JPH08261096A - Hydraulic surge absorbing device and its bellows assembly - Google Patents

Abstract

PURPOSE: To provide a hydraulic surge absorbing device and its bellows assembly which excel in surge absorption performance and are inexpensive and compact without increasing size of an equipment to be built in. CONSTITUTION: A bellows assembly 34 is provided with a metal bellows 36 having a bellows main body 40 which is provided with crests and valleys alternately along the axial direction and can be expanded and shrunk. The bellows forms an air-tight chamber 54 inside in which gas is sealed and of which volume is changed in accordance with expansion and shrinkage of the bellows main body. The bellows is arranged in a recessed section 32 which is formed in an equipment main body 12 and receives surge pressure in a condition in which it is compressed in the axial direction, and a liquid pressure chamber 72 which receives surge pressure is formed by an inner face of the recessed section and an outer face of the bellows main body to constitute a hydraulic surge absorbing device 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic surge which is incorporated in a device such as a fuel injection system of an internal combustion engine that generates hydraulic pressure and absorbs a pulsation (hydraulic surge) of hydraulic pressure generated in the device. The present invention relates to a bellows assembly of an absorber and a hydraulic surge absorber.

[0002]

2. Description of the Related Art For example, in a fuel injection system of a gasoline engine, fuel supplied from a fuel tank by a fail pump is pressure-fed to an injection nozzle via a fuel injection pump and an injection pipe. The injection nozzle is attached to a cylinder head or the like of the engine, and the fuel pumped by the fuel injection pump is injected from the injection nozzle into the combustion chamber.

In such a fuel injection system, surge pressure is generated in the fuel due to the intermittent fuel injection operation of the injection nozzle. This surge pressure reversely propagates through the injection pipe and propagates in the direction of the fail pump, which causes noise or deteriorates fuel efficiency. Therefore, in a relatively low-pressure fuel injection system such as a gasoline engine, a hydraulic surge absorber that absorbs the above surge pressure is provided.

As such a hydraulic surge absorber, for example, as disclosed in Japanese Patent Publication No. 5-500697, a diaphragm is provided in the fuel supply passage formed in the main body of the injection pump to store fuel. Chamber and pressure chamber are formed, or a rubber diaphragm and coil spring are provided inside the housing, and the inside of the housing is partitioned by the rubber diaphragm into an air chamber and a hydraulic chamber, and this hydraulic chamber is used as a fuel supply path. Pulsation dampers and the like are known that reduce surge pressure by communicating with each other.

In recent years, a metal bellows has been provided inside the housing instead of the rubber diaphragm, and the metal bellows divides the inside of the housing into a hydraulic chamber and an air chamber communicating with the fuel supply passage, and a surge generated after fuel injection. A hydraulic surge absorber that absorbs pressure by expansion and contraction of metal bellows has been proposed.

The hydraulic surge absorber using the metal bellows as described above is superior to the pulsation damper using the rubber diaphragm in the pressure resistance of the partition portion,
Further, compared with a diaphragm type device having pressure resistance, the metal bellows act as a plurality of diaphragms, so that the displacement amount is large and the surge absorbing ability is excellent.

[0007]

However, the hydraulic surge absorber using the metal bellows, like the pulsation damper, has an independent housing containing the metal bellows, and this housing is used as a fuel injection pump or a fuel supply. It is incorporated into the fuel injection system by mounting it on the outside of the pipe.

When such an independent housing is provided, the number of parts of the device increases and the housing requires a structure having excellent pressure resistance, which causes an increase in the manufacturing cost of the device. Further, as described above, the housing of the hydraulic surge absorber is attached to the outside of the device body and is incorporated in a state of protruding from the device body. Therefore, there is a problem that the entire device body such as the fuel injection pump becomes large due to the hydraulic surge absorber.

The present invention has been made in view of the above points, and an object thereof is to provide an inexpensive hydraulic surge absorbing device and a hydraulic surge that are excellent in surge absorbing performance without causing an increase in the size of equipment incorporated therein. To provide a bellows assembly of an absorber.

