Description

MEASURING SYSTEM FOR CRANK SHAFT DEFLECTION USING LINEAR ENCODER MODULE

Technical Field

[1] The present invention relates to a measuring system for crank shaft deflection of a marine engine, and more specifically to a measuring system for crank shaft deflection, transmitting the deflection value measured by a linear encoder module to a dedicated display device through wireless communications. Background Art

[2] In general, a marine diesel engine is composed of a cylinder, a piston, a crank shaft, etc. The crank shaft translates reciprocating linear piston motion into rotation in collaboration with a connecting rod, as assembled with a bed plate along with a main bearing shell. It is the most expensive component of an engine, typically accounting for more than 10 % of the price of an engine.

[3] Fig. 1 illustrates the crank shaft (1) of a large-sized diesel engine commonly used in ships. The crank shaft is composed of a crank throw (2), a thrust shaft (3), a main journal (4) and a flange journal (5).

[4] The crank throw (2) and the main journal (4) are united by shrink fitting after shaping ingot materials with a press and processing them with a special processing apparatus. During the processing of the crank shaft by shrink fitting, it is required to measure the deflection of each crank throw to produce high precision products.

[5] Also, when the crank shaft rotates, deflection of the crank throws (2) may occur. If the deflection is beyond the allowed range, the assemblage of the engine needs to be corrected.

[6] A manual dial gauge may be used to measure the deflection of the crank throw. An operator comes inside the bed plate while the crank shaft rotates, checks the deflection and notifies it to a recorder outside the bed plate. This method is inconvenient, inaccurate and dangerous because the operator has to come near the rotating crank shaft and check and notify the deflection with voice. Besides, it is inefficient because at least two people are required.

[7] A cabled digital gauge is used to solve these problems in measuring the deflection of a crank shaft. A measuring device is installed at the crank shaft and an operator reads the data from a display device connected to the measuring device by a cable. This method is advantageous in that the deflection can be monitored outside the engine, thanks to the signal cable connected to the measuring device. However, the signal cable may get entangled by the rotating crank shaft and the cable makes the

measuring inconvenient.

[8] In addition, conventional digital deflection sensors, such as an LVDT (linear variable differential transformer) sensor or a magnetic sensor which reads the deflection with a sensor header, are larger in size than 100 mm, the typical length of the opposite ends of crank throw of a medium-speed marine engine and cannot be applied to the deflection measurement of the crank shaft. Disclosure of Invention Technical Problem

[9] The present invention has been made to solve the afore-mentioned problems. The object of the present invention is to provide a measuring system for crank shaft deflection enabling more fast and convenient measurement of crank shaft deflection and measurement of the deflection of the crank shaft of a medium-speed engine, wherein the crank shaft deflection measured by a deflection measuring device is transmitted to a dedicated display device in real time through wireless communication, thereby providing safety and mobility to an operator. Technical Solution

[10] In order to attain the object, the present invention provides a measuring system for crank shaft deflection comprising a deflection measuring device that is equipped at the crank throw of a crank shaft of a marine engine and measures the deflection of the rotating crank throw and a dedicated display device that receives and displays the deflection value measured by the deflection measuring device, wherein the deflection measuring device comprises a linear encoder module which measures the deflection of the crank throw, a main controller which converts the deflection value measured by the linear encoder module into a digital value and a first wireless communication module which receives the digital value from the main controller, converts it according to a wireless communication protocol and transfers it, the dedicated display device comprises a second wireless communication module which receives the digital value transmitted from the first wireless communication module, a display which displays the digital value received by the second wireless communication module and a data manager which stores the digital value received by the second wireless communication module and the deflection measuring device and the dedicated display device are linked with each other wirelessly through the first and second wireless communication modules.

[11] The linear encoder module of the deflection measuring device comprises a slide guide which is equipped inside of a housing, a sensor strip which is equipped on the slide guide and has graduations with regular spacing and an encoder head which determines the linear displacement value of the sensor strip traveled along the slide

guide with reference to the graduations of the sensor strip.

[12] In an aspect of the present invention, the first and second wireless communication modules support the Bluetooth communication.

