JPS585592A - Hose for absorbing pulsation of pressure fluid - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a hose used for transmitting pressure fluid, and more particularly to an improvement in a hose for absorbing pulsations in a pressure fluid supply.

Generally, a pressure fluid device such as a power steering device of an automobile, various hydraulic devices, or various pneumatic devices is a pressure fluid supply device 1 such as a pump, as shown in the block diagram in FIG.
, an actuating device 2 operated by the pressure fluid, and a pressure transmission pipe 3 and a discharge pipe 4 that connect these devices. However, since pressure pulsations occur in the pressure fluid discharged from the discharge port A and supplied to the supply port B, the pressure transmission pipe 3 vibrates, generating noise, and is sent back to the port.

Therefore, as shown in FIG. 2, the pressure transmission pipe 3 that communicates the discharge port A of the supply device 1 with the supply port B of the actuating device 2 is made of a braided reinforcing layer with a certain volume expansion to absorb pressure pulsations. A flexible helical steel pipe 8 which is reinforced and has joint fittings consisting of a socket 5, a nipple 6 and a cap 7 at both ends, and one end is fixed within the nipple 6.
A rubber hose 3 in which a rubber hose is inserted has been proposed.

In this case, when considered acoustically, the structure of the rubber hose 3 corresponds to an expansion type muffler (one that prevents the propagation of sound energy by mainly utilizing the reflection of sound energy at discontinuous parts of the cross section). is assumed.

□1 In other words, in acoustic terms, an expansion type silencer in this case is one in which the length of the air body, which is the expansion part, is inserted into the air body t1, as schematically shown in Fig. 3(a). The length of the human-powered tube is t
a, the cross-sectional area of the hole in the input pipe and the tail pipe is S, and the cross-sectional area of the hole in the empty fuselage is 82, then the attenuation amount (△) is expressed as 20tog Iaosktal, and the frequency characteristics of the attenuation are shown in Fig. 3. As seen in (b), there are frequency valleys (shown by the dotted line) with poor attenuation compared to the frequency characteristics of the basic expansion muffler (shown by the dotted line).
The amount of attenuation (-0) is slightly smaller, and this is because the insertion of a part of the human-powered tube into the air body to form ta is effective, and the rubber hose 3 in Figure 2 is replaced by the rubber hose 3 in Figure 3. of(a
) When applied to the expansion type silencer shown in (b) of Fig. 6.
It is assumed that this is useful for absorbing pulsation as shown in the figure below. However, if such an assumption is made, there will also be a valley frequency in which there is no effect in (b) of Fig. 6. (Referring to device 1), the rotation speed changes due to the engine drive, and the frequency of the pulsating pressure also changes accordingly.
In the rubber hose 3 that functions as the expansion type muffler described above, there is a risk that uneven absorption of pulsation may occur, and a countermeasure for this problem is desired.

Moreover, in the case of the long rubber hose 3 structure, the flexible helical tube 8 also tends to be long, resulting in poor flexibility and a tendency to be expensive. Furthermore, each time the length of the rubber hose 3 changed, an experiment was required to find the appropriate length of the flexible helical tube 8.

In view of the above points, the present invention has been made for the purpose of providing a new pressure fluid pulsation absorbing hose that can efficiently absorb the pulsation pressure of pressure fluid discharged from a pressure fluid supply device. The gist of this is that in a hose that has fittings at both ends, one end of the hose is fixed in the nipple of the one fitting, and it is impossible to inflate with a pressure fluid. A short flexible tube is inserted into the hose, and an orifice is provided in the hose at the other end, which is the free end of the flexible tube, separated from the other end by an appropriate space. It's in the absorption hose.

Below, one embodiment of the pulsation absorbing hose of the present invention will be described with reference to the drawings. In FIG. 4, the hose has a fiber reinforced layer in its wall or is completely bent, similar to the rubber hose shown in FIG. 2. A reinforcing layer and the like are embedded, and joint fittings are attached to both ends as shown in FIG. Moreover, the second
As shown in the figure, the flexible spiral steel pipe 9, which has an outer diameter smaller than the inner diameter of the rubber hose B and cannot be expanded by pressure fluid, is installed in a shorter state than the flexible pipe 8 in Fig. 2. This is a part of the invention. 1o characterizes a part of the present invention, and is an orifice having a small hole 11 inserted in front of the free end side of the flexible tube 9 with an appropriate space in between, and this orifice constricts the flow of fluid (so-called fluid It is designed to act as a diaphragm.

