the pulsation reducing space 26 and opens on the peripheral surface of the push rod 24. The second low-pressure passage 32 communicates with the fuel tank 40 via the tank port 15, and releases the fuel pressure leaked into the gap between the push rod 24 and the plunger barrel 33 to the fuel tank 40, and the elastic seal member 30. So that the fuel pressure is not applied. Therefore, only the fuel pressure of approximately the atmospheric pressure, which is the pressure of the fuel tank 40, is applied to the elastic seal member 30, so that the sealing can be reliably performed.

On the other hand, the fuel discharge passage 23 passes through a high-pressure damper 39 provided in the upper part of the pump housing 7, and this high-pressure damper 39 suppresses high-pressure pulsation in the fuel discharge passage 23.

Here, the high-pressure damper (diaphragm type damper) 39 according to the present invention will be described. As shown in an enlarged manner in FIG. 2, the high-pressure damper 39 includes a back pressure chamber 41 in which a high-pressure gas is sealed in a case 44, and a pressure receiving chamber 49 for receiving a discharge pressure of fuel. Is the cover 4
The pressure receiving chamber 49 is defined by the diaphragm 43, the case portion 48 of the pump housing 7, and the diaphragm 43. In the present embodiment, the case 44 includes a cover 45 and a case 48 of the pump housing 7.

The diaphragm 43 is made of metal and has a peripheral portion 55 fixed to a fixing surface 51 of the case portion 48 (see FIG. 3).

The pressure receiving chamber 49 is provided on the seat surface 5 of the case 48.
It is communicated with the fuel discharge passages 23a and 23b formed at 0 to reduce high pressure pulsation during fuel discharge. The seat surface (support surface) 50 supports the deformed (displaced) diaphragm 43, regulates the amount of deformation (or displacement) of the diaphragm 43, and prevents the diaphragm 43 from being excessively deformed. .

A high pressure gas is sealed in the back pressure chamber 41, and the high pressure gas is confined in the back pressure chamber 41 by a sealing plug 59.

In this embodiment, as shown in FIG. 3, a continuous curved surface is formed in the sheet surface 50, the fixed surface 51, and the vicinity 53 of the boundary between them, in other words, no corner is formed. . That is, a part of the concave spherical surface is formed on the seat surface 50, and a concave surface that forms a part of the spherical surface with the radius of R1 is formed. On the other hand, on the fixed surface 51, a surface having a radius of R2 is formed so as to form a part of the convex spherical surface, and the seat surface 50 and the fixed surface 51 are each curved surfaces.

Near the boundary between the sheet surface 50 and the fixed surface 51 5
In No. 3, the concave surface having the radius R1 and the convex surface having the radius R2 form a continuous uneven curved surface in the vicinity of the inside of the seat surface 50 from the fixed surface 51, and the bending angle as in the related art is formed. θ (see FIG. 6) is not formed. That is, in the present embodiment, the bending angle in the seat surface 50, the fixed surface 51, and the vicinity 53 of the boundary between them is zero. Therefore, when the diaphragm 43 is displaced and the diaphragm 43 deforms on these surfaces, the bending angle is not formed in the diaphragm 43 itself. This can prevent the inconvenience of impairing the function of the diaphragm or causing damage.

The seat surface 50 and the fixed surface 51 of the case portion 48 are not limited to be formed by surfaces each having one of the radii R1 and R2, but may be any curved surface that does not form a bending angle. Alternatively, a plurality of surfaces having a plurality of radii R whose center positions are shifted may be formed continuously.

Next, the operation of the present embodiment will be described. When the cam 9 rotates, the plunger 5 moves up and down via the cam contact shoe 11, whereby fuel is supplied to the pump chamber 21 through the fuel supply path 19 and the fuel in the pump chamber 21 is removed. Pressurized and discharged to the discharge passage 23.

The fuel introduced into the discharge passage 23 is supplied to the discharge port 17 through the first discharge passage 23a, the high pressure damper (diaphragm type damper) 39, the second discharge passage 23b, and the like. In the high-pressure damper 39, the pulsation received in the pressure receiving chamber 49 is reduced by the displacement of the diaphragm 43 supported by the high-pressure gas in the back pressure chamber 41.

