Silencer and exhaust device for small engineering machinery

Abstract

The invention discloses a small engineering machinery silencer and an exhaust device.The small engineering machinery silencer comprises a mounting pipe and a silencing cavity, and the silencing cavity comprises a first Helmholtz resonator, a first cavity, a second cavity and a second Helmholtz resonator which are sequentially arranged through partition plates; the first Helmholtz resonator is communicated with the first chamber through a first short pipe, and the second Helmholtz resonator is communicated with the second chamber through a second short pipe and is used for reducing noise; the first chamber and the second chamber are communicated through a first perforated pipe, and one end, close to the second chamber, of the first perforated pipe is communicated with an exhaust pipeline; one end of the mounting pipe is communicated with the first cavity through the detachable silencing section, and the other end of the mounting pipe is connected to the small engineering machinery. The small engineering machinery silencer and the exhaust device are compact in structure, small in size, convenient to mount, dismount and clean, wide in noise reduction frequency band and good in application effect.

Description

Technical Field

[0001] The present invention relates to the technical field of construction machinery, and particularly relates to a muffler and an exhaust device for small construction machinery. Background Art

[0002] For small construction machinery, such as loaders, its main noise radiation sources are engines, including exhaust noise and surface radiation noise. By adopting a customized muffler structure, the contribution of exhaust noise can be significantly reduced.

[0003] From the perspective of spectral characteristics, the peak frequency of the noise of small construction machinery vehicles is mainly low frequency, but it also takes into account high-frequency noise. Due to the limited installation space of small construction machinery vehicles, large muffling equipment cannot be used. Therefore, a special muffler structure needs to be designed to take into account the processing of low-frequency noise and medium-high-frequency noise in specific frequency bands while ensuring a compact structure. This multi-objective optimization design needs to consider the collaborative optimization including acoustic performance, flow characteristics, and structural strength, etc., which has become a technical difficulty in the current field of construction machinery noise control and is also a key problem that needs to be solved urgently by relevant technical personnel. Summary of the Invention

[0004] Objective: In order to overcome the deficiencies in the prior art, the present invention provides a muffler and an exhaust device for small construction machinery, and the muffler for small construction machinery has a compact structure, is convenient to install, and can simultaneously target low-frequency noise in a specific frequency band and take into account medium-high-frequency noise.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a muffler for small construction machinery, including an installation pipe and a muffling chamber. The muffling chamber includes a first Helmholtz resonator, a first chamber, a second chamber, and a second Helmholtz resonator sequentially separated by a partition; The first Helmholtz resonator is communicated with the first chamber through a first short pipe, and the second Helmholtz resonator is communicated with the second chamber through a second short pipe, which is used to reduce noise; The first chamber and the second chamber are communicated through a first perforated pipe, and one end of the first perforated pipe close to the second chamber is communicated with an exhaust pipe; The installation pipe is communicated with the first chamber through a detachable muffling section, and the other end is connected to small construction machinery.

[0007] In some embodiments, a second perforated pipe is provided inside the second chamber. The second perforated pipe is communicated with the first chamber through its pipe orifice and is communicated with the second chamber through the perforations on its side surface.

[0008] In some embodiments, the perforations on the walls of the first perforated pipe and the second perforated pipe are evenly distributed, the aperture of the perforations is 4-5 mm, and the porosity is 17-20%.

[0009] In practical applications, on the premise of ensuring that the exhaust gas can pass through smoothly, the aperture and porosity of the perforations on the first perforated pipe and the second perforated pipe can be adjusted according to the silencing frequency to be applicable to different frequency bands and exhaust backpressure requirements, so as to achieve an ideal silencing effect.

[0010] In some embodiments, the sizes of the first Helmholtz resonator and the second Helmholtz resonator are related to the peak frequency of the noise of small construction machinery f 0 Satisfy: ; In the formula, c is the speed of sound; the resonance frequency of the first Helmholtz resonator f 0 is 1 times the peak frequency of the noise of the small construction machinery engine f 1 , S is the internal cross-sectional area of the first short pipe, l is the length of the first short pipe, d is the inner diameter of the first short pipe, V is the volume of the first Helmholtz resonator; The resonance frequency of the second Helmholtz resonator f 0 is 2 times the peak frequency of the noise of the small construction machinery engine f 2 , S is the internal cross-sectional area of the second short pipe, l is the length of the second short pipe, d is the inner diameter of the second short pipe, V is the volume of the second Helmholtz resonator.

