JPH0342597Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a temperature-sensitive switch that operates when the temperature of an object to be measured reaches a set temperature, and is used in exhaust gas purification devices for internal combustion engines, etc. The present invention relates to a thermosensor that is placed at an appropriate position inside a high-temperature device to detect an abnormal rise in temperature inside the device.

[Prior art] (1) A temperature-sensitive switch is constructed by utilizing the difference in thermal expansion between ceramic and metal.

(2) Use a spring to force the piston and fill it with fluid.
A normally open contact is formed between the fixed contact and the piston (Japanese Utility Model Publication No. 51-45070).

[Problems to be solved by the invention] However, the conventional technology has the following drawbacks.

In (1) above, since the difference in thermal expansion of solids is utilized, the opening and closing of the contacts is too slow, making it difficult to accurately set the opening and closing temperature of the switch, and chattering is likely to occur when the switch is opened and closed. Furthermore, malfunctions are likely to occur due to breakage of the ceramic member.

(2) above also tends to cause chattering when the switch is opened and closed. Furthermore, it is difficult to achieve both electrical continuity and airtightness between the piston and the conductor body.

The purpose of the present invention is to provide a temperature-sensitive switch that allows precise setting of the switch opening/closing temperature, allows quick opening/closing of contacts, reliably prevents chattering, and is highly reliable for redundant use.

[Means for solving the problem] In order to achieve the above object, the present invention includes a heat-resistant metal tube that encloses a fluid with a large coefficient of thermal expansion and has a closed end, and a gas-tight and axially displaceable tube. A movable terminal with a flange that is fitted into the rear end of the heat-resistant metal tube, a metal housing that is fitted onto the rear end of the heat-resistant metal tube and has a larger inner diameter on the tip side at the step, and an electrically insulating terminal. a fixed flanged terminal disposed inside the rear end of the housing; and an electrical insulator disposed between the flanged fixed terminal and the movable flanged terminal so that the tip and the movable flanged terminal form a normally open contact. and a plate spring that electrically connects the movable terminal and the housing by fixing one end to the collar of the movable terminal and slidingly contacting the other curved end to the inner circumferential wall of the housing. Adopted.

[Operations and effects of the invention] (Operations) The flanged movable terminal is displaced in the direction of the flanged fixed contact as the fluid in the heat-resistant metal cylinder expands.

When the leaf spring reaches the step, the flanged movable contact temporarily stops.

When the expansion of the fluid reaches the set value (= operating temperature of the temperature-sensitive switch), the leaf spring comes off the step and moves to the rear end of the small diameter metal housing, the coil spring contracts, and the movable flanged terminal and flanged The contact with the fixed terminal closes.

(Effects) (A) The temperature at which the switch closes can be precisely set by setting the position and size of the step and selecting the leaf spring.

(a) Since the contacts close quickly, chattering can be reliably prevented.

(c) The flanged movable contact and the heat-resistant metal tube have excellent gas tightness, and the leaf spring ensures continuity.

(d) Temperature-sensitive switches are highly reliable for redundant use.

