19results about How to "Reduce low frequency noise" patented technology

The invention provides a ventilation sound insulator and a silencer assembly, and the ventilation sound insulator comprises a closed box body which is hollow to form a cavity; the plurality of hollow pipes respectively penetrate through the box body to form a plurality of channels which are mutually separated and independent from the cavity; wherein an elastic film is fixed on the inner wall of one channel, and the elastic film and the cavity form a film resonator. By the adoption of the sound insulation box, low-frequency noise can be effectively reduced by means of the thin film resonator formed by the elastic film and the cavity with the proper size, meanwhile, the sound insulation channel is matched with a common channel, so that the section of the box body has enough air flow passing area, air resistance is reduced, and noise is reduced. The ventilation sound insulator can effectively reduce low-frequency noise, can keep enough ventilation area proportion, and can be applied to more actual scenes.

The utility model discloses a turbofan shell, centrifugal turbofan and breathing machine, wherein the turbofan shell comprises a volute upper cover, a volute lower cover fixedly installed below the volute upper cover, an air flow channel forming circumferential uniform section and an air outlet communicated with the air flow channel, the air outlet is tangent to the air flow channel, and the centrifugal turbofan is arranged in the volute lower cover. An air inlet is formed in the top of the volute upper cover, a filling block which is installed on the volute upper cover and is of a spiral structure is arranged in the airflow channel, the starting end of the filling block is located at a circumferential inlet of the airflow channel, and the tail end of the filling block right faces the air outlet. And the thickness of the filling block is linearly reduced to zero from the starting end along with the increase of the circumferential angle of the airflow channel. According to the utility model, the filling block with the spiral structure is arranged, and the thickness of the filling block is gradually reduced, so that the runner area of the airflow channel is gradually increased along with the increase of the circumferential angle in the circumferential direction, the flow change of airflow is better met, the pneumatic efficiency is improved, and the noise is reduced.

The utility model discloses an efficient air conveying system for processing ultra-fine calcium carbonate, which is characterized in that a blanking control valve is arranged on a blanking pipe, the rear end of the blanking pipe is connected with a main conveying pipe, the front end of the main conveying pipe is connected with a front-end fan, the main conveying pipe is connected with a plurality of conveying branch pipes, and the conveying branch pipes are connected with an air blower. According to the efficient air conveying system for ultra-fine calcium carbonate processing, the situation that in the prior art, in the actual use process, tail gas at the rear end is still directly exhausted as waste gas, waste of aerodynamic force and air pressure is caused, and noise is large is improved; by arranging the air suction pump and the return pipe, the whole air conveying system is integrally closed, the pressure loss in the conveying process can be reduced, the conveying efficiency can be improved, the energy consumption can be reduced, the closed system can reduce low-frequency noise in the equipment production process to a certain extent, and noise pollution is reduced.

This invention relates to the field of vehicles, providing a housing structure, a rear bumper assembly, a vehicle body, and a vehicle. The housing structure includes a housing body with a receiving groove for accommodating a pressure relief valve on a rear side panel. The housing body can be positioned on the outside of the rear side panel of the vehicle, and an exhaust passage communicating with the pressure relief valve is formed between the receiving groove and the rear side panel. The exhaust passage has an exhaust port facing the rear end of the vehicle. When the vehicle is in motion, the airflow outside the vehicle bypasses the housing body and flows towards the rear end of the vehicle. Since the exhaust port of the exhaust passage faces the rear end of the vehicle, the airflow outside the exhaust passage passing through the exhaust port causes minimal pressure changes within the exhaust passage, resulting in minimal pressure differential fluctuations between the exhaust passage and the inner side of the rear side panel. This effectively reduces the frequency and amplitude of the pressure relief valve's flapping action, thereby reducing low-frequency noise generated by pressure differential fluctuations in the acoustic cavity and ensuring passenger comfort.

This invention relates to a high-voltage, capacitor-free, low-noise linear regulator. It comprises a high-voltage switching voltage follower, a self-zeroing error amplifier, and voltage divider resistors. The high-voltage switching voltage follower significantly enhances the system's transient response to load changes and improves power supply rejection in the mid-frequency range. The self-zeroing error amplifier, together with the high-voltage switching voltage follower, forms a global slow loop. The self-zeroing error amplifier employs a ping-pong self-zeroing method, effectively reducing low-frequency flicker noise and offset while ensuring continuous operation in the time domain. This invention introduces a settling phase between the self-zeroing and amplification phases of the ping-pong module, significantly reducing output glitches caused by amplifier settling time. This invention operates stably without an external output capacitor, supports a wide input and output voltage range, and possesses excellent characteristics such as low noise, high power supply rejection, and fast response, making it suitable for various demanding high-voltage power supply applications.

