Background Art A traction motor that provides a propulsion power to an electric train generates a torque by an electromagnetic force applying to a conductor through which an electric current flows in a magnetic field. The torque of a traction motor induces a vibration, and the vibration gives a bad effect to stability and riding comfort.

Therefore, before the traction motor is loaded on a train, vibration by each speed is measured. During a test, a traction motor is rotated at a predetermined speed. A speed is inversely proportional to a load electricity, while a torque is directly proportional to a load electricity. Thus, a speed fluctuates always when an electricity flow is irregular.

Further, to measure a rotation speed and a vibration of a traction motor in a conventional art, a rotation speed meter 3 and a vibration meter 4 are employed as shown in FIG. 1. In the rotation speed meter 3, a speed sensor mounted on a rotation

shaft of a traction motor 1 generates an optic signal intermittently by a rotation of a rotation shaft. The signal is converted into a pulse and a frequency of the pulse produces a speed to be displayed on the speed meter.

In the same way, the vibration meter 4 receives a vibration signal from a vibration sensor 2 mounted on an upper/lower, right/left, and front/back portion of the traction motor 1 and displays its value on a monitor. According to the conventional art, an observer reads a value of a speed displayed on a monitor, and at the same time the observer must read a value of a vibration displayed on a monitor. hi the prior art, an observer scans each monitor of a speed meter and a vibration meter with the observer's eye, and records the values of a speed and a vibration. There is a problem that an accurate value of a vibration corresponding to a certain value of a speed cannot be obtained since a gap between a reading time of the speed and the vibration exists.

Disclosure of the Invention Accordingly, the present invention has been made with taking the above problems occurring in the prior art into consideration, and an object of the present invention is to provide an apparatus for measuring simultaneously the vibration and the rotation speed of a traction motor and method thereof in which a value of vibration corresponding to a rotation speed of a traction motor can be accurately measured.

Another object of the present invention is to provide an apparatus for measuring simultaneously the vibration and the rotation speed of a traction motor and method thereof in which, each of rotation speed and vibration of a traction motor is measured and the measured values are simultaneously stored on a buffer along the measured time, and all of the values can be simultaneously displayed.

In order to accomplish the above object, an apparatus for measuring simultaneously vibration and rotation speed of traction motor comprises a rotation speed sensor installed on a traction motor, a frequency/rotation speed converter for

converting a frequency of pulse transferred from the rotation speed sensor into a value of the rotation speed, a rotation speed analog-to-digital (A/D) converter for converting the value o f the r otation s peed t ransferred from t he frequency/rotation speed converter into a digital value, a vibration sensor for measuring a vibration of the traction motor, a vibration analog-to-digital (A/D) converter for converting a value of a vibration transferred from the vibration sensor into a digital value, a buffer for storing the digital value of both rotation speed and vibration transferred from the rotation and vibration A/D converter, a controller for reading the digital value of both rotation speed and vibration stored on the buffer and for storing the digital value as well as a time to read the digital value, and displaying simultaneously the value of the rotation speed and the vibration stored on the memory unit in a time according to a display signal transferred from the key input unit, a display unit for displaying the measured value of both rotation speed and vibration according to the display control signal of the controller, and a key input unit for inputting command and data into the controller.

Further, the buffer is comprised of two parallel shift registers, and each resister stores the data transferred from the rotation speed A/D converter or the vibration A/D converter as well as the vibration A/D converter or the rotation speed A/D converter depending on a clock signal (CLK) transferred from the controller.

Further, the controller transfers the control signal to the parallel shift registers as the clock signal, and the control signal has the same frequency as the sampling frequency of the A/D converter of both rotation speed and vibration, and the controller stores the digital data in regard to the rotation speed and the vibration having the same frequency as a sampling frequency into the memory unit.

In a method for measuring simultaneously vibration and rotation speed of traction motor, the method comprises the steps of : confirming whether a storage key is entered from a key input unit; writing start time of a storage when the storage key is entered, reading data of both rotation speed and vibration from a buffer, and storing a memory unit; writing stop time of a storage after storing the data of both rotation speed and vibration; and determining whether a time is entered when the

display command is entered from the key input unit, and if the time is entered, displaying data of both rotation speed and vibration corresponding to the inputted time.

Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. 1 is illustrative view of an apparatus for measuring a vibration of a traction motor according to a prior art; FIG. 2 is a block diagram illustrating an apparatus for measuring simultaneously a vibration and a rotation speed of a traction motor according to the present invention; FIG. 3 a block diagram illustrating a constitution of a buffer; and FIG. 4 is a flow chart illustrating the method for measuring simultaneously a vibration and a rotation speed of a traction motor according to the present invention.

Best Mode for Carrying Out the Invention This invention will be described in further detail by way of exemplary embodiments with reference to the accompanying drawings.

FIG. 2 shows a block diagram illustrating an apparatus for measuring simultaneously a vibration and a rotation speed of a traction motor.

