A device and method for detecting the inner wall of an engine cylinder based on digital holographic interference

Abstract

The invention discloses a device and method for detecting the inner wall of an engine cylinder based on digital holographic interferometry. The device comprises a dual-frequency laser, a beam expanding / collimating optical path, a beam splitting plate, a phase shifter, a conical surface reflecting mirror, a scanning motion device, a CCD camera and an upper computer. The optical principle, devices and optical path arrangement of the device are similar to those of a Tyman-Green interferometer. The device introduces the 90-degree conical reflecting mirror, so that a straight incident light beam isconverted into a radial light beam. The radial measurement light beam irradiates on the inner wall of an engine to be detected so as to form an annular light band, and the light band is a to-be-detected surface participating in the interference. The device drives the conical reflecting mirror to move in a straight line introducing the scanning motion device so as to complete the detection for thewhole inner wall. The device is high in measurement accuracy and good in real-time performance and meets a requirement of high efficiency of online detection. The device belongs to non-contact measurement and avoids scratches caused by a contact for the inner wall; and the device has the advantages of surface measurement, large measurement range, much measurement information and the like.

Description

technical field [0001] The invention belongs to the field of digital holographic interference measurement, in particular to a detection device and method for the inner wall of an engine cylinder based on digital holographic interference. Background technique [0002] At present, most passenger car engines are assembled by aluminum alloy cylinder blocks and cast iron cylinder sleeves to take into account the weight of the engine and the wear resistance of the inner wall of the cylinder. In order to further reduce the total weight of the engine and reduce the friction loss between the cylinder and the piston, researchers have proposed a new cylinder processing technology: inner wall spraying technology [1-4]. That is, molten cast iron is sprayed on the inner surface of the aluminum alloy cylinder block, and the coating is bored into the final cylinder inner wall. The thickness of the cast iron coating obtained by the inner wall spraying technology is roughly 100 microns to 20...

AI Technical Summary

Problems solved by technology

However, the inner surface of the cylinder has the characteristics of closed and narrow space (diameter less than 120mm), and it is impossible to put a laser interference system with a complex structure in it.

The detection beam generated by the traditional laser holographic interference system is approximately parallel light. If the system is placed outside the cylinder, it cannot irradiate the inner wall of the cylinder, so it is not suitable for the detection of three-dimensional surfaces in the ring.

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