The invention discloses a phase frequency detector, a phase-locked loop and a chip, the phase frequency detector comprises a first trigger, a second trigger, a first AND gate and a second AND gate, the CK end of the first trigger is connected with a reference signal, the D end of the first trigger is connected with a high potential, the first input end of the first AND gate is connected with the Q end of the first trigger, and the second input end of the first AND gate is connected with the Q end of the second trigger; the output end of the second AND gate is connected with the RST end of the first trigger, the CK end of the second trigger is connected with a feedback signal, the D end of the second trigger is connected with a high potential, the first input end of the second AND gate is connected with the Q end of the first trigger, the second input end of the second AND gate is connected with the Q end of the second trigger, and the output end of the second AND gate is connected with the RST end of the second trigger; the first trigger and the first AND gate are powered by a first power supply, the second trigger and the second AND gate are powered by a second power supply, and the first power supply and the second power supply are the same or different power supplies. According to the invention, the linearity of the phase frequency detector is improved, the low-frequency noise of the phase-locked loop is reduced, and the area and the power consumption are reduced.

The invention provides an air conditioner indoor unit and an air conditioner system. The indoor unit comprises a shell; the liquid pipe is partially located in the shell, the liquid pipe comprises a first pipe section and a second pipe section which are connected, the first pipe section penetrates through the shell, and the first pipe section is obliquely arranged towards the second pipe section from the exterior of the shell, so that a bent part is formed at the joint of the first pipe section and the second pipe section; a refrigerant flows into the liquid pipe from the inlet of the first pipe section, a filter is arranged between the inlet of the first pipe section and the bent part in the flowing direction of the refrigerant, a metal net is arranged in the filter, and an included angle is formed between the plane where the metal net is located and the flowing direction of the refrigerant; according to the air conditioner indoor unit, when a refrigerant flows to the bent part, the pulse impact amplitude generated by the refrigerant to the liquid pipe can be reduced more continuously, and therefore low-frequency noise caused by the fact that vibration of a pipeline is transmitted to the indoor unit shell is reduced.

A sound absorption structure for a volute of a noise-reducing centrifugal fan and its air inlet, wherein a sound absorption plate is fixed on the volute side plate by a mounting plate, and a muffler chamber is formed between the sound absorption plate and the volute side plate; a plurality of web sound absorption plates are evenly arranged horizontally and vertically on the volute web plate; a plurality of obliquely arranged arc guide blocks are arranged on the arc-shaped side wall of the volute air inlet. Compared with the existing technology, the beneficial effects of the present invention are as follows: the present invention adopts a spatial sound absorption structure design, which greatly increases the sound absorption "effective area"; has a good noise reduction effect; has a safe and reliable structure, and does not require repeated maintenance and replacement during the service life; the sound absorption material has little effect on the fan performance, and the effect on the fan efficiency is less than 1%; and can be widely used in ventilation and air supply industries with high requirements for environmental comfort (low noise).

The invention provides a non-metal acoustic board which comprises a shell and a sound absorber located in the shell, the shell comprises a panel (11), a back plate (12), an upper side plate (13) and a lower side plate (14), an opening cavity is formed in the side close to the panel (11), the opening cavity comprises a first layer cavity and a second layer cavity, and the first layer cavity is communicated with the second layer cavity. The first-layer cavity is located between the panel and the second-layer cavity, and openings in the open cavities all penetrate through the panel. The non-metal acoustic board is large in cavity inner area, large in cavity number, light in weight, high in strength and high in sound absorption coefficient.

The utility model discloses novel composite sound insulation vacuum laminated glass which comprises indoor glass, silicone sealant is fixedly arranged on the edge of the outer side of the indoor glass, a vacuum laminated glass assembly is fixedly arranged on the outer side of the silicone sealant, and a hollow cavity is formed between the indoor glass and the vacuum laminated glass assembly. The vacuum laminated glass assembly comprises laminated glass and outdoor glass matched with the laminated glass, a vacuum cavity is formed between the laminated glass and the outdoor glass, the vacuum laminated glass is formed by compounding three layers of glass, and the hollow cavity is formed in the vacuum laminated glass, so that the effects of isolating high-frequency noise and insulating heat are achieved; the vacuum layer and the double-layer laminated sheet are additionally arranged in the vacuum laminated glass assembly, the effect of reducing low-frequency noise can be achieved, the overall structural strength is high, the vacuum cavity and the hollow cavity are designed in a combined mode, the sound insulation and noise reduction effects are remarkable, and the vacuum laminated glass assembly has the characteristics of sunlight radiation prevention, good privacy, sound insulation and noise reduction.