An apparatus for measuring simultaneously a vibration and a rotation speed of a traction motor comprises a rotation speed sensor 12 installed on a traction motor 10, a frequency/rotation speed converter 14 for converting a frequency of pulse transferred from the rotation speed sensor 12 into a value of the rotation speed, a rotation speed analog-to-digital (A/D) converter 15 for converting the value of the rotation speed transferred from the frequency/rotation speed converter 14 into a

digital value, a vibration meter 13 for measuring a vibration of the traction motor 10, a vibration analog-to-digital (A/D) converter 16 for converting a value of a vibration transferred from the vibration meter 13 into a digital value, a buffer 17 for storing the digital value of both rotation speed and vibration transferred from each rotation speed and vibration A/D converter 15,16, a controller 18 for reading the digital value of both rotation speed and vibration stored on the buffer 17 and for storing the digital value as well as a time on a memory unit 19, and displaying simultaneously the value of the rotation speed and the vibration stored on the memory unit 19 in a time according to a display signal transferred from a key input unit 21, a display unit 20 for displaying the measured value of both rotation speed and vibration according to the display control signal of the controller 18, and a key input unit 21 for inputting command and data into the controller.

The traction motor 10 is mounted on a ground of a train, and each vibration sensor 11 is installed at a front/back, a right/left, and an upper/lower portion of the traction m otor 1 0. T he vibration s ignals d etected b y each v ibration s ensor 11 are transferred into the vibration meter 13 to calculate an average value of the signals.

The average value is outputted to the vibration A/D converter 16. At the vibration A/D converter 16, the inputted analogue value is converted into a digital value, and the digital value is outputted to the buffer 17.

On the other hand, the rotation speed sensor 12 installed on a rotation shaft of the traction motor 6 produces a pulse by a rotation speed of a rotation shaft. The produced pulse at the rotation speed sensor 12 is transferred into the frequency/speed converter 14. A frequency of a pulse is converted into a value of a speed at the frequency/speed converter 14. At the speed A/D converter 15, the analogue value transmitted from the frequency/speed converter 14 is converted into a digital value, and the digital value is outputted to the buffer 17.

The buffer 17 stores each digital data for a speed and a vibration that is transferred from either speed A/D converter 15 or vibration A/D converter depending on a control signal received from the controller 18. The buffer 17 is comprised of two parallel shift registers 31,32 (FIG. 3), and each resister stores the

data transferred from the rotation speed A/D converter 15 or the vibration A/D converter 16 as well as the vibration A/D converter 16 or the rotation speed A/D converter 15 depending on clock signal (CLK) transferred from the controller 18.

The controller 18 transfers the control signal to the parallel shift registers 31,32 as the clock signal, and the control signal has the same frequency as the sampling frequency of the rotation speed and vibration A/D converter 15,16. The controller 18 stores the digital data in regard to the rotation speed and the vibration having the same frequency as a sampling frequency into the memory unit 19.

Therefore, each sampling frequency generated from the rotation speed A/D converter 15 and the vibration A/D converter 16 is the same as or greater than a frequency of the control signal.

Otherwise, if a frequency of a control signal is greater than each frequency of each A/D converter, a data as the same as a previous one might be read in the condition the next sampling does not perform. As a result, that causes an error.

The controller 18 reads each data of a speed and a vibration stored at the buffer 17 and stores the data on the memory unit 19. At this time, a time that reads along the data of a speed and a vibration can be also stored on the memory unit 19.

Thus, a data value change of speed and vibration according to a time change can be displayed.

For instance, when a rotation speed of the traction motor 10 increases to 4, 000rpm from 3, 000rpm during 1 minute, a change status of a vibration can be stored on the memory unit 19.

An observer can enter a display command into the controller 18 using the key input unit 21. The controller 18 having received the display command shows the change status of a vibration that is stored on the memory unit 19. For example, if a rotation speed of the traction motor 10 increases to 4, 000rpm from 3, 000rpm during 1 minute, a change status of a vibration during a speed change period can be displayed.

On the other hand, when an observer enters a time as well as a display command to see a change status during a certain point, for example, from 20 second

to 40 second during the above 1 minute, the controller 18 displays a rotation speed and a vibration of the traction motor 10 at the duration (20 sec to 40 sec).

FIG. 4 shows a flow chart illustrating the method for measuring simultaneously a vibration and a rotation speed of a traction motor according to the present invention.

The controller 18 confirms whether a storage key is entered from a key input unit 21 (Sl). If the storage key is entered, a start time of storage is written (S2). The controller 18 reads a rotation speed data stored from a first parallel shift register 31 of the buffer 17 and a vibration data stored from a second parallel shift register 32 of the buffer 17, and stores both data on a memory unit (S3).

The buffer 17 is comprised of a first parallel shift register 31 in which a rotation speed data is stored and a second parallel shift register 32 in which a vibration data is stored. Thus, a rotation speed data is read from the first parallel shift register 31 and is stored on the memory unit 19. Thereafter, a vibration data is read from the second parallel shift register 32 and stored on the memory unit 19. The order may not be permanently fixed. Adversely, firstly the vibration data is read and then the rotation speed data is read, by which the same effect as the previous order can be obtained.

The data of both rotation speed and vibration are stored and a stop time of storage is written (S4). Thereafter, the controller determines whether a display command is entered from the key input unit 21 (S5). If the display command is not entered, returns to step S 1.

On the other hand, if the display command is entered, the controller determines whether a time is entered (S6). If the time is not entered, data of both rotation speed and vibration is simultaneously displayed on the display unit (S7). On the other hand, if the time is entered, data of both rotation speed and vibration corresponding to the inputted time is displayed on the display unit (S8).

Industrial Applicability

According to the invention, the buffer can simultaneously store values of rotation speed and vibration measured at the rotation speed sensor and the vibration sensor. The stored data is further stored on the memory unit, and the values of both rotation speed and vibration are simultaneously displayed. Therefore, since vibration can be accurately measured at a specific speed, vibration pattern by rotation speed can be accurately analyzed.