KR100528389B1 - Pulsation Reduction Device - Google Patents

Abstract

The pulsation reducing apparatus for reducing the pulsation of oil flowing in the hydraulic pipe line of the present invention includes a plurality of interiors of the closed pipe between the closed pipe branched from the pipe line and the terminal pipe is closed, and the branch point and the end from the pipe line. Install at least one stottle that divides it into areas.

Description

Pulsation Reduction Device

The present invention relates to a pulsation reducing device for reducing the pulsation of the pipeline for transmitting the hydraulic pressure.

A pulsation reduction device for reducing the pulsation of a fluid flowing in a hydraulic line is known, and a device for reducing the inhalation noise generated when the secondary air of a vehicle engine is introduced is disclosed in Japanese Patent Application Laid-Open No. 60 (1985) -40720. It is disclosed in the publication. The apparatus is provided with a silencer for a predetermined range of frequency components and an auxiliary silencer for other frequency components on the upstream side of the check valve of the secondary air passage communicating with the secondary air supply port of the exhaust system. The auxiliary silencer is formed by protruding a plurality of closed tubes having a length of 1/4 of a frequency wavelength to be silenced to the side of the secondary air passage. Plural pulsations can be effectively reduced by providing a plurality of closed tubes adapted to a plurality of frequency components included in the pulsation.

In the conventional apparatus, the noise effect is obtained by providing a closed tube having a length of 1/4 of the frequency wavelength to be noise. Therefore, if the frequency of noise is large, the number of the closed tube is also increased. Problem arises that is complicated and large.

In addition, if the pulsation reducing device is simply constituted by one closed tube, the maximum value of the transmission loss is obtained at an odd frequency of the quarter-wave resonant mode determined by the shape of the closed tube or the like. High frequency cannot be reduced effectively. That is, high frequency waves such as fundamental waves of pulsations and their secondary and tertiary waves cannot be efficiently reduced simultaneously.

(Initiation of invention)

An object of the present invention is to provide a compact pulsation reducing device that can reduce the pulsation of the fluid flowing in the hydraulic pipe.

In order to achieve the above object, the pulsation reducing device for reducing the pulsation of oil flowing in the hydraulic pipe line of the present invention comprises a closed pipe branched from the line and closed at the end, and between the branch point and the end from the line. Install at least one throttle to divide the interior of the closed tube into a plurality of zones.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows the principle of the pulsation reducing device of the first embodiment.

Fig. 2A is a view showing the whole of the pulsation reducing device of the first embodiment.

Fig. 2B is a view showing the terminal portion of the rubber hose.

2C is a sectional view of a throttle portion;

Fig. 3 is a diagram showing design values and measured values of transmission loss in the pulsation reducing apparatus of the first embodiment.

Fig. 4 is a diagram showing the principle of the pulsation reducing device of the second embodiment.

Fig. 5 is a diagram showing design values and measured values of transmission loss in the pulsation reducing apparatus of the second embodiment.

Fig. 6 is a diagram showing design values and measured values of transmission loss in the pulsation reducing apparatus of the third embodiment.

Fig. 7 is a diagram showing design values and measured values of transmission loss in the pulsation reducing apparatus of the fourth embodiment.

8 shows an example of another throttle.

9 shows an example of another throttle.

10 is a view for explaining a case where a part of the side brunch is installed inside the pump;

(The best mode for carrying out the invention)

First embodiment

Hereinafter, a first embodiment of the pulsation reduction device according to the present invention will be described with reference to FIGS.

1 is a principle diagram showing the apparatus of the first embodiment, 1 is a hydraulic pump, 2 is a main pipe for guiding hydraulic oil discharged from the hydraulic pump 1, 3 is a rubber hose formed by branching from the main pipe (2) Side brunch (closed pipe), 5 is a throttle representing hydraulic equipment such as a control valve, and 6 is a hydraulic oil tank.

As shown in Fig. 1, the side brunch 3 is connected to the main pipe 2 via the start end 3a, and the end 3d is closed to form a closed end. A metal throttle 4 is formed inside the side brunch 3, and the side brunches are divided into the start end 3a side and the end 3d side by the throttle 4.