Advantageous Effects

[13] In accordance with the present invention, the present invention is advantageous in that an operator can measure the deflection of a crank shaft quickly and conveniently since the deflection value measured by a digital sensor is transmitted in real time to a dedicated display device through wireless communications. Brief Description of the Drawings

[14] Fig. 1 illustrates a crank shaft used in ships;

[15] Fig. 2 schematically illustrates the construction of the measuring system for crank shaft deflection by wireless communication in accordance with the present invention;

[16] Fig. 3 schematically illustrates the cross-section of the deflection measuring device of the measuring system for crank shaft deflection; and

[17] Fig. 4 is a block diagram for the deflection measuring device shown in Fig. 3 and a dedicated display device. Mode for the Invention

[18] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be understand that the embodiments illustrated herein are intended to be in the nature of description rather than of limitation, and thus it will be appreciated that those skilled in the art, in consideration of this disclosure, may make modifications and improvements within the spirit and scope of the present invention.

[19] Fig. 2 schematically illustrates the construction of the measuring system for crank shaft deflection using wireless communication in accordance with the present invention. Fig. 3 schematically illustrates the cross-section of the deflection measuring device of the measuring system for crank shaft deflection. And, Fig. 4 is a block diagram for the deflection measuring device and the dedicated display device.

[20] As illustrated in Fig. 2, the measuring system for crank shaft deflection of the present invention comprises a deflection measuring device (20) that is equipped at the crank throw (11) of a crank shaft of a marine engine and measures the deflection of the crank shaft and a dedicated display device (30) that receives and displays the deflection value measured by the deflection measuring device. In accordance with the present invention, an operator does not need to check the measuring device inside the bed plate and the problem of the entanglement of the signal cable by the rotating crank shaft can be solved effectively by linking the deflection measuring device and the dedicated display device through wireless communication. And, efficiency and safety

are improved because the measurement can be carried out by a single operator. The wireless communication can be performed by a variety of methods, not restricted to a particular method. In an embodiment of the present invention, Bluetooth communication is used.

[21] As illustrated in Fig. 3, the deflection measuring device is equipped with a linear encoder strip (25) on a slide guide (24) inside a housing, which has graduations with a spacing of, normally, 1/100 mm. One side of the pole of the linear encoder strip supports one end of a measuring support bar (26). The other end of the measuring support bar contacts the inside of the crank throw during deflection measurement. A spring (not illustrated) is used to apply a tensile force between the slide guide and the housing of the deflection measuring device, so that the deflection measuring device is not detached while the crank shaft rotates. An encoder head (not illustrated) reads 50 to 2500 or more pulses per millimeter as the graduations of the linear encoder strip passes over it. The deflection of the crank shaft is measured by converting the pulses into a linear distance.

[22] Since the deflection measuring device in accordance with the present invention uses a linear encoder module, the deflection measurement of a crank shaft of a medium- speed engine, which cannot be carried out with conventional digital deflection sensors because of the sensor size, becomes possible.

[23] Inside the housing of the deflection measuring device is mounted a circuit board

(27) equipped with a main controller which converts the deflection value measured by the linear encoder module into a digital value and a wireless communication module which receives the digital value from the main controller and converts and transmits it in accordance with a wireless communication protocol.

[24] Fig. 4 is a block diagram for the deflection measuring device and the dedicated display device.

[25] The deflection measuring device comprises a linear encoder module (21) which measures the deflection of the crank throw, a main controller (22) which converts the deflection value measured by the linear encoder module into a digital value and a first wireless communication module (23) which receives the digital value from the main controller and converts and transfers it in accordance with a wireless communication protocol.

[26] And, the dedicated display device comprises a second wireless communication module (31) which receives the digital value from the first wireless communication module, a display (32) which displays the digital value received by the second wireless communication module and a data manager (33) which stores the digital value received by the second wireless communication module.

[27] In the measuring system for crank shaft deflection in accordance with the present

invention, the deflection measuring device and the dedicated display device are linked by wireless communication. The method of wireless communication is not particularly restricted. In an embodiment of the present invention, the Bluetooth communication is adopted and a Bluetooth adapter manufactured by HandyWave is used. As described earlier, an operator does not need to check the measuring device inside the bed plate and the problem of the entanglement of the signal cable by the rotating crank shaft can be solved effectively by linking the deflection measuring device and the dedicated display device through wireless communication. And, efficiency and safety are improved because the measurement can be carried out by a single operator.

[28] Those skilled in the art will appreciate that the concepts and specific embodiments disclosed in the foregoing description may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present invention. Those skilled in the art will also appreciate that such equivalent embodiments do not depart from the spirit and scope of the present invention as set forth in the appended claims. Industrial Applicability

[29] As apparent from the foregoing description, the present invention relates to a measuring system for crank shaft deflection of a marine engine, and more specifically to a measuring system for crank shaft deflection, transmitting the deflection value measured by a linear encoder module to a dedicated display device through wireless communications .