JPH07294342A - Device for fitting liquid temperature sensor - Google Patents

Abstract

PURPOSE:To prevent a thermistor from being deteriorated due to the entrance of a liquid and an O-ring from breakage and jutting out from an O-ring groove. CONSTITUTION:The tip end of a metallic tube 1 is closed and a thermistor 2 is inserted into the tip end of the tube 1, then the opened base end part of the tube 1 is buried in a body 7 made of synthetic resin and is jointed therewith. In such a fitting device for a liquid temperature sensor in which the tube 1 of the sensor is inserted into an insertion hole 14 of a cooling water container 8, for example, as a member to be fitted on, the clearance between the inner face of the hole 14 and the outer face of the tube 1 is sealed with an O-ring 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid temperature sensor for measuring the temperature of liquid such as cooling water of a water-cooled engine.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional device for mounting a liquid temperature sensor, in which a tip (a lower end in FIG. 2) of a tubular tube 1 made of a metal such as corrosion resistant metal is closed so as to be airtight. The base end (upper end in FIG. 2) has a larger radius and is opened. A thermistor 2, which is a semiconductor heat-sensitive element, is inserted so as to contact the tip (bottom) of the tube 1, and two lead wires 3 are drawn out from the thermistor 2. Are coated for mutual insulation. The tips of the two lead wires 3 are near the opening of the tube 1 and are connected to the two rod-shaped terminals 4 by soldering or the like, and the tube 1 is filled with a synthetic resin. The synthetic resin in the tube 1 is integral with the body 7 including the connector 5 and the flange 6, and when the body 7 made of synthetic resin is molded, the base end portion of the tube 1, the thermistor 2, the lead wire 3, the terminal 4, etc. The inserts are embedded and bonded. A plurality of insertion holes 10 are formed in the flange 6, and a reinforcing pipe 11 is fitted into the insertion holes 10 if desired.

For example, an insertion hole 14 is formed in a water outlet (wall) 13 of a cooling water container (attached member) 8 of a water-cooled engine, a tube 1 is inserted in the insertion hole 14, and a flange 6 is attached to an outer surface 19 of the water outlet 13. The screw is inserted into the insertion hole 10 (reinforcing pipe 11) and screwed into the screw hole (not shown) of the water outlet 13 to mount the liquid temperature sensor on the cooling water container 8. An annular O-ring groove 17 is formed on the flange surface 15 of the flange 6 facing the water outlet 13 and surrounding the tube 1, and an O-ring 18 is attached to the O-ring groove 17. The tip of the tube 1 located inside the water outlet 13 and the like come into contact with the cooling water, and the leakage of the cooling water between the insertion hole 14 and the outer peripheral surface of the tube 1 is caused by the O-ring 18 and the bottom surface of the O-ring groove 17. It is prevented by sealing between (the upper surface in FIG. 2) and the outer surface 19 of the water outlet 13. The temperature of the cooling water is transmitted to the thermistor 2 via the tip of the metal tube 1 having a high heat transfer coefficient, and the measurement output by the thermistor 2 is transmitted to the outside through the lead wire 3 and the terminal 4.
A liquid temperature sensor mounting device similar to the conventional liquid temperature sensor mounting device shown in FIG.
No. 5 publication.

In the liquid temperature sensor, there is a considerable difference in coefficient of thermal expansion between the synthetic resin such as the inside of the tube 1 and the body 7 and the metal of the tube 1, and the temperature of the cooling water changes considerably. In a conventional liquid temperature sensor mounting device, if such a state continues, a minute gap (gap, crack) is generated between the inner and outer surfaces of the tube 1 and the synthetic resin in contact therewith, and the gap forms the O-ring groove 17. The bottom surface opens between the tube 1 and the inner surface of the O-ring 17. Then, pressure acts on the cooling water container 8 so that the cooling water passes between the insertion hole 14 and the outer peripheral surface of the tube 1 and reaches between the inner surface of the O-ring 18 and the outer surface of the tube 1. It penetrates into the inside of the tube 1 along the gap and finally reaches the thermistor 2. Infiltration of cooling water causes deterioration of the thermistor 2 due to corrosion,
The durability of the liquid temperature sensor is reduced. In the conventional liquid temperature sensor mounting device, the O-ring groove 17 has an edge portion and a burr generated by the cutting process after molding the synthetic resin.
O-ring breakage occurs. Further, in the conventional liquid temperature sensor mounting device, when the opening of the O-ring groove 17 has a large chamfer, the O-ring 18 inserted into the O-ring groove 17 protrudes from the O-ring groove 17 during assembly and It becomes defective.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to prevent deterioration of a thermistor due to infiltration of liquid in a device for mounting a liquid temperature sensor, further prevent occurrence of O-ring breakage, and prevent O-ring O-ring. It is also an issue to prevent the protrusion from the groove.