In FIG. 1, the length from the shaft center of the main pipe 2 to the lower end of the throttle 4 (the lower end in FIG. 1) is L ₁ , and the length between the upper and lower ends of the throttle 4 is L ₂ and the throttle 4. Let L3 be the length from the upper end to the end 3d of the side brunch ₃ , A is the cross-sectional area of the inner diameter of the side brunch ₃ , and a cross-sectional area of the opening of the throttle 4 is a. The pressure pulsation and the flow rate pulsation at the start end 3a of the side brunch 3 are P _i and Q _i , respectively, and the pressure pulsation and the flow rate pulsation at the end 3d are respectively. If P ₀ and Q ₀ , the relationship of equation (1) is established between them. The matrix of Claims 1, 2, and 3 on the right side of the equation (1) has a length L ₁ portion of the side brunch 3, a throttle 4 portion of the length L _{2 at the} upper and lower ends, and a length L. ₃ ) Corresponds to each transfer matrix of parts. The transfer matrix of the throttle 4 of claim 2 is simplified by assuming that the length L ₂ is sufficiently short compared to the wavelength of the pulsation.

Where β (s) is the wave propagation coefficient in the fluid in the pipeline, Z ₀ is the characteristic impedance of the pipeline (= ρсξ _p (s) / A), ρ is the density of the fluid, c is the sound velocity of the fluid in the pipeline, ξ _p ( s) is the resistance coefficient according to the viscosity of the fluid in the duct, ξ ₀ (s) is the resistance coefficient according to the viscosity of the fluid in the throttle.

In equation (1), if the flow rate pulsation Q ₀ of the end 3d of the side brunch 3 is set to "0" (because the end 3d is a closed end), P _i and Q _i are obtained. The impedance Z _{s of} ) is as shown in equation (2).

The pressure pulsation and the flow rate pulsation at the inlet 3b of the main pipe 2 when the side brunch 3 is branched from the main pipe 2 are set to P ₁ and Q ₁ , respectively, and the main pipe ( 2) of the outlet (3c) of the pressure pulsation and flow rate pulsations, respectively P _2, Q ₂ in (1) and, if the transmission matrix T can be expressed by equation (3).

Here, since P ₁ = P _i = P ₂ , Q ₁ = Q _i + Q _2, the relationship of Q _i = P _i / Z _s obtained in Equation (2) is used, so that the transfer matrix (T) each coefficient is _{a, T 11 = 1, T 12} = 0, T 21 = 1 / Z s, T 22 = 1.

The transmission loss TL when the side impedance 3 branches and connects the characteristic impedance to the main pipe 2 of Z _c is given by equation (4) when expressed using the coefficient of the transfer matrix T. This equation (4) is derived from equations known in the field of transmission engineering and acoustic engineering.

Substituting the respective coefficients of the transfer matrix T described above in Equation (4), the transmission loss TL is the length of the conduit (L ₁ , L ₃ ) and the cross-sectional area (A) and the length of the throttle (L ₂ ). Is expressed by the cross-sectional area (a). Therefore, it is possible to set the transmission loss TL to the maximum at a desired frequency by varying the lengths L ₁ , L ₃ , the cross sectional area A, the throttle length L ₂ , and the cross sectional area a of the duct.

In the pulsation reducing device of the first embodiment, the length L ₁ , L ₃ , the cross-sectional area A, and the length of the throttle L ₂ , in each coefficient of the above-described formula (4) and the transfer matrix T, are given. ), The transmission loss can be set to obtain maximum values at two predetermined frequencies below the cross-sectional area (a). In other words, while the conventional side brunch can only obtain the maximum transmission loss at an odd frequency of the quarter-wave resonant mode, the pulsation reducing device of the first embodiment uses the length and the cross-sectional area of the side brunch 3 such as By determining the parameters according to the above formulas (1) to (4), the transmission loss maximum can be set at an arbitrary frequency. For example, the transmission is performed at the primary and secondary or secondary and tertiary frequencies of hydraulic pulsation. The loss maximum can be set.