[0011] In practical applications, according to the rated engine speed, installation space, exhaust temperature in the application scenario, etc., relevant parameters can be adjusted to ensure that the silencing frequency bands of the first Helmholtz resonator and the second Helmholtz resonator correspond to the peak frequency bands of the noise.

[0012] During adjustment, when considering the influence of the exhaust gas temperature, as the exhaust gas temperature rises, the density of the exhaust gas decreases and the speed of sound increases accordingly. By calculating the transmission loss, it can be found that the peak frequencies of the sound absorption frequency bands of the first Helmholtz resonator and the second Helmholtz resonator shift towards the high-frequency direction. Therefore, it is necessary to give priority to ensuring that the lengths of the first short pipe and the second short pipe remain unchanged or are extended, while maximizing the diameters of the first short pipe and the second short pipe, and facilitating the unified processing of other components. Using the exhaust port temperature as a reference can make the noise reduction frequency band wider and ensure that the first Helmholtz resonator and the second Helmholtz resonator correspond to the peak frequency band of the engine.

[0013] In some embodiments, the f 1 、f 2 The corresponding peak transmission loss satisfies: α A1 + β A2 + γ A3 = Ф; In the formula, A1 is the average value of the transmission loss of the muffler for small construction machinery in the frequency range of 0 - 2000 Hz, A2 is the peak transmission loss corresponding to the resonance frequency f 1 ; A3 is the peak transmission loss corresponding to f 2 ; α , β , γ are the weighting values of A1, A2, and A3 when Ф reaches the maximum value; both A2 and A3 are greater than 15 dB.

[0014] The cavity of the first Helmholtz resonator, the cavity of the second Helmholtz resonator, and the partition distance between the first chamber and the second chamber can be adjusted. According to α A1 + β A2 + γ A3 = Ф maximum value, the coupling design optimization of the cavity size, the inner diameter of the first short pipe, and the inner diameter of the second short pipe is carried out.

[0015] In some embodiments, the exhaust pipe is inclined to the ground, and the upper side edge of the exhaust pipe is longer than the lower side edge, that is, it prevents water from entering the inside of the muffler and corroding the pipe.

[0016] In some embodiments, the detachable muffler section is a cylindrical structure with two concentric inner and outer pipes, with a length of 750 - 800 mm and a diameter of 120 - 150 mm; The detachable silencing section includes a first circular tube on the inner side and a second circular tube on the outer side. One end of the first circular tube is fixedly connected to the installation tube, and the other end is detachably connected to the first chamber; the ends of the first circular tube and the second circular tube away from the first chamber are flange-connected. The flange connection can realize the closing or opening of the chamber between the first circular tube and the second circular tube of the detachable silencing section.

[0017] In some embodiments, the other end of the first circular tube is connected to the first chamber by a clamp, and the clamped part can be rotated at an angle, so that the angle of the small construction machinery muffler relative to the construction machinery can be adjusted.

[0018] In some embodiments, the first circular tube is a densely perforated tube with a pore diameter of 4-8 mm, and the perforation spacing is 2-8 mm. The inner tube diameter can be adjusted according to the requirements of the silencing frequency band, and it is satisfied that the diameter of the first circular tube is larger than the diameter of the installation tube and smaller than the diameter of the second circular tube.

[0019] In some embodiments, when sound-absorbing material is filled between the first circular tube and the second circular tube, the detachable silencing section is used as a resistive muffler; when the space between the first circular tube and the second circular tube is empty, the detachable silencing section is used as a reactive muffler. The sound-absorbing material can be selected from porous sound-absorbing materials such as felt. By disassembling the flange structure, the sound-absorbing material can be replaced or cleaned through the opening.

[0020] In practical applications, the length and diameter of the detachable silencing section can be adjusted according to the silencing frequency of different construction machinery engines and the installation space.

[0021] In a second aspect, the present invention provides a small construction machinery exhaust device, including an exhaust pipe and the small construction machinery muffler according to any one of claims 1-6; the exhaust pipe includes a mounting seat, an intake pipe and a flexible connection. One end of the flexible connection is connected to the mounting seat through the intake pipe, and the other end is connected to the installation pipe of the small construction machinery muffler.

