JP2002055014A - Exhaust pressure detector for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an exhaust pressure detector attenuating pulse motion of exhaust gas, preventing particulates from adhering to the pressure detector and hardly transmitting exhaust heat to a pressure detection part. SOLUTION: The exhaust pressure detector is provided with a detector body 22 and a cap 23, and a hose 14 connecting to the exhaust path 11 of an engine is connected to the hose attachment part 23b of the cap. To the tip end opening of the hose attachment part 23b, a reducer 23d is provided. Inside the hose attachment part 23b, a columnar body 27 with an outer diameter smaller than the inner diameter of the hose attachment part 23b and larger than the inner diameter of the reducer 23d is provided in the vicinity of the pressure detection part 22d, to set a prescribed gap to the pressure detection part 22d in the screwed-in state of the cap. The column body 27 can be a carbon solid or hollow body or ceramic body coated with carbon on the surface. The reducer is provided in the region, except for the lower part of all circumference of the tip end opening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detector for detecting the exhaust pressure of an engine, comprising a detector main body and a cap for attaching the main body to a bracket.

[0002]

2. Description of the Related Art The exhaust gas of an engine contains soot, and particulates such as hydrocarbons, sulfates and metals adhering to the soot. In a diesel engine in which a relatively large amount of the particulates is generated, an exhaust filter device is provided in the exhaust pipe to prevent the particulates from being collected and released to the atmosphere. The conventional exhaust filter device includes a particulate filter that actually collects the particulates, and when the high-pressure exhaust gas discharged from the engine passes, the particulate filter captures the particulates in the exhaust gas. It is configured as follows.

[0003] However, when the particulate filter is in the over-collection state, the exhaust gas pressure of the engine increases, so that fuel efficiency and power performance may be reduced. For this reason, a regenerating device such as a backwash device for regenerating a particulate filter in an over-collected state or a particulate combustion device has been developed. The exhaust filter device is provided with a detector that detects the exhaust pressure of the engine that rises when the particulate filter reaches an over-collection state, and these regenerating devices use the particulate filter based on the detection output of the exhaust pressure detector. It is configured to determine whether the curated filter is in the over-collection state and to operate when necessary.

A general exhaust pressure detector has a detector main body and a cap for attaching the main body to a bracket, and a male thread is formed on a body of the detector main body. Is formed. On the other hand, the cap is configured so that the exhaust pressure detector is attached to a predetermined bracket by being screwed into a male screw portion. Since the exhaust of the engine pulsates, an exhaust pressure detector is connected via a hose that communicates with the exhaust passage of the engine to attenuate the pulsation, and the cap has a hollow hose mounting part for mounting the hose. Formed continuously. Part of the engine's exhaust gas enters this hose from the exhaust path and the pulsation is attenuated, and the exhaust pressure is detected by the pressure detector formed at the tip of the male threaded portion that is continuous with the hose mounting part. I have.

[0005]

However, depending on the vehicle or equipment on which the exhaust pressure detector is mounted, a hose having a length sufficient to attenuate the pulsation may not be provided, and even if the hose is relatively short. An exhaust pressure detector that can sufficiently attenuate pulsation is desired. On the other hand, when the hose is short, the exhaust gas enters into the vicinity of the pressure detection unit, and the particulates in the exhaust gas adhere to the pressure detection unit, thereby deteriorating the detection sensitivity. In addition, a general exhaust pressure detector uses natural rubber as a component of the pressure detection unit, and detects exhaust pressure by measuring the amount of deformation of the rubber due to exhaust pressure, so that deterioration of the rubber is suppressed. In order to ensure reliability for a relatively long time, it is preferable to avoid the exhaust pressure detector itself from being exposed to high temperatures. An object of the present invention is to attenuate exhaust pulsation in an engine,
It does not adhere to the particulate pressure detector,
Another object of the present invention is to provide an exhaust pressure detector that does not easily transmit the heat of the exhaust to the pressure detector.

