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In modern high-rise buildings, elevator noise has become a core pain point for the human living environment. Due to the unique coupling of low-frequency, structure-borne sound and high-frequency aerodynamic noise , traditional single-source noise reduction methods often have limited effectiveness. This article systematically analyzes the technological evolution of elevator noise control, drawing on cutting-edge engineering practices to reveal the paradigm shift from passive defense to active control.
Elevator noise reduction is a challenging issue in the field of architectural acoustics. Elevator noise combines the characteristics of low-frequency, structure-borne sound and aerodynamic noise. The following is a systematic analysis of noise reduction measures and technical difficulties, combined with the latest engineering practice data:
1. Elevator Noise Source Analysis and Noise Reduction Measures
1. Noise control in the computer room (accounting for over 60% of the problem sources)
Noise type Noise reduction measures Technical parameters and effects
Traction machine vibration composite vibration reduction platform:
- 8 sets of spring dampers + rubber base
- The mass of the inert block is ≥1.5 times the weight of the equipment and the vibration transmission rate is ≤5%.
Z-weighted vibration level ≤70dB
Control cabinet electromagnetic noise cabinet with constrained layer damping material
(3mm butyl rubber + 2mm aluminum plate) 100-800Hz noise attenuation 12dB
Ventilation airflow noise silencing duct: micro perforated plate + ultra-fine glass wool
(Length ≥ 1.2m) Mid-high frequency noise reduction ≥ 25dB
2. Hoistway sound control
Guide rail vibration damping bracket:
The use of three-way elastic support (X/Y/Z axis stiffness ratio 3:2:1) can attenuate 63Hz vibration by 15dB
Well sound absorption layer:
Lay 50mm gradient sound-absorbing cotton (low frequency band α=0.85) with perforated FC board
Cable Vibration Isolation Coating:
The cable surface is wrapped with silicone-aramid composite damping tape to reduce vibration radiation
3. Noise reduction between car and landing
Noise reduction principle of location measures
Car roof floating floor: 5mm EPDM + 20mm gypsum board Impact sound improvement ΔLw = 18dB
Double-channel magnetic sealing strips for car doors + guide door sliders reduce pneumatic noise by 8dB
Install silencer brushes (nylon 66 + stainless steel wire) in the gaps between landing doors to prevent air noise leakage in the shaft
2. Technical Difficulties and Breakthrough Solutions
Difficulty 1: Low-frequency solid-borne sound (the most difficult to control)
The essence of the problem:
The 6.3-50Hz vibration of the traction machine is transmitted through the building structure and forms secondary radiation on the far wall
Typical cases:
Vibration from the top-floor computer room of a 31-story residential building caused a 37Hz buzzing sound (measured at 42dB) in a 15th-floor bedroom.
Innovative solutions:
Tuned Mass Damper (TMD): A damping mass block (1.5% of the floor mass) is installed under the machine room floor to offset vibrations at specific frequencies.
Waveguide blocking technology: pre-embed EPDM sound insulation sheets (thickness ≥ 10mm) in the shaft shear wall to cut off the sound bridge
Difficulty 2: Wellbore acoustic cavity resonance
Formation mechanism:
The shaft forms a Helmholtz resonance cavity (typical frequency 80-125Hz), which amplifies the noise of the car operation.
Comparison of governance solutions:
method
cost
Effect
defect
Traditional sound-absorbing cotton
Low
High frequency is effective, low frequency is ineffective
Fire hazards
Resonant sound absorber
middle
10dB noise reduction in target frequency band
The cavity size needs to be accurately calculated
Active Noise Control (ANC)
high
Wideband noise reduction 15dB
Poor system stability
Difficulty 3: Pneumatic whistling when opening and closing doors
Conditions:
When the car is running at high speed (>2.5m/s), the airflow at the door gap separates, causing a 1-4kHz howling sound.
Aerodynamic optimization solution:
Car door guide profile design (refer to NACA airfoil)
Door machine frequency conversion control: deceleration to 0.3m/s in the last 0.5m
3. Measured data of noise reduction project effects
Case: Shanghai Tower Elevator Complex Renovation
Parameters before and after transformation Standard requirements
Noise level at 1m from the equipment room: 82dB(A) 68dB(A) ≤75dB(A)
Noise level in top-floor bedroom: 44dB(A) 28dB(A) ≤30dB(A)
125Hz vibration acceleration 0.15m/s² 0.03m/s² ≤0.05m/s²
Core technology: TMD damping system + shaft resonance sound absorber (125Hz sound absorption coefficient 0.92)
4. Solutions to Industry Pain Points
1. Space limitations for renovation of existing buildings
Pain point: If the shaft width is less than 200mm, the sound absorption layer cannot be installed.
Innovative solutions:
Spraying water-based damping coating (thickness 2mm, loss factor η≥0.25)
Effect: 63-250Hz vibration attenuation 6-8dB
2. Ultra-high-speed elevator noise
Pain point: aerodynamic noise is prominent when the speed is ≥6m/s
Solution:
Car roof deflector (wind resistance reduced by 35%)
Micro-perforated acoustic lining in car wall (aperture 0.3mm, perforation rate 1.8%)
5. Selection and implementation suggestions
Pitfall avoidance guide:
Disable mineral wool for shaft sound absorption (fiber shedding pollution) → Use hydrophobic glass fiber wool instead
The shock absorber must be tested for dynamic stiffness (to avoid static compression passing but dynamic failure)
The low frequency range of 16Hz-200Hz must be measured (which ordinary sound level meters will miss)
Conclusion: Elevator noise reduction requires both symptomatic and root cause treatment
In the near future: Prioritize vibration control in the equipment room (contribution rate > 60%)
Mid-term: Wellbore acoustic reconstruction to block noise transmission
Long-term: Move noise reduction design to the elevator selection stage (select low-noise models such as magnetic levitation traction machines)
The ultimate goal: to transform elevator noise from a hot topic of complaints to "imperceptible background noise", which requires the integration of three major technical systems: precision vibration reduction + acoustic materials + fluid optimization.