[0022] The setting of the flexible connection isolates or reduces the vibration transmission between the engine body and the muffler structure.

[0023] In some embodiments, the inner diameter of the flexible connection is greater than or equal to the outer diameters of the intake pipe and the installation pipe.

[0024] Beneficial effects:

[0025] The small construction machinery muffler and exhaust device provided by the present invention are structurally compact, small in size, can adjust the installation angle, and are convenient to install; the Helmholtz resonator is used to specifically reduce the low-frequency noise in a specific frequency band, and the perforated pipe in the muffler chamber is used to reduce the medium and high-frequency noise. The detachable muffler section can be filled with sound-absorbing materials or kept empty to use the detachable muffler section as a resistive muffler or a reactive muffler to achieve the effect for different noise reduction frequency bands. In addition, the flange structure can efficiently realize the replacement or cleaning of the sound-absorbing materials. Based on the above structure, the noise reduction frequency band of the muffler takes into account both the low-frequency specific frequency band and the medium and high-frequency noise frequency band, and the noise reduction frequency band is wider.

[0026] During the actual application process, the noise at the peak frequency can be specifically eliminated according to the engine speed, installation space, and exhaust temperature, and the noise reduction effect of the medium and high-frequency noise is ensured through the first perforated pipe, the second perforated pipe, and the detachable muffler section. At the same time, the resistance in the area where the air flow passes through the whole device is small, ensuring that the exhaust back pressure of the engine meets the requirements and the application effect is good. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0028] Figure 1 It is a three-dimensional structure schematic diagram of the exhaust device of the small construction machinery in the embodiment of the present invention.

[0029] Figure 2 It is a planar structure schematic diagram of the exhaust device of the small construction machinery in the embodiment of the present invention.

[0030] Figure 3 It is a structure schematic diagram of the detachable muffler section in the embodiment of the present invention.

[0031] Figure 4 It is a schematic diagram of the transmission loss curve of the exhaust device of the small construction machinery in the embodiment of the present invention.

[0032] In the figure: 1, air inlet; 2, flexible connection; 3, second round pipe; 4, clamp connection; 5, first Helmholtz resonator; 6, first short pipe; 7, first chamber; 8, second chamber; 9, first perforated pipe; 10, second perforated pipe; 11, second short pipe; 12, second Helmholtz resonator; 13, exhaust pipe; 14, first round pipe; 15, flange structure. Detailed Embodiments [[ID=�1]]

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use.

[0034] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that for the convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the said technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may also include different values. It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0035] Embodiment 1:

[0036] This embodiment provides a muffler for small construction machinery, as Figure 1 、 Figure 2 shown, which includes an installation pipe and a muffler chamber. The muffler chamber includes a first Helmholtz resonator 5, a first chamber 7, a second chamber 8, and a second Helmholtz resonator 12 sequentially separated by partitions; the installation pipe is connected to the first chamber 7 through a detachable muffler section, and the other end is connected to the small construction machinery; the first Helmholtz resonator 5 is connected to the first chamber 7 through a first short pipe 6, and the second Helmholtz resonator 12 is connected to the second chamber 8 through a second short pipe 11; the first chamber 7 and the second chamber 8 are connected through a first perforated pipe 9, and one end of the first perforated pipe 9 close to the second chamber 8 is connected to an exhaust pipe 13; one end of the installation pipe is connected to the first chamber 7, and the other end is an air inlet 1, and the air inlet 1 is connected to the engine exhaust port of the small construction machinery by bolts.

[0037] A second perforated pipe 10 is provided inside the second chamber 8. The second perforated pipe 10 is connected to the first chamber 7 through its pipe orifice and is connected to the second chamber 8 through the perforations on its side.

[0038] In this embodiment, the lengths of the first short pipe 6 and the second short pipe 11 are 44 mm, and this length includes the length of the partition hole of 2 mm. A number of perforations are evenly distributed on the walls of the first perforated pipe 9 and the second perforated pipe 10, the aperture of the perforations is 4 mm, and the porosity is 17%.

