A method for testing and analyzing noise of a mechanical hydraulic steering system

Abstract

This invention specifically relates to a method for testing and analyzing the noise of a mechanical hydraulic steering system. The method includes: S1, placing microphones at the driver's inner and outer ears in the vehicle under test, simultaneously reading the engine speed, and measuring the in-vehicle noise level and corresponding engine speed under typical operating conditions; S2, warming up the vehicle's engine; S3, measuring typical noise under idling conditions; S4, measuring typical noise under driving conditions; S5, analyzing the measured data according to experimental data processing methods to determine whether noise problems exist. This invention describes a method for testing and analyzing typical NVH problems that may exist in mechanical hydraulic steering systems under vehicle conditions, proposing a method for testing and analyzing the noise of mechanical hydraulic steering systems, and solving the problem of insufficient testing methods in this field for the high-quality development of commercial vehicles.

Description

Technical Field

[0001] This invention belongs to the field of vehicle noise testing, specifically relating to a method for testing and analyzing the noise of a mechanical hydraulic steering system. Background Technology

[0002] Before the widespread adoption of electronic power steering, mechanical hydraulic steering systems were widely used in various commercial and passenger vehicles. Because they can provide more force than electronic power steering systems, they are now primarily used in commercial vehicles. However, with the development of the automotive industry, pickup trucks and light trucks using mechanical hydraulic steering systems have increasingly higher requirements for vibration and noise reduction (NVH) performance. The poor NVH performance of mechanical hydraulic steering systems has gradually become a prominent issue.

[0003] Since the trend of developing high-quality commercial vehicles is still in its early stages in the domestic market, research on vibration and noise evaluation and testing methods for mechanical hydraulic steering systems is insufficient. There are no testing and data analysis methods specifically addressing typical NVH problems that may exist in mechanical hydraulic steering systems under vehicle conditions. Therefore, specialized testing and data analysis methods for mechanical hydraulic steering system noise are needed to address the lack of testing methods in this area of ​​high-quality commercial vehicle development. Summary of the Invention

[0004] This invention patent describes a testing and data analysis method for typical NVH problems that may exist in a mechanical hydraulic steering system under vehicle conditions. It proposes a testing and data analysis method for the noise of a mechanical hydraulic steering system, which solves the problem of insufficient testing methods in this field for the high-quality development of commercial vehicles.

[0005] The method includes:

[0006] S1. Place microphones at the driver's inner and outer ears of the vehicle under test, and simultaneously read the engine speed. Measure the in-vehicle noise level and corresponding engine speed under typical operating conditions.

[0007] S2, The tested vehicle's engine is warm;

[0008] S3. Measure typical noise under idling conditions;

[0009] S4. Measure typical noise under driving conditions;

[0010] S5. Analyze the measured data according to the experimental data processing method to determine whether there is a noise problem.

[0011] Furthermore, in step S1, the method for reading the engine speed includes reading using a Hall sensor and reading using an EMS output signal.

[0012] Furthermore, in step S2, when warming up the vehicle under test, ensure that the cooling system water temperature reaches 90°C and continue warming up for at least 10 minutes.

[0013] Furthermore, in step S3, the idling condition includes constant flow abnormal noise, idling abnormal noise, and stalled abnormal noise.

[0014] Furthermore, in step S3, when measuring the noise of the constant flow abnormal noise condition, the vehicle is kept in P gear at idle speed, and the steering wheel is in the middle position and the left 90° position for 30 seconds each; when measuring the noise of the idle speed abnormal noise condition, the vehicle is kept in P gear at idle speed, and the steering wheel is in the middle position for 30 seconds; when measuring the noise of the stalled abnormal noise condition, the vehicle is kept in P gear at idle speed, and the steering wheel is turned to the limit position and held for 10 seconds.

[0015] Furthermore, in step S4, the driving conditions include creeping noise and driving noise.

[0016] Furthermore, in step S4, when measuring the noise of creeping abnormal noise, the vehicle speed is below 20km / h and the vehicle is driven at a constant speed for 30 seconds; when measuring the noise of driving abnormal noise, the vehicle is driven in third gear, and the vehicle is driven at the lowest stable speed of that gear until the engine speed reaches 3500rpm. Then, the gear is kept unchanged, the accelerator is released, and the vehicle is allowed to coast to the lowest stable speed corresponding to that gear.

[0017] Furthermore, in step S4, when measuring the noise of the creeping abnormal noise condition, the fixed gear corresponding to the current vehicle speed is selected when the vehicle is traveling at the lowest stable speed.

[0018] Furthermore, in step S5, the experimental data processing method is as follows:

[0019] When the abnormal noise occurs under normal operating conditions, calculate the noise spectrum inside the vehicle when the steering wheel is in the middle position and when it is turned 90° to the left, and compare whether there are significant differences in the noise spectrum in certain frequency ranges under the two steering wheel angles. If the abnormal noise exists, it is a wideband noise of 800Hz to 1500Hz.

[0020] When the idling noise occurs, the noise spectrum inside the vehicle is calculated. The idling noise is the order noise of the steering pump. By calculating the transmission ratio between the engine and the steering pump, and based on the structural characteristics of the steering pump, the presence of typical order noise is identified.