In addition, the length (L ₁ ), (L ₃ ), cross-sectional area (A), throttle length (L ₂ ), cross-sectional area (a), etc. of the pipe for the maximum transmission loss (TL) at a desired frequency are It can obtain | require by calculating Formula (4) mentioned above, changing these values. It can also be obtained by repeating the start of the side brunch and measuring the transmission loss by experiment or the like. In addition, by combining computer simulation and experimental measurement, an efficient and highly accurate side brunch can be designed.

The length L ₁ is 770 mm, the L ₃ is 210 mm, the cross-sectional area A is 283.5 mm _2, and the throttle 4 inside the side brunch length L ₂ is 52 mm and the cross-sectional area a is 12.6 mm ₂ . Substituting into Equation (4), as indicated by the solid line (design value) in Fig. 3, the maximum value of the transmission loss appears as f ^* r.1 = 230 Hz and f ^* r.2 = 460 Hz. In this case, when the fundamental frequency of hydraulic vibration (pulsation) is 230 Hz, the vibration up to the secondary high frequency can be effectively reduced by one side brunch 3.

In 1st Embodiment, the material of the side brunch 3 is comprised by the rubber hose. The "(circle)" point plotted in FIG. 3 represents the measured value in said parameter, and there exists a difference from the design value shown by the solid line. This difference is mainly due to the reduction of the cross-sectional area of the caulking and the joint of the rubber hose, and the difference is almost eliminated when designed in consideration of this.

Thus, in the first embodiment, by forming the throttle 4 inside the side brunch 3, the reflection coefficient (or transmission coefficient) determined by the inertial effect (ρL ₂ / a) of the fluid in the throttle 4 portion The length of the pipe on both sides of the throttle 4 is adjusted to minimize the impedance Z _s of the side brunch 3 at two desired frequencies, that is, the transmission loss due to the side brunch 3 is reduced. You can do the best. Therefore, by one side brunch (closed tube), vibration reduction characteristics can be obtained in accordance with the frequency distribution of the pulsation.

In addition, since the first embodiment adopts a simple structure, the reliability of the device can be improved and the cost can be kept low compared with the case where a plurality of side brunch is provided.

Fig. 2 shows a mounting example in which the pulsation reducing device of the first embodiment is adapted to the reduction of the pulsation of the hydraulic pump. As shown in Fig. 2A, the discharge oil from the hydraulic pump 1 is supplied through a main pipe (delivery hose) 2, for example, toward a control valve or the like. One end of the main pipe 2 is connected to a block 1a provided at the delivery port of the hydraulic pump 1, and one end of the rubber hose 31 as the side brunch 3 is connected to the block 1a. It is. As shown in FIG. 2B, the other end of the rubber hose 31 is blocked by the blind plug 32, and the blind plug 32 is attached to the bracket 34 fixed to the main frame 35 through the bolt 33. It is installed. The rubber hose 31, i.e., the side brunch communicates with the main pipe 2 by the inner conduit of the block 1a. And 7 is a suction pipe.

As shown in FIG. 2C, a metal throttle 40 is inserted in the middle of the rubber hose 31, and the throttle 40 is tightened and fixed by a caulking ring 36 on the outside of the rubber hose 31. .

Second embodiment

Hereinafter, a second embodiment of the pulsation reducing device according to the present invention will be described with reference to FIGS. 4 and 5.

As shown in Fig. 4, in the apparatus of the second embodiment, two throttles 41 and 42 are provided in one side brunch 3A. In Fig. 4, the length from the shaft center of the main pipe 2 to the lower end of the throttle 41 (lower in Fig. 4) is L ₁ , and the length between the upper and lower ends of the throttle 41 is L ₂ , the throttle. The length from the upper end of the 41 to the lower end of the throttle 42 (the lower end in FIG. 4) is L ₃ , and the length between the upper and lower ends of the throttle 42 is L ₄ , and the side is in the state of the throttle 42. The length to the end 3d of the brunch 3A is L ₅ , the cross-sectional area of the inner diameter of the side brunch 3A is A, the cross-sectional area of the opening of the throttle 41 is a, and the cross-sectional area of the opening of the throttle 42 is b. do. When the pressure pulsation and the flow rate pulsation at the start end 3a of the side brunch 3 are P _i and Q _i , respectively, and the pressure pulsation and the flow rate pulsation at the end 3d are P _o and Q _o , respectively. The relationship of equation (5) holds between them.

