JP2002039101A - Accumulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an accumulator capable of reducing a frequency and widening a frequency band of pulsation frequency of pressure oil to be absorbed. SOLUTION: A bottom shell 20 and a cap shell 30 are mutually joined to constitute a shell 10, and the inside of the shell 10 is partitioned into an oil chamber 11 and a gas chamber 12 by a bellows assembly 70. A port 50 is provided in the cap shell 30, and a resonance box 74 is provided between an oil passage 51 of the port 50 and the oil chamber 11. A plug 80 in which orifices 81, 82 having different diameters are formed is mounted in the oil passage 51 so that pressure oil flows into the resonance box 74 through the orifices 81, 82.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accumulator used for a hydraulic circuit of a hydraulic control device, for example, and more particularly to a structure of a port oil passage.

[0002]

2. Description of the Related Art Generally, in an accumulator, the inside of a cylindrical shell is divided into a gas chamber and an oil chamber by a bellows, and the pressure fluctuation of the pressure oil flowing into the oil chamber is controlled by the expansion and contraction of the bellows. As a component that absorbs by expansion and contraction of gas and effectively suppresses pulsation generated in pressure oil flowing through a hydraulic circuit, it is widely applied to, for example, a hydraulic circuit of an automobile.

In the accumulator, a bellows for partitioning the interior into an oil chamber and a gas chamber is housed in a shell constituting a sealed container, and the shell has an oil passage communicating the hydraulic circuit and the oil chamber. In general, there is a type in which a resonance port is provided between the oil passage of the port and the oil chamber. In that case, the pressure oil flowing through the hydraulic circuit enters the resonance box through the oil passage of the port, and further flows into the oil chamber via the communication passage provided in the resonance box.

According to such an accumulator, when the oil pressure in the resonance box exceeds the gas pressure in the gas chamber,
Oil in the resonance box flows into the oil chamber from the communication path, and pressure fluctuations of the pressure oil generated by pulsation are absorbed by expansion and contraction of gas in the gas chamber due to expansion and contraction of the separation membrane. On the other hand, when the pressure of the oil in the resonance box is lower than the gas pressure in the gas chamber, the pulsation of the pressure oil is canceled and absorbed by the resonance action of the oil in the resonance box.

[0005]

When the pressure of the pressure oil is low and the pulsation is absorbed by the oil in the resonance box, the frequency of the absorbed pulsation is in an optimum range for the user, and A wide band is desirable.
For example, when the accumulator is provided in the hydraulic circuit of the engine oil of the vehicle, if the pulsation during idling, which is the lowest rotation, and the pulsation in the rotation range of the engine frequently used during operation (for example, around 2,000 rotations) are absorbed,
It can be said that the function of the accumulator is sufficiently performed. However, the conventional accumulator has a complaint that the frequency of the absorbed pulsation, that is, the peak of the pulsation absorption performance is one, the band is narrow, and it is difficult to absorb the pulsation in the low frequency range.

Accordingly, an object of the present invention is to provide an accumulator capable of lowering the pulsation frequency of a pressure oil to be absorbed and achieving a wider band.

[0007]

SUMMARY OF THE INVENTION The present invention provides a cylindrical shell, a separation membrane for partitioning the inside of the shell into an oil chamber and a gas chamber, and an oil passage communicating the outside of the shell with the oil chamber. An accumulator for buffering pressure fluctuations of oil flowing into the oil chamber from the oil passage by expansion and contraction of gas in the gas chamber due to expansion and contraction of the separation membrane. It is characterized by having a configuration having a plurality of orifices.

According to the present invention, when the pressure oil of the hydraulic circuit passes through the plurality of orifices and flows into the oil chamber, the pressure of the pressure oil is low, and the pulsation is absorbed by the oil in each orifice. The pulsation of the pressure oil is absorbed by the resonance of the natural vibration corresponding to the cross-sectional area of each orifice with the pulsation of the pressure oil. Since the cross-sectional areas of the plurality of orifices are different, the peak of the pulsating frequency to be absorbed is equal to the number of the orifices, and the frequency decreases as the cross-sectional area decreases. Therefore, by adjusting the cross-sectional area of the orifice, pulsation at a low frequency can be absorbed and pulsation at a desired frequency can be absorbed by each orifice. As a result, the pulsation frequency to be absorbed can be reduced and the band can be broadened. From the viewpoint that the frequency band in which the pulsation is absorbed becomes wider, it is desirable that the difference between the cross-sectional areas of the orifices is large.

