JP2004011888A - Pulsation absorbing hose - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulstaion absorbing hose which easily eliminates liquid left in the hose after inspecting a leak even in the case of using a resin tube as a flexible tube to reduce weight of the hose. <P>SOLUTION: This pulstaion absorbing hose is provided with a hose main body 2 and one or two or more resin flexible tubes 3 to be inserted into the hose main body 2 for fixation and having a free end at least in one end thereof. A side surface of each flexible tube 3 is provided with fine holes 5 having 0.1-1.5mm of diameter with a space at 10-50mm in the longitudinal direction of the flexible tube. With this structure, liquid draining property after inspecting a leak is secured without lowering the pulsation absorbing property. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulsation absorbing hose that forms a pipeline for a fluid that is pressure-fed from a fluid supply source and absorbs pulsation when the fluid is pressure-fed, such as a power steering device for an automobile.
[0002]
[Prior art]
BACKGROUND ART A power steering device of an automobile includes a hydraulic pump serving as a fluid supply source, a steering device operated by hydraulic pressure from the hydraulic pump, and a hydraulic pump and a steering device for connecting the hydraulic pump and the steering device to transmit hydraulic pressure to the steering device. A high-pressure hose and a low-pressure hose for returning hydraulic pressure from the steering device to the hydraulic pump are provided.
[0003]
In such a power steering device, pulsation due to the hydraulic pump cannot be avoided in the hydraulic pressure discharged from the hydraulic pump, and the pulsation may cause the high-pressure hose and the steering device to vibrate and generate abnormal noise. There is.
[0004]
For this reason, a pulsation absorbing hose that attenuates the pulsation while the fluid (oil) passes through the high-pressure hose and suppresses abnormal noise (ie, silences) through pulsation damping has been proposed. For example, a flexible tube made of metal or synthetic resin is inserted into an elastic high-pressure hose, one end of the flexible tube is connected and fixed to one end of the high-pressure hose, and the other end of the flexible tube is connected to the free end. Numerous proposals have been made to obtain a pulsation reducing effect by forming a Helmholtz resonator (resonator) in which the cavity between the inner peripheral surface of the high-pressure hose and the outer peripheral surface of the flexible tube is formed (see, for example, 56-80585, JP-A-60-201194). Further, in order to improve the effect of pulsation damping, two flexible tubes are inserted into the high-pressure hose such that their free ends face each other (for example, JP-A-2000-146076) or a flexible tube in the high-pressure hose. (For example, Japanese Patent Application Laid-Open No. 6-107192) have been proposed in which the fixing position of the flexible tube is not the end but the middle, and both ends of the flexible tube are free ends.
[0005]
[Problems to be solved by the invention]
A high-pressure hose (pulsation absorption hose) for a power steering device needs to be subjected to a leak test before assembly and after shipment, but water that is easy to handle is usually used as a fluid for the leak test. In power steering devices, incompressible oil is used as the fluid for transmitting the working pressure. Therefore, accurate measurement cannot be performed if compressible air is used for leak inspection, and inspection is performed if oil is used for leak inspection. This is because later post-processing becomes complicated. In addition, it is also possible to use liquids, such as alcohols other than water.
[0006]
Conventionally, as a flexible tube inserted into a high-pressure hose, a metal-made helical tube made of steel or the like (usually a tube formed by twisting two steel strips in a spiral) has been used. When a high-pressure hose using such a metal helical tube as a flexible tube was subjected to a leak test, water remaining in the hose after the test could be easily removed by air blowing the hose, which was not a problem. .
[0007]
On the other hand, in response to a demand for reduction in the weight of automobiles, resin tubes have recently been used as flexible tubes instead of metal spiral tubes. However, it was found that when a resin tube was used, the water remaining in the hose after the leak test could not be easily removed simply by air blowing, and the following problems occurred.
