JPS62118188A - Pressure pulsation damper - 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] [Industrial Application Field] The present invention relates to a pressure pulsation damping device, and more specifically, for example, a pump pressure damping device that is most effective for suppressing noise from a hydraulic pump in a hydraulic pressure generating device. The present invention relates to a pressure pulsation damping device for damping pulsations.

[Prior Art] Fig. 8 shows a conventional pressure pulsation damping device (1), in which end plates (3) and (4) with both ends of a cylindrical main body (2) closed, each having a lower end than the main body (2). Inlet pipes of small diameter and the same diameter as each other (5
) and an outlet pipe (6).

Conventionally, pressure pulsation damping devices have been designed with the primary fundamental frequency of pressure pulsations from a hydraulic pump as the target, and this fundamental frequency [r+] is given by equation (1).

Here, N: pump rotation speed, plow nib plunger or vane number.

For example, suppose the pump is driven by a 4-pole motor at 50 Hz and has 7 plungers.

becomes.

On the other hand, the propagation speed of pressure waves in hydraulic fluid is (
2) Equation becomes.

Here, K: Bulk modulus of hydraulic oil δ: Thickness of tube wall E: Young's modulus γ of tube material. : Pipe radius ρ : Density of hydraulic oil Further, the propagation speed of the pressure wave shown in equation (2) is about 1100 m/see to 1300 m/see in general applications.

In order to obtain a practical attenuation effect for the first fundamental frequency, the wavelength [λ] must be extremely large, e.g., λ, = V
/r, twist, λ1 = about 746CII, and the main body (
2) length b = 160 c + s. In other words, a piston pump with seven plungers operates at 1500 rpm.
When driven with
= 1 6 0 cml = f2/2 = 80
c+5 13=120cm, and the total length of the device is 15+1. +16. +
Z3=240cm. Therefore, the weight of the device is also large.

As shown in FIG. 9, such a pressure pulsation damping device (1) is connected via a rubber hose (9) to a discharge pipe (8a) of a hydraulic pump (8) driven by an electric motor (). , and was used while being supported and fixed by an appropriate support member (10). (8b) is the suction port of the hydraulic pump (8).

[Problems to be Solved by the Invention] The conventional pressure pulsation damping devices as described above were designed based on the primary fundamental frequency of pressure waves, and were large and heavy, making them difficult to use in hydraulic pumps, etc. There were problems in that it was difficult to connect directly and use it, and the installation area was large.

The present invention has been made to solve these problems, and an object of the present invention is to provide a pressure pulsation damping device that is small and lightweight enough to be directly connected to a hydraulic pump or the like.

[Means for Solving the Problems] The pressure pulsation damping device according to the present invention includes a cylindrical body that causes harmonic interference in internal wave phenomena, and a body that is attached to the body and has the same diameter. with smaller diameter inlet and outlet tubes.

[Operation] In the present invention, the acoustic power of pressure pulsations is directly attenuated by harmonic wave interference.

[Embodiment] Fig. 1 shows an embodiment of the present invention, in which a pressure pulsation damping device (11) includes a cylindrical body (12) that causes wave interference in harmonics of pressure pulsations; End plates (13) (14) with both ends closed, an inlet pipe (15) attached to the side wall of the main body (12) and having a smaller diameter than the main body (12), and an end plate (
14) and has the same diameter as the inlet pipe (15).
6).

Here, the relationship between the actual hydraulic pump pressure pulsation waveform and harmonics is as shown in Fig. 2, when a hydraulic pump with seven plungers is driven at 1450 rpm. Third harmonics are prominently occurring. Also,
The seventh and higher harmonics are also included internally. The specifications shown in FIG. 1 for attenuating harmonics by causing wave interference in such harmonics can be obtained from equation (3).

Equation (3) is a well-known calculation equation for automobile mufflers, etc., which ignores the viscosity of oil, etc., and the attenuation amount (L) is given by: Here, f: Frequency [1-1zl 11: Inlet pipe length [,] 12: Body length [鵠] 13: Outlet pipe length [ring] Al: Inlet pipe and outlet pipe cross-sectional area [em2] A2: Main body cross-section Area [C x 2] A: Constant determined by the shape of the main body a: Speed of sound inside the device [Tsuru/sea].