According to the present invention, in addition to the above-described structure, a resonance box communicating between the oil passage and the oil chamber is provided between the oil passage and the oil chamber, and the communication passage connecting the resonance box and the oil chamber has different cross-sectional areas. This includes a configuration having a plurality of orifices. This configuration is effective when the pressure of the oil in the resonance box exceeds the gas pressure in the gas chamber and the pulsation of the pressure oil is absorbed by the expansion and contraction of the gas in the gas chamber accompanying the expansion and contraction of the separation membrane. That is, in this case, the pressure oil flows into the oil chamber from the plurality of orifices constituting the communication path of the resonance box, and the pulsation of the pressure oil is absorbed by the natural vibration of the separation membrane according to the cross-sectional area of the orifice.
There is a peak in the frequency of pulsation absorption according to the number of orifices, and when the pressure of the pressure oil is high and the pulsation is absorbed by the expansion and contraction of the gas in the gas chamber due to expansion and contraction of the separation membrane, the pulsation absorption frequency can be broadened. Is achieved.

[0010]

Next, embodiments of the present invention will be described with reference to the drawings. (1) First Embodiment FIG. 1 shows a longitudinal section of an accumulator according to a first embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a cylindrical shell constituting a sealed container.

The shell 10 is formed by joining a bottom shell 20 and a cap shell 30 which are divided in the axial direction. The bottom shell 20 forms the main body of the shell 10 and has a longer axial length than the cap shell 30. Each of the shells 20 and 30 is formed by press-forming a substantially uniform thickness with a metal such as steel, and body portions extending in the axial direction are joined by projection welding.

At the joint ends of the shells 20 and 30, annular peripheral portions 21 and 31 bulging outward are formed over the entire circumference. These annular peripheral parts 2
Although the end faces of 1, 31 are joined,
An annular bellows protector 40 is fitted into an annular recess formed inside both of them and having a trapezoidal cross section. The bellows protector 40 is made of an insulating resin or the like. The inner diameter of the bellows protector 40 is equal to the inner diameter of the shell 10, and a groove 41 is formed on the entire outer peripheral surface thereof. Bellows protector 40 includes shells 20 and 30.
This prevents sparks generated when welding the two members from being damaged by hitting a bellows 71 of a bellows assembly 70 described later. The beads generated during the welding are:
It is housed in the groove 41.

A cylindrical portion 32 projecting inward (upward in FIG. 1) is formed at the center of the end of the cap shell 30 by burring. The port 50 is hermetically pressed into the hole 33 of the cylindrical portion 32 from the inside. The port 50 has an oil passage 51 and protrudes outside from the hole 33 of the cylindrical portion 32. A screw portion 52 used as a connection portion to a hydraulic circuit (not shown) is formed at the protruding end.

The port 50 is joined to the cap shell 30 by fillet welding the outer peripheral surface thereof to the outer peripheral edge 32 a of the cylindrical portion 32. Reference numeral 60 in FIG. 1 denotes a bead formed by welding.
Are provided over the entire circumference of the port 50. In addition,
For the fillet welding, arc welding or the like is employed.

A plug 80 is mounted at an end of the port 50 on the inner side of the oil passage 51.
As shown in FIGS. 2A and 2B, two orifices 81 and 82 communicating with the oil passage 51 and the inside of the shell 10 are formed. These orifices 81 and 82 have a circular cross section and different diameters. In this case, the diameter of the orifice 82 is larger than the diameter of the orifice 81.
It is about 0 times. The plug 80 is fixed to the port 50 by press fitting or welding. At the inner end of the port 50, a bottom seal 72 of a bellows assembly (separation membrane) 70 described below is integrally formed.
The bottom seal 72 is in contact with the inner end surface of the cylindrical portion 32.

Inside the shell 10, a metal bellows assembly 70 for partitioning the inside of the shell 10 into an oil chamber 11 and a gas chamber 12 is housed. The bellows assembly 70 includes a substantially cylindrical bellows 71 which expands and contracts in the axial direction, a bottom seal 72 joined to one end of the bellows 71, and a bellows cap 73 joined to the other end of the bellows 71. A resonance box 74 is joined to the bottom seal 72, and a space defined between the bellows assembly 70 and the resonance box 74 is the oil chamber 11. Then, the bellows assembly 70 and the shell 10
A space defined between the gas chamber 12 and the gas chamber 12 constitutes the gas chamber 12. The oil passage 51 of the port 50 communicates with the inside of the resonance box 74 via orifices 81 and 82, and a hole (communication passage) 74 communicating with the oil chamber 11 is provided at the center of the resonance box 74.
a is formed. The means for joining the bottom seal 72 and the bellows cap 73 to the bellows 71 and the means for joining the resonance box 74 to the bottom seal 72 are as follows.
By welding means such as TIG or plasma.