[0010]

In order to achieve the above object, the hydraulic surge absorber according to the present invention is constructed by utilizing the device body itself which produces a hydraulic surge as a housing. That is, the hydraulic surge absorber according to the present invention accommodates a metal bellows in a recess formed in a main body of a device that generates a hydraulic surge and receiving a surge pressure, and the bellows are ridged along the axial direction. The bellows body has an expandable and contractible bellows body that is provided with alternating valleys and troughs.The bellows body forms an airtight chamber in which gas is enclosed and whose volume changes according to the expansion and contraction of the bellows body. It is disposed in the recess in a state of being compressed in the axial direction, and the inner surface of the recess and the outer surface of the bellows form a hydraulic chamber that receives the surge pressure, and the hydraulic pressure acting on the hydraulic chamber is increased. Accordingly, the bellows body expands and contracts to reduce the surge pressure.

The bellows assembly according to the present invention is incorporated in a device having a device body and a recess formed in the device body by opening to the outer surface of the device body and receiving a surge pressure. A bellows assembly constituting a hydraulic surge absorber, comprising a metal bellows having an expandable bellows body in which peaks and valleys are alternately provided along the axial direction, wherein the bellows has a gas And an airtight chamber whose volume changes in accordance with expansion and contraction of the bellows body, and the bellows body is disposed in the recess while being compressed in the axial direction, and the inner surface of the recess and the bellows are arranged. A hydraulic chamber that receives the surge pressure is formed by the outer surface of the bellows, and the bellows body expands and contracts according to the hydraulic pressure acting on the hydraulic chamber to reduce the surge pressure. It is characterized in.

[0012]

For example, a fuel chamber in which a surge pressure is generated is connected to a hydraulic chamber formed by an inner surface of a recess formed in the main body of a fuel injection device for an internal combustion engine and an outer surface of a bellows.
A pressurized liquid such as fuel flows into the hydraulic chamber. In this case, the fluid pressure acts in a direction to bend the bellows body in the axial direction, and the contraction of the bellows body reduces the volume of the airtight chamber formed in the bellows body according to the magnitude of the fluid pressure. At the same time, the volume of the hydraulic chamber increases in accordance with the decrease in the volume of the airtight chamber, and the pressure of the liquid flowing into the hydraulic chamber is reduced. On the contrary, when the pressure of the fuel chamber acting on the hydraulic chamber is reduced, the bellows body expands to increase the volume of the airtight chamber, and accordingly the volume of the hydraulic chamber decreases. As a result, the liquid in the hydraulic chamber flows into the fuel chamber and absorbs the pressure drop in the fuel chamber. The surge pressure is absorbed by the expansion and contraction operation of the bellows body according to the hydraulic pressure acting on the hydraulic chamber.

Further, in the hydraulic surge absorber and the bellows assembly of the present application, the bellows body is housed in the recess formed in the main body of the device so that the inner surface of the recess and the outer surface of the bellows body form the hydraulic chamber. Is formed. Therefore, the device body itself can be used as the housing of the hydraulic surge absorber, and it is not necessary to provide a housing independent of the device body. Therefore, the hydraulic surge absorber can be configured only by attaching the bellows assembly to the device body, and the manufacturing cost can be reduced by simplifying the configuration of the device and reducing the number of parts.

Further, since the bellows body is incorporated into the equipment body while being housed in the recess of the equipment body, the hydraulic surge absorber does not project from the equipment body, and the enlargement of the equipment body is prevented.

The metal bellows has a large expansion / contraction stroke in the axial direction as compared with the rubber diaphragm.
Excellent surge absorption performance can be obtained. Further, when the bellows body bends due to the liquid pressure, the pressure of the airtight chamber changes according to the amount of bending of the bellows body, so that the outer surface and the inner surface of the bellows body balance the liquid pressure and the gas pressure.
Therefore, no differential pressure is generated in the bellows body, and the hydraulic surge absorber can be used in high-pressure pipes of diesel engines and the like without any problems.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 3 is a fuel injection device 1 incorporating a hydraulic surge absorber according to an embodiment of the present invention.
0 is shown. A fuel injection device 10 as a device that causes a hydraulic surge includes a device body 12, and a fuel chamber 14 and a fuel injection pump 16 that communicates with the fuel chamber are provided in the device body 12. An injection nozzle 20 is connected to the discharge port of the fuel injection pump 16 via an injection pipe 18.