In particular, if the harmonic frequency is set to obtain practical attenuation of the 5th to 7th order, it will be λ = f5 = = 107 cm, which is significantly shorter than the wavelength of λt = 746e theory. The specifications shown in Figure 1 are "l" = 115 = 11
s= 10cei1+2=41+1=40a plow1+4=b2/2=20e1s3=30cm Therefore, the total length of the device is 112+1,3 with the thickness of the end plate (13) t=0.3c plow 11'14+L=50.3cm, making the device smaller and lighter.

In addition, by removing harmonics, the pressure pulsation waveform is
The result is as shown in FIG.

As mentioned above, the compact and lightweight pressure pulsation damping device (
11), as shown in FIG. 4, the inlet pipe (15) is directly connected and attached to the discharge port (8a) of the hydraulic pump (8);
can be supported.

Note that the inlet pipe (15) in Fig. 1 is the end plate (13).
The same damping effect can be obtained.

FIG. 5 shows another embodiment, in which the pressure pulsation damping device (21)
The interior of the cylindrical main body (22), which is closed at both ends with end plates (23) and (24), is divided into two chambers by a partition wall (2)), and an insertion tube (28) is inserted into the partition wall (2)). Attach an inlet pipe (25 mm) to the side wall of each divided chamber to connect the two chambers.
) and the outlet pipe (26) are installed parallel to each other.

In this way, by forming the harmonic wave interference space into a two-stage structure, the pressure pulsation damping effect is further improved.

The above pressure pulsation damping device (21) connects the inlet pipe (25) to the discharge port (8a) of the hydraulic pump (8), as shown in FIG.
) is installed and supported directly in conjunction with the

In Fig. 5, the inlet pipe (25) and the outlet pipe (26) are arranged parallel to each other and in the same direction, but as shown in Fig. 7, they can be arranged at any angle (θ). They can be arranged in different directions.

By adopting such a structure, the damping effect is not affected.
The piping can be installed to suit the situation, and the degree of freedom in manufacturing can be expanded.

[Effect of the invention] As is clear from the above description, the present invention has an inlet pipe,
Since harmonic interference of the wave phenomenon is caused inside the cylindrical main body to which the outlet pipe is attached, a significant reduction in size and weight can be achieved.

[Brief explanation of drawings]

Figures 1 to 4 show an embodiment of the present invention, where Figure 1 is a plan cross-sectional view, Figures 2 and 3 are pressure pulsation waveform diagrams, and Figure 40 is a plan view of the installed state. be. 5 and 6 show other embodiments, FIG. 5 shows the knee, -
- A plan sectional view, and FIG. 6 is a plan view of the installed state. FIG. 7 is a side view of still another embodiment. FIG. 8 is a plan sectional view of a conventional pressure pulsation damping device, and FIG. 9 is a plan view of the installed state. (11) (21)...Pressure pulsation damping device, (12)
(22)...Body, (13) (14) and (23)
) (24)... end plate, (15) (25)... inlet pipe, (18) (26)... is outlet pipe, (2))...
- Bulkhead, (28)...insertion tube. In each figure, the same reference numerals indicate the same or corresponding parts. Patent applicant: Mitsubishi Precision Co., Ltd. Figure 1 Figure 2 Figure 1 Missing base liquid 6; Arrow height 8! J 1; Missing fundamental wave Figure 8 Figure 9

Claims (4)

[Claims] (1) A cylindrical body with both ends closed to cause harmonic interference in internal wave phenomena due to pressure pulsation input, and a cylindrical body with a diameter smaller than that of the main body and the same diameter as the other. A pressure pulsation damping device comprising an inlet pipe and an outlet pipe. (2) The pressure pulsation damping device according to claim 1, wherein the pressure pulsation is a pump pressure pulsation of a hydraulic pump. (3) A partition wall that divides the interior of the main body into two chambers, an insertion tube attached to the partition wall that communicates the two chambers with each other, and an inlet tube and an outlet tube respectively arranged in the two chambers. A pressure pulsation damping device according to claim 1. (4) Claim 3, wherein the inlet pipe and the outlet pipe are arranged on the main body peripheral wall in different directions at arbitrary angles.
Pressure pulsation damping device as described in .