JP2008096349A - Temperature sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature sensor capable of preventing a tip of a thermocouple from being damaged when the sensor is accidentally dropped or brought into collision with an object. <P>SOLUTION: The thermocouple is formed of thermocouple wires 16a and 16b, a contact plate 17, and a protection plate 18. The thermocouple is mounted to a protection tube 24 freely displacably in the axial direction, and a shape memory alloy 8 serving as a temperature responsive member is coupled to the thermocouple. By deformation of the shape memory alloy 8, the contact plate 17, which is to be pressed to an object to be detected, at the tip of the thermocouple is inserted into the protection tube 24 at a low temperature, and at a high temperature, it is protruded from an opening 32 of the protection tube 24. When the opening 32 of the protection tube 24 is pressed to the object to be detected, the shape memory alloy 8 is deformed by heat of the object to be detected if temperature of the object is high, and the contact plate 17 at the tip of the thermocouple is pressed to the object to be detected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a temperature sensor used for detecting the temperature of a high-temperature detection object such as a steam trap and confirming whether the operation is good or not, and in particular, a thermocouple is pressed against the detection object with a desired force. About what you did.

  A conventional temperature sensor in which the thermocouple is pressed against the object to be detected with a desired force is attached to the protective tube so that the thermocouple can be displaced in the axial direction, and the thermocouple is urged by the spring to the object to be detected. The tip of the thermocouple to be pressed is protruded from the opening of the protective tube, and the tip of the thermocouple is pressed against the object to be detected and pushed into the opening of the protective tube, thereby compressing the spring by a certain amount.

The above-mentioned conventional temperature sensor has a thermocouple tip that protrudes from the opening of the protective tube when the thermocouple is not being pressed against the object to be detected. There was a problem of damaging the tip of the thermocouple.
Japanese Utility Model Publication No. 3-83829

  The problem to be solved is to provide a temperature sensor that does not damage the tip of the thermocouple even if it is accidentally dropped or applied to an object.

  In the present invention, a thermocouple is attached to a protective tube so as to be axially displaceable, a temperature sensitive member is connected to the thermocouple, and the tip of the thermocouple that presses against an object to be detected by deformation of the temperature sensitive member is placed in the protective tube at a low temperature. The tip of the thermocouple is deformed by the heat of the object to be detected due to the heat at the high temperature of the object to be detected by pressing the opening of the protection tube against the object to be detected. Is pressed against the object to be detected.

  In the present invention, the tip of the thermocouple is immersed in the protective tube due to the deformation of the temperature responsive member at a low temperature when the object is not pressed against the object to be carried. Therefore, an excellent effect is obtained that the tip of the thermocouple is not damaged even if it is accidentally dropped or applied to an object.

  The temperature sensor of the present invention is configured such that the tip of the thermocouple pressed against the object to be detected by deformation of the temperature-responsive member is immersed in the protective tube at a low temperature and protrudes from the opening of the protective tube at a high temperature. Is pressed against the object to be detected, and the tip of the thermocouple is pressed against the object to be detected by the deformation of the temperature-responsive member due to the heat of the object to be detected when the temperature is high. For this reason, the tip of the thermocouple is immersed in the protective tube due to deformation of the temperature responsive member at a low temperature when it is not pressed against the object to be detected such as when it is carried. Therefore, the tip of the thermocouple is not damaged even if it is accidentally dropped or applied to an object.