The invention discloses an exhaust silencer with a self-adaptive adjusting valve. The exhaust silencer comprises a first exhaust pipe and an adjusting valve assembly. Channels extending from the air outlet end to the air inlet end of the first exhaust pipe in the extending direction of the first exhaust pipe are formed in the opposite positions of the pipe wall of the first exhaust pipe, and a plurality of through silencing holes are formed in the pipe wall of the first exhaust pipe in the circumferential direction and the extending direction of the first exhaust pipe; the adjusting valve assembly comprises a fixing base, two elastic pieces and a valve plate. The fixed seat is fixedly connected to the outer wall of the first exhaust pipe; the valve plate comprises a baffle plate and at least two connecting strips; the blocking piece is vertically arranged and slidably connected into the first exhaust pipe. The first ends of the two connecting strips are fixedly connected to the opposite positions of the edge of the blocking piece correspondingly, and the two connecting strips are slidably connected in the two channels correspondingly. The first ends of the two elastic pieces are connected with the second ends of the two connecting strips respectively, and the second ends of the two elastic pieces are connected with the fixing base. Corresponding to different application working conditions, the position of the valve plate can be adjusted in a self-adaptive mode, and the noise reduction performance is improved under the condition that smooth tail gas circulation is guaranteed.

The utility model relates to the field of brakes, and discloses a fixed brake caliper without low-frequency noise, which comprises a caliper body, the caliper body consists of an inner caliper body and an outer caliper body, a jaw is formed on one side, close to a brake disc, of the caliper body, a caliper back is arranged on one side, far away from the brake disc, of the caliper body, and a caliper back opening is formed on the caliper back; a guide rod is installed in the caliper back opening and arranged in the axial direction, and the inner brake block and the outer brake block are arranged on the guide rod in a sleeving mode and located at the two ends of the guide rod. An arc-shaped noise reduction blocking piece is formed on the outer edge of the caliper back opening of the outer brake block, and the outer brake block is located on the inner side of the noise reduction blocking piece. The brake caliper has the advantages of being stable and reliable in structure, neater in appearance, few in parts, free of low-frequency noise and the like.

The present invention relates to the field of angular displacement measurement technology, and more specifically, to a high-resolution angular displacement measurement device and method with a variable range. When the angle to be measured is small, the device is in a high-resolution mode, at which time the two light spots on the detector are superimposed and interfered, and the angular displacement is measured using the interference effect; when the angle to be measured is large, the device is in a large-range mode, at which time the two light spots on the detector are separated, and the angular displacement is measured using the optical lever effect. While achieving high-resolution angular displacement measurement, the present invention takes into account a larger range, and at the same time uses a periodic square wave modulation method to suppress low-frequency noise in the angle measuring device, and achieves two-dimensional angle measurement.

The utility model discloses an air inlet noise reduction structure and gas heating water heater, the air inlet noise reduction structure comprises a noise reduction pipe and noise reduction cotton, the noise reduction pipe is provided with an air inlet end, an air buffer end and a connecting end, the air inlet end is provided with a trumpet-shaped air inlet, the air buffer end is of a round inverted L-shaped structure, and the connecting end is connected with the noise reduction cotton. The joining end is provided with a joining port for joining a premixer; the silencing cotton sleeve is arranged at one end of the air inlet end close to the air inlet. According to the air inlet noise reduction structure, through the structure that the noise reduction pipe is combined with the noise reduction cotton, the noise reduction cotton is used for absorbing noise generated by friction between air and the inner wall of the pipeline in the air inlet process, the air inlet noise is prevented from being further expanded through the pipeline, and through the action of the long and smooth noise reduction pipe, the air inlet noise is further reduced; the ignition deflagration sound of the subsequent water heater and the low-frequency noise generated during small fire combustion are reduced.