Then, the transmission loss TL can be calculated by deriving an equation similar to the equation (4) according to the equation (5).

If the length L ₁ 615㎜, the 26㎜ L _2, L ₃ of the 186㎜, L ₄ the 42㎜, 108㎜ the L _5, 283.5㎟ the cross-sectional area A, the cross-sectional area of a 12.6㎟, the cross-sectional area b in 7.1㎟ As shown by the solid line (design value) in Fig. 5, the maximum value of the transmission loss appears as f ^* r.1 = 230 Hz, f ^* r.2 = 460 Hz and f ^* r.3 = 690 Hz. In this case, when the fundamental frequency of the hydraulic vibration is 230 kHz, the vibration up to the first, second and third high frequencies can be effectively reduced by one side brunch 3A.

In the second embodiment, the material of the side brunch 3A is formed of a rubber hose. As shown in FIG. 5 by the measured value "(circle)", it is the same as that of the 1st measured example about the point where the measured value differs in a design value in a high frequency range.

Third embodiment

Hereinafter, the present embodiment will be described with reference to FIGS. 1 and 6. The third embodiment employs a side brunch using a steel pipe instead of the rubber hose of the apparatus of the first embodiment. In addition, about the component same as 1st Embodiment, the same code | symbol as 1st Embodiment is attached | subjected and description is abbreviate | omitted.

In Fig. 1, the length L ₁ is 990 mm, the L ₃ is 250 mm, the cross-sectional area A is 295.6 mm ₂ , the length L ₂ of the throttle 4 inside the side brunch is 55 mm and the cross-sectional area a is 12.6 mm ₂ . Substituting into 1) to (4), as shown by the solid line (design value) of FIG. 6, the maximum value of the transmission loss appears by f ^* r.1 = 250 Hz and f ^* r.2 = 500 Hz.

As indicated by the point "○" in Fig. 6, the measured value of the transmission loss agrees well with the designed value in the third embodiment. This is because the steel pipe has a uniform cross-sectional area over its entire length, and a mathematical model with high precision regarding wave propagation characteristics is established. In the third embodiment, when the fundamental frequency of the hydraulic vibration is 250 Hz, the secondary frequency component can be effectively attenuated together with the fundamental frequency component.

Fourth embodiment

Hereinafter, the present embodiment will be described with reference to FIGS. 4 and 7. The fourth embodiment employs side brunch by steel pipe instead of the rubber hose of the device of the second embodiment. In addition, about the component same as 2nd Embodiment, the same code | symbol as 1st Embodiment is attached | subjected and the description is abbreviate | omitted.

In Fig. 4, length L ₁ is 738 mm, L ₂ is 30 mm, L ₃ is 225 mm, L ₄ is 48 mm, L ₅ is 134 mm, cross-sectional area A is 295.6 mm 2, cross-sectional area a is 12.6 mm 2, cross-sectional area b Is 7.1 mm 2, the maximum value of the transmission loss appears as f ^* r.1 = 250 Hz, f ^* r.2 = 500 Hz and f ^* r.3 = 750 Hz, as shown by the solid line (design value) in FIG. .

As indicated by the point "○" in FIG. 7, since the steel pipe in which the cross-sectional area is uniform for the side brunch 3A and a mathematical model with high precision is established, the measured value of the transmission loss is shown. Is in good agreement with the design. In the fourth embodiment, when the fundamental frequency of the hydraulic vibration is 250 Hz, the secondary and tertiary high frequency components can be effectively attenuated together with the fundamental frequency components.

In the first to fourth embodiments, a plurality of pipes connected in series through the throttles 4 and 41 and 42 are formed of the same material (rubber hose or steel pipe), but the plurality of pipes are made of different materials. In this case, the frequency characteristics of the pulsation reduction can be variously controlled by the combination of materials, and the change in the mounting surface in consideration of performance and cost can be increased.

