JPH10252658A - Pump and fuel feed pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pump and a fuel feed pump to prevent corrosion of a bellows. SOLUTION: In a fuel feed pump formed such that a fuel feed pump is provided with a bellows 27 to receive leak fluid through a slide clearance between a plunger 5 and a plunger barrel 33, fluid positively flows in a bellows chamber 27a from an inflow mechanism 63, and fluid in the bellows chamber 27a lows out from an outflow mechanism 63. Since fluid in the bellows chamber 27a is caused to generate a flow, it is prevented from occurring that fluid gathers in the bellows chamber 27a for a long period to separate water and the bellows 27a is corroded due to residence for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump for compressing a fluid by sliding a plunger in a plunger barrel, and more particularly to a fuel supply pump provided in a direct injection combustion injection device or the like.

[0002]

2. Description of the Related Art As a pump of this kind, a bellows is provided which covers an end of a plunger which slides in a plunger barrel and receives leaked fuel from a sliding clearance between the plunger barrel and the plunger. Pumps having a sealed configuration are known.

Further, as disclosed in Japanese Patent Application Laid-Open No. Hei 8-232848, for example, there is a so-called bellows pump having a structure in which a working chamber of a fluid by a plunger and a working chamber of another fluid are separated by a bellows. It is known.

[0004] In these pumps, the bellows chamber defined by the bellows receives fuel (fluid) and accumulates or fills with fuel. Since such bellows are required to have mechanical strength due to expansion and contraction,
Generally, a metal thing is used.

[0005]

On the other hand, a fluid such as fuel may contain a small amount of water, or even if it does not contain water, water may be generated due to decomposition of the fuel. Then, there is a problem that when water is accumulated in the bellows chamber, the metal bellows is corroded.

In particular, in the case of a configuration in which the bellows receives the leaked fuel, the amount of fuel flowing into the bellows chamber (the inside of the bellows) is very small, and it is difficult to replace the fuel stored in the bellows chamber. There is a problem that water easily accumulates locally and the bellows is likely to corrode.

Accordingly, an object of the present invention is to provide a pump and a fuel supply pump which can prevent corrosion of the bellows.

[0008]

According to one aspect of the present invention, there is provided a plunger barrel, a plunger sliding in the plunger barrel to pressurize a fluid in a pump chamber, and a plunger. A pump having a bellows forming a bellows chamber for receiving a leak fluid from a sliding clearance with a plunger barrel, comprising: an inflow mechanism for flowing fluid into the bellows chamber; and an outflow mechanism for flowing fluid from the bellows chamber. It is characterized by the following.

According to the first aspect of the present invention, the leak fluid leaking from the sliding clearance between the plunger and the plunger barrel is stored in the bellows chamber, but the fluid is positively injected into the bellows chamber from the inflow mechanism. Flowed into
In addition, the fluid in the bellows chamber is discharged from the discharge mechanism. For this reason, since a flow occurs in the fluid in the bellows chamber, it is unlikely that the same fluid stays for a long time to separate water or that the fluid itself corrodes and corrodes the bellows. Therefore,
Bellows corrosion can be prevented.

According to a second aspect of the present invention, the plunger slides inside the plunger barrel to pressurize the fuel, a pulsation defined by the plunger, a push rod sliding the plunger, and the plunger barrel. Reduced space,
A pulsation reducing passage communicating the pulsation reducing space with the fuel suction portion, a bellows forming a bellows chamber for receiving a leak fluid from a sliding clearance between the plunger and the plunger barrel, and an outflow passage for flowing out the fluid in the bellows chamber. In the fuel supply pump provided, the plunger barrel has an inflow passage through which one end is opened to the sliding surface of the push rod of the plunger barrel and the other end is opened into the bellows chamber to flow fuel. It is.

According to the second aspect of the present invention, in the fuel supply pump having a pulsation reducing mechanism, fuel is introduced into the bellows chamber by communicating the sliding surface of the push rod with the bellows chamber with the barrel. Since the inflow passage is provided, the fuel is positively flown into the bellows chamber from the inflow passage in addition to the leak fluid. Since the fuel in the bellows chamber is discharged from the outflow passage, a positive flow is generated in the fuel stored in the bellows chamber, so that the fluid stays for a long time to separate water and corrode the bellows. Therefore, corrosion of the bellows can be prevented. Moreover, since only the opening of the inflow passage is formed in the plunger barrel, the configuration is simple and the production is easy.