[0021] When encountering abnormal noise during stall conditions, calculate the noise spectrum inside the vehicle to identify whether there are prominent steering pump order, harmonic order, and half-order noises inside the vehicle. If the main order of the steering pump is 10th, then the 15th, 20th, 25th, and 30th order noises should also be identified under this condition.

[0022] During creeping noise conditions, calculate the in-vehicle noise spectrum to identify whether there is prominent steering pump order noise inside the vehicle;

[0023] When abnormal noise occurs during driving, calculate the noise order curve inside the vehicle. The calculated order includes the main order and harmonic order corresponding to the steering pump, and identify the relationship between this order noise and the main order and harmonic order noise of the engine.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. System testing for typical operating conditions can quickly identify potential NVH problems.

[0026] 2. Compared to electronic power steering, mechanical hydraulic steering systems are outdated technologies. However, this configuration is still the preferred solution for certain vehicle types, especially those with high axle loads such as pickup trucks and high-performance off-road vehicles. However, these types of vehicles have higher requirements for comfort than commercial vehicles. Often, during the development and problem identification process, the identification of NVH problems for such "outdated" configurations is not comprehensive enough. A systematic preliminary testing scheme and data processing method are needed, which corresponds to the subject of this patent.

[0027] 3. This patent combines development experience and various customer usage conditions to summarize typical NVH problems of mechanical hydraulic steering systems, and proposes effective testing and data analysis methods for these problems, thereby improving the development efficiency of NVH performance in the product development process and expanding the problem identification efficiency in corresponding customer usage scenarios. Attached Figure Description

[0028] Figure 1 This is a flowchart of the method corresponding to an embodiment of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention combines development experience with various customer usage conditions to summarize typical NVH problems in mechanical hydraulic steering systems, and proposes effective testing and data analysis methods for these problems, thereby improving the development efficiency of NVH performance in the product development process and expanding the problem identification efficiency in corresponding customer usage scenarios.

[0031] Typical NVH problems are as follows:

[0032] 1) Frequent abnormal noise: When the vehicle is idling, and the steering wheel is in different turning angles, there is a "shush" sound in the vehicle, similar to the busy tone of an air conditioner or radio.

[0033] 2) Idle noise: When the vehicle is idling, the engine is fully warmed up and the water temperature reaches the ideal engine operating temperature, usually 90℃. Due to the increase in power steering fluid temperature and the change in viscosity, a single-frequency "humming" sound can be heard in the car.

[0034] 3) Crawl noise: When the vehicle is traveling at the lowest stable speed or a low speed, usually below 20km / h, a low-frequency "humming" sound with a relatively single frequency can be heard inside the vehicle as the steering wheel angle changes.

[0035] 4) Abnormal noises during driving: When the vehicle is traveling at medium to high speeds, usually above 20 km / h, a sharp, easily identifiable noise can be heard from the steering system inside the vehicle during tip-in and tip-out conditions.

[0036] 5) Steering noise when stuck: When the vehicle is idling or driving at low speed, if the steering wheel is turned to the limit and held, the steering system inside the vehicle will make a noticeable whistling sound.

[0037] The purpose of this invention is to propose an NVH evaluation method that comprehensively covers operating conditions and is suitable for high-quality product development, encompassing typical NVH problems of mechanical hydraulic steering systems.

[0038] like Figure 1 The diagram shows a flowchart of a method for testing and analyzing noise in a mechanical hydraulic steering system according to an embodiment of the present invention. The steps are as follows:

[0039] The first step is to place microphones 20cm away from the driver's inner and outer ears on the driver's seat, and at the same time use Hall sensors or EMS output signals to read the engine speed, and then measure the in-vehicle noise level and corresponding engine speed under typical operating conditions.

[0040] The second step is to fully warm up the vehicle under test, that is, to continue warming up the vehicle for at least 10 minutes after the cooling system water temperature reaches 90°C.

[0041] Step 3: Typical noise test under idling conditions:

[0042] 1) Frequent abnormal noise: Keep the vehicle in P gear at idle speed, and hold the steering wheel in the middle position and the left 90° position for 30 seconds each;

[0043] 2) Abnormal noise at idle speed: Keep the vehicle in P gear at idle speed with the steering wheel in the middle position for 30 seconds;

[0044] 3) If there is a noise when the vehicle is stuck, keep the vehicle in P gear and idle, turn the steering wheel to the limit and hold for 10 seconds;

[0045] Step 4: Typical noise test under driving conditions:

[0046] 1) Crawl noise: When the vehicle is traveling at the lowest stable speed or a low speed, select the fixed gear corresponding to the current speed. The speed is usually below 20km / h, and the vehicle travels at a constant speed for 30 seconds.

[0047] 2) Abnormal noise while driving: When the vehicle is in third gear, accelerate smoothly from the lowest stable speed of that gear to the engine speed of 3500 rpm, then keep the gear unchanged, release the accelerator, and let the vehicle coast to the lowest stable speed corresponding to that gear.