The bellows cap 73 has a recess 73a protruding toward the oil chamber 11, and a rubber self-seal 76 for closing the hole 74a of the resonance box 74 is adhered to the inner surface on the oil chamber 11 side. Have been. Also, bellows cap 73
A ring-shaped bellows guide 75 is attached to the flange-shaped periphery. This bellows guide 75 is used for the bottom shell 2
The bellows 71 is slidably fitted with the inner peripheral surface of the bellows 0 and guides the bellows cap 73 in the axial direction so that the bellows cap 73 does not shake when the bellows 71 expands and contracts. The bellows guide 75 has a not-shown groove communicating with the gas chambers 12 on both sides partitioned by the bellows guide 75 itself.
The gas pressure in 2 is made uniform.

In the oil chamber 11, a port 50 is provided from a hydraulic circuit.
Pressure oil flows through the oil passage 51, the orifices 81 and 82, the resonance box 74, and the hole 74a. On the other hand, the gas chamber 12
Is filled with an appropriate amount of liquid (eg, hydraulic oil) for adjusting the gas volume, and is filled with an inert gas such as nitrogen gas at a predetermined pressure. The liquid and the inert gas are injected into the gas chamber 12 from a gas injection hole 22 formed at the center of the end of the bottom shell 20. The gas injection hole 22 is sealed by a plug 23 joined to the bottom shell 20. In the center of the end of the bottom shell 20, a plug 2
A head 24 having a hexagonal cross section covering the head 3 is joined. The means for joining the plug 23 and the head 24 to the bottom shell 20 is welding means such as projection welding.

Next, the operation of the accumulator having the above configuration will be described. The pressure oil flowing through the hydraulic circuit is
The oil enters the resonance box 74 from the oil passage 51 through the orifices 81 and 82. When the oil pressure in the resonance box 74 exceeds the gas pressure in the gas chamber 12, the pressure oil flows from the hole 74a to the oil chamber 11
And the oil pressure in the oil chamber 11 exceeds the gas pressure in the gas chamber 12, whereby the bellows 71 expands and the gas chamber 1
The gas in 2 shrinks. On the other hand, when the pressure of the pressure oil in the oil chamber 11 becomes lower than the gas pressure in the gas chamber 12, the bellows 71 contracts and the gas pressure in the gas chamber 12 expands. Due to the expansion and contraction of the gas in the gas chamber 12, the pressure fluctuation of the pressure oil in the hydraulic circuit is absorbed, and the pulsation of the pressure oil is suppressed. FIG.
The two-dot chain line indicates the position of the bellows cap 73 during the longest stroke of the bellows assembly 70.

On the other hand, when the oil pressure in the resonance box 74 becomes lower than the gas pressure in the gas chamber 12, the bellows 71 contracts, the self-sealing 76 comes into close contact with the resonance box 74, and the hole 74a is closed. Thereby, self-sealing is performed so that the pressure in the oil chamber 11 does not become lower than the same pressure as the gas chamber 12. At this time, the collapse of the bellows 71 due to the gas pressure is prevented by the self-sealing 76. The pulsation of the pressure oil is canceled and absorbed by the resonance action of the oil in the resonance box 74.

According to the accumulator of the present embodiment, when the pressure of the pressure oil flowing through the hydraulic circuit is at a level at which the bellows 71 does not operate, the pulsation of the pressure oil is caused by the inherent oil of the resonance box 74. The vibration is absorbed by resonance with the pressure oil. Here, the natural vibration of the oil in the resonance box 74 depends on the cross-sectional area of each of the orifices 81 and 82. Therefore, since the cross-sectional areas of the orifices 81 and 82 are different, there are two peaks of the pulsation frequency to be absorbed. I do.

In this case, the orifice 81 having a small sectional area is used.
Thus, the pulsation on the low frequency side is absorbed, and the pulsation on the high frequency side is absorbed by the orifice 82. Therefore, by adjusting the cross-sectional areas of the orifices 81 and 82, pulsation at a desired frequency can be absorbed. For example, when the accumulator is provided in the hydraulic circuit of the engine oil of the vehicle, the diameter of the orifice 81 is set so as to absorb the pulsation during idling, which is the lowest speed, and the rotation range of the engine that is frequently used during operation (for example, 2
If the diameter of the orifice 82 is set so as to absorb the pulsation of about 000 rotations), the function of the accumulator can be sufficiently performed. As described above, according to the accumulator of the present embodiment, the pulsation frequency absorbed by the resonance box 74 can be reduced in frequency and broadened.

FIG. 3 is a pulsation absorption performance curve showing a frequency band in which pulsation is absorbed by the resonance box 74. The figure shows the case where the orifices 81 and 82 are provided in the oil passage 51 (two orifices), the case where only the orifice 81 is provided (small diameter), the case where only the orifice 82 is provided (medium diameter), and the case where no orifices 81 and 82 are provided The results of measuring the frequency to be absorbed for each of the four types with only 51 (no orifice) are shown. According to this figure, there is one peak of the absorption performance near the high frequency when the orifices 81 and 82 are not provided, and the peak of the absorption performance when only the orifice 81 and only the orifice 82 is on the low frequency side. There is one. On the other hand, the orifice 81,
It can be seen that there are two peaks in the absorption performance in the case where 82 is provided on the low frequency side, separated from each other on the low frequency side, and the low frequency and wide band frequencies are absorbed.

