JPH10177000A - Sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent foreign bodies from being stuck to both an inside protective cover and an outside protective cover in a sensor which is provided with the protective covers doubly. SOLUTION: A plurality of opening parts 45 are formed in the circumferential direction in an outside protective cover 4 at a sensor 1 which is attached to a mounting member 100 which is vibrated in an indefinite direction. An inside protective cover 5 is coupled to the bottom face 21 of a base part 2 and to the inner face 61 at the bottom part 6 of the external protective cover 4, and a plurality of opening parts 55 are formed in the circumferential direction. When the mounting member 100 is vibrated, a moving member 7 which is formed to be ring-shaped is moved inside a space 200 which is partitioned by the inner circumferential face 41 of the external protective cover 4, by the outer circumferential face 52 of the inner protective cover 5, by the bottom face 21 of the base part 2 and by the inner face 61 at the bottom part 6 of the external protective cover 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor, and more particularly, to a sensor with a double protective cover which is mounted on a mounting member with vibration.

[0002]

2. Description of the Related Art In order to prevent an object from hitting and being damaged by a sensor element, or to prevent a foreign matter from adhering to the surface of the sensor element and lowering the detection performance of the sensor, a sensor element is provided with a hole. Covering with a protective cover is widely practiced. Then, an annular ring is provided outside the protective cover so that the hole of the protective cover is not blocked by foreign matter, and the annular ring is moved and rotated on the outer peripheral surface of the protective cover by the flow of the gas to be detected. A sensor has been disclosed which removes foreign matter adhering to the outer peripheral surface of a protective cover (see Japanese Utility Model Laid-Open No. 5-4002).

[0003]

However, although the device disclosed in the above publication can prevent foreign substances from adhering to the outer peripheral surface of the protective cover, the double protective cover does not adhere to the sensor element. In the sensor provided with the above, it is not possible to prevent foreign matter from adhering to both the inner protective cover and the outer protective cover. In view of the above problems, the present invention
In a sensor having a heavy protective cover, an object is to prevent foreign matter from adhering to both the inner protective cover and the outer protective cover.

[0004]

According to the first aspect of the present invention, there is provided a sensor with a double protective cover attached to an attachment member, wherein the sensor element is fixed to the attachment member, and is formed in a cylindrical shape. An outer protective cover having an introduction passage for the fluid to be detected and fixed to the mounting member, and an inner protective cover formed in a cylindrical shape and having an introduction passage for the fluid to be detected and spaced apart inside the outer protective cover, A movable member which is fixedly disposed adjacent to the inside of the outer protective cover and is movable by the vibration of the mounting member. In the sensor configured as described above, the movable member disposed inside the outer protective cover hits the outer protective cover from the inside due to vibration, and the inner protective cover hits from the outer side, and a foreign substance adhered to the outer protective cover and the inner protective cover. Is removed.

According to the invention of claim 2, in the invention of claim 1, the inner protective cover is fixed to the mounting member, and the movable member moves between the outer cover and the inner cover. A sensor is provided. In the sensor configured as described above, the movable member moves between the outer cover and the inner cover, and removes foreign matter attached to the outer protective cover and the inner protective cover.

According to a third aspect of the present invention, there is provided the sensor according to the first aspect of the present invention, wherein the inner protective cover is the movable member. In the sensor configured in this way, the inner protective cover itself moves by vibration and hits the outer protective cover, and as a result, foreign matter adhered to the inner protective cover,
Remove any foreign matter adhering to the outer protective cover.

According to a fourth aspect of the present invention, there is provided a sensor as set forth in the first aspect, wherein the movable member is provided with a projection extending outward through the detected fluid introduction passage of the outer protective cover. Provided. In the sensor configured as described above, the protrusion provided on the movable member removes foreign matter adhering to the introduction path of the fluid to be detected of the outer protective cover.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a view for explaining the structure of the first embodiment of the present invention. The sensor indicated by reference numeral 1 generally includes a base 2, a sensor element 3, an outer protective cover 4, and an inner protective cover 5. It is fixed to the mounting member 100 by an appropriate method. Here, the mounting member 100 is a member that vibrates in an unspecified direction,
For example, it corresponds to a pipe wall of an intake pipe or an exhaust pipe of an internal combustion engine.