[0008]
That is, for a hose using a conventional helical tube, air is blown after a leak test to remove most of the water, and then heated air at about 60 to 90 ° C. is passed through the hose to completely remove the inside of the hose. Drying has been done. However, in the case of a hose using a resin tube, there is a large amount of residual water that cannot be completely removed by air blowing, so that it is necessary to greatly extend the drying time as compared with the conventional method, resulting in reduced productivity. Further, when the inside of the hose is dried, the air containing moisture stays in the dead space in the hose, and when the hose is cooled to room temperature after the drying is completed, dew condensation occurs in the portion.
[0009]
Therefore, an object of the present invention is to provide a pulsation absorbing hose that can easily remove water remaining in a hose after a leak test even when a resin tube is used as a flexible tube.
[0010]
[Means for Solving the Problems]
First, the present inventors have investigated the difference in water removal behavior depending on the type of flexible tube in order to understand the cause of the above problem, and have found that such a difference occurs due to the following mechanism.
[0011]
The hose 11 shown in FIG. 5 has a structure in which two steel spiral tubes 13 are installed as flexible tubes in a hose body 12 with their free ends 13f facing each other. In the leak inspection, a water pipe for leak inspection is connected to both ends of the hose 11, and water is filled in the hose 11 and pressurized to check for leakage. After the leak test, water remains in the hose 11, but when air is blown from one end of the hose 11, not only the water inside the spiral tube 13 but also the space 14 between the hose body 12 and the spiral tube 13 It is assumed that the accumulated water A is also sucked into the spiral tube 13 through the small gap between the steel strips constituting the spiral tube 13 and easily discharged out of the hose 11.
[0012]
On the other hand, the hose 21 in FIG. 6 is a case where the resin tubes 23 (23a, 23b) are flexible tubes instead of the steel spiral tubes in FIG. Even if the hose 21 is leak-inspected and air blown from the 23b side, the air blown out from the distal end of the tube 23b is filled with the water A1 accumulated in the space 24a between the hose body 22 and the tube 23a. Is sprayed through the gap between the end of the hose body 22 and the hose body 22, so that the water A1 is pressed into the space 24a, which is a dead space, and cannot be discharged out of the hose 21. On the other hand, although the air blown from the distal end of the tube 23b is not directly blown to the water A2 accumulated in the space 24b between the hose body 22 and the tube 23b, the suction force by the air acts on the water A2. Since the width of the space portion 24b is narrow, the suction force of the air does not sufficiently act on the water A2 at the back of the space portion 24b, and the surface tension of the water is superior, so that a considerable amount of water A2 remains. Resulting in. Therefore, even if air is blown from the opposite side of the hose 21, the water A <b> 1 and A <b> 2 cannot be sufficiently removed outside the hose 21. In addition, even if a method of sucking air from one end of the hose 21 is used instead of the air blow, the suction force can be increased, but the cross-sectional area of the hose body 22 contracts due to the suction, and the width of the space 24 is further reduced. Therefore, it is impossible to sufficiently remove the water A1 and A2 at the back of the spaces 24a and 24b.
[0013]
Therefore, the inventors have thought that it is possible to remove water remaining in the space portion by providing a gap on the tube wall surface for communicating the inside of the tube and the space portion, and have made the following invention.
[0014]
The invention according to claim 1 is a hose for absorbing a pulsation of a fluid pressure-fed from a fluid supply source, comprising: a hose body; and a hose inserted and fixed in the hose body and having at least one end as a free end. A pulsation absorbing hose comprising: two or more flexible tubes; and at least one minute hole for removing a liquid after a leak test is provided on a wall surface of each flexible tube.
[0015]
The invention according to claim 2 is the pulsation absorbing hose according to claim 1, wherein the diameter of the minute hole is 0.1 to 1.5 mm.
[0016]
The invention according to claim 3 is the pulsation absorbing hose according to claim 1 or 2, wherein the minute holes are provided at intervals of 10 to 50 mm in a longitudinal direction of each flexible tube.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following first to fourth embodiments, the number of flexible tubes is two, but the number is not limited thereto, and the present invention can be similarly applied to a case of one tube or a case of three or more tubes. . In the following first to fourth embodiments, the hose is a straight pipe, but is not limited to this, and can be applied to a curved pipe in the same manner.