According to a third aspect of the present invention, in the second aspect of the present invention, the opening on the sliding surface side of the push rod in the inflow passage opens when the push rod moves in a direction in which the bellows extends, thereby reducing the pulsation. The opening is formed at a position where the opening is closed when the bellows moves in a direction in which the bellows contracts, communicating with the space.

According to the third aspect of the present invention, the opening of the inflow passage through which fuel flows into the bellows chamber opens and closes in conjunction with the movement of the push rod with respect to the plunger barrel. Therefore, since the opening time of the inflow passage is limited,
Since only the amount required for fuel replacement can flow into the bellows chamber, the influence on the fuel flowing in and out of the bellows chamber, such as the effect on the fuel supply pump and the low-pressure supply pump that supplies fuel to this fuel supply pump, is minimized. Can be

[0014]

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 sectional view of the fuel supply pump according to the embodiment of the present invention cut from the front side, FIG. 2 is an enlarged sectional view showing a portion including a plunger barrel and a bellows, and FIG. It is a figure showing the operating state of a push rod and a bellows.

[0015] 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 is provided with a suction port 13 to which low-pressure fuel is supplied and a discharge port 17 to discharge fuel pressurized by the plunger 5. The suction port 13 is connected to a pump chamber (fuel compression chamber) 21 through a fuel supply passage 19 formed in the pump housing 7.
The discharge port 17 is connected to the fuel discharge passage 23.
Through the pump chamber 21 through opening and closing of the valve.
The fuel compressed in the pump chamber 21 is discharged from the discharge port 17.

A fixed member 29 is screwed into a large-diameter hole formed in the pump housing 7, and a plunger barrel 33 for guiding sliding of the plunger 5 is fixed inside the fixed member 29. ing. A bellows 27 is disposed below the fixed member 29 so that its axis is substantially coincident with the axis of the plunger 5. The upper end of the bellows 27 is fixed to a fixed member 29 assembled to the pump housing 7, and the lower end of the bellows 27 is fixed to a support member 31 that contacts the lower end of the plunger 5. The bellows 27 expands and contracts in conjunction with the vertical movement of the plunger 5, and receives fuel leaked from a sliding clearance between the plunger 5 and the plunger barrel 33, and a bellows chamber formed inside the bellows 27. The leak fuel is received in the inside 27a and is sealed to the cam chamber 9a, and is formed in a bellows shape made of metal.

An opening (outflow mechanism) 61 communicating with the return port 14 is formed in the fixed member 29 to which the upper end of the bellows 27 is fixed (see FIG. 1), and this opening 61 is formed in the bellows space 27a. To allow the fluid in the bellows space 27 a to flow out to the return port 14.

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. It may be one. The plunger 5 slides up and down along the plunger barrel 33. In plunger 5,
The lower end of the spring 35 is in contact. The spring 35 constantly urges the plunger 5 downward. As shown in FIG. 1, the upper end of the spring 35 is supported on the lower surface of the fixed member 37. The pump chamber 21 for pressurizing the fuel is formed between the lower surface of the fixing member 37 and the plunger 5.

The plunger barrel 33 includes 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 ratio between the fuel supply port 13 and the pump chamber 21 is, for example, 1: 2. When the plunger 5 descends, the suction amount decreases with respect to the volume ratio 2 of the fuel sucked into the pump chamber 21. The return amount from the space 26 becomes 1,
When the plunger 5 is raised, the fuel is supplied only from the fuel supply passage 19 to the pulsation reduction space 26, so that the amount returned to the fuel supply port 13 becomes -1. Therefore, the volume ratio of the fuel sucked from the fuel supply port 13 depends on the plunger 5
Is generally 1 in each case at the time of falling and rising. This eliminates intermittent pulsation of suction.

The plunger barrel 33 is further provided with an inflow passage 63 at a sliding portion of the push rod 24, and the inflow passage 63 has one end 63a at one end of the push rod 2a.
4, and the other end 63b is connected to the bellows chamber 27a.
Open inside. The inflow passage 63 is communicated with the pulsation reducing space 26 when the push rod 24 is at the lower end position, and is closed by the push rod 24 when the push rod 24 is at the upper end position. 26 is formed at a position where the communication with the block 26 is interrupted.
In other words, the fuel in the bellows chamber 27a is replaced every time the engine is operated.