The outer protective cover 4 is formed in a cylindrical shape having a bottom 6, and the end opposite to the longitudinal direction of the bottom 6 is formed on the base 2.
Is connected to the bottom surface 21. Further, a plurality of openings 45 are formed in the circumferential direction. The inner protective cover 5 is formed in a cylindrical shape without a bottom, and one end is joined to the inner surface 61 of the bottom 6 of the outer protective cover 4 and the other end is joined to the bottom surface 21 of the base 2. . Further, a plurality of openings 55 are formed in the circumferential direction. The distance between the opening 45 of the outer protective cover 4 and the bottom surface 21 of the base 2 is different from the distance between the opening 55 of the inner protective cover 5 and the bottom surface 21 of the base 2 so that the distance in the fluid to be detected is different. Foreign matter is prevented from directly hitting the sensor element 3.

Reference numeral 7 denotes a movable member formed in an annular shape. The thickness t of the movable member 7 in the radial direction is determined by the inner peripheral surface 4 of the outer protective cover 4.
1 and the gap c between the outer peripheral surface 52 of the inner protective cover 5 and the inner protective cover 5
Not even fixed. Therefore, the mounting member 10
By vibrating 0, the movable member 7 includes the inner peripheral surface 41 of the outer protective cover 4 and the inner peripheral surface 51 of the inner protective cover 5.
The space 200 defined by the bottom surface 21 of the base 2 and the inner surface 61 of the bottom 6 of the outer protective cover 4 can be moved in the directions indicated by the double-headed arrow V and the double-headed arrow H.

The fluid to be detected around the outer protective cover 4 is:
When the movable member 7 enters the space 200 through the opening 45 of the outer protective cover 4 and is at a position as shown in the figure, a gap between the movable member 7 and the inner peripheral surface 41 of the outer protective cover 4. Alternatively, through the gap between the movable member 7 and the outer peripheral surface 51 of the inner protective cover 5, and when the movable member 7 is at both ends, the movable member 7 reaches the opening 55 of the inner protective cover 5 as it is. It enters the space 300 inside the inner protective cover 5 and contacts the sensor element 3. Sensor element 3
Generates, for example, a signal voltage corresponding to the concentration of a specific component in the fluid to be detected, and the signal voltage passes through a lead wire 30 attached to the base, and an external signal processing device (not shown).
Sent to

Here, as described above, in the process of flowing the fluid to be detected, foreign substances in the fluid to be detected are removed by the outer protective cover 4.
Of the inner protective cover 5 and the outer peripheral surface 52 and the opening 55 of the inner protective cover 5, but when the movable member 7 moves in the space 200 due to the vibrations as described above, these surfaces are used. It does not adhere because it collides with and scrapes off. Further, the movable member 7 hits the outer protective cover 4 or the inner protective cover 5, and the outer protective cover 4 or the inner protective cover 5 is vibrated, so that the outer surface 42, the inner surface Adhesion of foreign matter to the inner surface 51 of the protective cover 5 is also suppressed.

FIG. 2 is a view showing the structure of a second embodiment of the present invention. Unlike the first embodiment, the inner protective cover indicated by reference numeral 9 has a longitudinal end portion, Both ends of the bottom surface 21 of the base 2 and the inner surface 61 of the bottom 6 of the outer protective cover 4 which are not fixed are formed in a cylindrical shape with both open ends, and the inner protective cover 9 itself serves as a movable member and serves as an outer protective cover. 4 moves in the V and H directions in the space surrounded by 4.

Here, the outer diameter D9 of the inner protective cover 9 with respect to the inner diameter D4 of the outer protective cover 4 so that the inner protective cover 9 does not greatly incline and come into contact with the sensor element 3.
Further, the length L9 in the longitudinal direction of the inner protective cover 9 with respect to the length L4 in the longitudinal direction inside the outer protective cover 4 is determined. A passage 95 is formed in a portion where the end of the inner protective cover 5 faces the bottom surface 21 of the base 2, and a passage is formed in a portion where the other end of the inner protective cover 5 faces the bottom 6 side of the outer protective cover 4. 96 are formed. Width w1 of passage 95
And the width w2 of the passage 96 differs depending on the longitudinal position of the inner protective cover 9, but w1 + w2 is constant and w
1 + w2 = L4-L9.