  An embodiment showing a specific example of the above technical means will be described (see FIG. 1). In this embodiment, a temperature sensor according to the present invention is combined with a vibration sensor. A vibration transmission plate 2 formed with a female screw is screwed to the vibration detection needle 1 formed with a small-diameter male screw at the lower portion, and the upper surface of the vibration transmission plate 2 is in contact with the lower surface of the large diameter portion. An upper electrode plate 3, a piezoelectric element 4, a lower electrode plate 5, and a weight 6 are sequentially inserted below the vibration transmission plate 2, and are brought into contact with each other by nuts 7 and fixed to the vibration detection needle 1. The vibration detection needle 1 and the vibration transmission plate 2 are made of stainless steel, the upper and lower electrode plates 3 and 5 are made of phosphor bronze, and the weight 6 is made of zirconia ceramic. A vibration detection unit of a vibration sensor is formed from the vibration detection needle 1, the vibration transmission plate 2, the upper electrode plate 3, the piezoelectric element 4, the electrode plate 5, and the weight 6.

  The vibration detection unit includes an upper wall in which the upper surface of the vibration transmitting plate 2 and the lower surface of the weight 6 are provided with a cut toward the front side, and a bifurcated spring portion extending further downward from the end on the opposite side of the upper wall. The upper surface of the vibration transmitting plate 2 is brought into contact with the lower surface of the upper wall of the switch fitting 9. The switch fitting 9 has two side walls on both sides extending downward from the upper wall, and the vibration detection unit is attached to the casing 10 by holding the side walls and the upper wall with the inner wall of the casing 10. ing. The casing 10 is formed of two casing members on the opposite side and the near side of the drawing, and is connected by taper screws 11 and 12. The switch fitting 9 is made of stainless steel, and the casing 10 is made of PEEK. Lead wires (not shown) from the upper and lower electrode plates 3 and 5 are connected to terminals 14 and 15 of the signal processing circuit 13.

  The thermocouple wires 16a and 16b made of long thin plates of chromel and alumel have four legs that are bent inward at the upper ends of each of the thermocouple wires 16a and 16b. A contact plate 17 having a hole and a disc-shaped protection plate 18 having a hole in the center are fixed by welding. A thermocouple is formed from the thermocouple wires 16 a and 16 b, the contact plate 17 and the protection plate 18. The hollow cylindrical heat insulation pipe 19 located inside the thermocouple is composed of an upper small diameter portion, a lower large diameter portion, and a long middle diameter portion in the middle, leaving an upper end and a lower end in the middle diameter portion. Two windows 20a and 20b having substantially the same width as the diameter of the portion and communicating with each other through the hollow portion are formed on both sides, and the remaining portions on the upper side of both windows 20a and 20b are cut vertically, and both windows 20a , 20b, the remaining portion is cut inwardly upward.

  The thermocouple is wound by a ring 22 in which thermocouple wires 16a and 16b are wound into a large-diameter hole from the outside of the small-diameter portion of the heat insulating tube 19 into the window and from the outside of the large-diameter portion through the bottom surface and press-fitted into the large-diameter hole. It is fixed. The portions located in the windows of the thermocouple wires 16a and 16b are formed as elastically deforming portions 23a and 23b that are bent inward in advance. A protective tube 24 having an inner diameter slightly larger than the outer diameter of the medium diameter portion is inserted outside the small diameter portion and the medium diameter portion of the heat insulating tube 19. The protective tube 24 is fitted into a protrusion 25 indicated by a dotted line formed at the lower end of the side surface of the middle diameter portion of the heat insulating tube 19 to prevent the extraction. A coil-shaped shape memory alloy 8 as a temperature responsive member that displaces the thermocouple in the axial direction of the protective tube 24 is disposed between the heat insulating tube 19 and the protective plate 18. One end of the shape memory alloy 8 is fixed to the heat insulating tube 19 and the other end is fixed to the protective plate 18. The shape memory alloy 8 is deformed in accordance with the temperature, and if it is a predetermined temperature, for example, 60 degrees or less, it is transformed into a short shape that has been preliminarily memorized by martensite transformation from the parent phase to the martensite phase, and the tip of the thermocouple. The contact plate 17 is immersed in the protective tube 24, and when it reaches a predetermined temperature or more, it is transformed into a long shape by reversely transforming from the martensite phase to the parent phase, and the contact plate 17 at the tip of the thermocouple is attached. It protrudes from the opening 32 of the protective tube 24. The thermocouple, the shape memory alloy 8, the heat insulating tube 19, the ring 22 and the protective tube 24 form a temperature measuring unit for the temperature sensor. The contact plate 17, the protection plate 18, and the protection tube 24 are made of stainless steel, the heat insulation tube 19 is made of PEEK, and the ring 22 is made of bakelite. The thermocouple wires 16 a and 16 b are covered with insulation from a portion facing the lower end of the foot of the contact plate 17 to a portion facing the upper portion of the large diameter portion of the heat insulating tube 19.