The inflow passage 63 can be easily formed only by forming a straight hole in the peripheral surface of the plunger barrel.

On the other hand, the fuel discharge passage 23 passes through a high-pressure damper 39 provided on the upper part of the pump housing 7, and this high-pressure damper 39 suppresses high-pressure pulsation in the fuel discharge passage 23. The high-pressure damper 39 has a pressure receiving portion 41 in which gas is sealed.
1 is defined by a case 45 and a diaphragm 43. On the pressure receiving portion 41 side, a stopper (restriction member) 46 is provided on the back surface of the diaphragm 43.
The deformation of the diaphragm 43 to the side is prevented from being excessively damaged. The deformation toward the fuel discharge passage 23 is prevented from being excessively deformed by the pump body 7 in which the passage is formed.

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, fuel discharge passage 2
3 is discharged.

When the plunger 5 rises, fuel is sucked into the pulsation reducing space 26 from the fuel supply port 13 side. When the plunger 5 is lowered, the pump chamber 21
Is supplied to the pump chamber 21 via the fuel supply passage 19, so that the amount of fuel supplied from the fuel supply passage 19 is reduced when the plunger 5 is lowered and when the plunger 5 is raised. At the same time, the amount of fuel sucked from the suction port 13 is equalized or leveled as shown in FIG. 5, so that suction pulsation is reduced.

On the other hand, from the sliding clearance on the circumferential surface between the push rod 24 and the plunger barrel 33,
Although slightly, fuel leaks into the bellows chamber 27a,
Fuel gradually accumulates in the bellows chamber 27a. Further, as shown in FIG. 3, the push rod 24 moves downward in the bellows chamber 27a, and at a position where the bellows 27 extends, the push rod 24 extends from one end 63a of the inflow passage 63.
The one end 63a is opened to the pulsation reducing space 26, and the pulsation reducing space 26 and the bellows chamber 27a are communicated.
Fuel in the pulsation reducing space flows to the bellows chamber 27a.
At the same time, the fuel in the bellows chamber 27a is led to the return port 14 from the opening 61, which is an outflow mechanism. Therefore,
Since the opening time of the inflow passage 63 is limited, only the amount necessary for fuel replacement can flow into the bellows chamber 27a, so that the low-pressure supply pump capacity for supplying low-pressure fuel to the high-pressure fuel pump is not impaired.

Next, as shown in FIG. 2, when the push rod 24 moves upward and the bellows 27 contracts, the push rod 24 closes the opening at one end 63a of the inflow passage 63 with its sliding surface. In particular, since the bellows chamber 27a contracts, the fuel in the bellows chamber 27a is positively discharged from the opening 61.

That is, according to the present embodiment, every time the engine is operated, the fuel actively flows in and out of the bellows chamber 27a to generate a flow in the bellows chamber 27a. It is possible to prevent separation of water generated by fuel remaining in the chamber 27a for a long time. Therefore, corrosion of the bellows is prevented. In addition, the fuel is not always supplied to the bellows chamber, but the fuel replacement amount is minimized only at a certain time, so that there is almost no influence on the pump capacity.

Next, a modification of the present embodiment will be described with reference to FIGS. In the modified examples shown in FIGS. 4 and 5, the same parts as those in the above-described embodiment are denoted by the same reference numerals, and the detailed description of those parts will be omitted, and only the characteristic parts will be described. And

In the embodiment shown in FIG. 4, the inflow passage 63 formed in the plunger barrel 33 is not linear but substantially L-shaped.
The push rod 24 is formed in the shape of a letter and is opened toward the lower side of the push rod 24. In the modification shown in FIG. 5, the fuel can flow toward the lower side of the bellows chamber 27a where the fuel easily stays, so that the flow of the fuel can be increased throughout the bellows chamber 27a.

In the embodiment shown in FIG. 5, the inflow passage 63 formed in the plunger barrel has a substantially T-shape, and an opening 63 b is formed toward the outside of the plunger barrel 33.
In addition to opening 63 toward the lower side of the push rod 24,
c. In the modification shown in FIG. 4, the fuel flows into the bellows chamber 27a toward both the side and the lower side of the plunger barrel 33, so that the inside of the bellows chamber 27a can flow more effectively. And the stagnation of fuel can be reliably prevented.

