1. Ride quality.
Ride quality is the term that stands for the following set of aspects: – Jerk – Car acceleration – Vertical car vibration – Lateral car vibration – Sound inside the car 1.1 Jerk Jerk, unit: m/s3, is the time-derivative of acceleration. If the elevator moves with high jerk, acceleration changes are very abrupt and can be felt as bumps. 1.2 Car acceleration Car acceleration, unit: m/s 2, determines how long it takes before the car reaches its maximum speed. A high acceleration is generally considered uncomfortable, however, it gives the impression that the car moves very fast. 1.3 Vertical car vibration Vibration is also measured as acceleration, unit: m/s 2. This kind of vibration can be felt by the feet of a person, but is also discerned by the stomach and the internal ear. It is mostly caused by vibrations of the drive and frequency converter. These are transferred to the car by the traction media. 1.4 Lateral car vibration Lateral car vibration is caused by non-straightness of the guide rails, play between car and guide rails and non-smooth guide rail transitions. Generally Generally,, it causes low-frequent lateral movements of the car. 1.5 Sound in the car Generally,, sound levels in elevators should be low enough not to interfere Generally with speech, but hearing the elevator in motion is desirable from a psychological point of view.
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Information on noise and vibration
Noise and vibration performance
Adjacent room roomss1 LpAmax 30 dB(A) incl. impulse noise Shaft2 LpAeq LpAmax
62 dB(A) 65 dB(A) impulse noise
Structure-borne Structure-born e noise3 Octave [Hz] 63 125 250 500
Lamax [dB] 90 90 85 85
Landing Door noise4 LpAmax 60 dB(A) Pass-by noise LpAmax 50 dB(A) Impulse noise at top floor LpAmax 55 dB(A)
Car Sound pressure level LpAeq 50 ±3 dB(A) 57 dB(A) impulse noise LpAmax Vibrations (ride (ride quality) Lateral – ISO MPtP < 15 mg – ISO A95 < 10 ±3 mg Vertical – ISO MPtP – ISO A95
< 25 mg < 15 ±5 mg
1
VDI 2566-2:2004 prescribes a maximum permissible A-weighted sound level L pAmax in adjacent rooms of 30 dB(A). It is the responsibility of the architect / building designer to ensure that the walls and roof of the shaft provide enough air-borne and structure-borne noise attenuation. The main parameter is the area-specic mass of the hoistway wall. Table 2 of VDI 2566-2:2004 provides rules for the design of the walls depending on the room conguration. These rules are based on standard DIN 4109 supplement 1 a.
2
VDI 2566-2:2004 species a maximum sound pressure level in the hoistway of 75 dB(A).
3
The levels listed are the levels according to VDI 2566-2:2004. The Schindler 3300 and Schindler 5300 elevator systems generally fulll these levels with a large margin, depending on the type of wall.
4
VDI 2566-2:2004 species a maximum A-weighted A-weighted sound pressure level level for door noise of of 65 dB(A).
Information on noise and vibration
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Denitions
LpAeq
LpAmax
Sound A-weighted equivalent sound pressure level: the steady sound level that, over a specied period of time, would produce the same energy equivalence as the uctuating sound level actually occurring. (Can be interpreted as a mean level and measured directly with an integrating sound level meter.) Maximum A-weighted sound pressure level All sound pressure level measurements require setting «FAST» of the sound level meter. Vibration / structure-borne noise
Lamax ISO MPtP
ISO A95
Maximum acceleration level [dB] lin re: 1·10-6 m/s 2 ISO-weighted Maximum Peak-to-Peak vibration value, according to ISO 18738:2003 ISO-weighted A95 vibration value according to ISO 18738:2003. 95% of all peaks of the ISO-weighted signal are below this value.
Applicable standards VDI 2566-2:2004 ISO 2631-1:1997
Mechanical vibration and shock – Evaluation of human exposure to whole-body vibration – Part 1: General requirements
ISO 18738:2003
Lifts (elevators) – Measurements of lift ride quality
ISO 8041:1990 and Amd.1:1999
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Acoustical design for lifts without machine room
Information on noise and vibration
Human response to vibration – Measuring instrumentation
2. Sound – basics.
Sound is an air pressure variation that is sensed by the ears. An example of sound generating equipment is a loudspeaker. The movement of the loudspeaker membrane causes a varying rarefaction and compression of the air in front of it.