[0006]

According to the present invention, a metal tube (1) of a liquid temperature sensor has a closed end,
Insert the thermistor (2) into the tip of the (1)
The open base end of (1) is embedded and connected to the synthetic resin body (7), and the tube (1) of the liquid temperature sensor is inserted into the insertion hole (14) of the mounted member (8). In the liquid temperature sensor mounting device, the O-ring (18) seals the space between the inner surface of the insertion hole (14) and the outer surface of the tube (1). The tube (1) has a large diameter section (25),
The outer step portion (22) and the middle diameter portion (26) are continuously formed, and the insertion hole (14) is continuously formed with the large diameter portion (30), the step portion (33) and the middle diameter portion (31). The O-ring mounting groove (34) is formed by the outer stepped portion (22) / medium diameter portion (26) of the tube (1) and the large diameter portion (30) / stepped portion (33) of the insertion hole (14). Can be configured. In addition to this, the tube is formed by deep drawing, and the radius R of the portion (A) where the large diameter portion (25) of the tube and the outer step portion (22) intersect and the diameter W of the O-ring (18). Can be set such that R / W = 0.15 to 0.40. Also, the tip of the metal tube (1) of the liquid temperature sensor is blocked, and the thermistor (2) is attached to the tip inside the tube (1).
Is inserted and the thermistor (2) is connected to the terminal (4) through the lead (3), the open proximal end of the tube (1), the thermistor (2), the lead (3), the terminal (4)
Is connected to the synthetic resin body (7) and the cooling water container (8)
In the mounting device of the liquid temperature sensor in which the tube (1) of the liquid temperature sensor is inserted into the insertion hole (14) of the water outlet (13), the tube (1) formed by the deep drawing method has a large diameter. Section (25), outer step section (22) and medium diameter section (2
6) are continuously formed, and the insertion hole (14) has a large diameter portion (3
0), the stepped portion (33) and the medium diameter portion (31) are continuously formed, and the outer stepped portion (22) / medium diameter portion (26) and the insertion hole (14) of the tube (1) are formed.
O-ring mounting groove (34) due to the large diameter part (25) and step (33) of
The O-ring (18) is mounted in the O-ring mounting groove (34), and the space between the inner surface of the insertion hole (14) and the outer surface of the tube (1) is sealed by the O-ring (18). It is configured.

[0007]

[Function] The tip of the metal tube (1) of the liquid temperature sensor is closed, the thermistor (2) is inserted into the tip of the tube (1), and the liquid temperature is measured by the thermistor (2).
The measurement output is retrieved. The open base end of the tube (1) is embedded and connected to the synthetic resin body (7), and the tube (1) of the liquid temperature sensor is inserted into the insertion hole (14) of the mounted member, Temperature is transmitted to the thermistor (2) through the tip of the tube (1). The inner surface of the insertion hole (14) and the outer surface of the tube (1) are sealed by an O-ring (18) to prevent leakage and infiltration of liquid. The tube (1) has a large diameter part (25), an outer step (22) and a medium diameter part (2).
6) are continuously formed, and the insertion hole (14) has a large diameter portion (30) and a step portion.
(33) and the medium diameter portion (31) are continuously formed, and the outer stepped portion (22) and the medium diameter portion (26) of the tube (1) and the large diameter portion (30) of the insertion hole (14)
The inner surface of the insertion hole (14) and the tube (1) such that the stepped portion (33) constitutes an O-ring mounting groove (34).
The sealing between the outer surface and the outer surface of the can be made more reliable.

[0008]

FIG. 1 shows an embodiment of a mounting device for a liquid temperature sensor according to the present invention. In the description of the embodiment of FIG. 1, the same components as those of the conventional example of FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted in principle. In the embodiment of the present invention, the tube 1 is formed by deep drawing a stainless steel plate, and the tube 1 has a large diameter portion 25 and an outer step portion 22.
(Portion approximately perpendicular to the axis of tube 1), medium diameter part 2
6. A gentle step portion 23 and a small diameter portion 27 are continuously formed. When the tube 1 is joined to the body 7, the outer step portion 22 is located at a portion slightly apart from the flange surface 15, and the thermistor 2 is inserted into the closed tip of the small diameter portion 27. The tube 1 becomes a large-diameter portion 25 from the outer step portion 22 toward the base end, the diameter is enlarged at the base end portion, and the base end has a flange shape. The synthetic resin in the tube 1 is integral with the body 7 including the connector 5 and the flange 6, and when the body 7 is molded, half of the large diameter portion 25 of the tube 1, the thermistor 2, the lead wire 3, the insert of the terminal 4, etc. Are embedded and combined. Also in the liquid temperature sensor mounting device according to the embodiment of the present invention, a minute gap (gap or crack) is generated between the inner and outer surfaces of the tube 1 and the synthetic resin body in contact therewith, and the gap is a flange. It is a surface of the surface 15 and opens in the vicinity of the tube 1.