In the first to fourth embodiments, the inside of one side brunch is divided by the throttle, but instead of dividing by the throttle, a tube of different diameter inserted between at least two pipes is used as a choke throttle. You may comprise a closed pipe so that it may have the same effect.

Four or more pipes may be connected in series by providing three or more throttles inside one side brunch. In this case, the maximum point of the pulsation reduction frequency can be increased in correspondence with the number of divided tubes. The pulsation reduction device according to the present invention can also be applied to pulsation reduction of other gases and liquids such as air pressure and water pressure.

In addition, in the above-described first embodiment, as shown in FIG. 2C with respect to the throttle, an example in which a metal throttle 40 is inserted in the middle of the rubber hose 31 to caulk the outside of the rubber hose 31 is shown. It does not need to be limited to this content. For example, an example of another throttle is shown in FIG. In FIG. 8, two rubber hoses 41 and 42 are connected by a joint (adapter) 43, and a throttle 43a having a reduced cross-sectional area is formed inside the joint 43. In FIG. The mouthpieces 44 and 45 are attached to the rubber hoses 41 and 42 to enable connection with the joint 43. The joint 43 is provided with an "O" ring 46 for the purpose of sealing. 2A and 2B, the other end of the rubber hose 41 is connected to the block 1a, and the other end of the rubber hose 42 is closed by the blind plug 32 to close the bolt 33. It is installed on the bracket 34 fixed to the mainframe 35 through. The rubber hoses 41 and 42 may be replaced by steel pipes.

9 shows an example of another throttle. The rubber hoses 51 and 52 are relayed to the relay bracket 53 through the joints 54 and 55, and the relay bracket 53 is a throttle narrower than the inner diameter of the rubber hoses 51 and 52. 53a is formed. The joints 54 and 55 are inserted into the bracket 53, and the mouthpieces 56 and 57 are attached to the rubber hoses 51 and 52 so as to be connected to the joints 54 and 55. The relay bracket 53 is mounted on the main frame. Joints 54 and 55 are equipped with " O " rings 58 for sealing purposes. In this way, the entire side brunch is fixed to the main frame.

In the first to fourth embodiments, an example in which the side brunch is mounted on the outside of the pump has been described, but the present invention is not necessarily limited to the content thereof. For example, the first throttle portion of the side brunch may be mounted inside the pump. Fig. 10 is a conceptual diagram showing the contents of an axial swash plate pump as an example. 61 shows the external appearance of the pump. As for the pump 61, the cylinder part 65 rotates by the rotation of the rotating shaft 64, The piston 66 is adjusted by the swash plate 67, and reciprocates, and the oil is sucked in inlet 62 The oil is discharged from the discharge port 63. 68 is a valve board. In the example of FIG. 10, the branch to the 1st side brunch 70 is formed in the vicinity of the valve plate 68 of the piping 69 to the discharge port 63. The first side brunch 70 is led to the first side brunch outlet 71. At the first side brunch outlet 71, a joint 72 having a throttle 72 a formed therein is mounted as in the joint of FIG. 8, and the second side brunch 73 is connected to the outside of the pump 61. . The mouthpiece 74 is attached to one end of the second side brunch to connect the second side brunch 73 to the joint 72. The end of the second side brunch 73 is closed by a blind plug as shown in FIG. 2B and fixed to a frame or the like. The throttle portion 72a of the joint 72 is thinner than the inner diameters of the first side brunch 70 and the second side brunch 73. The joint 72 is also equipped with an "O" ring 72b for the purpose of sealing. Corresponding to Fig. 1 of the first embodiment, the L ₁ portion of the side brunch 3 of Fig. 1 is connected to the first side brunch 70 of Fig. 10, and the throttle 4 of Fig. 1 is the joint of Fig. 10. At 72, L ₃ portions of the side brunch 3 in FIG. 1 correspond to the second side brunch 73 in FIG. 10, respectively.

