GB/T 37153-2018Acoustic vehicle alerting system of electric vehicles running at low speed (English PDF)

3.1 acoustic vehicle alerting system; AVAS

a system for issuing a prompt sound to effectively transmit information to other road users when the noise value emitted by the vehicle is below a certain value

3.2 acoustic vehicle alerting system of electric vehicle running at low

speed a prompt sound from the vehicle’s acoustic-alerting system when the speed of the electric vehicle is lower than a certain value

3.6 rear plane of the vehicle

a vertical plane tangent to the trailing edge of the vehicle

3.7 sound pressure level; SPL

the base 10 logarithm of the ratio of the square root sound pressure to the reference sound pressure multiplied by 20

3.8 weighted sound level

sound level measured by a weighted network filter

4.1 Working speed range

The working speed range of the acoustic-alerting system shall be at least greater than 0km/h and less than or equal to 20km/h.

4.2 Sound level limit

4.2.1 The noise of the electric vehicle measured by the measurement method

specified in 5.6.2 shall be on each 1/3 octave included in it. At least two of the 1/3 octaves are not less than the sound levels specified in Table 1, and at the same time meet the requirements for the total sound level in Table 1.

4.2.2 Vehicles equipped with the acoustic-alerting system shall not emit more

than 75dB(A) of noise at the most when driving.

4.3 Frequency requirements

4.3.1 Frequency range

The sound of a vehicle equipped with the acoustic-alerting system shall contain at least two 1/3 octaves as specified in Table 1, and at least one 1/3 octave below 1600 Hz (including 1600). The minimum sound level of these two 1/3 octaves shall not be lower than the corresponding sound level limit specified in

Table 1.

4.5 Pause switch

4.5.1 For vehicles equipped with the acoustic-alerting system, the manufacturer

can choose whether to configure the pause switch.

4.5.2 The pause switch shall be placed in a position where the driver can see, touch and operate under normal driving conditions.

4.5.3 When the pause switch is activated, there shall be a clear signal device

(acoustic, optical, electrical or other device) release signal to alert the driver that the acoustic-alerting system running at low speed has been suspended.

5.1 Test equipment

5.1.1 Meteorological measuring equipment

Meteorological measuring instruments are mainly used to monitor environmental conditions during the test. The accuracy shall meet the following requirements.

5.1.2 Acoustic measuring equipment

5.2 Weather condition

During the test, meteorological conditions shall meet the following requirements.

5.3 Test site

5.3.1 Outdoor test

5.3.1.1 Outdoor test conditions

Outdoor test sites and pavements shall comply with the requirements of GB 1495.

5.3.1.2 Microphone position

The microphone placement position is shown in P and P' in Figures 1 and 2.Its distance to the CC' line is 2.0m +/- 0.05m, and 1.2m +/- 0.02m upward on the ground surface. The reference direction shall be horizontal and point vertically to the CC' line of the vehicle's operation.

5.3.2 Indoor semi-anechoic or muffling test

5.3.2.1 Indoor semi-anechoic or muffling test conditions

This clause specifies the conditions on the road that simulate the operation of all systems during the test, or only the conditions applicable to the acoustic-alerting system operating mode.

5.4 Vehicle status

The vehicle test mass is the curb weight +75kg.

5.5 Background noise

5.5.1 Measurement method of background noise A-weighted sound level

When measuring background noise, measure at least 10s continuously. When calculating the background noise by using a 10s sound obtained from the measurement, make sure that the sound is typical background noise and does not contain any transient interference.

5.5.2 Correction method of vehicle A-weighted sound level measurement

The noise outside the vehicle shall be corrected according to the difference between the maximum and minimum values of the background noise at the time of measurement. Ltest correction = Ltest - Lcorrection.

5.6.2.2 Constant speed test

5.6.2.2.1 Constant speed test when the vehicle moving forward

When testing in the outdoor field shown in Figure 6, the path of the vehicle centerline shall be as close as possible to the CC' line throughout the test. The front plane of the vehicle shall pass through the AA' line at the beginning of the test. The rear plane of the vehicle shall pass through the BB' line at the end of the test, as shown in Figure 1.The vehicle shall maintain a constant test speed throughout the operation.

5.6.2.2.2 Simulated constant speed test under vehicle static state

When the vehicle is being tested indoors or outdoors, the front plane of the vehicle shall be placed on the PP' line as shown in Figure 4 of 5.3.2.2.By providing an external signal to simulate the test vehicle speed, the vehicle shall maintain a constant simulated test vehicle speed of at least 5s.

5.6.2.3 Reverse test

5.6.2.3.1 Reverse test during driving

When the vehicle is tested in the outdoor field shown in Figure 6, the path of the vehicle centerline shall be as close as possible to the CC' line throughout the test. The rear plane of the vehicle shall pass through the AA’ line at the beginning of the test. The front plane of the vehicle shall pass through the BB' line at the end of the test, as shown in Figure 2.The vehicle shall maintain a constant test speed throughout the operation.

5.6.3 Measurement data and recorded values

Under each test condition, at least 4 measurements shall be taken on both sides of the vehicle.

5.7 Frequency shift test

5.7.1 Analytical equipment requirements

Digital sound recording system shall be at least 16-bit accurate. Sampling rate, range, and dynamic range are suitable for signals that require testing.

The frequency of the test results shall have sufficient accuracy. The setting of the analytical equipment shall be determined by the automobile manufacturer and the testing agency.

5.7.2 Instrument and signal processing

The sound analysis system shall have the ability to perform a spectrum analysis of a frequency range containing all frequencies of interest at a certain sampling rate.

5.7.3 Test selection

For the frequency shift requirement in 4.3.2, choose one of the following methods for detection.

Method One. outdoor vehicle road operation test.

Method Two. outdoor vehicle road simulation test. use an external signal generator to drive the acoustic-alerting system running at low speed to simulate vehicle operation.