  A temperature measuring unit is passed through the vibration detection needle 1 and inserted from the upper end opening of the casing 10. The portions of the thermocouple wires 16a and 16b located outside the large diameter portion of the heat insulating tube 19 are connected in contact with the thermocouple contacts 28 and 29 connected to the terminals 26 and 27 of the signal processing circuit 13. The upper and lower slits are provided around the screw holes of the casing 10 corresponding to the taper screws 11 and 12, respectively, and the inner portions 30 and 31 of the respective slits are inwardly directed by screwing the taper screws 11 and 12. Transformed. As a result, the thermocouple wires 16 a and 16 b and the thermocouple contacts 28 and 29 are firmly pressed together and the temperature measuring unit is fixed to the casing 10. The taper screws 11 and 12 constitute biasing means, and the temperature measuring unit can be pulled out of the casing 10 by loosening the taper screws 11 and 12.

  Next, the operation of the vibration sensor with a temperature sensor of this embodiment will be described. The shape memory alloy 8 is deformed into a short shape at a low temperature when it is not pressed against an object to be detected such as when being carried, and the contact plate 17 at the tip of the thermocouple is immersed in the protective tube 24. Therefore, the contact plate 17 at the tip of the thermocouple is not damaged even if it is accidentally dropped or applied to an object. The tip of the vibration detection needle 1 is pressed against the surface of the steam trap as the object to be detected, and is pushed up to the upper surface of the opening 32 of the protective tube 24 against the elastic force of the spring portion of the switch fitting 9. The shape memory alloy 8 is deformed into a long shape by the heat of the steam trap, and the contact plate 17 at the tip of the thermocouple is pressed against the steam trap with a desired force.

  The mechanical vibration of the steam trap is transmitted to the vibration transmission plate 2 through the vibration detection needle 1 and acts on the piezoelectric element 4 as pressure fluctuation. In response to this, voltage fluctuations occur in the piezoelectric element 4. This voltage fluctuation is sent from the electrode plates 3 and 5 to the terminals 14 and 15 of the signal processing circuit 13 via the conductors, amplified and detected by the signal processing circuit 13, and calculated to an average value, a peak value, etc. Part (not shown). On the other hand, the temperature signal of the steam trap is detected by the thermocouple wires 16a and 16b through the contact plate 17, and is sent to the terminals 26 and 27 of the signal processing circuit 13 through the thermocouple contacts 28 and 29, and is amplified and displayed. Is displayed.

It is sectional drawing of the vibration sensor with a temperature sensor which combined the temperature sensor of the Example by this invention with the vibration sensor.

Explanation of symbols

8 Shape memory alloys 16a and 16b Thermocouple wire 17 Contact plate 19 Heat insulation tube 24 Protection tube 32 Protection tube opening

Claims (1)

A thermocouple is attached to the protective tube so that it can be displaced in the axial direction, a temperature sensitive member is connected to the thermocouple, and the tip of the thermocouple that presses against the object to be detected by deformation of the temperature sensitive member is immersed in the protective tube at low temperatures. Sometimes it protrudes from the opening of the protective tube, and when the opening of the protective tube is pressed against the object to be detected, the tip of the thermocouple is detected by the deformation of the temperature sensitive member due to the heat at the high temperature of the object to be detected. A temperature sensor characterized by being pressed against.

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