Since the second embodiment is configured as described above, the fluid to be detected around the outer protective cover 4 enters the space 200 through the opening 45 of the outer protective cover 4 and from there the passage 95 or the passage 95 or the like. Through 96, it enters the space 300 inside the inner protective cover 9 and contacts the sensor element 3. In the process of flowing the fluid to be detected in this manner, foreign substances in the fluid to be detected are likely to adhere to the opening 45 and the inner peripheral surface 41 of the outer protective cover 4, the outer peripheral surface 91 of the inner protective cover 9, and the passages 95 and 96. However, due to the vibration, the inner protective cover 9 causes the inner surface 41 of the outer protective cover 4 and the inner surface 21 of the base 2 to move.
As it moves while hitting, it is scraped off and does not adhere. In addition, since the outer protective cover 4 and the inner protective cover 9 vibrate when the inner protective cover 9 hits the outer protective cover 4, foreign matter on the outer surface 42 of the outer protective cover 4 and the inner surface 91 of the inner protective cover 9 is also reduced. Is also suppressed.

FIG. 3 is a view showing the structure of a third embodiment of the present invention. In the third embodiment, the inner protective cover 9 and the outer protective cover 4 in the second embodiment are different from each other.
The second embodiment differs from the second embodiment in that a projection 93 extending outward through the inside of the opening 45 is provided, but the other configuration is the same as that of the second embodiment. The inner protective cover 5 moves and performs the same operation as in the case of the second embodiment.
Foreign matter that will adhere to the opening 45 of the outer protective cover 4 is reliably removed. Further, since the projection 93 also serves as a stopper for restricting the movement of the inner protective cover 9, it is possible to reliably prevent the inner protective cover 9 from being tilted more than necessary and being stuck inside the outer protective cover 4 and not moving. There is an advantage.

In the second embodiment and the third embodiment, the inner protective cover 9 may be a member having a bottom. By doing so, the contact area between the inner protective cover 9 and the bottom 6 of the outer protective cover 4 is increased, the movement of the inner protective cover 9 in the direction of arrow H is smoothed, and the inner protective cover 9 is moved inside the outer protective cover 4. Can be prevented.

[0018]

According to the invention of each claim, in a sensor having a double protective cover, foreign substances are prevented from adhering to the inner protective cover and the outer protective cover, and the double protective cover is applied to the sensor. Thus, contact of the fluid to be detected with the sensor can be ensured while preventing foreign matter from adhering, and the performance of the sensor can be stabilized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a structure according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a structure according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sensor 2 ... Base part 3 ... Sensor element 4 ... Outer protective cover 5 ... Inner protective cover 7 ... Movable member 9 ... Inner protective cover 45 ... Detected fluid introduction passage 55 ... Detected fluid introduction passage 93 ... Protrusion 95 ... Detected Fluid introduction passage 96 ... Detected fluid introduction passage 100 ... Mounting member

Claims (4)

[Claims] 1. A sensor with a double protective cover attached to a mounting member, comprising: a sensor element fixed to the mounting member; and a cylindrically formed passage for introducing a fluid to be detected. A fixed outer protective cover, an inner protective cover formed in a cylindrical shape and having a passage for introducing a fluid to be detected and spaced apart inside the outer protective cover, and non-fixedly disposed inside the outer protective cover. A movable member that is moved by the vibration of the mounting member. 2. The sensor according to claim 1, wherein the inner protective cover is fixed to the mounting member, and the movable member moves between the outer cover and the inner cover. 3. The sensor according to claim 1, wherein the inner protective cover is the movable member. 4. The sensor according to claim 1, wherein the movable member is provided with a projection extending outward through the passage of the fluid to be detected of the outer protective cover.