[0006]

The invention according to claim 1 is
As shown in FIG. 1 and FIG.
A detector main body 22 having a male threaded portion 22b at the body portion and a pressure detecting portion 22d at the tip of the body portion; and a female threaded portion 23a screwed to the male threaded portion 22b, and a bracket is attached in a threaded state. A hose 23 which is attached to the bracket 16 together with the portion 22a and has a hollow hose mounting portion 23b formed continuously with the female screw portion 23a, and the hose mounting portion 23b communicates with the exhaust passage 11 of the engine.
4 is an improvement of the exhaust pressure detector of the connected engine. The characteristic configuration is that a reduced-diameter portion 23d is provided at the distal end opening of the hose mounting portion 23b, and an outer diameter smaller than the inner diameter d1 of the hose mounting portion 23b and larger than the inner diameter d2 of the reduced-diameter portion 23d inside the hose mounting portion 23b. The columnar body 27 having D and having carbon exposed on the surface is provided facing the pressure detecting unit 22d so as to have a predetermined gap W with the pressure detecting unit 22d in a screwed state of the cap.

In the invention according to the first aspect, the hose 14
The pulsation transmitted to the exhaust pressure detector 21 via the reaches the pressure detecting unit 22d via the air or gas existing in the gap between the inner surface of the hose mounting portion 23b and the outer surface of the columnar body 27. However, since the gap therebetween is extremely small, the pulsation reaches the pressure detection unit 22d in a state of being significantly attenuated. On the other hand, since the outer diameter D of the columnar body 27 is larger than the inner diameter d2 of the reduced diameter portion 23d, the columnar body 27 does not fall out of the hose mounting portion 23b and has a predetermined gap W with the pressure detecting portion 22d. An error does not occur in the detection output by coming into contact with the detection unit 22d.

Further, since the carbon is exposed on the surface of the columnar body 27, even if the exhaust gas enters the hose mounting portion 23b, the particulates in the exhaust gas are adsorbed by the carbon exposed on the surface, and the particles in the exhaust gas are absorbed. Curate is prevented from adhering to the pressure detecting portion 22d. Further, since carbon has a relatively low heat transfer coefficient, the columnar body 27 on which carbon is exposed also functions as a heat insulating material.
To be transmitted to

A second aspect of the present invention is the exhaust pressure detector for an engine according to the first aspect, wherein the columnar body 27 is a solid carbon body or a hollow body having both ends sealed. According to the second aspect of the present invention, a relatively large amount of particulates can be adsorbed, and the particulates in the exhaust gas are effectively prevented from adhering to the pressure detecting portion 22d. The invention according to claim 3 is the invention according to claim 1, wherein the columnar body 27 is a ceramic columnar body whose surface is coated with a carbon layer. According to the third aspect of the present invention, the columnar body can be obtained relatively inexpensively. The invention according to claim 4 is claim 1
The invention according to any one of claims 1 to 3, wherein the hose mounting portion 2
3b is an exhaust pressure detector for an engine in which a reduced diameter portion 23d is provided in an opening excluding a lower portion of the opening at the tip end of the engine 3b. According to the fourth aspect of the present invention, the columnar body 2 is provided without attenuating the exhaust pressure itself transmitted through the hose 14.
7 can be effectively prevented from coming out of the hose mounting portion 23b.

[0010]

Next, an embodiment of the present invention will be described. As shown in FIG. 3, the engine is provided with an exhaust pipe 11 as an exhaust passage, and an exhaust filter device 12 is provided in the middle of the exhaust pipe. The exhaust filter device 12 includes:
A columnar particulate filter 12a for actually collecting particulates, and a particulate filter 12a;
This particulate filter 12 is coaxial with the center axis of
a, and holding plates 12c, 12c respectively inserted at both ends of the housing tube 12b so as to hold both end edges of the particulate filter 12a. These holding plates 12c, 12c Housing tube 1
Lids 12d, 12d welded to both ends of 2b
Is held down by An exhaust take-out pipe 13 is provided on the lid 12d on the upstream side of the exhaust filter device 12,
One end of the hose 14 is connected. A bracket 16 is provided in the vicinity of the exhaust filter device 12, and the exhaust pressure detector 21 is attached to the bracket 16 and a hose 14 is provided.
Are connected to each other.