On the other hand, when assembling the high-pressure damper 39, the diaphragm 43 is fixed to the fixing surface 51 and the cover 4
After assembling the high pressure gas into the back pressure chamber 41, the high pressure gas is confined with the sealing plug 59. When the high-pressure gas is filled, almost no pressure acts on the pressure receiving chamber 49, so that the pressure in the back pressure chamber 41 becomes extremely large as compared with the pressure receiving chamber 49, and the diaphragm 43 is placed on the sheet surface of the pressure receiving chamber 49. It transforms like 50. In this case, the diaphragm 4
In the vicinity 53 of the boundary between the fixed surface 51 and the sheet surface 50 of No. 3,
Since it has a continuous curved surface shape and no bending angle is formed, no bending angle is formed even when the diaphragm 43 is deformed. Accordingly, since the outer peripheral portion of the diaphragm 43 does not undergo plastic deformation and can maintain elastic deformation, the function of the diaphragm 43 can be prevented without damaging its function.

In particular, not only the vicinity 53 of the boundary between the fixed surface 51 to which the diaphragm 43 is fixed and the seat surface 50, but also the entire seat surface 50, the seat surface 50 has a concave spherical surface shape. , No plastic deformation occurs at all the parts where it acts.

On the other hand, even when the operation of the high-pressure pump is stopped after the assembly, the pressure in the pressure receiving chamber 49 decreases, so that the pressure in the back pressure chamber 41 becomes extremely large as compared with the pressure receiving chamber 49, and the diaphragm 43 Is deformed following the sheet surface 50 of the case portion 48. Also in this case, the vicinity 5 of the boundary between the fixed surface 51 of the diaphragm 43 and the seat surface 50
In No. 3, the outer peripheral portion of the diaphragm is not plastically deformed because it has a continuous curved shape and has no bending angle similarly to the above-described assembling.

The present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention. For example, the diaphragm type damper 39 according to the present invention is not limited to the fuel supply pump, and the same effect can be obtained even if the damper is used for a hydraulic circuit, a water pipe, or the like.

Further, a supporting portion and a regulating member for receiving the deformation of the diaphragm are provided on the back pressure chamber 41 side, and the vicinity of the boundary between the back pressure chamber 41 and the fixing surface on the cover side for fixing the diaphragm is also curved. You may do.

[0036]

According to the first aspect of the present invention, a continuous curved surface is formed in the vicinity of the boundary between the fixed surface of the diaphragm and the support surface, so that the diaphragm is deformed following the support surface. Also, no bending angle is formed in the diaphragm. Therefore, plastic deformation of the diaphragm can be prevented.

According to the second aspect of the present invention, not only in the vicinity of the fixed surface to which the diaphragm is fixed, but also in the entire supporting surface, the entire supporting surface has a curved shape, so that the entire diaphragm can be prevented from plastic deformation.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a fuel supply pump according to the present invention, cut from the front side.

FIG. 2 is a sectional view of a high-pressure damper of the fuel supply pump shown in FIG.

FIG. 3 is an enlarged sectional view showing a relationship between a fixing surface and a support surface of the high-pressure damper shown in FIG. 2;

FIG. 4 is a cross-sectional view showing a state in which the diaphragm has been deformed following a support surface.

FIG. 5 is a sectional view of a conventional high-pressure damper.

6 is a cross-sectional view showing a state in which the conventional diaphragm shown in FIG. 5 has been deformed following a support surface.

[Explanation of symbols]

 39 High pressure damper (diaphragm type damper) 41 Back pressure chamber 43 Diaphragm 45 Cover 48 Case part (case) 49 Pressure receiving chamber 50 Seat surface (supporting surface) 51 Fixed surface 53 Near boundary 55 Peripheral portion

Claims (2)

[Claims] An outer peripheral portion of a metal diaphragm is fixed to a fixing surface of a case, and is divided into a back pressure chamber filled with gas in the case and a pressure receiving chamber receiving fluid pressure, so that the diaphragm is deformed. A diaphragm type damper in which a deformed surface of the diaphragm is supported by a support surface of a pressure receiving chamber, wherein a vicinity of a boundary between the fixed surface of the case and the support surface is formed into a continuous curved surface shape. 2. The diaphragm-type damper according to claim 1, wherein the support surface has a concave curved surface that is continuous over the entire surface on the pressure receiving chamber side.