The feed pump 2 is provided on the outer surface of the device body 12.
2 are installed. The feed pump 22 sucks fuel from the fuel tank 24 via the suction pipe 23,
The fuel is supplied to the fuel chamber 14 via a supply pipe 27 provided with a fuel filter 26. Further, an overflow pipe 28 for returning the overflowed fuel to the fuel tank 24 is connected to the fuel filter 26 and the injection nozzle 20.

In the fuel injection device 10 having the above structure, the fuel sucked from the fuel tank 24 by the feed pump 22 is filtered by the fuel filter 26 and then supplied to the fuel chamber 14. And the fuel in the fuel chamber 14 is
It is sucked and compressed by the fuel injection pump 16, and is pressure-fed to the injection nozzle 20 through the injection pipe 18. Thereby, the fuel is intermittently injected from the injection nozzle 20 into the cylinder of the gasoline engine, for example.

In such a fuel injection device, surge pressure is generated in the fuel due to the intermittent fuel injection operation of the injection nozzle 20. This surge pressure reversely propagates through the injection pipe 18 and propagates to the fuel chamber 14. Therefore, the fuel injection device 10 incorporates the hydraulic surge absorber 30 that absorbs the surge pressure propagated to the fuel chamber 14.

More specifically, as shown in FIGS. 1 to 3, a circular recess 3 is formed in the device body 12 of the fuel injection device 10.
2 is formed. The recess 32 is open to the outer surface of the device body 12 and communicates with the fuel chamber 14 via a communication passage 33 that is open to the bottom surface 32 a of the recess. As a result, the surge pressure described above is also propagated to the recess 32 via the communication passage 33. And the hydraulic surge absorber 3
0 is composed of the recess 32 and a bellows assembly 34 mounted in the recess.

The bellows assembly 34 includes a metal bellows 36 and a cover plate 38 to which the bellows 36 is fixedly supported. The bellows 36 has a substantially cylindrical bellows body 40, and circular first and second end plates 42 and 43 fixed to both axial ends of the bellows body. The first end plate 42 is airtightly welded to the fixed side end of the bellows body 40 over the entire circumference to close the fixed side end of the bellows body. Further, a convex portion 45 that protrudes inward of the bellows body 40 is formed at the center of the first end plate 42. The second end plate 43 is a bellows body 40.
The end of the bellows is hermetically welded to the free end of the bellows to close the free end of the bellows body. The outer diameters of the bellows body 40 and the first and second end plates 42, 43 are smaller than the diameter of the recess 32.

As shown in FIG. 4, the bellows body 40
Is formed by alternately forming peaks 46 and valleys 47 along the axial direction, and is expandable and contractable in the axial direction. Each intermediate abdomen 48 connecting the peak 46 and the valley 47 forms a corrugated diaphragm having a convex portion 50 and a concave portion 51 along the radial direction of the bellows body 40. Each mountain 46 and valley 4
7 is formed in an acute angle shape, and is formed so that the intermediate abdomen portions 48 adjacent to each other can overlap each other until they are substantially in contact with each other in the axial direction of the bellows body 40.

The bellows 36 having such a shape has a close contact length, that is, the bellows 36 has the maximum length as compared with a normal bellows (one in which the cross section of the peak and the valley are formed in U shape and the intermediate abdomen is flat). The length of the bellows 36 when it bends and reaches a close contact state can be made extremely small. The convex portion 45 of the first end plate 42 is formed at a height substantially equal to the contact length of the bellows body 40.

The material of the bellows body 40 is a thin metal tube, and the peak 46, the valley 47, and the intermediate abdomen 48 are formed by plastic working such as hydraulic bulging. . The bellows body 40 can significantly reduce the manufacturing cost as compared with a welded bellows manufactured by sequentially connecting peaks and valleys by welding.