As shown in FIG. 1, the exhaust pressure detector 21 has a detector main body 22 and a cap 23 for attaching the main body 22 to the bracket 16. The detector body 22 has a bracket mounting portion 22a formed at the base end, and a male screw portion 2 at the body.
2b is formed. The bracket mounting portion 22a is formed with a seating surface 22c facing one surface of the bracket 16, and has an outer diameter formed in a hexagonal shape whose rotation can be fixed by a tool such as a spanner. The male screw portion 22b is formed so as to protrude from the center of the seating surface 22c, and the pressure detecting portion 22d for actually sensing the pressure of the exhaust gas is formed at the tip of the male screw portion 22b which is the body. The bracket 16 is formed with a mounting hole 16a slightly larger in diameter than the male screw portion 22b, and the male screw portion 22b is inserted into the mounting hole 16a from the tip via a ring-shaped packing 24.

On the other hand, the cap 23 has a female screw portion 23a which is screwed with the male screw portion 22b of the detector main body 22.
Male thread 2 inserted into mounting hole 16a of bracket 16
2b is screwed through a ring-shaped packing 24. By screwing the female screw portion 23a into the male screw portion 22b in this manner, the edge of the cap 23 becomes the seat surface 2 of the detector main body 22.
3c together with the bracket mounting portion 22a to clamp the bracket 16 around the mounting hole 16a.
6 attached. Further, a hollow hose mounting portion 23b is formed in the cap 23 so as to be continuous with the female screw portion 23a. A large-diameter portion 23c is formed at the end of the hose mounting portion 23b for swelling the outer periphery of the hose, and the other end of the hose 14 is fastened from the periphery by the fixing band 26 in a state of being fitted into the hose mounting portion 23b. Connected.

As shown in FIG. 1 and FIG. 2, a reduced diameter portion 23d is provided at an opening at the distal end of the hose mounting portion 23b. The reduced diameter portion 23d in this embodiment is the hose mounting portion 2
Since it is provided except for a range of 90 degrees from the center in the lower part of the distal end opening in 3b, the reduced diameter portion 23d is provided in 75% of the entire circumference. The range in which the reduced diameter portion 23d is provided is not limited to 75%,
It is desirable to be in the range of 5% to 90%. Inside the hose mounting part 23b, the outer diameter D (FIG. 2) is smaller than the inner diameter d1 of the hose mounting part 23b by 20 μm to 1 mm and the reduced diameter part 23d.
The columnar body 27 whose outer diameter is larger than the inner diameter d2 of the
It is provided facing 2d. This columnar body 27 is a cap 2
When the female screw portion 23a is screwed into the male screw portion 22b, the female screw portion 23a is inserted into the hose mounting portion 23b in advance, and the female screw portion 23a is screwed into the male screw portion 22b in this state.
7 is provided inside the hose mounting portion 23b. The column 27 in this embodiment is made of a solid carbon whose surface is exposed to carbon, and the column 27 is screwed with the cap 23 and is in contact with the pressure detecting portion 22d in the range of 20 μm to 1 mm.
Is formed so as to have a gap W (FIG. 1).

The engine exhaust pressure detector 21 configured as described above detects the pressure of the engine exhaust through the hose 14. Exhaust gas flowing through the exhaust pipe 11 serving as an exhaust path pulsates and is transmitted to the inside of the hose 14, and the pulsation is transmitted to the exhaust pressure detector 21 via the hose 14. The pulsation transmitted to the exhaust pressure detector 21 reaches the pressure detection unit 22d via air or gas existing in a gap between the inner surface of the hose mounting portion 23b and the outer surface of the columnar body 27,
Since the gap therebetween is extremely small, the pulsation reaches the pressure detection unit 22d in a state of being significantly attenuated. Therefore, the exhaust pressure detector 21 can detect the exhaust pressure with relatively little fluctuation. In this case, the columnar body 27 is
Since the outer diameter is larger than the inner diameter of d, it does not come off from the hose mounting part 23b, and the pressure detecting part 22d and the
Since the gap W has a width of 1 mm, the columnar body 27 does not directly contact the pressure detection unit 22d and does not cause an error in the detection output.