p0 + p(t) [Pa]
compression zones
p0
p0
0 p0 + p(t)
t[s] rarefaction zones
Figure 2.1
The speed with which the rareed and compressed zones travel away from the speaker is the sound speed c. At room temperature 20 °C, c = 344 m/s. The pressure variation p(t) is added to the local atmospheric pressure p0. It is only this pressure variation that is heard by the ear. To accommodate the large range of human hearing, the sound pressure level (SPL) is dened: Lp : = 20·log
p p0
where: Lp Sound pressure level [dB] p Instantaneous sound pressure [Pa] p0 Reference pressure, equals 20_Pa (threshold of hearing) Normally, the sound pressure level is A-weighted, see gure 2.2. An A-weighted sound pressure level is designated with dB(A). A-weighting is widely considered the best weighting to represent human hearing. Low-frequency components are strongly attenuated by this type of frequency weighting.
Information on noise and vibration
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Figure 2.2 A-weighting curve
Correction [dB] 10
0
–10
–20
– 30
– 40
–50
– 60
–70
– 80 101
102
103
104
f [Hz]
Examples of different A-weighted sound pressure levels are shown in table 2.1.
Table 2.1
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Information on noise and vibration
Phenomenon
SPL [dB(A)]
Jet taking off, 25 meters, threshold of pain
140
Live concert
120
Heavy truck at small distance
100
Noisy ofce
80
Conversational speech, 1 m
60
Room at home
40
Whisper, leaves rustling
20
Threshold of hearing
0
3. Vibration – basics.
a
a
[m/s2]
[mg]
0.01
1.02
0.1
10.2
1
102
Within the elevator industry, the recognized unit for vib ration is milli-g (mg). One mg equals ca. 0.01 m/s 2. Values in mg and m/s2 can be easily converted using table 3.1. Subjective vibration perception The way people «feel» vibrations depends strongly on the vibration direction. One has to distinguish between vertical vibration and horizontal vibration, the latter often called lateral vibration. The difference in perception is resembled by the ISO-lter that is described in ISO 8041 Amd.1:1999. The lter weighting curves for horizontal and vertical vibrations are shown in gures 3.1 and 3.2.
Table 3.1 The threshold of vibration perception is about 2–3 mg for vertical vibrations.
Figure 3.1 Filter weighting curve for horizontal vibrations according to ISO 8041 Amd. 1:1999
Weighting, dB 0 –10 –20 – 30 – 40 –50 – 60 –70 – 80 0,1 0,16 0,25 0,4 0,63
1
1,6
2,5
4
6 ,3
10
16
25
40
63 100 160 250 400
Frequency, Hz Figure 4.2 Filter weighting curve for vertical vibrations according to ISO 8041 Amd.1:1999 From the weighting curves it can be seen that humans are most sensitive for horizontal vibrations in the frequency range 0.5–2 Hz. For vertical vibrations, this range is 5–12 Hz.
Weighting, dB 0 –10 –20 – 30 – 40 –50 – 60 –70 – 80 0,1 0,16 0,25 0,4 0,63
1
1,6
2,5
4
6 ,3
10
16
25
40
63 100 160 250 400
Frequency, Hz
Information on noise and vibration
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4. Structure-borne noise.
Above 20 Hz, vibration may be called structure-borne noise. Such vibrations may generate audible sound. Generally Generally,, structure-borne noise can be considered important for frequencies below 1000 Hz. Standard VDI 2566-2:2004, «Acoustical design for lifts without machine room», presents a guideline for the amount of structure-borne noise that may be present in a hoistway wall of an elevator. The purpose of this guideline is to minimize perception of elevator noise in adjacent rooms according to international standards. Whereas vibrations have unit m/s2 or mg, structure-borne noise is measured in dB because of its strong relation with airborne noise. La : = 20·log
a a0
where: La Vibration level [dB] a Instantaneous acceleration [m/s 2] a0 Reference acceleration according to ISO, a 0 = 1·10-6 m/s 2 The maximum permissible values are listed in table 4.1. Octave band
La,max
mid-frequency [Hz]
[dB] lin re: 1E-6m/s2
63
90
125
90
250
85
500
85
Table 4.1
8 0 . 5 0 . N E . b i v & e s i o n . M M O C B G
www.schindler.com
These levels do not automatically g uarantee that the sound pressure level in adjacent rooms will not exceed 30 dB(A). The walls need to have a specic mass such that this requirement can be fullled. Architects and building contractors have the responsibil ity to assure that the building interface is designed appropriately.