The present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist of the present invention. For example, the fuel supply pump according to the present invention is not limited to being used as a gasoline fuel injection pump, and the same applies to a light oil fuel injection pump or the like used for a diesel engine or an oil or other fluid pump. The effect can be obtained.

The invention is not limited to the construction in which the fuel in the bellows chamber is replaced every time the engine is operated. An opening and closing mechanism for opening and closing may be separately provided.

Further, in the above-described embodiment, the plunger 5 and the push rod 24 are formed as separate bodies.
The same effect can be obtained even when these are integrally formed and the push rod 24 substantially forms a part of the plunger 5.

[0036]

According to the first aspect of the present invention, the fluid flows into the bellows chamber positively from the inflow mechanism, and the fluid in the bellows chamber flows out from the outflow mechanism and flows into the bellows chamber. Therefore, the same fluid is unlikely to stay in the bellows chamber for a long time to separate water or corrode the bellows due to long-term residence. Therefore, corrosion of the bellows can be prevented.

According to the second aspect of the present invention, in the fuel supply pump having the pulsation reducing mechanism, the barrel is connected to the sliding surface of the push rod and communicates with the bellows chamber to introduce fuel into the bellows chamber. Since the passage is provided, in addition to the leak fluid, the fuel is positively introduced into the bellows chamber from the inflow passage and flows out from the fuel outflow passage. Corrosion can be prevented. Moreover, since only the opening of the inflow passage is formed in the plunger barrel, the configuration is simple and the production is easy.

According to the third aspect of the present invention, the opening of the inflow passage through which fuel flows into the bellows chamber opens and closes in conjunction with the movement of the push rod with respect to the plunger barrel, and reduces pulsation at the position where the bellows extends. Since it is configured to communicate with the space and close the communication when it contracts, the fuel in the pulsation reducing space can be positively sucked into or out of the bellows chamber by utilizing the expansion and contraction of the bellows, so that the flow in the bellows chamber can be further improved. Can be active.

[0039]

[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 an enlarged sectional view showing a portion including a bellows of the fuel supply pump shown in FIG. 1;

FIG. 3 is a sectional view showing an operation state of a portion including the bellows shown in FIG. 2;

FIG. 4 is a sectional view showing a modified example of the fuel supply pump according to the present embodiment.

FIG. 5 is a sectional view showing another modified example of the fuel supply pump according to the present embodiment.

[Explanation of symbols]

 Reference Signs List 3 fuel supply pump (pump) 5 plunger 21 pump chamber (fuel compression chamber) 24 push rod 26 pulsation reduction space 27 bellows 27a bellows chamber 61 opening (outflow mechanism) 63 inflow passage (inflow mechanism)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akinao Minegishi 3-13-26 Yayumicho, Higashimatsuyama-shi, Saitama Inside of Zexel Higashimatsuyama Plant

Claims (3)

[Claims] 1. A plunger barrel, a plunger sliding in the plunger barrel to pressurize a fluid in a pump chamber,
A pump having a bellows forming a bellows chamber for receiving a leak fluid from a sliding clearance between the plunger and the plunger barrel, comprising: an inflow mechanism for flowing fluid into the bellows chamber; and an outflow mechanism for flowing fluid out of the bellows chamber. A pump comprising: 2. A pulsation reducing space defined by a pump chamber that pressurizes fuel by sliding a plunger in a plunger barrel, a plunger, a push rod that slides the plunger, and a plunger barrel. A fuel having a pulsation reducing passage communicating a space with a fuel suction portion, a bellows forming a bellows chamber for receiving a leak fluid from a sliding clearance between a plunger and a plunger barrel, and an outflow passage for flowing out the fluid in the bellows chamber. In the supply pump, the plunger barrel is provided with an inflow passage through which one end opens to a push rod sliding surface of the plunger barrel and the other end opens into the bellows chamber to flow fuel. 3. The opening on the sliding surface side of the push rod in the inflow passage opens when the push rod moves in a direction in which the bellows extends, and communicates with the pulsation reducing space, and closes when the bellows moves in a contracting direction. The fuel supply pump according to claim 2, wherein the fuel supply pump is formed at a position.