JPH0845696A - X-ray generating device - Google Patents

Abstract

PURPOSE:To facilitate maintenance of a rotary anode X-ray tube by substantially extending the lifetime of the water seal part of X-ray tube. CONSTITUTION:An X-ray generating device has a rotary anode part 3 including a rotary shaft 6 and stationary part, and the gap between the shaft 6 and stationary part is sealed by a water seal part 9 of rubber against a cooling water 12 which cools the rotary anode part 3. The output of a power limit setting device 20 to set the maximum of the electric power to be supplied to rotary anode X-ray tube is compared with the supply power, and an appropriate signal is passed to an X-ray power controlling part 21 and also sent to a motor speed controlling part 26. Control is made so that the revolving speed of a motor 16 to rotate the rotary anode part 3 is retarded with smaller setting value of power limiting, and the lifetime of the water seal part 9 is prolonged substantially.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray generator used in an X-ray diffraction analyzer and the like.

[0002]

2. Description of the Related Art An X-ray tube continuously supplied with an electric power of 4 kW or more rotates its anode at a high speed to physically form a heat generating portion (focal point) like a long strip, and the inside of the tube is flushed with running water. It is cooled so that the focal point of the anode is not melted by heat. For example, in an X-ray tube having a maximum output of 18 kW, an anode having a diameter of about 10 cm is used to rotate at a high speed of about 6000 rpm. When the X-ray is generated, the rotating anode is always in a high-speed rotating state assuming the maximum power, regardless of the magnitude of the power actually supplied. Further, this rotation is generally driven by a three-phase cage induction motor, and the rotation speed cannot be easily changed. Also, 50H
As a device to match the rotation speed corresponding to the power supply frequency of z and 60 Hz, the diameter of the pulley attached to the motor is also changed according to the power supply frequency.

[0003]

In the above-mentioned prior art, the rotation speed of the anode is fixed at a high speed assuming the maximum supply power. A major problem here is the short life of the seal on the rotating shaft of the cooling water that cools the rotating anode. Normally used rubber water seals have extremely short life when the shaft rotation speed is high. For example, 3000r
pm has a life of several thousand hours, but 6000 rpm has a life of several hundred hours. It is an object of the present invention to substantially extend the life of this rubber water seal to facilitate maintenance of the rotating anode X-ray tube.

[0004]

In order to solve the above problems, according to the present invention, cooling water is supplied from the inside of the rotating shaft of the anode to the rotating anode part through the water seal part from the cooling water inlet to form the rotating shaft. In a water-cooled X-ray generator that discharges to a cooling water outlet via a return pipe provided inside the power limiting setting means for setting the maximum value of the power supplied to the rotating anode X-ray tube, and the rotating speed of the rotating anode. The rotational speed control means for controlling the water seal is provided, and the rotational speed of the rotating anode is controlled to the required minimum value in association with the set value of the power limit, thereby extending the life of the water seal.

In order to control the rotating speed of the rotating anode, it is preferable to use an inverter motor as a motor for driving the rotating anode and to control the rotating speed by an inverter power supply.

[0006]

When the rotary anode X-ray tube is used in an X-ray diffraction analyzer, the output is not always maximized, and the output is often lowered depending on the analysis sample and the purpose of analysis. Then, for safety, the rotating anode X
The setting value of the power limit that determines the maximum value of the power supplied to the wire tube is also lowered. Then, the rotation speed of the anode is lowered in conjunction with the set value of the power limit, so that the life of the water seal portion is greatly extended and the maintenance of the rotary anode X-ray tube is facilitated.

[0007]

Embodiment An embodiment of the present invention will be described with reference to FIG. The rotating anode X-ray tube 1 has a structure in which a rotating shaft 6 is supported by a bearing (not shown) so that the rotating anode portion 3 can rotate in the vacuum container 2. The cooling water 12 for cooling the rotating anode part 3 passes through the inside of the rotating shaft 6 from the cooling water inlet 10 to cool the rotating anode part, and then passes through the cooling water return pipe 7 provided at the center of the rotating shaft for cooling. Water outlet 1
Emitted from 1. The vacuum of the rotary shaft 6 and the vacuum container 2 is sealed by a vacuum seal portion 8 using a magnetic fluid or the like, and the cooling water is sealed by a water seal portion 9 made of rubber. The rotation of the rotating anode part is controlled by the motor 16 by the pulley 13,
Given through the belt 15 and the pulley 14,
The rotation speed of the motor 16, that is, the rotation speed of the rotating anode section is determined by the motor rotation speed control section 26.