In the insertion hole 14 of the water outlet 13 of the cooling water container (attached member) 8, the tapered portion 2 is formed in order from the outer surface.
9. A large diameter portion 30, a step portion 33 (a portion substantially perpendicular to the center line of the insertion hole 14), and a medium diameter portion 31 are continuously formed, and the step portion 33
Is located at about half the depth of the insertion hole 14. The O-ring 18 is attached from the tip of the tube 1 and is moved in the proximal direction of the tube 1 to bring the O-ring 18 into contact with the outer step 22 of the tube 1 to prepare for mounting the liquid temperature sensor. When the liquid temperature sensor is attached to the cooling water container 8, the tube 1 is inserted from the tip into the insertion hole 14 of the water outlet 13, and the flange surface 15 of the liquid temperature sensor is at the outer surface of the water outlet 13 at the position shown in FIG. Abut 19. In the state shown in FIG. 1, the outer stepped portion of the tube 1
22.Step between outer surface of medium diameter part 26 and water outlet 13
An annular O-ring mounting groove 34 is formed by 33 and the inner surface of the large diameter portion 30. The O-ring mounted in the O-ring mounting groove 34
The outer surface of the ring 18 is in close contact with the outer surface of the outer step portion 22 and the middle diameter portion 26 of the tube 1 and the inner surface of the large diameter portion 30 of the water outlet 13.

The tip of the tube 1 located inside the water outlet 13, the small diameter portion 27, the step portion 23 and a part of the middle diameter portion 26 are in contact with the cooling water. Regarding the cooling water which is about to leak from the inner surface of the middle diameter portion 31 of the insertion hole 14 and the outer surface of the middle diameter portion 26 of the tube 1, the O ring 18 has an inner peripheral surface of the O ring mounting groove 34 (of the tube 1). This is prevented by sealing between the outer surface of the medium diameter portion 26) / the outer step portion 22 and the outer peripheral surface (the large diameter portion 30 of the water outlet 13). Even when the O-ring 18 is separated from the outer step 22 of the tube 1, the cooling water is prevented by the O-ring 18 sealing the inner peripheral surface and the outer peripheral surface of the O-ring mounting groove 34. It The sealing not only prevents the cooling water from leaking to the outside of the cooling water container 8, but also allows the cooling water to enter the inside of the liquid temperature sensor, that is, the surface of the flange surface 15 in the vicinity of the tube 1. Cooling water is prevented from entering through the gap opening to the thermistor 2 through the inside of the tube 1. In the embodiment of the present invention, the tube 1 has an outer step portion.
22 is formed and the step portion 33 is formed in the insertion hole 14, but the formation of the outer step portion 22 and the step portion 33 is omitted, and instead, the annular groove is formed in the insertion hole 14 and the O-shaped groove is formed. By mounting the ring, it is possible to prevent the inflow of cooling water as in the embodiment of the present invention. The O-ring in the annular groove seals the space between the outer surface of the tube 1 and the inner surface of the insertion hole 14, and the cooling water that leaks through between the outer surface of the tube 1 and the inner surface of the insertion hole 14. This is because it is possible to prevent the passage of

The relationship between the radius W of the portion A where the outer step 22 of the tube 1 and the large diameter portion 25 intersect and the diameter W of the O-ring 18 is set to R / W = 0.15 to 0.40. Due to
Further, since the portion A is processed by the deep drawing method, the occurrence of burrs is eliminated, so that when the liquid temperature sensor is attached (assembled) to the cooling water container 8, the O ring protrudes and the O
The ring can be prevented from being damaged. Here, when R / W is smaller than 0.15, the A portion becomes an edge portion to cause O-ring breakage, and when R / W is larger than 0.40, O-ring protrusion occurs. The two surfaces of the outer stepped portion 22 and the medium diameter portion 26 of the O-ring mounting groove 34 are surfaces processed by the deep drawing method and have no burrs. Is less likely to occur. The tube 1 is formed by the deep drawing method, and the outer surface of the tube 1 has a small surface roughness.
The ring 18 can be mounted smoothly.