[0039] In some embodiments, the dimensions of the first Helmholtz resonator 5 and the second Helmholtz resonator 12 are related to the peak frequency of the noise of small construction machinery f 0 Satisfy: ; Wherein, c is the speed of sound; the resonance frequency of the first Helmholtz resonator 5 f 0 is 1 times the peak frequency of the noise of the small construction machinery engine f 1 , S is the inner cross-sectional area of the first short tube 6, l is the length of the first short tube 6, d is the inner diameter of the first short tube 6, V is the volume of the first Helmholtz resonator 5; The resonance frequency of the second Helmholtz resonator 12 f 0 is 2 times the peak frequency of the noise of the small construction machinery engine f 2 , S is the inner cross-sectional area of the second short tube 11, l is the length of the second short tube 11, d is the inner diameter of the second short tube 11, V is the volume of the second Helmholtz resonator 12.

[0040] In this embodiment, f 1 = 80 Hz, f 2 = 160 Hz.

[0041] In some embodiments, the f 1 、f 2 corresponding peak transmission loss satisfies: α A1 + β A2 + γ A3 = Ф; Wherein, A1 is the average value of the transmission loss of the small construction machinery muffler in the frequency range of 0 - 2000 Hz, A2 is the peak transmission loss corresponding to the resonance frequency f 1 ; A3 is the peak transmission loss corresponding to f 2 ; α , β , γ are the weighted values of A1, A2 and A3 when Ф reaches the maximum value; both A2 and A3 are greater than 15 dB.

[0042] In this embodiment, α , β , γ The three weighting values are respectively set to 1, 1, and 0.5. By adjusting the position of the partition, the internal volume of the first Helmholtz resonator 5 is determined to be 0.0005 m 3 , and the internal volume of the second Helmholtz resonator 12 is 0.00165 m 3 . The inner diameter of the first short pipe 6 is 12.8 mm, and the inner diameter of the second short pipe 11 is 11.4 mm. At this time, A2 and A3 are 20.2 dB and 16.6 dB respectively, and the Ф value is 57.8 dB, reaching the maximum within the optional dimension range of the installation space. The muffler structure designed according to this ratio can specifically reduce the noise at the peak frequency of 80 Hz, while taking into account the noise reduction requirements of 160 Hz and medium-high frequency noise.

[0043] Figure 4 FIG. is a schematic diagram of the transmission loss curve of the exhaust device of small and medium-sized construction machinery in this embodiment. As can be seen from the figure, the peak frequencies of the noise reduction frequency bands of the first Helmholtz resonator 5 and the second Helmholtz resonator 12 shift towards the high-frequency direction.

[0044] The exhaust pipe 13 is inclined to the ground, and the upper side edge of the exhaust pipe 13 is longer than the lower side edge.

[0045] In this embodiment, as Figure 3 shown, one end of the detachable muffler section is fixedly connected to the installation pipe, and the other end is detachably connected to the first chamber 7 through a clamp connection 4. Further, the detachable muffler section is composed of a first circular pipe 14 on the inner side, a second circular pipe 3 on the outer side, and a flange structure 15. The first circular pipe 14 and the second circular pipe 3 are concentrically distributed. The length of the second circular pipe is 750 mm, and the inner diameter is 120 mm.

[0046] The first circular pipe 14 is a densely perforated pipe, and the perforation diameter on the pipe wall is 4 - 8 mm, and the hole pitch is 2 - 8 mm. The first circular pipe 14 and the second circular pipe 3 are fixedly connected at the end close to the first chamber, and there is an opening at the end far from the first chamber, and a flange structure 15 is provided at the opening position.

[0047] In this embodiment, a felt is filled between the first circular pipe 14 and the second circular pipe 3 as a sound-absorbing material and used as a resistive muffler. The overall muffler constitutes an impedance composite muffler structure. The felt can be filled or replaced and cleaned by disassembling and installing the flange structure 15.

[0048] In some embodiments, no sound-absorbing material is filled between the first circular pipe 14 and the second circular pipe 3, and it is used as a reactive muffler.

[0049] Embodiment 2:

[0050] This embodiment provides a small construction machinery exhaust device, including an exhaust pipe and the small construction machinery muffler as described in Embodiment 1; the exhaust pipe includes a mounting seat, an intake pipe, and a flexible connection 2. One end of the flexible connection 2 is connected to the mounting seat through the intake pipe, and the other end is connected to the installation pipe of the small construction machinery muffler; the inner diameter of the flexible connection 2 is greater than or equal to the outer diameters of the intake pipe and the installation pipe.

[0051] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only used to explain the relative positional relationship and movement conditions between components in a certain specific posture. If this specific posture changes, the directional indication will also change accordingly. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application.