A negative high voltage of -20 to -60 kV is applied to the filament 5 in the vacuum container by the X-ray power control unit 21, and the electron beam hits the X-ray generation unit 4 at the ground potential, whereby X-rays are emitted. Occurs. The tube current value is also controlled to the value set by the X-ray power control unit 21. To monitor the operating state of the X-ray tube, a current monitor 22 and a voltage monitor 23 for monitoring the tube current and the tube voltage, and a power monitor 24 for calculating the product of the tube current and the tube voltage are provided. On the other hand, a power limit setter 20 for setting the maximum value of the power supplied to the rotating anode X-ray tube is provided, and the set value and the output value of the power monitor 24 are input to the comparator 25. By comparing these two values, if the actual power (output of the power monitor) exceeds the set power limit value, the output of the comparator 25 is immediately sent to the X-ray power control unit 21 and the power is turned off. Is configured.

The value set by the power limit setting unit 20 is given to the motor rotation speed control unit 26, and the rotation speed of the motor is determined according to the value. That is, when the electric power limit value is small, the rotation speed of the motor becomes slower,
When the electric power limit value is large, the rotation speed of the motor is controlled to be high. The motor 16 that rotates the rotating anode unit is an inverter motor, and the motor rotation speed control unit 26 including an inverter power supply can set the rotation speed to an arbitrary value. The respective diameters of the pulley 13 and the pulley 14 are appropriately determined based on the relationship between the rotation speed of the motor 13 which is easy to control and the desired rotation speed of the rotary anode portion.

For example, in the case of a rotating anode X-ray tube having a maximum supply power of 18 kW and a rotating anode having a diameter of 10 cm, the anode is rotated at a maximum speed of about 6000 rpm. Depending on the purpose of analysis, etc.
When operating at kW, the power limit setter is set to 9 kW. This is to prevent accidents caused by accidentally increasing the power too much. Then, the rotation speed of the anode is automatically changed to about 4000 rpm by the motor speed control unit in association with the set value of the power limit setter. The water seal made of rubber has a life of several hundred hours under the use condition of a rotation speed of 6000 rpm, but at 4000 rpm, it has a life several times as long as that of the maintenance-free state.
Since the vacuum seal uses magnetic fluid, its life is significantly longer than that of the water seal.

Various methods such as a numerical input and a switch setting can be considered as the method of setting the power limit value. Further, the transmission of information from the power limit setting unit 20 to the motor speed control unit 26 is not limited to the method of giving a DC voltage proportional to the set value, but may be serial or parallel digital communication means.

[0012]

According to the present invention, since the rotating speed of the rotating anode can be reduced according to the actual use condition, the life of the water seal portion is greatly extended and the rotating anode X-ray tube can be easily maintained. Further, since the rotating speed of the rotating anode is not affected by the power supply frequency, it is not necessary to replace the pulley depending on the installation area.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention.

[Explanation of symbols]

1 ... Rotating anode X-ray tube 2 ... Vacuum container 3
... Rotating anode part 4 ... X-ray generating part 5 ... Filament 6
… Rotating shaft 7… Cooling water return pipe 8… Vacuum seal part 9
... Water seal part 10 ... Cooling water inlet 11 ... Cooling water outlet 1
2 ... Cooling water 13 ... Pulley 14 ... Pulley 1
5 ... Belt 16 ... Motor 20 ... Electric power limit setting device 21 ... X-ray power control unit 2
2 ... current monitor 23 ... voltage monitor 24 ... power monitor 2
5 ... Comparator 26 ... Motor speed controller

Claims (1)

[Claims] 1. A water cooling system which supplies cooling water from a cooling water inlet to a rotating anode part from the inside of a rotating shaft of an anode through a water seal part and discharges the cooling water to a cooling water outlet via a return pipe provided inside the rotating shaft. In the X-ray generator of the method, a power limit setting means for setting the maximum value of the electric power supplied to the rotating anode X-ray tube and a rotating speed control means for controlling the rotating speed of the rotating anode are provided.
An X-ray generator characterized in that the rotational speed of the rotating anode is controlled to a required minimum value in association with the set value of the electric power limit to extend the life of the water seal.