Evaluation apparatus of hub unit and evaluating method of hub unit

• US 20090040935A1
• Filed: 07/24/2008
• Published: 02/12/2009
• Est. Priority Date: 07/26/2007
• Status: Active Grant

• Current Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Original Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Inventors: Maeda, Toshiyuki, Murata, Junji, Hakata, Toshihiro
• Granted Patent: US 7,821,950 B2
• Time in Patent Office: Days
• US Class Current: 370/242
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis

Abstract

In an evaluation apparatus of a hub unit, a signal processing unit outputs frequency analysis signals which indicate such a result obtained by that an output signal of an acceleration sensor fixed on a hub unit by a magnet is processed via an A/D converting unit and an envelope detecting unit, and thereafter, the processed sensor signal is analyzed for a frequency analysis by an FFT unit. Then, an evaluation output unit evaluates damage conditions of the hub unit based upon signal strengths of specific frequencies, and overall values, which are acquired from the frequency analysis signals, and then, outputs the evaluated damage condition to a display unit.

Claims

1. An evaluation apparatus of a hub unit, comprising:

an acceleration sensor which contains a magnetic force mounting unit and a main body of the acceleration sensor fixed on said magnetic force mounting unit, said magnetic force mounting unit being fixed on a fixing-sided member of the hub unit of a vehicle by utilizing a magnetic force thereof;

a signal processing unit which includes an envelope detecting unit and a frequency analyzing unit, said envelope detecting unit performing an envelope detection with a signal entered from said acceleration sensor, and said frequency analyzing unit performing a frequency analysis with a signal entered from said envelope detecting unit so as to produce a frequency analysis signal which contains a signal strength of a specific frequency and an overall value; and

an output unit for outputting said frequency analysis signal entered from said signal processing unit.

2. An evaluation apparatus of a hub unit, according to claim 1, wherein the signal processing unit includes an A/D converting unit which converts an analog signal entered from the acceleration sensor into a digital signal, an envelope detecting unit which performs an envelope detection with the digital signal entered from the A/D converting unit, and an FFT unit functioning as the frequency analyzing unit to perform the frequency analysis with a signal entered from the envelope detection unit so as to produce the frequency analysis signal which contains the signal strength of the specific frequency and the overall value, and

wherein the output unit includes an evaluation output unit which evaluates and outputs a damage condition of the hub unit based upon the signal strength and the overall value.

3. An evaluation apparatus of a hub unit, according to claim 1, wherein the hub unit corresponds to a hub unit of a driven wheel of the vehicle,

the evaluation apparatus further comprises a driven wheel driving unit for rotating the driven wheel.

4. An evaluating method for a hub unit, comprising steps of:

rotating wheels of a vehicle;

fixing an acceleration sensor on a fixing-sided member of the hub unit of said vehicle by utilizing a magnetic force produced by a magnetic force mounting unit of said acceleration sensor;

performing a an envelope detection and subsequently a frequency analysis with a signal outputted from said acceleration sensor so as to acquire a frequency analysis signal which contains a signal strength of a specific frequency and an overall value; and

evaluating a damage condition of said hub unit based upon the signal strength of the specific frequency of said frequency analysis signal and the overall value thereof.

5. An evaluating method for a hub unit according to claim 4, wherein an analog signal entered from the acceleration sensor is converted into a digital signal by an A/D converting unit and the digital signal is detected for the envelope detection, and thereafter the digital signal is analyzed for the frequency analysis using fast Fourier transformation so as to acquire the frequency analysis signal which contains the signal strength of the specific frequency and the overall value.