JPS643037Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a novel pulsation absorbing hose. More specifically, the present invention relates to a pulsation absorbing hose that can completely prevent noise caused by pulsations by efficiently absorbing pulsations in pressure oil discharged from a pump of a power steering unit.

[Prior Art] As shown in FIG. 5, a power steering unit usually includes a pump 10 for delivering pressure oil;
It is comprised of a steering device 11 such as a cabinet or cylinder operated by pressure oil, and a high-pressure side hose 12 and a low-pressure side hose 13 that communicate the pump 10 and the steering device 11. Since such a power steering unit uses a positive displacement pump such as a vane pump, it generates a lot of noise, and furthermore, the pressure oil flowing out from the pump 10 causes pulsations, so the steering device 11, hose 12,
13 etc. vibrate and generate noise, and in severe cases, the operation of the steering device 11 becomes unstable.

In order to solve such problems, the present applicant has published U.S. Pat.
A pulsation absorbing hose described in Japanese Patent No. 146411 has been proposed.

The pulsation absorbing hose (hereinafter referred to as the conventional example) described in Japanese Utility Model Application Publication No. 54-165829 has a spiral pipe connected to a connecting fitting connected to a discharge port of a pump. In addition, the pulsation absorbing hose described in Japanese Utility Model Application Publication No. 54-146411 (hereinafter referred to as the conventional example) has a connection fitting connected to the discharge port of the pump and a connection fitting connected to the supply port of the steering device. An orifice member is formed inside the flexible tube, and the orifice member is also inserted inside the flexible tube.

[Problems to be solved by the invention] In the conventional pulsation absorbing hose, a portion of the pressure oil is squeezed through the gaps and perforations in the spiral pipe.
This creates a phase difference between the pressure waves of the compressed pressure oil and the pressure waves of the unrestricted pressure oil passing through the inside of the spiral tube. When the pressure waves, which have a phase difference in this manner, merge at the outlet of the spiral tube, they interfere with each other and the pressure waves are smoothed.

This conventional example has achieved considerable results based on the above-mentioned pulsation absorption principle. However, there is one major drawback. The problem is that pulsations of a specific frequency cannot be effectively absorbed. The reason for this is that in a spiral pipe with a certain length, a certain diameter, and a gap of a certain size, the pressure within a certain range,
This is because unless the pulsating pressure has a frequency within a specific range, the aperture will not work effectively and no phase difference will be produced.
Therefore, it cannot be used for units with different specifications for the pump 10 and steering device 11, or even for units with the same specifications, the pump discharge amount changes greatly depending on the vehicle speed, so it is difficult to absorb pulsation sufficiently. Problems arise, such as the fact that there are limits to what can be done.

Next, in the conventional pulsation absorbing hose, 3
All of the pressure oil is gradually squeezed using individual orifice members, thereby smoothing out pulsations. In this conventional example, there is no part where pressure waves with different phase differences interfere, but pulsation is absorbed by reducing the pressure difference each time the pressure waves are throttled.

However, this conventional example also has the same drawbacks as the aforementioned conventional example. That is, the pressure difference can be effectively reduced by an orifice member having a certain size and shape only in a specific range of pressure and pulsating pressure of a specific range of frequencies.

In view of these circumstances, the present invention aims to provide a hose that can effectively absorb pulsation over a wide range.

[Means for Solving the Problems] The present invention includes a first connecting fitting for connecting one end to a discharge port of a pump of a power steering unit, and a steering wheel operated by pressure oil discharged from the pump. a second connecting fitting for connecting one end to the supply port of the collecting device; a flexible tube connected to the other ends of each of the first connecting fitting and the second connecting fitting; a tubular orifice member inserted in the middle, a first spiral tube with one end inserted into the other end of the first connecting fitting and disposed within the flexible tube, and one end fitted into the orifice member, The gist of the present invention is a pulsation absorbing hose for a power steering unit, which comprises a second spiral tube disposed within the flexible tube so as to extend toward the steering device.

[Operation] In the present invention, the high pressure oil discharged from the pump is first throttled by the first spiral pipe. At this time, the high-pressure oil is divided into the high-pressure oil that is squeezed through the gap in the spiral tube and the high-pressure oil that comes out through the spiral tube, but there is a phase difference in the pressure waves between the two. Therefore, they will interfere with each other near the exit of the first spiral tube. Although the first pulsation absorption is performed in this way, the features of the present invention are brought about by the orifice member inserted midway through the flexible tube and the second spiral tube.