As shown in FIG. 1, inside the bellows body 40, an airtight chamber 54 is formed by the inner surface of the bellows body 40 and the inner surfaces of the first and second end plates 42, 43. A valve member 58 having an introduction hole 56 communicating with the airtight chamber 54 is fixed to the convex portion 45 of the first end plate 42. The airtight chamber 54 is filled with air as a gas and oil 60 as an adjusting liquid for adjusting the volume of the airtight chamber 54. The introduction hole 56 is closed by a steel ball 62 after enclosing air and oil. The axial length L1 of the bellows 36 after enclosing the air and oil 60 is set longer than the depth L2 of the recess 32. When air is sealed in the airtight chamber 54 when manufacturing the bellows 36, first, the oil 60 is introduced into the airtight chamber 54 through the introduction hole 56, and the bellows 36 is extended in the axial direction to the length L1. Thereby, the introduction hole 5
Air is introduced into the airtight chamber 54 through 6. Then, in this state, the introduction hole 56 is closed by the steel ball 62. The introduction hole 56 may be closed by an appropriate sealing means such as welding or caulking.

In an application requiring a high initial pressure, gas such as nitrogen gas is enclosed in the airtight chamber 56 together with oil instead of air. Further, the oil 60 is enclosed in order to adjust the volume of the airtight chamber 56 and prevent the bellows body 40 from being crushed. If such measures are not required, only air or gas is stored in the airtight chamber 56. Enclosed.

As shown in FIG. 2, the bellows assembly 34 configured as described above has a through hole formed in the peripheral portion of the lid plate 38 in a state where the bellows 36 is accommodated in the recess 32 of the device body 12. The bolt 64 inserted into the screw 63 is screwed into the screw hole 6 formed outside the recess 32 in the device body 12.
It is fixed to the device body 12 by being screwed into the device 6. In the device body 12, an annular groove 68 is formed between the recess 32 and the screw hole 66, and a sealing ring 70 is mounted in this groove. Therefore, the opening of the recess 32 is closed by the lid plate 38 and is liquid-tightly sealed by the sealing ring 70.

Bellows assembly 3 as described above
By mounting 4 on the device main body 12, the hydraulic chamber 72 communicating with the fuel chamber 14 is formed by the inner surface of the recess 32 and the outer surface of the bellows 36, and the hydraulic surge absorber 30 is configured. Since the axial length L1 of the bellows 36 before attachment is longer than the depth L2 of the recess 32, the second end plate 43 of the bellows 36 abuts the bottom surface 32a of the recess 32, and the bellows 36 is Its axial length is L
It is housed in the recess 32 in a state of being compressed to 2. Therefore, the volume of the airtight chamber 54 is smaller than that before the attachment, and the pressure of the airtight chamber 54 is raised to a range that does not affect the durability of the bellows body 40 due to the pressure difference between the airtight chamber 54 and the hydraulic chamber 72. ing.

In the fuel injection device 10 in which the hydraulic surge absorber 30 constructed as described above is incorporated, the surge pressure generated during the fuel injection operation from the injection nozzle 20 causes an instantaneous high pressure in the fuel chamber 14. The fuel generated and pressurized flows into the hydraulic chamber 72 of the hydraulic surge absorber 30 through the communication passage 33. In this case, as shown in FIG. 5, the hydraulic pressure acts in a direction to bend the bellows body 40 in its axial direction, and the contraction of the bellows body 40 reduces the volume of the airtight chamber 54 according to the magnitude of the hydraulic pressure. To do. At the same time, the volume of the hydraulic chamber 72 increases as the volume of the hermetic chamber 54 decreases, and the pressure of the fuel flowing into the hydraulic chamber is reduced.

When a high hydraulic pressure acts, the bellows body 40 of the bellows 36 has a second end plate 43 and a first end plate 42.
Shrinks to the point where it abuts the convex portion 45, and the air in the airtight chamber 54 is compressed to a state where there is almost no air. At this time, the bellows body 40 is prevented from being crushed by the oil 60 in the airtight chamber 54.