[0018]
[Embodiment 1]
FIG. 1 shows an embodiment (Embodiment 1) of a pulsation absorbing hose according to the present invention. As shown in FIG. 1, the hose 1 includes a hose main body 2 and two flexible tubes 3 (3a, 3b) inserted into the hose main body 2. One end of each flexible tube 3 (3a, 3b) is fixed to the end opening of the hose body 2 with a nipple, and the other end is a free end. They are placed apart. As the flexible tube 3, it is recommended to use a resin tube which is easy to manufacture, inexpensive and lightweight, but a thin metal tube can also be used.
[0019]
The diameters and lengths of the flexible tubes 3 (3a, 3b) are appropriately determined in advance so that pulsations at a specific frequency (wavelength) generated by a specific power steering device to which the hose 1 is applied can be most effectively absorbed. Adjusted and selected. The two flexible tubes 3a and 3b may have the same length. However, in a case where pulsations of a plurality of different frequencies (wavelengths) are superimposed, the lengths are different from each other to improve the pulsation absorption effect. You may make it do.
[0020]
As the hose body 2, for example, a rubber tube in which a reinforcing wire is embedded is used as an elastic body that withstands high pressure.
[0021]
Thus, a Helmholtz resonator is formed by using the space 4 between the inner peripheral surface of the hose body 2 and the outer peripheral surface of the flexible tube 3 as a fluid reservoir space, and a predetermined frequency can be absorbed to reduce pulsation.
[0022]
Further, a minute hole 5 (5a, 5b) communicating with the space 4 (4a, 4b) is provided on the wall surface of the flexible tube 3 (3a, 3b). As a result, the water A remaining in the space 4 (4a, 4b) passes through the minute holes 5 (5a, 5b) by the same air blow from the end of the hose as in the conventional product, and the inside of the flexible tube 3 (3a, 3b). And is easily removed from the hose together with the blown air.
[0023]
The diameter of the micropores 5 is preferably 0.1 to 1.5 mm, more preferably 0.2 to 1.0 mm. If the diameter is too small, the amount of water suction decreases and it takes a long time to remove water, and it becomes difficult to drill holes. On the other hand, if the diameter is too large, it is optimally adjusted before bending. This is because the characteristics of the resonator thus changed are changed, and the pulsation absorbing effect is reduced. When a resin tube is used as the flexible tube 3, the minute hole 5 can be easily opened by, for example, a metal pin.
[0024]
Further, the number of the micro holes 5 (5a, 5b) is not particularly limited, and it is sufficient that at least one micro hole 5 is provided for each flexible tube 3 (3a, 3b). It is preferable to provide the flexible tube 3 (3a, 3b) at a position as close as possible to the mounting portion (at a position of 50 mm or less from the mounting portion) so that water at the back of the portion 4 is easily sucked. A plurality of micro holes 5 (5a, 5b) may be provided in the circumferential direction of the flexible tube 3 (3a, 3b) so that water A remaining in the space 4 (4a, 4b) can be removed in a short time. preferable.
[0025]
It is also preferable to provide a plurality of micro holes 5 (5a, 5b) at a predetermined interval L in the longitudinal direction of the flexible tube 3 (3a, 3b) because water A can be removed in a short time. It is recommended to be 50 mm. If the interval is too small, the labor for drilling increases, while if it is too large, the effect of shortening the drainage time decreases.
[0026]
The cross-sectional shape of the fine hole 5 is not particularly limited, and may be a square, a rectangle, a slit, or the like, in addition to the circle in the present embodiment.
[0027]
Here, JP-A-2000-146076 describes that "at least one wall (wall surface) of two tubular members (flexible tubes) has a large number of holes preferably arranged radially. There is a description. The purpose of this hole is to "fluid flows across the wall (wall) across the direction of transport, thereby creating eddies in the cavity (space) and achieving further damping of pulsations". It is supposed to be. However, in order to achieve further attenuation of pulsation due to the presence of such holes, it is necessary to increase the hole diameter to a considerable extent, and furthermore, the change in characteristics as a resonator due to the provision of many such large holes. It is necessary to reset the diameter and the length of the flexible tube in consideration of the above, and it takes a great deal of trouble to cope with the pulsation characteristics that differ for each vehicle type. On the other hand, the present invention is characterized by easily improving the liquid drainage after a leak test by providing micropores in a range that does not substantially change the pulsation damping (absorption) ability. The purpose, configuration, and effects are different from those of JP-A-2000-146076.
