JP2010164352A - Fluorescent x-ray analyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve quietness by suppressing noise to the utmost while preventing the overheating of an X-ray tube which emits exciting X rays. <P>SOLUTION: The air blast amount of an air blast fan for cooling the X-ray tube by air can be changed over by two large and small stages. An air blast amount is set to "small" at the time of starting of the fluorescent X-ray analyzer (S1 and S2) and, when the atmospheric temperature in the analyzer is more than T1 and the output set value of the X-ray tube is more than a prescribed value Q, the air blast amount is changed over to "large" (S3-S5). Further, when the atmospheric temperature in the analyzer becomes below T1, the output set value of the X-ray tube becomes below the prescribed value Q and the surface temperature of the X-ray tube becomes below T2 in the state of the air blast amount "large", the air blast amount is changed over to "small" (S6-S9). By this constitution, noise can be suppressed by lowering the rotational speed of the air blast fan in a case that the surface temperature of the X-ray tube is made impossible to exceed an operation security upper limit value while performing proper cooling so that the surface temperature of the X-ray tube does not exceed the operation security upper limit value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fluorescent X-ray analyzer that irradiates a sample with excitation X-rays emitted from an X-ray source and thereby detects fluorescent X-rays emitted from the sample.

  In general, an X-ray fluorescence analyzer irradiates a solid, powder or liquid sample with primary X-rays, and detects the fluorescent X-rays that are excited by the primary X-rays and emitted from the sample. To qualitatively and quantitatively determine the elements contained in the sample. X-ray fluorescence analyzers are broadly classified into energy dispersion type and wavelength dispersion type. Particularly, in the energy dispersion type X-ray fluorescence analyzer, an X-ray tube having a relatively small output (for example, about 50 W at the maximum) is an X-ray tube. Often used as a radiation source. Such an X-ray tube has a structure in which an X-ray generation part is accommodated inside a case in which oil for heat radiation is enclosed, and the entire case is cooled by air or water to prevent overheating (Patent Literature). 1 etc.).

  Although water cooling is superior to air cooling in terms of cooling effect, water cooling has a complicated structure and greatly increases costs. Therefore, in the X-ray tube of the fluorescent X-ray analyzer, air cooling is generally used because of its simple structure and low cost. In the case of air cooling, air is forcibly applied to the case of the X-ray tube using a blower fan, but there is a problem that noise increases when the amount of blown air is increased in order to enhance the cooling effect. In addition, when the amount of blown air is large, power consumption increases accordingly. On the other hand, if the rotational speed of the blower fan is decreased to suppress noise, the X-ray tube may not be sufficiently cooled. In the worst case, the target of the X-ray generation source may melt and cause a failure.

JP 2003-107021 (paragraph 0010)

  The present invention has been made to solve the above-mentioned problems, and its main purpose is to prevent the overheating of the X-ray tube and reduce the noise caused by the blower fan for air cooling. An analyzer is provided.

In order to solve the above-mentioned problems, the present invention is directed to irradiating a sample with excitation X-rays emitted from an X-ray source having variable output, thereby detecting fluorescent X-rays emitted from the sample. In the analyzer
a) an air blowing means capable of changing the air blowing amount for air-cooling the X-ray source;
b) first temperature detecting means for detecting the ambient temperature inside the apparatus housing;
c) Based on at least the atmospheric temperature detected by the first temperature detection means and the output set value of the X-ray source, the air flow is controlled so that the surface or internal temperature of the X-ray source does not exceed a specified temperature. Control means for controlling the amount of air blown by the means;
It is characterized by having.

  Here, as an aspect of the X-ray source, an X-ray tube in which an X-ray generation unit is provided in a case in which oil is sealed can be considered. In this case, the surface temperature of the X-ray source is the surface temperature of the case, and the internal temperature is the temperature of oil in the case.

  The first temperature detection means can be provided at an appropriate position inside the apparatus housing, but preferably, at a position where it does not receive direct radiant heat from the X-ray source and is not directly blown by the blowing means. It is good to install.