That is, the pressure oil exiting the first spiral tube is throttled by the orifice member or the second spiral tube, and the increased pressure generated by the throttle is pushed back toward the first spiral tube. This pushed back pressure wave was originally the first
Further interference is added to the primary interference between the pressure wave coming out of the gap between the spiral tubes and the pressure wave coming out from inside the spiral tube, where a phase difference is caused by the spiral tube. Due to this interference interaction (secondary interference), in the present invention, the absorption of pulsation is achieved to a considerable extent before it is constricted by the second spiral tube.

Furthermore, the pressure and frequency of the pressure wave pushed back by the second spiral tube depend on the distance between the second spiral tube and the first spiral tube. Therefore, if the insertion positions of the orifice member and the second spiral tube are optimally selected based on theoretical analysis or experimental results, the range in which pulsations can be effectively absorbed can be considerably expanded.

As described above, the high-pressure oil undergoes pressure wave interference primarily by the first spiral pipe and secondarily between the first spiral pipe and the second spiral pipe, and finally It is constricted by the second spiral tube, thereby creating a phase difference again, and interference (tertiary interference) occurs at the exit, completing the pulsation absorption.

As described above, in the present invention, in addition to the pressure wave interference caused by the first spiral tube, mutual interference occurs due to the pressure waves pushed back by the second spiral tube, so that pulsation can be effectively absorbed over a fairly wide range.

[Example] The pulsation absorbing hose of the present invention will be described below with reference to the drawings.

1 and 2 are cross-sectional views showing one embodiment of the pulsation absorbing hose of the present invention, FIG. 3 is a block diagram of a measuring device for measuring the effect of pulsation absorption, and FIG.
The figure is a pulsating pressure absorption graph showing the results measured by the measuring device of FIG. 3, and FIG. 5 is a block diagram of the power steering unit.

In FIG. 1, 1 is a discharge port A of a pump 10a.
The first connecting fitting 2, 3 has one end connected to the pressure oil supply port B of the gearbox 11a of the power steering unit, which is a steering device. It is a flexible tube whose one end and the other end are connected to the outer circumferences of the other ends of the connecting fitting 1 and the second connecting fitting 2, respectively. The first connecting fitting 1 and the second connecting fitting 2 include pipe members 1a and 2a, nipples 1b and 2b attached to one end of the pipe members 1a and 2a, and the nipple 1, respectively.
The sockets 1c and 2c are fixed to the outer circumferences of the sockets 1c and 2b via a flexible tube 3. 4 is a first spiral tube whose one end is tightly fitted into the inner hole 1d of the nipple 1b. Reference numeral 5 denotes an orifice member inserted into the flexible tube 3 and fixed therein. The orifice member 5 is fixed together with a caulking member 6 provided on the outer periphery of the flexible tube 3 by caulking through the flexible tube 3. One end of the second spiral tube 7 is firmly fitted into the orifice member 5, and the second spiral tube is arranged within the flexible tube 3 so as to extend toward the steering device 11 side. The spiral tubes 4 and 7 are tube-shaped tubes formed by densely spirally winding one or more elastic materials such as metal or synthetic resin, and adjacent loops are tightly connected to each other by their respective elasticities. There is.

The fifth pulsation absorbing hose constructed as described above
If the high-pressure hose 12 as shown in the figure is adopted, the pressure oil with pulsating pressure flowing out from the pump 10 will flow through the spiral pipes 4 and 7 within the pulsation-absorbing hose.
The pulsating pressure is attenuated as it passes through the hose, and the pressure oil has almost no pulsating pressure when exiting from the pulsation absorbing hose.

Next, another embodiment of the present invention will be explained based on FIG. In the embodiment described above, the inner hole 1d in the nipple 1b is bored to have the same diameter so that the pressure fluid can flow through it without resistance. good. In that case, the pulsation absorption effect can be further enhanced.

Further, the orifice member 5 also has an inner hole 5a.
The orifice portion 5b may be formed by making a part of the hole thinner. In that case, the pulsation absorption effect can be further enhanced.

Next, the effects of the pulsation absorbing hose of the present invention will be explained using examples.

Example 1 Nipples 1b, 2b and pipe members 1a, 2a
and a connecting fitting 1 consisting of a socket 1c, 1c,
2 to both ends of a nylon braided hose with an outer diameter of 21 mm, an inner diameter of 10 mm, and a length of 400 mm, and a first spiral with an outer diameter of 6.4 mm, an inner diameter of 4.1 mm, and a length of 200 mm to the nipple 1b of the first connecting fitting 1. Insert and secure tube 4,
A second spiral tube 7 similar to the first spiral tube 4 and an orifice member 5 were inserted into the center of the hose and fixed from the outer circumference of the hose with a caulking member to prepare a sample (FIG. 1).

Example 2 A pulsation absorbing hose constructed in the same manner as in Example 1, with an inner diameter of 3.8 mm and a length of 20 mm in the nipple 1b.
A pulsation absorbing hose was used as a sample, in which an orifice portion 1e of 1 mm in diameter was formed, and an orifice portion 5b with an inner diameter of 3.8 mm and a length of 20 mm was formed in the orifice member 5 (FIG. 2).

Comparative Example 1 Connecting fittings similar to those in Example 1 were fixed to both ends of a nylon braided hose similar to those in Example 1 to serve as a sample.

Comparative Example 2 For the sample of Comparative Example 1, the inner diameter of the hose was 4 mm,
An orifice member with a length of 40 mm was inserted and fixed by caulking with a caulking member inserted into the outside of the hose, and used as a sample.

The pulsation absorption effect of four types of samples constructed as described above was measured using the measuring device shown in FIG. The measuring device connects the discharge port of a pump P (a 10-blade vane pump) rotated by a motor M to a measuring block BK through a sample S, which is further connected to a gearbox G, and the pump P is attached to the gearbox G. Return hose R to tank T
It has a closed-loop pipe configuration in which the water is returned by For such a conduit, a pressure transducer H was placed immediately after the pump P discharge port and immediately after the sample.
After converting the pulsating pressure of those measurement devices into electrical signals, they are amplified by charge amplifiers CA1 and CA2, and
It was analyzed and recorded using a channel FFT analyzer F and an X-Y recorder X. The measurement conditions at this time were: pump rotation speed 900 rpm, load pressure 40 Kg/cm ² ,
Oil temperature is 80℃.

Figure 4 shows the degree of pulsation attenuation determined from the measurement results as described above. From the graph in FIG. 4, it can be seen that the samples of Examples 1 and 2 have significantly improved pulsation absorption effects compared to the samples of Comparative Examples 1 and 2. Furthermore, the sample of Example 2 has a further improved pulsation absorption effect compared to the sample of Example 1, and has excellent pulsation absorption effect in all frequency bands. Furthermore, in a power steering unit that uses the pulsation-absorbing hose of the present invention as the high-pressure hose, the generation of noise has been significantly reduced.

[Effects of the invention] The invention can absorb pulsations over a wide range. Therefore, there is an advantage that the same pulsation absorbing hose can be used between power steering units having different specifications of the pump steering device.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views showing embodiments of the pulsation absorbing hose of the present invention, Figure 3 is a block diagram of a measuring device for measuring the effect of pulsation absorption, and Figure 4 is the measuring device shown in Figure 3. FIG. 5 is a block diagram of the power steering unit. Main symbols in the drawing: 1: first connection fitting, 2: second connection fitting, 3: flexible tube, 4: first spiral tube, 5: orifice member, 1e, 5b: orifice part, 6: caulking Member 7: second spiral tube.

Claims (1)

[Scope of utility model registration request] A first connecting fitting for connecting one end to the discharge port of the pump of the power steering unit, and a second connecting fitting for connecting one end to the supply port of the steering device operated by pressure oil discharged from the pump. a flexible tube connected to the other end of each of the first connecting fitting and the second connecting fitting, a tubular orifice member inserted in the middle of the flexible tube, and the first connecting fitting. a first spiral tube, one end of which is inserted into the other end of the connecting fitting, and disposed within the flexible tube, and one end of which is fitted into the orifice member, and disposed within the flexible tube so as to extend toward the steering device side. A pulsation absorbing hose for a power steering unit consisting of a second spiral pipe.