(2) Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG. The accumulator of this embodiment has the same configuration as that of the first embodiment except that two orifices are provided instead of the holes 74a of the resonance box 74. Therefore, in FIG. 4, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In the center of the resonance box 74, FIG.
As shown in (b), orifices 91 and 92 are formed instead of the holes 74a. These orifices 9
Reference numerals 1 and 92 have circular cross sections and different diameters, and the orifice 9
2 is larger than the diameter of the orifice 91 by, for example, about 2 to 10 times.

In the present embodiment, when the bellows 71 is at the operating level, that is, the oil pressure in the resonance box 74 exceeds the gas pressure in the gas chamber 12 and the pulsation of the pressure oil is reduced by the bellows 7.
This is effective when the gas in the gas chamber 12 is absorbed by the expansion and contraction of the gas chamber 12 due to the expansion and contraction. In that case, the resonance box 74
Pressure oil flows into the oil chamber 11 through the orifices 91 and 92, and the pulsation of the pressure oil is absorbed by the natural vibration of the bellows 71 according to the cross-sectional area of the orifice 91 or the orifice 92.

In this embodiment, the pulsation frequency absorbed by the operation of the bellows 71 has two peaks according to the orifices 91 and 92, and the pulsation frequency is broadened accordingly.

(3) Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. In FIG. 6, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The accumulator of this embodiment has the same basic configuration as that of the first embodiment except that the resonance box 74 of the first embodiment shown in FIG. 1 is not provided. The depth of the recess 73b of the bellows cap 73 is deeper than the depth of the recess 73a of the first embodiment.
With this configuration, when the bellows 71 shrinks most,
A self-seal 76 attached to the inner surface of the bellows cap 73 is configured to directly close the orifices 81 and 82.

According to this embodiment, the pressure oil of the hydraulic circuit is
It flows into the oil chamber 11 through the plurality of orifices 81, 82, but when the pressure of the pressure oil is low and the pulsation is absorbed by the oil in each of the orifices 81, 82, the same as in the first embodiment. In addition, the natural vibration corresponding to the cross-sectional area of each of the orifices 81 and 82 resonates with the pulsation of the pressure oil, so that the pulsation of the pressure oil is absorbed.

In the accumulator of each of the above embodiments, a metal bellows assembly 70 is used as a separation membrane for partitioning the inside of the shell 10 into an oil chamber 11 and a gas chamber 12, but the bellows assembly 70 is made of metal. Other materials may be used. Further, the separation membrane is not limited to the bellows assembly, but may be a piston, a diaphragm, a balloon, or the like. In this case, the shell is hermetically bonded to the shell by means depending on the type of the separation membrane.

[0032]

As described above, according to the present invention, since the oil passage leading from the hydraulic circuit to the oil chamber has a plurality of orifices having different sectional areas, the pulsation frequency of the absorbed pressure oil is reduced. A lower frequency and a wider band can be achieved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an accumulator according to a first embodiment of the present invention.

FIGS. 2A and 2B are a side sectional view and a plan view of a plug having an orifice according to a first embodiment of the present invention. FIGS.

FIG. 3 is a diagram showing the pulsation absorbing performance of the accumulator according to the first embodiment of the present invention and other accumulators.

FIG. 4 is a longitudinal sectional view of an accumulator according to a second embodiment of the present invention.

5A is a side sectional view showing an orifice according to a second embodiment of the present invention, and FIG. 5B is a plan view.

FIG. 6 is a longitudinal sectional view of an accumulator according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Shell 11 ... Oil chamber 12 ... Gas chamber 50 ... Port 51 ... Oil passage 70 ... Bellows assembly (separation membrane) 74 ... Resonance box 74a ... Hole (communication passage) 81, 82 ... Orifices 91, 92 on the oil passage side ... Orifice on the communication passage side

Claims (2)

[Claims] 1. A cylindrical shell, a separation membrane for partitioning the inside of the shell into an oil chamber and a gas chamber, and a port having an oil passage communicating the outside of the shell and the oil chamber, Pressure fluctuation of oil flowing into the oil chamber from the oil passage,
An accumulator for buffering by expansion and contraction of gas in the gas chamber accompanying expansion and contraction of the separation membrane, wherein the oil passage of the port has a plurality of orifices having different cross-sectional areas. 2. A resonance box communicating between the oil passage and the oil chamber is provided between the oil passage and the oil chamber, and the communication passage connecting the resonance box and the oil chamber has a plurality of orifices having different cross-sectional areas. The accumulator according to claim 1, wherein the accumulator has a configuration.