[Example] The temperature-sensitive switch of the present invention has a tip 11 closed with a stopper 12 made of a heat-resistant metal such as stainless steel, and a rear end 13 made of a heat-resistant metal such as stainless steel with an open end. A cylinder 1, a front end side part 21 inserted into the rear end of the thermosensitive cylinder 1, a rear end side part 24 having a contact material layer 22 made of noble metal, copper, or an alloy thereof on the end surface, and the temperature sensitive cylinder. A cylindrical movable terminal 2 made of a conductive material is comprised of an intermediate flanged portion 25 that is locked to the end surface of the temperature sensing tube 1;
A metal cylindrical switch housing 3 externally fitted and fixed to the rear end 13, and a rear end 3 of the housing 3.
An electric wire 4 with an insulating coating 41 is inserted from the outer periphery of the electric wire 4 and fixed to the housing 3 by crimping 33 from the outer periphery, and a core wire 43 is inserted into the center hole 42 of the insulating coating 41 and is fitted inside the center hole 42. a rear end small diameter portion 51 fitted inside the coil 44 connected to the movable terminal 2; A fixed terminal 5 made of a conductive material, which is composed of a flange-like part 55 in contact with the end surface 42 of the insulating coating 41 and forms a switch S between it and the movable terminal 2.
and a coil spring 30 having an electrically insulating property and subjected to a surface treatment such as enamel or fluorine resin coating, interposed between the flange-like part 25 of the movable terminal 2 and the flange-like part 55 of the fixed terminal 5.
, an electrical insulating layer 50 formed on the inner circumferential wall surface of the housing 3 at a position corresponding to the fixed terminal 5 , an electric insulating layer 50 formed between the tip side portion 21 of the movable terminal 2 and the inner circumferential wall of the temperature-sensitive tube 1 . A heat-resistant O-ring 6 made of fluorocarbon rubber or the like is a sealing means for allowing displacement of the movable terminal in the axial direction, and one end 72 is welded, fastened, etc. to the outer periphery of the brim 25 of the movable terminal 2. The curved other end 71 is fixed by the fixing means of the housing 3, and the curved other end 71 is brought into sliding contact with the inner peripheral wall of the housing 3, and locks the movable terminal 2 with a predetermined frictional force. A leaf spring 7 electrically connects the movable terminal 2 and the housing 3, a stopper 16 welded to the outer wall of the temperature sensing cylinder 1, and a stopper 16 loosely fitted behind the stopper 16 of the temperature sensing cylinder 1. It consists of a hollow bolt 17 for mounting, and an inert gas G such as air or nitrogen is sealed inside the temperature sensing cylinder 1. The temperature sensing tube 1 is inserted into a mounting screw hole provided in the high temperature device, and the hollow bolt 17 is inserted.
It is concluded by. When the temperature inside the high-temperature device is normal (below the set temperature), the inert gas in the temperature sensing tube 1 is at low pressure and the switch S is in an open state. When the temperature inside the high-temperature device increases abnormally, the movable terminal 2 is pressed by the pressure applied to the tip side portion 21 as the pressure of the gas G in the temperature sensing cylinder 1 increases, and the spring 30 The fixed terminal 5 is gradually displaced in the direction of the fixed terminal 5 against the spring load, the resultant force of the frictional force between the leaf spring 7 and the housing, and the frictional force of the O-ring 6 serving as a sealing means. In this embodiment, a step 35 is provided on the inner periphery of the housing 3 to engage the rear end 71 of the leaf spring 7.
is provided. The movable terminal 2 is temporarily stopped at a position where the rear end 71 of the leaf spring 7 abuts against a step 35 provided on the inner periphery of the housing due to a step-like increase in resistance. The movable terminal 2 is stopped at the position where the rear end 71 of the leaf spring 7 is locked to the step 35 until the internal pressure of the temperature sensing cylinder 1 reaches the set pressure, and when the set pressure is exceeded, the lock is stopped. The movable terminal 2 is quickly displaced so as to collide with the fixed terminal 5. By appropriately selecting the step 35 and the leaf spring 7, the set temperature when the switch S is closed can be set arbitrarily and accurately.
Also, chattering when closing can be reliably prevented. When the temperature of the high-temperature device falls below the set temperature, the internal pressure of the temperature sensing cylinder 1 drops and the terminal 2 returns to its original position by the spring force of the coil spring 30.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the temperature-sensitive switch of the present invention. In the figure, 1... Temperature sensing tube (heat-resistant metal tube), 2... Cylindrical movable terminal made of conductive material (movable terminal with flange), 3...
Metal cylinder switch housing (metal housing), 5... Fixed terminal with flange (fixed terminal), 7... Leaf spring, 11... Tip, 13... Rear end, 25... Intermediate flanged part (flange) , 30...Coil spring, 3
5... Stage, 55... Flange-like part (flange), S... Switch (normally open contact), G... Inert gas (fluid).

Claims (1)

[Claims for Utility Model Registration] A heat-resistant metal tube that encloses a fluid with a large coefficient of thermal expansion and has a closed end, and a heat-resistant metal tube that is fitted into the rear end side of the heat-resistant metal tube so as to be gas-tight and displaceable in the axial direction. a movable terminal with a flange; and a movable terminal fitted externally to the rear end of the heat-resistant metal cylinder;
A metal housing having a larger inner diameter on the tip side at the step, a flange fixed terminal electrically insulated and installed inside the rear end of the housing, and a tip of the flange fixed terminal and the flange. an electrically insulating coil spring disposed between the movable terminal and the movable terminal so that the movable terminal constitutes a normally open contact point; A temperature-sensitive switch comprising a leaf spring that electrically connects a movable terminal and a housing.