安全預警研發-車輛系油壓煞車失效安全預警裝置研究

THE DEVELOPMENT OF AN ALARM DEVICE FOR FAILURE PREVENTION OF AUTOMOBILE HYDRAULIC BRAKE SYSTEM

林克峰(Ke-Feng Lin)

指導教授 ： 李碩仁

元智大學/工程學院/機械工程學系/碩士(1997年)

摘要

本論文主要目的在於研發可應用於車輛油壓煞車系統之安全預警裝置，能針對煞車狀態進行監測，並在即將發生失效前提供警訊給予駕駛者，使其加以排除而避免危險的發生。

安全預警系統採用「現象監控」概念，將煞車來令片溫度、分泵油品溫度及煞車油含水量三者列為系統的安全預警指標，主要藉由這些物理量的監測來反應車輛煞車操作情況。預警指標與油壓煞車失效具關鍵影響性，因為煞車作動主要是依靠煞車來令片與煞車鼓或碟盤間的摩擦力來達成制動效果，此過程也將伴隨著高熱量的產生，而這種高溫現象通常是造成煞車失效的主因。特別是來令片因為碳化層的堆積造成煞車制動力下降，同時煞車油品也將會因為高溫沸騰而導致液壓不足，此外，油品的沸點也將會隨著含水量而改變。從另一方面來說，若煞車系統發生某些異常或操作不當，也會反應到溫度的表現。所以，藉由安全預警指標可作為煞車安全的整體判斷。

本研究將利用動態煞車模擬試驗進行相關煞車實驗，以建立煞車失效數據資料庫，從中歸納失效模式與建立預警判斷法則，作為安全預警系統參考判斷的依據。最後，利用硬體的方式將安全預警系統實現，其中包含了溫度預警裝置、含水量預警裝置以及可作煞車降溫冷卻的主動式灑水裝置。

關鍵字

油壓煞車系統安全預警裝置 ； 煞車油含水 ； 煞車測試 ； 煞車來令片溫度監測 ； 煞車油過熱 ； 自動灑水裝置

並列摘要

The purpose of this research is to develop an alarm device for the failure of hydraulic brake system of automobiles. The device can monitor the braking status and send an alarm signal to warm the driver who should then take precaution and/or prevention actions before the failure occur.
From both of the theorem and experience, we selected three failure indicators, the temperature of the brake shoes, the temperature of the hydraulic fluid in wheel cylinders, and the moisture of the hydraulic fluid. In general, the braking is generated by the friction force between brake shoes and brake drum or disk. The rapid rising of temperature may result in the safety concerns of the brake shoes and the wheel cylinders. The continuous high temperature will carbonize the brake shoes. Ashes of the carbonized brake shoe stacked on the brake shoe surface may cause the friction coefficient to decrease. Then, the braking system will break down. The high temperature will also be transferred to wheel cylinders. This may cause the hydraulic fluid to boil. When it happens, the phenomena of vapor locking will result in loss of hydraulic pressure. However, the hydraulic fluid is amenable to moisture and the moisture content will lower boiling temperature of the hydraulic fluid. Higher percentage of moisture content in the hydraulic brake fluid may make the fluid to boil at lower temperature easily. And then the hydraulic brake fluid becomes compressible which will cause failure of the brake system.
In this research, an alarm device is developed which can detect high temperature of braking shoes, the hydraulic fluid temperature in wheel cylinders, and the moisture content in the hydraulic fluid and then provide a safety alarm before failure. We make experiments with dynamometer testing and establish failure modes and alarm trigger points base on collected data.

並列關鍵字

alarm device for failure prevention of hydraulic system ； the moisture content in the brake fluid ； testing of the brake system ； the temperature sensing of brake shoes ； the overheating of hydraulic fluid ； auto-sprinkler

參考文獻

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[15] Limpert, Rudolf, and Dennis F. Andraws, "Analysis in truck accidents," SAE Paper No. 870503, 1987.

[16] Wulter S. Reed and A. Taner Keskin, "A comparison of Automobile and Truck Decelerations During Emergency Braking," SAE Paper No. 870502, 1987.

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