| The brake performance is one of the main property of automobile, it directivity determine the traffic safety. As a key component of the brake system, the qualification of the Vacuum Booster and Master Cylinder is of great importance, however there is no international test standard for it and some domestic products are from other countries, so the technologic requirements and structure are different. For those seasons the producer has to follow the old standard, restricting the unification and the serialization of the products. In addition, some of the domestic test equipments are relative backward in both hardware and software. Development of new equipment with independent intellectual property rights is of great realistic significance.In this paper, a test equipment was developed according to the technical condition and testing approach with Vacuum Booster and Master Cylinder. It can complete all the test items specified in the People 's Republic of China Industry Standard and some other test items specified in the enterprise standard, it's to be common used. The hardware and software of the control system is described, each composition and function were introduced in detail. The test methods and control system with quick response, high accuracy, safety and reliable performance was provided by product quality detection and measurement.This paper introduced some important performance indicators and gave specific test methods and testing procedures, amended many unreasonable methods described in the old standard, so that it could more accurately reflect the important information of the products, and greatly improved the efficiency of detection and brought benefits to the producer. Take the Lost-Travel test for instance, in accordance with industry standards QC/T31l《Hydraulic Brake Master Cylinder and Technical Conditions》, a method called"air bubble method"is used for detecting the Lost-Travel, however this method has some drawbacks. In this paper we overcame these shortcomings by using software algorithms and the help of both displacement and pressure sensor. This new method is not only very convenient, but also can receive higher detection accuracy. In addition, it is can similarly be used to detect the return Lost-Travel. The software has also added some new test items which are described in the new testing standards, such as the booster seal testing. According to QC 307-1999《Vacuum Booster's Technical Conditions》booster sealing, the detection with vacuum booster below Aid-force point was added in the software, ensuring a comprehensive assessment to the sealing properties. The newly developed equipment could complete 28 test items in total including the basic input-output characteristics test, Lost-Travel, action / release, vacuum sealing, low pressure sealed, high-pressure sealing, bleeding test, pressure difference, etc. These test methods are proved to be very feasible by large quantity of product testing. In this paper we also conducted an initial study on the active booster with emergency brake assist device.The software debugging on the spot is a repeated and complex process, the biggest problem is the interference from external signals, and because of this we used some appropriate algorithms in the software to filter the initial data. In order to avoid causing too much accuracy loss we increased the data sampling frequency of the hardware. By doing this we acquired very good results. To achieve the goal of detecting the output pressure's suddenly subtle changes in the Lost-Travel test, in addition to the linear fitting for the data, we also used a method so called Reverse Inquiry in the software to find out the mutation of the output hydraulic, effectively eliminated the external interference before the hydraulic is established. As for servo motor, we set up the parameters of the S-shaped speed curve according to the difference of the speed, thus the loading device can obtain high moving accuracy at both low and high speed. |
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