[0048] The fifth step is to analyze the measured data according to the experimental data processing methods to determine whether there is any noise problem:

[0049] 1) For constant abnormal noise, calculate the noise spectrum inside the vehicle when the steering wheel is in the middle position and when it is turned 90° to the left, and compare whether there are significant differences in the noise spectrum in certain frequency ranges under the two steering wheel angles. If the abnormal noise exists, it is usually a wideband noise of 800Hz to 1500Hz, and the difference in peak spectral noise is usually >2dB(A).

[0050] 2) Idle noise: Calculate the noise spectrum inside the vehicle. This idling noise is usually the order noise of the steering pump. By calculating the transmission ratio between the engine and the steering pump, and based on the structural characteristics of the steering pump, identify whether there is typical order noise. For example, if the engine idles at 700 rpm, the transmission ratio is 1.5, and the steering pump is a ten-blade double-acting mechanical pump, then the noise inside the vehicle is the 10th, 20th, and 30th order of the steering pump, corresponding to frequencies of 175 Hz, 350 Hz, and 525 Hz.

[0051] 3) For abnormal noises caused by stalling, calculate the noise spectrum inside the vehicle and identify whether there are prominent steering pump order, harmonic order and half-order noises inside the vehicle. For example, if the main order of the steering pump is 10th, then under this condition, the 15th, 20th, 25th and 30th order noises should also be identified.

[0052] 4) Crawl noise: Calculate the in-vehicle noise spectrum to identify whether there is a prominent steering pump order noise in the vehicle.

[0053] 5) For abnormal noises during driving, calculate the noise order curve inside the vehicle. The calculated order mainly corresponds to the main order and harmonic order of the steering pump. Identify the relationship between this order noise and the main order and harmonic order noise of the engine.

Claims

1. A method of testing and data analysis of mechanical hydraulic steering system noise, characterized in that, The method comprises: S1, arranging microphones at the inner and outer ears of the driver of the vehicle under test, while reading the engine speed, measuring the noise level in the vehicle under typical working conditions and the corresponding engine speed; S2, warming up the engine of the vehicle under test; S3, measuring the noise under idling working conditions; The idling working conditions include normal flow abnormal sound, idling abnormal sound and stall abnormal sound; When measuring the noise under normal flow abnormal sound working conditions, the vehicle is kept in P gear idling, and the steering wheel is respectively in the middle position and the left turning 90° position for 30 seconds each; when measuring the noise under idling abnormal sound working conditions, the vehicle is kept in P gear idling, and the steering wheel is in the middle position for 30 seconds; when measuring the noise under stall abnormal sound working conditions, the vehicle is kept in P gear idling, and the steering wheel is turned to the limit position and kept for 10 seconds; S4, measuring the noise under typical running working conditions; The running working conditions include creeping abnormal sound and running abnormal sound; When measuring the noise under creeping abnormal sound working conditions, the vehicle is driven at a speed lower than 20 km / h for 30 seconds; when measuring the noise under running abnormal sound working conditions, the vehicle is driven at the third gear, and is uniformly accelerated from the lowest stable speed of the gear to the speed at which the engine speed reaches 3500 rpm, then the gear is kept unchanged, the throttle is released, and the vehicle is coasted to the lowest stable speed of the gear; S5, analyzing the measured data according to the experimental data processing method to determine whether there is a noise problem; The experimental data processing method is as follows: Under normal flow abnormal sound working conditions, the noise spectrum in the vehicle is calculated when the steering wheel is in the middle position and the left turning 90° position respectively, and whether there is an obvious difference in the noise spectrum at the two steering wheel angles in some frequency bands is compared, if the abnormal sound exists, it is a wide frequency noise from 800 Hz to 1500 Hz; Under idling abnormal sound working conditions, the noise spectrum in the vehicle is calculated, the idling abnormal sound is the steering pump order noise, whether there is a typical order noise is identified by calculating the transmission ratio of the engine and the steering pump and according to the structural characteristics of the steering pump; Under stall abnormal sound working conditions, the noise spectrum in the vehicle is calculated, whether there is a prominent steering pump order, harmonic order and half order noise in the vehicle is identified; if the main order of the steering pump is 10, the order noises of 15, 20, 25 and 30 should also be identified under this working condition; Under creeping abnormal sound working conditions, the noise spectrum in the vehicle is calculated, whether there is a prominent steering pump order noise in the vehicle is identified; Under running abnormal sound working conditions, the noise order curve in the vehicle is calculated, the orders include the main order and the harmonic order of the steering pump, and the relationship between the order noise and the main order and the harmonic order of the engine is identified.

2. The method of noise testing and data analysis of claim 1, wherein, In step S1, the method for reading the engine speed includes using a Hall sensor to read and using an EMS output signal to read.

3. The method of noise testing and data analysis of claim 1, wherein, In step S2, when the vehicle under test is warmed up, the water temperature of the cooling system is ensured to reach 90℃, and then the engine is warmed up for at least 10 minutes.

4. The method of noise testing and data analysis of claim 1, wherein, In step S4, when measuring the noise under creeping abnormal sound working conditions, the vehicle is driven at the lowest stable speed, and the gear is selected as the fixed gear corresponding to the current speed.

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