This invention discloses a multi-layer composite sound insulation cotton for drain pipes. It comprises, from the outside in, a release paper layer, a first butyl rubber layer, an IXPE foam layer, a second butyl vibration damping layer, and a non-woven protective layer, stacked sequentially. The first butyl rubber layer is made of modified butyl rubber; the IXPE foam layer is made of cross-linked polyethylene foam with an independent closed-cell structure; and the second butyl vibration damping layer is made of high-damping butyl rubber. The sound insulation cotton of this invention achieves low-temperature continuous bonding and initial vibration damping and waterproofing through the first butyl rubber layer; it achieves sound absorption, sound insulation, and heat preservation through the IXPE foam layer; it forms a constrained damping structure with the second butyl vibration damping layer, the first butyl rubber layer, and the IXPE foam layer to suppress pipe vibration and block sound bridge transmission; and it forms a double waterproof structure with the non-woven protective layer and the first butyl rubber layer to prevent external water vapor penetration. It integrates multiple functions such as bonding, vibration damping, sound absorption, sound insulation, heat preservation, waterproofing, and protection.

The invention provides an air conditioner indoor unit and an air conditioner system. The indoor unit comprises a shell; the liquid pipe is partially located in the shell, the liquid pipe comprises a first pipe section and a second pipe section which are connected, the first pipe section penetrates through the shell, the first pipe section is obliquely arranged towards the second pipe section from the exterior of the shell, and the first pipe section is at least provided with a first bent part; the fixing structure is used for fixing the liquid pipe on the shell; a refrigerant flows into the liquid pipe from an inlet of the first pipe section, and the first bent part is arranged between the inlet of the first pipe section and the fixing structure in the flowing direction of the refrigerant in the liquid pipe; according to the air conditioner indoor unit, pulse impact generated by a refrigerant on the liquid pipe at the fixing structure is reduced, so that the vibration amplitude of the liquid pipe at the fixing structure is reduced, and low-frequency noise caused by the fact that vibration is transmitted to the indoor unit shell is reduced.

The utility model discloses a photovoltaic distribution box, comprising a distribution box body, an opening of the distribution box body is provided with a circle of baffle plate with a T-shaped cross section; the multifunctional protection mechanism comprises a sealing strip arranged on the outer side of the baffle in a sleeving mode, and a hollow filling cavity is formed in the outer side of the sealing strip; a plurality of air holes are evenly distributed in the sealing strip, and the hollow filling cavity is filled with a plurality of spherical activated carbon particles. Corresponding water retaining protruding edges are integrally formed and outwards arranged at the positions, not provided with the hollow filling cavities, of the sealing strip. And the box door is installed at the opening of the distribution box body in an openable and closable manner, and after the box door is closed to the opening of the distribution box body, the box door extrudes and abuts against the outer end part of the sealing strip. According to the utility model, a reasonable gas circulation effect can be effectively formed so as to realize heat dissipation of the distribution box, and sufficient waterproof and moisture-proof performance can be formed so as to ensure the operation stability and safety of the distribution box.

The utility model relates to a balance weight part, a pipeline, a pipeline balance weight assembly and an air conditioner. A mounting hole (11) and a first anti-rotation structure (12) are arranged on the counterweight part (1), the mounting hole is suitable for allowing a pipeline body (21) to penetrate through, and the first anti-rotation structure is suitable for being matched with a second anti-rotation structure (22) arranged on the pipeline body so as to limit circumferential rotation of the counterweight part. According to the technical scheme, even if the pipeline vibrates, the balance weight piece cannot rotate accidentally, so that the preset gravity center is prevented from shifting, then the inherent frequency of the pipeline is prevented from changing, and low-frequency noise caused by the pipeline is reduced.

The application discloses a double-layer noise reduction air guide ring, which comprises an inner air guide ring layer and an outer air guide ring layer. The inner air guide ring layer comprises a circular ring segment, a mounting panel, an inlet flow guide segment and an outlet diffuser segment. The inlet flow guide segment and the outlet diffuser segment are fixedly connected with the two ends of the circular ring segment respectively. The inlet flow guide segment is in a circular arc shape. The mounting panel is fixedly connected with the side of the inlet flow guide segment, which is away from the circular ring segment. The outer air guide ring layer comprises a flat segment, a circular arc segment and a partition plate. The end of the circular arc segment, which is close to the inner air guide ring layer, is provided with an outer layer outlet end. The end of the circular arc segment, which is away from the inner air guide ring layer, is provided with an outer layer inlet end. The mounting panel and the flat segment are provided with a connecting structure. The partition plate is provided with a plurality of partition plates. The resonant cavities between the adjacent partition plates are different in size. The application further discloses a fan comprising the double-layer noise reduction air guide ring. The application has the advantages of high fan efficiency and low air inlet noise.