[0012]

According to the present invention, the thermistor is inserted into the tip of the tube, the open base end of the tube is embedded in the body made of synthetic resin, and the body is made of synthetic resin. The tube is inserted, and the inner surface of the insertion hole and the outer surface of the tube are sealed by an O-ring. Therefore, the liquid is prevented from leaking from between the inner surface of the insertion hole and the outer surface of the tube, which prevents the liquid from entering the gap between the tube and the body and prevents the deterioration of the thermistor due to the liquid entering. It can be prevented. Further, the tube has a large diameter portion, an outer step portion, and a medium diameter portion formed continuously, and the insertion hole has a large diameter portion, a step portion, and a medium diameter portion formed continuously, and the outer step portion of the tube The O-ring mounting groove is composed of the medium-diameter portion and the large-diameter portion / stepped portion of the insertion hole, and the O-ring is mounted in the O-ring mounting groove, so it is possible to more reliably prevent liquid leakage and intrusion into the gap. Done. The relationship between the radius R of the intersection of the large diameter portion of the tube formed by the deep drawing method and the outer step portion and the diameter W of the O ring is R / W = 0.15.
Since it is set to ~ 0.40, the O-ring is prevented from protruding when the liquid temperature sensor is attached, the intersection does not form an edge, and there is little burr due to deep drawing, so
O-ring damage can be prevented. And since the tube is deep-drawn, the surface roughness of the tube is small,
The O-ring can be attached to the tube smoothly.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of an attachment device for a liquid temperature sensor of the present invention.

FIG. 2 is a sectional view of an embodiment of a conventional liquid temperature sensor mounting device.

[Explanation of symbols]

 1 tube 2 thermistor 3 lead wire 4 terminal 7 body 8 cooling water container 13 water outlet 14 insertion hole 18 O-ring 22 outer step 25 large diameter 26 medium diameter 30 large diameter 31 medium diameter 33 step 34 O ring Mounting groove

Claims (4)

[Claims] 1. A liquid temperature sensor has a metal tube whose tip is closed, a thermistor is inserted into the tip of the tube, and an open base end portion of the tube is embedded in a body made of synthetic resin to be bonded to the body. A liquid temperature sensor mounting device in which a tube of a liquid temperature sensor is inserted through an insertion hole of a mounting member, characterized in that an O-ring seals between an inner surface of the insertion hole and an outer surface of the tube. Sensor mounting device. 2. The tube has a large diameter portion, an outer stepped portion and a medium diameter portion formed continuously, and the insertion hole has a large diameter portion, a stepped portion and a medium diameter portion formed continuously, and the outer side of the tube. Step /
The mounting device for a liquid temperature sensor according to claim 1, wherein an O-ring mounting groove is formed by the medium-diameter portion and the large-diameter portion / step portion of the insertion hole, and the O-ring is mounted in the O-ring mounting groove. 3. A tube formed by the deep drawing method is formed with a large diameter portion, an outer stepped portion and a medium diameter portion continuously, and a large diameter portion, a stepped portion and a medium diameter portion are continuously formed in the insertion hole. The O-ring mounting groove is formed by the outer stepped portion / medium diameter portion of the tube and the large diameter portion / stepped portion of the insertion hole, and the O ring is mounted in the O ring mounting groove, and the large diameter portion of the tube is formed. Radius R and O-ring diameter W at the intersection of the outer step with the outer step
The mounting device for a liquid temperature sensor according to claim 1, wherein the relationship of R / W is set to R / W = 0.15 to 0.40. 4. The liquid temperature sensor has a metal tube with a closed tip, a thermistor inserted into the tip of the tube, the thermistor connected to a terminal through a lead wire, and an open base end of the tube, a thermistor, and a lead. The wire and terminal are connected to the body made of synthetic resin, and the tube of the liquid temperature sensor is inserted through the insertion hole of the water outlet of the cooling water container. Is
A large diameter portion, an outer step portion and a middle diameter portion are continuously formed, and a large diameter portion, a step portion and a middle diameter portion are continuously formed in the insertion hole, and the outer step portion and the middle diameter portion of the tube are An O-ring mounting groove is formed by the large-diameter portion and the stepped portion of the insertion hole, the O-ring is mounted in the O-ring mounting groove, and the O-ring seals between the inner surface of the insertion hole and the outer surface of the tube. A device for mounting a liquid temperature sensor, which is characterized in that: