JP3193272B2 - Pressure switch ventilation structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure switch for detecting pressure of lubricating oil or the like which is mounted on an engine of an automobile or the like, and more particularly to a pressure switch for communicating a back pressure chamber of the pressure switch with the outside. The present invention relates to a switch ventilation structure.

[0002]

2. Description of the Related Art Conventionally, a pressure switch 90 as shown in FIG. 7 has been used to detect whether or not the pressure of lubricating oil is maintained at a predetermined value or more by being attached to an automobile engine or the like. The pressure switch 90 includes a housing 10 including a metal base 3 screwed into an oil hole 2 formed through a cylinder block 1 of an automobile engine and a cup-shaped resin cap 4 fixed to the base 3. It has. The space in the housing 10 is divided into two by a diaphragm 5, one of which is a pressure receiving chamber 6 and the other is a back pressure chamber 7. The terminal 9 to which the electric wiring 8 connected to the pressure switch 90 is attached is connected to the resin cap 4.
Is fixed to the resin cap 4 by a rivet 12 inserted into a through hole 11 penetrating through the resin cap 4.

In such a pressure switch 90, the back pressure chamber 7 needs to be connected to the outside air so that the pressure can be accurately detected without being affected by changes in temperature and atmospheric pressure. is there. Therefore, generally, as disclosed in Japanese Utility Model Application Laid-Open No. 3-44843, a back hole is inserted through the housing to insert a rivet or a bolt for fixing the terminal to the housing. BACKGROUND ART A ventilation structure that allows a pressure chamber to communicate with outside air is widely used.

That is, in the pressure switch 90 shown in FIG. 7, a notch 13a for ventilation of a washer 13 for receiving a coil spring 14 for urging the diaphragm 5 toward the pressure receiving chamber 6; The air in the back pressure chamber 7 communicates with the outside air via a ventilation path S including a gap between the inner wall surface of the rivet 12 and the outer surface of the rivet 12 and a ventilation notch 9 a provided in the terminal 9. .

[0005]

The ventilation path S of the conventional pressure switch 90 has a short path length and a large cross-sectional area. Therefore, the pressure switch 9
In the event that a seal failure or breakage of the diaphragm 5 occurs, the lubricating oil in the engine is transferred from the pressure receiving chamber 6 to the back pressure chamber 7 and the pressure switch 9 through the above-described ventilation path S.
0 will leak out. Further, when moisture enters the housing 10 from the ventilation path S, the moisture adheres to the contact portion and corrodes the contact portion. Therefore, the contact portion may cause poor contact due to rust and reduce the reliability of the switch. Becomes

That is, in order to reduce the amount of leakage of the lubricating oil per unit time and the amount of intrusion of moisture as described above, the cross-sectional area of the ventilation path S is reduced or the length of the ventilation path S is increased. The lubricating oil or moisture may pass through the ventilation path S
It is sufficient to increase the flow path resistance when passing through. However, if the cross-sectional area of the ventilation path S is too small, the amount of ventilation decreases and foreign substances and the like are easily clogged. Therefore, the cross-sectional area of the ventilation path S cannot be reduced too much from the viewpoint of securing ventilation. In addition, it is difficult to make the ventilation path S long with the conventional ventilation structure of the pressure switch 90. Therefore,
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, and it is possible to secure a good ventilation path, provide a sufficiently large flow path resistance to a liquid, and have a simple structure of a pressure switch ventilation structure. Is to provide.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to divide a space inside a housing into two parts by a diaphragm so that one is a pressure receiving chamber and the other is a back pressure chamber, and a terminal tightening member is inserted. In a ventilation structure of a pressure switch in which a through hole formed in a housing is a ventilation path for communicating the back pressure chamber with the outside air, one end of the contact surface which is brought into close contact between the housing and the terminal has the as the other end communicates with the through hole communicates with the outside air, the dense
The penetrating surface is recessed on at least one surface of the mounting surface.
A plurality of annular grooves arranged concentrically with respect to the axis of the hole,
The surface of at least one side of the contact surface is recessed and adjacent
A stray path consisting of a communicating groove communicating each of these annular grooves in contact with each other.
This is achieved by a ventilation structure of a pressure switch, wherein a passage-like ventilation port is provided.

[0008] Preferably, at least two vents are provided. More preferably, the vent is provided on at least one surface of the contact surface, a plurality of annular grooves concentrically disposed with respect to the axis of the through hole, and at least one of the contact surfaces. A communication groove which is provided on the surface on the side and which is alternately provided with a phase shift of 180 degrees to alternately connect the adjacent annular grooves.

According to the above configuration, the axis of the through hole is opposed to the axis of the through hole.
Annular grooves arranged concentrically and
Maze-shaped ventilation consisting of a communication groove communicating with the annular groove
Mouth, said being arranged on the contact surface to be brought into close contact between the housing and the terminal, since the path length of the gas passage for communicating the back pressure chamber in the housing to the outside air can be sufficiently long, While ensuring good ventilation, sufficient flow resistance can be imparted to the liquid. The ventilation hole can be formed by an annular groove and a communication groove that are recessed in a contact surface that is brought into close contact between the housing and the terminal, and is easily formed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a pressure switch ventilation structure according to one embodiment of the present invention will be described in detail with reference to the accompanying drawings. As shown in FIG. 1, a pressure switch 100 according to the present embodiment includes a metal base 21 screwed into an oil hole 2 provided through a cylinder block 1 of an automobile engine, and a cup fixed to the base 21. The housing 20 includes a resin cap 22 having a shape of a circle.

The space inside the housing is the diaphragm 2
3 divides the pressure receiving chamber 24 into a pressure receiving chamber 24 and a back pressure chamber 25. The diaphragm 23 is urged toward the pressure receiving chamber 24 by a coil spring 26. The contact terminal 28 attached to the spring receiver 27 that engages with the tip of the coil spring 26 is in contact with the housing-side contact terminal 29 attached to the base 21.

On the other hand, a rivet 31, which is a tightening member, is inserted through a through hole 22a penetrating the distal end portion of the resin cap 22 and communicating with the back pressure chamber 25. And
The rivet 31 secures the washer 32 for receiving the end of the coil spring 26 and the terminal 33 to the resin cap 22. An electric wiring 34 indicated by a two-dot chain line is attached to the tip of the terminal 33.

When the driver turns the ignition key from the OFF position to the ON position,
Since the engine is not rotating, the lubricating oil pressure is zero. As a result, the diaphragm 23 is urged toward the pressure receiving chamber 24 by the urging force of the coil spring 26, and the diaphragm-side contact terminal 28 and the housing-side contact terminal 29 are urged.
Are in contact with each other. In this state, the electric wiring 34
Are grounded to the engine block 1 via terminals 33, rivets 31, washers 32, coil springs 26, spring supports 27, contact terminals 28 on the diaphragm side, and contact terminals 29 on the housing side. Therefore, a current flows through the electric wiring 34, and the hydraulic warning light in the instrument panel is turned on.

Next, when the driver of the automobile rotates the ignition key to the start position to start the engine, the hydraulic pump rotates and the pressure of the lubricating oil increases. Then, the pressure of the lubricating oil is introduced through the oil hole 2 of the cylinder block 1, and the pressure in the pressure receiving chamber 24 increases. As a result, the diaphragm 23 is pushed toward the back pressure chamber 25 against the urging force of the coil spring 26, so that the diaphragm-side contact terminal 28 is separated from the housing-side contact terminal 29.
Therefore, no current flows through the electric wiring 34, and the hydraulic warning light in the instrument panel goes off.

When the diaphragm 23 is displaced toward the back pressure chamber 25, a part of the air in the back pressure chamber 25 is discharged to the outside of the housing 20 through the ventilation path S. The ventilation path S of the pressure switch 100 according to the present embodiment includes a ventilation notch 32a of the washer 32, a gap between the inner wall surface of the through hole 22a and the outer surface of the rivet 31, and the housing 20 and the terminal 33. A maze-shaped vent 4 recessed in the terminal contact surface 22b of the resin cap 22, which is a contact surface that is brought into close contact with each other.
0 and a cutout portion for ventilation 33b cut out in the resin cap contact portion 33a of the terminal 33.

As shown in FIGS. 2 and 3, the vent hole 40 is provided on the terminal contact surface 22b of the resin cap 22 and has a plurality of annular holes arranged concentrically with respect to the axis of the through hole 22a. The annular rib wall 41 forming the grooves 43, 44, 45, 46 and the adjacent annular grooves 43, 44, 4
The annular rib wall 41 is cut out of the annular groove wall 41 and the communication groove 42 is formed in a labyrinth with the phase shifted alternately by 180 degrees so as to communicate the respective elements 5 and 46.

The annular grooves 43, 4 forming the ventilation port 40
4, 45, 46 and the communication groove 42, as shown in FIG.
They are themselves open to the atmosphere. However, as shown in FIG. 1, when the resin cap contact portion 33a of the terminal 33 is in close contact with the distal end surface of the annular rib wall 41, the open portion is closed, and these vents 40 have a tunnel shape. One end of the ventilation port 40 is provided with the resin cap 2.
The other end is in communication with the ventilation notch 33b of the terminal 33. As a result, the air in the back pressure chamber 25 communicates with the atmosphere through the vent 40.

The flow of air in the vent 40 formed as described above will be described with reference to FIG. First, air that has entered through the through hole 22a of the resin cap 22 into the annular groove 43 located at the innermost position in the radial direction through the entrance A advances clockwise or counterclockwise in the annular groove It reaches point B which is out of phase. The air that has entered the outer adjacent annular groove 44 through the communication groove 42 is
Go clockwise or counterclockwise in the annular groove 44 and
Reach point C, which is 80 degrees out of phase. Thereafter, in the same manner, the air traveling clockwise or counterclockwise through the annular groove 45 and reaching the point D travels to the outlet E while passing through the outermost annular groove 46, and further vents the terminal 33 (not shown). It flows out of the housing through the notch 33b.

That is, the vent hole 40 of this embodiment is formed by combining the plurality of annular grooves 43, 44, 45, 46 extending in the circumferential direction and the communication groove 42 into a maze-like shape of the terminal contact surface 22b.
, The total length thereof can be made sufficiently long. Thereby, this vent 40
Since the flow resistance when the lubricating oil flows out of the inside becomes large, even in the event of a bad seal or breakage of the diaphragm 23, the lubricating oil in the engine is transferred from the pressure receiving chamber 24 to the back pressure chamber 25, In addition, it is difficult to leak out of the pressure switch 100 via the ventilation path S described above. Of course, it is difficult for moisture to enter the housing 20 from the ventilation path S.
On the other hand, since the viscosity of the air is sufficiently smaller than the viscosity of the lubricating oil, the air can easily pass through the inside of the ventilation port 40. Thus, there is no problem in communicating the back pressure chamber 25 with the outside air.

In addition, as shown in FIG. 3, in the ventilation port 40 of the present embodiment, since each of the annular grooves 43, 44, 45, and 46 constitutes two systems of ventilation grooves, a foreign substance or the like is provided on one side. Even if clogged, the other ventilation groove does not hinder ventilation,
Good ventilation can be ensured. Here, for example, like the ventilation hole 50 of the modified example shown in FIG. 4, the annular rib wall 51 extending in the circumferential direction, the vertical wall 53 extending in the radial direction, and the communication groove 52 are completely independent. Two systems of ventilation grooves 54 and 55 may be formed.

Further, the ventilation port 40 in the ventilation structure of the pressure switch 100 according to the present embodiment is formed by connecting the rib wall 41 and the communication groove 42 constituting the annular grooves 43, 44, 45, 46 extending in the circumferential direction with the resin cap. 22 is integrally formed with the terminal contact surface 22b by injection molding, and the resin cap contact portion 33a of the terminal 33 is adhered to the tip end surface of the rib wall 41 so as to form a tunnel. , And can be manufactured at low cost.

The ventilation structure of the pressure switch of the present invention is as follows.
It is needless to say that the present invention is not limited by the above-described embodiment, and various changes can be made based on the gist of the present invention. For example, in the embodiment described above,
The ventilation holes are all recessed in the terminal contact surface on the housing side. For example, like the pressure switch 200 shown in FIG. 5, the terminal contact surface of the resin cap 62 is made flat, and the terminal 63 is brought into contact with the resin cap. A vent 60 similar to the vent 40 is provided on the resin cap contact surface of the portion 63a.
The same effect can be obtained by forming a recess by pressing or the like.

Further, as in a pressure switch 300 shown in FIG. 6, a resin cap 7 serving as a terminal contact surface on the housing side is provided.
The ventilation hole 70 can also be formed by combining the annular groove 74 recessed on the second side and the communication groove 75 recessed on the resin cap contact surface of the resin cap contact portion 73a on the terminal 73 side. In addition, as shown in FIG. 6, a portion of the washer 32 that receives the coil spring 26 and the resin cap 72 are in close contact with each other.
It is needless to say that the can be recessed.

[0024]

As is clear from the above description, the ventilation structure of the pressure switch according to the present invention has the same structure with respect to the axis of the through hole.
A plurality of annular grooves arranged in a center and adjacent ones of these annular grooves
A maze-shaped ventilation port composed of a communication groove communicating with the groove,
The housing and are arranged on the contact surface to be brought into close contact between said terminals, since the path length of the gas passage for communicating the back pressure chamber in the housing to the outside air can be sufficiently long, good air And a sufficient flow resistance can be provided to the liquid. Therefore, even in the event of poor sealing or damage to the diaphragm,
Lubricating oil in the engine hardly leaks from the pressure receiving chamber to the outside of the pressure switch via the back pressure chamber and the ventilation path. Of course, it is difficult for moisture to enter the housing from the ventilation path. On the other hand, the viscosity of air is sufficiently smaller than the viscosity of lubricating oil or moisture, so that air can easily pass through the ventilation holes. Thus, there is no problem in communicating the back pressure chamber with the outside air. Further, the vent can be formed by an annular groove and a communication groove which are recessed in a contact surface which is brought into close contact between the housing and the terminal, and molding is easy. Therefore, it is possible to provide a ventilation structure of the pressure switch, which can secure a favorable ventilation path, provide a sufficiently large flow path resistance to the liquid, and have a simple structure.

[Brief description of the drawings]

FIG. 1 is an overall vertical cross-sectional view and a main part enlarged cross-sectional view showing a ventilation structure of a pressure switch according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a main part of the pressure switch shown in FIG.

FIG. 3 is a front view of a vent shown in FIG. 2;

FIG. 4 is a front view showing a modified example of the vent shown in FIG.

FIG. 5 is an enlarged sectional view of a main part showing a ventilation structure of a pressure switch according to another embodiment of the present invention.

FIG. 6 is an enlarged sectional view of a main part showing a ventilation structure of a pressure switch according to another embodiment of the present invention.

7A and 7B are an overall vertical sectional view and a main part enlarged sectional view showing a ventilation structure of a conventional pressure switch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Oil hole 20 Housing 21 Base 22 Resin cap 22a Through hole 22b Terminal contact surface 23 Diaphragm 24 Pressure receiving chamber 25 Back pressure chamber 26 Coil spring 27 Spring receiver 31 Rivet 33 Terminal 33a Contact portion 33b Notch portion for ventilation 40 Vent port 41 rib wall 42 communication groove 43,44,45,46 annular groove 100 pressure switch

──────────────────────────────────────────────────続 き Continued on the front page (56) References JP-A-7-249359 (JP, A) JP-A-7-141970 (JP, A) JP-A-3-44843 (JP, U) JP-A 5- 36735 (JP, U) JP-A 60-166939 (JP, U) JP-A 62-198637 (JP, U) JP-A 62-1721 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01H 35/24-35/40

Claims (3)

(57) [Claims] 1. A space inside a housing is divided into two by a diaphragm, one of which is a pressure receiving chamber and the other is a back pressure chamber, and a through hole formed in the housing for inserting a terminal tightening member is provided in the housing. In the ventilation structure of the pressure switch, which is a ventilation path that allows the pressure chamber to communicate with the outside air, the contact surface that is tightly contacted between the housing and the terminal has one end communicating with the through hole and the other end communicating with the outside air. To communicate with each other, at least one side of the contact surface
It is recessed in the surface and is arranged concentrically with respect to the axis of the through hole.
A plurality of annular grooves placed and at least one of the contact surfaces
These adjacent annular grooves which are recessed on the surface on the side of
A ventilation structure for a pressure switch, wherein a maze-like ventilation port comprising a communication groove through which the pressure switch passes is provided. 2. The ventilation structure for a pressure switch according to claim 1, wherein at least two ventilation ports are provided. 3. A plurality of annular grooves recessed in at least one surface of the contact surface and arranged concentrically with respect to an axis of the through hole, wherein at least one of the contact surfaces is provided. 3. A communication groove according to claim 1, wherein said groove is formed on the surface on one side and is provided with a communication groove which is alternately provided with a phase shift of 180 degrees so as to communicate with the adjacent annular grooves. Pressure switch ventilation structure.