  As an aspect of the fluorescent X-ray analysis apparatus according to the present invention, the air blowing means can switch the air blowing amount in at least two stages, and the control means operates such that the air blowing means operates with a small air blowing amount. In the state, when the output set value of the X-ray source is equal to or higher than a predetermined value and the ambient temperature is equal to or higher than a first predetermined temperature, the blower unit is controlled to switch the blower amount from small to large can do.

  For example, the first predetermined temperature is set to a temperature at which the apparatus is normally used (for example, the upper limit of the performance guarantee temperature range), and the predetermined value as a reference for determining the output set value is the first predetermined temperature of the ambient temperature It is preferable to determine the minimum value of the X-ray output that may exceed the upper limit value (the specified temperature) of the operation guarantee of the surface (or internal) temperature of the X-ray source at the temperature. Thereby, under conditions where the surface temperature or the internal temperature of the X-ray source may exceed the specified temperature, the air flow rate is set large, and the cooling effect can be enhanced.

  Moreover, one aspect of the fluorescent X-ray analysis apparatus according to the present invention further includes second temperature detection means for detecting the temperature of the surface or inside of the X-ray source, and the control means is the blowing means. Is operating with a large air flow rate, the output setting of the X-ray source is less than a predetermined value, the ambient temperature is less than a first predetermined temperature, and the X-ray source temperature is less than a second predetermined temperature. When it becomes, it can be set as the structure which controls the said ventilation means so that ventilation volume may be switched from large to small.

  According to this configuration, when the condition that the surface temperature or the internal temperature of the X-ray source does not exceed the specified temperature is satisfied, the rotation speed of the blowing unit can be reduced to suppress noise.

  Further, as another aspect of the X-ray fluorescence analyzer according to the present invention, the control means is configured such that the output setting of the X-ray source is less than a predetermined value in a state where the blowing means is operating at a large blowing amount. It is good also as a structure which controls the said air blower so that air volume may be switched from large to small when the state where the said atmospheric temperature is less than 1st predetermined temperature continues more than predetermined time. The predetermined time may be determined based on the result of measuring in advance the time required for the X-ray source to be sufficiently cooled.

  According to this configuration, the rotational speed of the blowing unit is reduced when the conditions that the surface temperature or the internal temperature of the X-ray source does not exceed the specified temperature are satisfied without directly measuring the X-ray source temperature. Noise can be suppressed.

  Since it is assumed that the temperature of the X-ray tube is sufficiently lowered when the apparatus is activated, the control means may operate the blowing means with a small amount of air when the apparatus is activated.

  According to the fluorescent X-ray analyzer according to the present invention, when the X-ray source is overheated and reliably prevented from exceeding the specified temperature, that is, the upper limit temperature determined for the X-ray source, there is no risk of overheating. In addition, noise can be reduced by reducing the rotation speed of the blower fan. In addition, power consumption can be reduced. In this way, it is possible to balance the prevention of overheating of the X-ray source and the quietness of the apparatus. Note that the upper limit of the guaranteed operating temperature of the X-ray source differs depending on the structure and material of the X-ray source, so appropriate determination conditions (a predetermined value for determining the output set value) are set for each type of X-ray source. It is preferable to determine and change the determination condition according to the X-ray source actually used.

1 is a schematic configuration diagram of an energy dispersive X-ray fluorescence analyzer which is an embodiment of the present invention. The figure which showed the relationship between atmospheric temperature and output setting value when switching ventilation volume from "small" to "large." The control flowchart of the ventilation fan in the fluorescent X-ray-analysis apparatus of a present Example. The control flowchart of the ventilation fan in the fluorescent X-ray-analysis apparatus of another Example.

  A fluorescent X-ray analyzer according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of an energy dispersive X-ray fluorescence spectrometer according to this embodiment.

  As shown in FIG. 1, when a sample 2 is irradiated with primary X-rays emitted from an X-ray tube 3 inside the apparatus housing 1, the sample 2 is excited to emit fluorescence. X-rays are emitted. This fluorescent X-ray is introduced into the semiconductor detector 4 such as a lithium drift Si detector and detected, and this detection signal is processed by the data processing unit 8 to obtain the energy (wavelength) and intensity of the fluorescent X-ray. .

  The X-ray tube 3 has a structure in which an X-ray generation part 32 is accommodated in a case 31 and cooling oil 33 is filled in the case 31 so as to surround the X-ray generation part 32. Driving power is supplied from the high-voltage power supply 6 to the X-ray generation unit 32 of the X-ray tube 3, and the control unit 7 controls the driving power so that the X-ray output changes within a predetermined range. This X-ray output is set as one of analysis conditions from the operation unit 9. The blower fan 5 generates an air flow to air-cool the X-ray tube 3, and the blower amount can be switched in two stages by the control unit 7.

  A temperature sensor (corresponding to the second temperature detection means in the present invention) 11 is mounted on the outer surface of the case 31 of the X-ray tube 3, and this temperature sensor 11 detects the surface temperature of the X-ray tube 3. The temperature sensor 11 may be installed so as to be immersed in the oil 33 in the case 31 (the position indicated by the dotted line in FIG. 1) so that the temperature inside the X-ray tube 3 can be detected. On the other hand, a temperature sensor (first temperature in the present invention) for detecting the ambient temperature inside the apparatus at a position away from the X-ray tube 3 and not directly blown by the blower fan 5 inside the apparatus housing 1. (Corresponding to detection means) 10 is installed. As an example, the temperature sensor 10 can be installed on a circuit board on which circuit components constituting the control unit 7 are mounted.

  The control unit 7 is configured mainly with a microcontroller including a CPU, a ROM, a RAM, and the like, and by executing a control program written in advance in the ROM on the CPU, characteristic control as described later is performed. • Processing is achieved.

  In the fluorescent X-ray analyzer of this embodiment, the following specifications or conditions are assumed as an example. That is, the variable range of the X-ray output is 0 to 50 W, the assumed maximum temperature of the room where the apparatus is installed is 40 ° C., the upper limit of the guaranteed performance temperature of the apparatus is 30 ° C., and the guaranteed operation temperature of the X-ray tube 3 (surface temperature). The upper limit of is assumed to be 50 ° C.

  FIG. 3 is a control flowchart of the blower fan 5 in the fluorescent X-ray analysis apparatus of this embodiment, and FIG. 2 is a diagram for explaining this control. With reference to FIG.2 and FIG.3, control operation | movement of the ventilation fan 5 performed by the control part 7 is demonstrated.

  When the apparatus is turned on and the control unit 7 is energized, the apparatus is activated (step S1). At the time of start-up, the control unit 7 starts the operation by setting the blowing amount “small” for the blowing fan 5 (step S2). As a result, air is blown from the blower fan 5, and cooling (forced heat dissipation) of the X-ray tube 3 is started. When the amount of blown air is “small”, the operation sound of the blower fan 5 is low, and it is a noise that is hardly noticed. Thereafter, the control unit 7 reads the ambient temperature Ta detected by the temperature sensor 10, and determines whether or not the ambient temperature Ta is equal to or higher than a predetermined temperature T1 (step S3). T1 is assumed to be 30 ° C., which is a normal performance guarantee temperature.

  When the atmospheric temperature Ta is equal to or higher than the predetermined temperature T1, it is next determined whether or not the output set value of the X-ray tube 3 set as one of the analysis conditions from the operation unit 9 is equal to or higher than the specified value Q. (Step S4). Assuming that the allowable upper limit temperature of the surface temperature of the X-ray tube 3 is 50 ° C. as described above, and that the output set value that may exceed this is 30 W under the condition that the air flow rate is “small”. The specified value Q is set to 30W. When the output setting value of the X-ray tube 3 is equal to or greater than the specified value Q, the control unit 7 controls the blower fan 5 so as to switch the blower amount from “small” to “large” (step S5). Thereby, although the rotational speed of the blower fan 5 increases and noise increases, the cooling effect of the X-ray tube 3 increases. FIG. 2 shows the relationship between the ambient temperature Ta and the output set value when the air flow rate is switched from “small” to “large”. In FIG. 2, the air flow rate is switched from “small” to “large” under the condition in the range indicated by the oblique lines.

  When the atmospheric temperature Ta is lower than the predetermined temperature T1 in step S3, and when the output set value of the X-ray tube 3 is lower than the specified value Q in step S4 even if the atmospheric temperature Ta is equal to or higher than the predetermined temperature T1. Since there is no possibility that the surface temperature of the X-ray tube 3 exceeds 50 ° C., the process returns to step S 3, and the operation of the blower fan 5 is continued with the blower amount “low”.

  After the air flow rate is switched to “large” in step S5, the control unit 7 also reads the ambient temperature Ta detected by the temperature sensor 10 and determines whether or not the ambient temperature Ta is less than the predetermined temperature T1 ( Step S6). If the atmospheric temperature Ta is lower than the predetermined temperature T1, it is next determined whether or not the output set value of the X-ray tube 3 is lower than a specified value Q (step S7). Further, when the output set value of the X-ray tube 3 is less than the specified value Q, the control unit 7 reads the surface temperature Tb of the X-ray tube 3 detected by the temperature sensor 11, and this surface temperature Tb is the predetermined temperature T2. It is determined whether it is less than (step S8). Here, the predetermined temperature T2 may be set to a certain lower temperature than 50 ° C. which is the allowable upper limit temperature of the X-ray tube 3, for example, 40 ° C.

  If the surface temperature Tb is less than the predetermined temperature T2, the control unit 7 controls the blower fan 5 so as to switch the blower amount from “large” to “small” (step S9). Thereby, although the cooling performance of the ventilation fan 5 falls, a noise level also falls. At this time, since the surface temperature of the X-ray tube 3 is lowered, and the ambient temperature and the output set value are conditions that do not cause the surface temperature to be raised to 50 ° C. or higher, there is no problem even if the cooling performance is lowered. . After the air flow is switched to “small”, the process returns to step S3 and the above-described control is continued.

  When the atmospheric temperature Ta is equal to or higher than the predetermined temperature T1 in step S6, and the output set value of the X-ray tube 3 is equal to or higher than the specified value Q in step S7 even if the atmospheric temperature Ta is lower than the predetermined temperature T1. Since the surface temperature of the X-ray tube 3 may exceed the allowable upper limit temperature of 50 ° C., the cooling performance cannot be lowered. Therefore, the process returns to step S5, and the operation of the blower fan 5 is continued in a state where the blower amount is “large”. Further, even if the ambient temperature Ta is less than the predetermined temperature T1 and the output set value of the X-ray tube 3 is less than the specified value Q, if the X-ray tube temperature Tb is equal to or higher than T2, high cooling performance is achieved. Therefore, in order to lower the surface temperature of the X-ray tube 3, the process returns to step S <b> 5 to continue the operation with the air flow rate “large”.

  With the above-described air flow rate switching control, overheating of the X-ray tube 3 can be reliably avoided, and damage or failure of the X-ray tube 3 can be prevented. On the other hand, in a state where there is no fear of overheating of the X-ray tube 3, the rotational speed of the blower fan 5 decreases and noise is reduced. In this way, the balance between prevention of overheating of the X-ray tube 3 and quietness of the apparatus is maintained.

  FIG. 4 is a control flowchart of the blower fan in the fluorescent X-ray analyzer according to another embodiment of the present invention. Since the operation from when the air flow rate is set to “small” to when the device is activated until the air flow rate is switched to “large” is the same as the example shown in FIG.

  After the air flow rate is switched to “large” in step S5, the control unit 7 reads the atmospheric temperature Ta detected by the temperature sensor 10 and determines whether or not the atmospheric temperature Ta is less than the predetermined temperature T1 (step). S6). If the atmospheric temperature Ta is lower than the predetermined temperature T1, it is next determined whether or not the output set value of the X-ray tube 3 is lower than a specified value Q (step S7). Further, when the output set value of the X-ray tube 3 is less than the specified value Q, the control unit 7 determines that the state, that is, the ambient temperature Ta is lower than the predetermined temperature T1, and the output set value of the X-ray tube 3 is the specified value Q. It is determined whether or not the state of less than the predetermined time has continued for a predetermined time (step S10). Here, the predetermined time is measured in advance when the surface temperature of the X-ray tube 3 is lowered when the ambient temperature Ta is lower than the predetermined temperature T1 and the output set value of the X-ray tube 3 is lower than the specified value Q. It is preferable to decide by preliminarily. Since the oil 33 of the X-ray tube 3 has a large heat capacity (that is, it is hard to be warmed and hard to cool), it is actually important that the temperature of the oil 33 is sufficiently lowered, and the predetermined time is determined thereby. Here, the predetermined time is, for example, 30 minutes.

  And if it is Yes at step S10, the control part 7 will control the ventilation fan 5 so that ventilation volume may be switched from "large" to "small" (step S9). Thereby, although the cooling performance of the ventilation fan 5 falls, a noise level also falls. Unlike the above embodiment, the surface temperature of the X-ray tube 3 is not directly measured at this time, but there is a state where the ambient temperature Ta is less than the predetermined temperature T1 and the output set value of the X-ray tube 3 is less than the specified value Q. If it continues for a predetermined time or more, it can be estimated that the surface temperature of the X-ray tube 3, that is, the temperature of the oil 33 having a large heat capacity is sufficiently lowered. Therefore, there is no problem even if the air flow rate drops and the cooling performance decreases. After the air flow is switched to “small”, the process returns to step S3 and the above-described control is continued.

  It should be noted that any of the above-described embodiments is an example of the present invention, and it is obvious that modifications, corrections, and additions may be made as appropriate without departing from the spirit of the present invention. For example, the present invention can be applied to a wavelength dispersion type fluorescent X-ray analyzer as long as it is an X-ray fluorescent analyzer using an air-cooled X-ray tube.

DESCRIPTION OF SYMBOLS 1 ... Apparatus housing 2 ... Sample 3 ... X-ray tube 31 ... Case 32 ... X-ray generation part 33 ... Oil 4 ... Semiconductor detector 5 ... Blower fan 6 ... High voltage power supply 7 ... Control part 8 ... Data processing part 9 ... Operation Part 10, 11 ... temperature sensor

Claims (5)

In a fluorescent X-ray analyzer that irradiates a sample with excitation X-rays emitted from an X-ray source having variable output and thereby detects fluorescent X-rays emitted from the sample,
a) an air blowing means that is capable of varying the air flow for air-cooling the X-ray source;
b) first temperature detecting means for detecting the ambient temperature inside the apparatus housing;
c) Based on at least the ambient temperature detected by the first temperature detection means and the output set value of the X-ray source, the air flow is controlled so that the surface or internal temperature of the X-ray source does not exceed a specified temperature. Control means for controlling the amount of air blown by the means;
A fluorescent X-ray analysis apparatus comprising: The fluorescent X-ray analyzer according to claim 1,
The air blowing means is capable of switching the air blowing amount at least in two stages of large and small,
The control means is sent when the output setting value of the X-ray source is equal to or higher than a predetermined value and the ambient temperature is equal to or higher than a first predetermined temperature in a state where the air blowing means operates with a small air flow rate. A fluorescent X-ray analyzer characterized by controlling the air blowing means so as to switch the air volume from small to large. The fluorescent X-ray analyzer according to claim 2,
A second temperature detecting means for detecting the temperature of the X-ray source on or inside the X-ray source;
The control means is configured such that the output setting of the X-ray source is less than a predetermined value, the ambient temperature is less than a first predetermined temperature, and the X-ray source temperature is in a state in which the blowing means is operating at a large blowing amount. The X-ray fluorescence analyzer is characterized in that the air blowing means is controlled so that the air blowing amount is switched from large to small when the temperature becomes lower than a second predetermined temperature. The fluorescent X-ray analyzer according to claim 2,
The control means is in a state where the output setting of the X-ray source is less than a predetermined value and the ambient temperature is lower than a first predetermined temperature for a predetermined time or more in a state where the air blowing means is operating at a large air flow rate. The X-ray fluorescence analyzer characterized by controlling the said ventilation means so that it may switch ventilation volume from large to small when it continues. The fluorescent X-ray analyzer according to any one of claims 2 to 4,
The fluorescent X-ray analysis apparatus characterized in that the control means operates the blowing means with a small amount of blowing air when the apparatus is activated.

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