Furthermore, in this case, the orifice 10 is fixed by compressing and reducing the diameter of the socket 12 from the outside of the rubber hose 3, but the position may also be fixed with a hose band or the like, and the position of the orifice 1o alone cannot be moved. If this does not occur, the socket 12 and hose band are not necessarily necessary.

Similarly to FIG. 2, 16 is a protective cap placed over the free end of the flexible tube 9 to prevent the free end from damaging the inner circumferential surface of the rubber hose.

In such a configuration, internal pressure fluid passes through the flexible tube 9 from the direction of the arrow and enters the cap 1 as shown in FIG.
6 and reaching the free end of the cap 13, some of the flow expands in a straight line into the small hole 11 of the orifice 10 facing the other, and some of the flow flows straight into the inner circumferential surface of the rubber hose 6 by hitting the end face of the orifice 1o. The flow is divided into those flowing into the gap 14 formed on the outer circumferential surface of the flexible pipe 9.

In this case, the fluid exiting the free end of the cap 16 acts to be contracted by the small hole 11 of the orifice 10, and since the cavity 14 acts acoustically as a closed pipe, it acts to further reflect the reflected flow. The pulsation of the Pinglin fluid that exits 10 becomes smaller or the pulsation component disappears, and it reaches the actuating device.

The results of a test conducted to examine the pulsation absorbing effect of the hose according to the present invention are as follows.

The test method was to use an automotive power steering system with a pressure supply device at a rotation speed of 11,000 rpm and a flow rate of 6 t/.
Connect one end of a rubber hose with an effective length of 490 mm to the hydraulic pump of the After amplification, frequency analysis was performed to obtain the pulsating pressure frequency component unique to hydraulic pumps. The test results are shown in the table below, and compared to the conventional hose, the level of pulsating pressure when using the hose of the present invention was reduced by 8 degrees Fahrenheit, i.e., i/2.5. .

In this case, ta in the table is the length from the nipple tip surface to the free end surface of the flexible tube, which corresponds to ta in FIG. 3(a).

40dB=0. IKy/cJ In this example, although not shown as a flexible tube 9, two types of thin copper strips with trapezoidal and triangular cross sections are spirally wound while in contact with each other, making expansion by pressure fluid impossible. Although a case is shown in which a spiral tube structure is used, the flexible tube is not limited to this structure as long as it is flexible and cannot be expanded by pressure fluid. do not have.

As described above, the pressure fluid pulsation absorbing hose of the present invention has a flexible pipe inserted and fixed into a hose having fittings at both ends with one end fixed to one fitting, and
Furthermore, by adopting a structure in which an orifice is inserted and fixed in front of the free end of the flexible tube with an appropriate space between them, the pulsation of the pressure fluid is alleviated and the pulsation pressure is reduced to 1/2 that of the conventional hose, as shown in the experimental results. 5, thereby reducing the noise generated by pulsation.

Further, unlike conventional rubber hoses, there is no need to change the length of the flexible tube according to the length of the rubber hose, and it is therefore economical. Therefore, its industrial value is extremely limited.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a pressure fluid device, Fig. 2 is a longitudinal sectional view showing a conventional hose, and Figs. 3 (a) and (b).
) is a schematic diagram of an insertion tube expansion type muffler and a glass showing the damping characteristics of the muffler, and FIG. 4 is a longitudinal cross-sectional view of a hose showing an embodiment of the present invention. 1: Pressure fluid supply device, 2: Actuation device, 3: Pressure transmission piping (rubber hose), 4: Discharge pipe, 5, 12: Socket, 6: Nipple, 7: Base, 8.9 = Flexible spiral steel pipe, 10 Niorifice, 11: Small hole, 16: Protective cap, 14: Void.

Claims (1)

[Claims] A hose having fittings connected to both ends thereof, and a flexible tube having one end fixed in the nipple of said one fitting, which cannot be expanded by pressure fluid, and which is shorter than said hose. Pressure fluid pulsation absorption characterized in that an orifice is provided at the other end side, which is the free end of the flexible tube, separated by an appropriate space from the other end. hose.