On the contrary, in the suction process of the fuel injection pump 16, the pressure in the fuel chamber 14 decreases and the hydraulic pressure acting on the hydraulic chamber 72 also decreases. In this case, the bellows body 40 expands to increase the volume of the airtight chamber 54, and accordingly the volume of the hydraulic chamber 72 decreases. As a result, the fuel in the hydraulic chamber 72 is pushed out to the fuel chamber 14 and absorbs the pressure drop in the fuel chamber. The expansion / contraction operation of the bellows body 40 according to the hydraulic pressure acting on the hydraulic chamber 72 absorbs the surge pressure and stabilizes the hydraulic pressure in the fuel chamber 14.

According to the hydraulic surge absorber 30 and the bellows assembly 34 of the hydraulic surge absorber constructed as described above, the recess 3 formed in the device main body 12
By accommodating the bellows 36 inside 2, the hydraulic chamber 72 is formed by the inner surface of the recess 32 and the outer surface of the bellows 36. Therefore, the device body 12 itself can be used as a housing of the hydraulic surge absorber 30, and it is not necessary to provide a housing independent of the device body 12. Therefore, the bellows assembly 34 is attached to the device main body 12
The hydraulic surge absorber 30 can be configured only by attaching the device to the device, and the manufacturing cost can be reduced by simplifying the configuration of the device and reducing the number of parts.

Further, since the bellows 36 is incorporated in the device body 12 while being housed in the recess 32 of the device body 12, the hydraulic surge absorber 30 does not protrude from the device body 12, and the device body is enlarged. Can be prevented. In particular, since the bellows 36 is accommodated in the recess 32 in a compressed state shorter than the length before being attached to the device body 12, the installation space of the bellows 36 can be reduced, and the hydraulic surge absorber 30 and the device body 12 can be installed. Can be further miniaturized.

Further, the metal bellows 36 can have a large expansion / contraction stroke in the axial direction as compared with the rubber diaphragm, and can obtain excellent surge absorbing performance. Further, when the bellows body 40 is bent by the hydraulic pressure, the pressure of the airtight chamber 54 is changed according to the bending amount of the bellows body, so that the liquid pressure and the gas pressure are balanced between the outer surface and the inner surface of the bellows body. . Therefore, the bellows body 40
Since no differential pressure is generated in the hydraulic surge absorber, the application range of the hydraulic surge absorber can be expanded.

The present invention is not limited to the above-described embodiments, but can be variously modified within the scope of the present invention. For example, although the bellows 36 is fixed to the cover plate 38 which is a separate body in the above embodiment, the first end plate 42 may also serve as the cover plate as shown in FIG. That is, in this embodiment, the first end plate 42 is formed relatively thick and has a diameter larger than that of the recess 32. Then, the bellows assembly 34 is attached to the device body 12 by directly fixing the peripheral portion of the first end plate 42 to the device body 12 with a plurality of bolts 64.

With such a structure, the hydraulic surge absorber and the bellows assembly can be provided in a more compact and inexpensive manner by simplifying the structure and reducing the number of parts.

In the case where the bellows 36 exerts only a hydraulic pressure equal to or lower than its pressure resistance, as shown in FIG. 7, the lid plate is omitted and the oil in the airtight chamber 54 is omitted.
Alternatively, the entire bellows unit 34 may be installed in the recess 32.

That is, according to this embodiment, the first end plate 42 has a diameter substantially equal to that of the recess 32 and is housed in the recess 32. An annular groove 68 is formed on the peripheral surface of the first end plate 42, and a sealing ring 70 is attached to the annular groove 68. Then, the first end plate 42
Are mounted liquid-tight in the recess 32 by a retaining ring 80. Also, in this embodiment, the bellows body 40
In this case, each mountain and valley are curved in a U shape. In the embodiment shown in FIG. 7, the same parts as those in the above-mentioned embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

According to the above structure, a more compact and inexpensive hydraulic surge absorber and bellows assembly can be provided by simplifying the structure and reducing the number of parts.

The present invention is not limited to the surge absorption of the fuel injection system, and is normally used at a pressure of 10 kgf / cm as in a petroleum plant including plants for fluids such as water and chemicals.
It can also be used for surge absorption of about ₂ or less.

[0041]

As described above in detail, according to the present invention, by utilizing the device body as the housing,
It is possible to provide an inexpensive and compact hydraulic surge absorber that is excellent in surge absorbing performance without increasing the size of equipment to be incorporated.

Further, according to the present invention, an inexpensive bellows can be constructed which does not increase the size of the equipment to be incorporated and can be constructed as a compact hydraulic surge absorber having excellent surge absorbing performance only by being attached to the equipment. An assembly can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a bellows assembly according to an embodiment of the present invention and a device body to which the bellows assembly is attached.

FIG. 2 is a cross-sectional view showing this hydraulic surge absorber which is configured by attaching the bellows assembly to a device body.

FIG. 3 is a diagram schematically showing an entire fuel injection device in which the hydraulic surge absorber is incorporated.

FIG. 4 is an enlarged sectional view showing a part of a bellows body of the bellows assembly.

FIG. 5 is a cross-sectional view when high pressure acts on a hydraulic chamber of the hydraulic surge absorber.

FIG. 6 is a sectional view of a hydraulic surge absorber according to another embodiment of the present invention.

FIG. 7 is a sectional view of a hydraulic surge absorber according to still another embodiment of the present invention.

[Explanation of symbols]

10 ... Fuel injection device, 12 ... Device body, 14 ... Fuel chamber,
16 ... Fuel injection pump, 30 ... Hydraulic surge absorber, 3
2 ... Recess, 34 ... Bellows assembly, 36 ... Bellows, 38 ... Lid plate, 40 ... Bellows body, 42 ... First end plate, 43 ... Second end plate, 54 ... Airtight chamber, 72 ... Hydraulic chamber .

Claims (6)

[Claims] 1. A metal bellows is housed in a recess formed in a device body of a device that generates a hydraulic surge to receive a surge pressure, and the bellows are provided with peaks and valleys alternately along an axial direction. The bellows has an airtight chamber in which gas is enclosed and whose volume changes according to the expansion and contraction of the bellows body, and the bellows body is compressed in the axial direction. In the recess, the inner surface of the recess and the outer surface of the bellows form a hydraulic chamber that receives the surge pressure, and the bellows body expands and contracts according to the hydraulic pressure acting on the hydraulic chamber. This is a hydraulic surge absorber that reduces fluctuations in hydraulic pressure due to hydraulic surge. 2. The bellows includes a first end plate fixed to one end of the bellows body in the axial direction and adjacent to the opening of the recess, and a bellows fixed to the other end of the bellows body in the axial direction of the recess. A second end plate facing the bottom surface; and a closing member fixed to the device main body to close the opening of the recess and the first end plate fixed to the closing member. The hydraulic surge absorber according to claim 1. 3. The hydraulic surge absorber according to claim 1, wherein either one of air and nitrogen gas is sealed in the airtight chamber. 4. The hydraulic surge absorber according to claim 1, wherein the airtight chamber contains a control liquid for adjusting the volume of the airtight chamber. 5. A hydraulic surge absorber is incorporated in a device including a device main body and a recess formed in the device main body so as to be opened on an outer surface of the device main body and receiving a surge pressure. A bellows assembly, comprising a metal bellows having an expandable bellows body in which peaks and valleys are alternately provided along the axial direction, wherein the bellows has a gas enclosed therein and a bellows body. Has an airtight chamber whose volume changes according to expansion and contraction, and the bellows body is disposed in the recess in a state of being compressed in the axial direction, and the surge pressure is applied by the inner surface of the recess and the outer surface of the bellows. A bellows assembly which forms a receiving hydraulic chamber and reduces the surge pressure by expanding and contracting the bellows body in accordance with the hydraulic pressure acting on the hydraulic chamber. 6. The bellows includes a first end plate fixed to one end of the bellows body in the axial direction and adjacent to an opening of the recess, and one end plate fixed to the other end of the bellows body in the axial direction of the recess. A second end plate facing the bottom surface; and a closing member fixed to the device main body to close the opening of the recess and the first end plate fixed to the closing member. The bellows assembly according to claim 5.