The male screw portion 22b is inserted into the mounting hole 16a via the packing 24, and the cap 23 is screwed through the packing 24 to be mounted on the bracket 16. For this reason, the exhaust gas flows from the hose 14 to the hose mounting portion 23.
b and is not discharged to the outside. Therefore, the exhaust gas does not enter the periphery of the pressure detecting portion 22d through the hose 14, and even if the exhaust gas enters the hose mounting portion 23b, the particulates in the exhaust gas remain on the surface of the columnar body 27. The particulates in the exhaust gas are not adsorbed to the exposed carbon and do not adhere to the pressure detecting portion 22d to lower the detection sensitivity. Further, since carbon has a relatively low heat transfer coefficient, the columnar body 27 on which carbon is exposed also functions as a heat insulating material. , And the deterioration of the rubber used in the pressure detection unit 22d is suppressed. As a result, the reliability of the exhaust gas pressure detector 21 over a relatively long period can be ensured.

In the above-described embodiment, the description has been made using the columnar body 27 made of solid carbon. However, the columnar body 27 may be a hollow body made of carbon with both ends sealed, 27 may be a ceramic columnar body whose surface is covered with a carbon layer having a thickness of 2 to 100 μm. Even such a columnar body whose surface is exposed to carbon can adsorb particulates in exhaust gas,
And it can function as a heat insulating material.

[0017]

As described above, according to the present invention, since the columnar body smaller than the inner diameter of the hose mounting portion is provided inside the hose mounting portion, the exhaust gas transmitted to the exhaust pressure detector via the hose is provided. Pulsation can be sufficiently attenuated. In addition, since the columnar body has an outer diameter larger than the inner diameter of the reduced diameter portion, it does not come out of the hose mounting portion and has a predetermined gap with the pressure detecting portion. Does not cause an error. In addition, since carbon is exposed on the surface of the columnar body, even if exhaust gas enters the hose mounting part, the particulates in the exhaust are adsorbed by the carbon exposed on the surface, and the particulates in the exhaust detect the pressure. It can be prevented from adhering to the part. Furthermore, carbon has a relatively low heat transfer coefficient,
The columnar body on which carbon is exposed also functions as a heat insulating material, preventing the temperature from being directly transmitted to the pressure detector even if relatively high-temperature exhaust gas enters the hose. Long-term reliability can be secured.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a detector of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is a diagram showing an attached state of the detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Exhaust passage 14 Hose 16 Bracket 21 Exhaust pressure detector 22 Detector main body 22a Bracket mounting part 22b Male screw part 22d Pressure detecting part 23 Cap 23a Female screw part 23b Hose mounting part 23d Reduced diameter part 27 Column-shaped body d1 Inner diameter d2 of hose mounting part Inner diameter of reduced diameter part D Outer diameter of columnar body W Predetermined gap

Claims (4)

[Claims] 1. A detector body (22) having a bracket mounting portion (22a) at a base end, a male screw portion (22b) at a body portion, and a pressure detection portion (22d) at a tip of the body portion. , The external thread (22
b) has a female screw portion (23a) that is screwed onto the bracket (16) together with the bracket mounting portion (22a) in a screwed state, and is a hollow hose mounting portion (continuous with the female screw portion (23a)). An exhaust pressure detector for the engine, wherein a hose (14) communicating with an exhaust passage (11) of the engine is connected to the hose mounting portion (23b). A reduced diameter portion (23d) is provided at a distal end opening of the mounting portion (23b), and the hose mounting portion (23b) is provided inside the hose mounting portion (23b).
A columnar body (27) having an outer diameter (D) smaller than the inner diameter (d1) of the reduced diameter portion (23d) and larger than the inner diameter (d2) of the reduced diameter portion (23d) and having carbon exposed on the surface is screwed into the cap (23). In the state, the pressure detection unit (22d) and the pressure detection unit so as to have a predetermined gap (W)
An exhaust pressure detector for an engine, which is provided facing (22d). 2. The exhaust pressure detector for an engine according to claim 1, wherein the columnar body (27) is a solid carbon body or a hollow body having both ends sealed. 3. The exhaust pressure detector for an engine according to claim 1, wherein the columnar body (27) is a ceramic columnar body whose surface is coated with a carbon layer. 4. The exhaust pressure of an engine according to claim 1, wherein a reduced-diameter portion (23d) is provided in a range excluding a lower portion of the tip opening at a tip opening of the hose mounting portion (23b). Detector.