The pulsation frequency varies depending on the rotational speed of the pump 61 and the like, and also depends on the use situation of the pump. Therefore, the frequency to be reduced also varies accordingly. However, even if the length of the first side brunch 70 inside the pump 61 cannot be adjusted, the diameter of the throttle or the second side brunch 73 of the joint 72 mounted on the outside of the pump 61 can be adjusted. Since it is possible to adjust the length and the like, it is possible to achieve a reduction in a desired frequency. As a result, up to the first throttle can be formed inside the pump to be common, contributing to the standardization and cost reduction of the pump capable of responding to pulsation reduction. The first side brunch 70 and the second side brunch 73 may be rubber hoses or steel pipes as in the above-described embodiment.

In addition, the branch of the side brunch is most efficient to form in the portion corresponding to the middle portion of the pulsation. Therefore, it is efficient to set as close to the valve plate as possible as in the example of FIG. However, considering the wavelength of the pulsation and the like, it is sufficiently effective even if it is provided outside the pump as shown in Fig. 2A of the first embodiment. For example, if the pulsation frequency is 200 kHz and the sound velocity in the pipe is 1,000 m / sec, the distance between the middle part and the middle part is 2.5 m. Exert.

Although the hydraulic pumps were described in the first to fourth embodiments, the present invention is not necessarily limited thereto. For example, in a construction machine etc., it is applicable also to the other actuator etc. which use hydraulic pressure. That is, it is possible to apply to all the parts which a pulsation becomes a problem in hydraulic pressure.

Claims (8)

In the pulsation reducing device for reducing the pulsation of the oil flowing in the hydraulic pipe, Branch and branch terminations from the conduit such that side branches branch off from the conduit and the transmission loss takes maximum at a plurality of frequencies including at least the fundamental frequency and the second harmonic of the pulsation. And at least one throttle for dividing the inside of the side brunch into a plurality of regions between the and the circumference. In the pulsation reducing device for reducing the pulsation of the oil flowing in the hydraulic pipe, A plurality of areas inside the side brunch between the branch and the end of the branch branch from the conduit such that a side branch branched from the conduit and the terminal is closed and a transmission loss at a plurality of frequencies is maximized. An inner diameter of the side brunch, the respective lengths of the plurality of regions, and the throttle, having at least one throttle divided into a plurality, so that at least the fundamental frequency of the pulsation and the transmission loss at the second harmonic have a maximum value. Pulsation reduction device, characterized in that for determining the characteristics of. The method of claim 2, The side brunch is divided into two regions by one throttle, and the inner diameter of the side brunch, each of the two regions, so that at least the fundamental frequency of the pulsation and the transmission loss at the second harmonic take maximum. Pulsation reduction device, characterized in that the length and the characteristics of the throttle are determined. The method of claim 2, The side brunch is divided into three regions by two throttles, and at least at the fundamental frequency, the second harmonic and the third harmonic of the pulsation, the inner diameter of the side brunch, the so that the transmission loss takes maximum. Pulsation reduction device, characterized in that each length of the three regions and the respective characteristics of the two throttles are determined. The method according to any one of claims 1 to 4, The side brunch is made of one tube, the throttle is a member inserted into the side brunch, pulsation reduction device, characterized in that fixed at a predetermined position. In the pulsation reducing device for reducing the pulsation of the oil flowing in the hydraulic pipe, At least two pipes having a side brunch branched from the conduit and closed at one end, the side brunch having a maximum transmission loss at a plurality of frequencies including at least the fundamental frequency and the second harmonic of the pulsation; And a joint member having a different diameter inserted between the two or more tubes so as to be a choke-type throttle. In the hydraulic pump for reducing the pulsation of the discharge oil, The main hydraulic line leading the oil to the discharge port, the side brunch branched off from the main hydraulic line, and at least a plurality of frequencies including the fundamental frequency and the second harmonic of the pulsation to maximize the transmission loss. And at least one throttle for dividing the inside of the side brunch into a plurality of areas between the branch point from the main hydraulic pipe line and the end, and at least a part of the plurality of areas is installed inside the hydraulic pump. Hydraulic pump, characterized in that. The method of claim 7, wherein And an area formed outside the hydraulic pump of the side brunch is replaceable.