[0052] In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0053] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood through specific circumstances.

[0054] The above is only the preferred embodiment of the present application. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present application, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present application.

Claims

1. A muffler for a small construction machinery, characterized in that, It includes an installation pipe and a muffler chamber. The muffler chamber includes a first Helmholtz resonator, a first chamber, a second chamber, and a second Helmholtz resonator that are successively separated by a partition plate. The first Helmholtz resonator is communicated with the first chamber through a first short pipe, and the second Helmholtz resonator is communicated with the second chamber through a second short pipe for reducing noise. The first chamber and the second chamber are communicated through a first perforated pipe, and one end of the first perforated pipe close to the second chamber is communicated with an exhaust pipe. One end of the installation pipe is communicated with the first chamber through a detachable muffling section, and the other end is connected to a small construction machinery.

2. The small construction machinery muffler according to claim 1, characterized in that, A second perforated pipe is provided inside the second chamber. The second perforated pipe is communicated with the first chamber through its pipe orifice and is communicated with the second chamber through the perforations on its side surface.

3. The small construction machinery muffler according to claim 2, characterized in that, The perforations on the pipe walls of the first perforated pipe and the second perforated pipe are evenly distributed, the aperture of the perforations is 4-5 mm, and the porosity is 17-20%.

4. The small construction machinery muffler according to claim 1 or 2, characterized in that, The sizes of the first Helmholtz resonator and the second Helmholtz resonator satisfy: ； Wherein, c is the speed of sound; the resonance frequency of the first Helmholtz resonator f 0 is the 1x noise peak frequency of the small construction machinery engine f 1 , S is the inner cross-sectional area of the first short tube, l is the length of the first short tube, d is the inner diameter of the first short tube, V is the volume of the first Helmholtz resonator; Resonance frequency of the second Helmholtz resonator f 0 Is twice the peak noise frequency of the small construction machinery engine f 2 , S Is the inner cross-sectional area of the second short tube, l Is the length of the second short tube, d Is the inner diameter of the second short tube, V Is the volume of the second Helmholtz resonator.

5. The small construction machinery muffler according to claim 4, characterized in that, The f 1 、f 2 corresponding peak transmission loss satisfies: α A1 + β A2 + γ A3 = Ф; where A1 is the average transmission loss of the muffler for small construction machinery in the frequency range of 0 - 2000 Hz, and A2 is the peak transmission loss corresponding to the resonance frequency f 1 ; A3 is the peak transmission loss corresponding to f 2 ; α , β , γ are the weighted values of A1, A2, and A3 when Ф reaches the maximum value; both A2 and A3 are greater than 15 dB.

6. The small construction machinery muffler according to claim 1, wherein The exhaust pipe is inclined to the ground, and the upper side edge of the exhaust pipe is longer than the lower side edge.

7. The small construction machinery muffler according to claim 1, characterized in that, The detachable muffling section is a cylindrical structure with two concentric inner and outer pipes, with a length of 750-800 mm and a diameter of 120-150 mm. The detachable muffling section includes a first circular pipe inside and a second circular pipe outside. One end of the first circular pipe is fixedly connected to the installation pipe, and the other end is detachably connected to the first chamber. The ends of the first circular pipe and the second circular pipe away from the first chamber are flange-connected.

8. The small construction machinery muffler according to claim 7, characterized in that, The first circular pipe is a densely perforated pipe with an aperture of 4-8 mm and a hole spacing of 2-8 mm. The diameter of the first circular pipe is larger than the diameter of the installation pipe and smaller than the diameter of the second circular pipe.

9. The small construction machinery muffler according to claim 7 or 8, characterized in that, When sound-absorbing materials are filled between the first circular pipe and the second circular pipe, the detachable muffling section is used as a resistive muffler. When the space between the first circular pipe and the second circular pipe is empty, the detachable muffling section is used as a reactive muffler.

10. An exhaust device for a small construction machinery, characterized in that, It includes an exhaust pipe and a small construction machinery muffler according to any one of claims 1-9. The exhaust pipe includes a mounting seat, an air inlet pipe, and a flexible connection. One end of the flexible connection is connected to the mounting seat through the air inlet pipe, and the other end is connected to the installation pipe of the small construction machinery muffler. The inner diameter of the flexible connection is greater than or equal to the outer diameters of the air inlet pipe and the installation pipe.

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