[0028]
[Embodiment 2]
FIG. 2 shows another embodiment (Embodiment 2) of the pulsation absorbing hose according to the present invention. As shown in FIG. 2, the hose 1 is such that one flexible tube 3 is inserted into the hose body 2 and the intermediate part thereof is caulked and fixed together with the hose body 2 so that both ends are free ends. Be composed. As in the first embodiment, it is recommended to use a straight tube made of resin that is easy, inexpensive, and lightweight as the flexible tube 3. By changing the position of the caulking portion 6, the same effect as that of inserting two flexible tubes of different lengths in the first embodiment can be obtained. Also in this embodiment, the water A remains in the space 4 after the leak inspection. Therefore, the minute hole 5 is provided in a portion other than the caulked portion 6 on the wall surface of the flexible tube 3. The hole diameter, the number, and the interval of the minute holes 3 may be determined in the same manner as in the first embodiment.
[0029]
[Embodiments 3 and 4]
3 and 4 show another embodiment (Embodiments 3 and 4) of the pulsation absorbing hose according to the present invention. In these embodiments, two flexible tubes are fixed at one end and an intermediate portion of the hose body 2 respectively. In the third embodiment, as shown in FIG. 3, two flexible tubes 3 are installed with their free ends directed in the same direction. As shown in FIG. 4, the fourth embodiment is a combination of the first and second embodiments (see FIGS. 1 and 2). By selecting an appropriate one from the above embodiments including the first and second embodiments, it is possible to provide an optimal pulsation absorbing hose for various pulsations having different frequencies for each vehicle type.
[0030]
Also in the third and fourth embodiments, the water A remains in the space 4 after the leak inspection. Therefore, the minute hole 5 is provided in a portion other than the caulked portion 6 on the wall surface of the flexible tube 3. The hole diameter, number, and interval of the micro holes 5 may be determined based on the same concept as in the first embodiment.
[0031]
【The invention's effect】
As described above, according to the present invention, even if a resin tube (or a thin metal tube) is used as a flexible tube, pulsation can be achieved by providing a micropore in the resin tube (or a thin metal tube). The liquid remaining in the hose after the leak test can be easily removed by air blow without lowering the absorption capacity. This makes it possible to provide a lightweight, high-quality pulsation absorbing hose.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a pulsation absorbing hose according to a first embodiment.
FIG. 2 is a sectional view showing a pulsation absorbing hose according to a second embodiment.
FIG. 3 is a sectional view showing a pulsation absorbing hose according to a third embodiment.
FIG. 4 is a sectional view showing a pulsation absorbing hose according to a fourth embodiment.
FIG. 5 is a cross-sectional view showing a pulsation absorbing hose using a conventional steel helical tube as a flexible tube.
FIG. 6 is a cross-sectional view showing a pulsation absorbing hose having a flexible tube made of a resin tube having no minute holes.
[Explanation of symbols]
1,11,21 ... Hose 2,12,22 ... Hose body 3,13,23 ... Flexible tube 4,14,24 ... Space part 5 ... Micro hole 6 ... Crimping part A ... Water

Claims (3)

What is claimed is: 1. A hose for absorbing a pulsation of a fluid pressure-fed from a fluid supply source, comprising: a hose body; A pulsation absorbing hose, characterized in that at least one microhole for removing the liquid after the leak test is provided on the wall surface of each flexible tube. The pulsation absorbing hose according to claim 1, wherein the diameter of the micropore is 0.1 to 1.5 mm. 3. The pulsation absorbing hose according to claim 1, wherein the micro holes are provided at intervals of 10 to 50 mm in a longitudinal direction of each flexible tube.

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