JP3388728B2 - Engine exhaust pressure detector - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Exhaust gas from an engine contains soot, hydrocarbons adhering to the soot, particulates such as sulfates and metals. In a diesel engine in which a large amount of particulates are generated, an exhaust filter device is provided in the middle of 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 through, the particulate filter collects the particulates in the exhaust gas. Is configured as follows.

However, when the particulate filter is in an excessively trapped state, the exhaust gas pressure of the engine increases, which may result in a reduction in fuel consumption and power performance. For this reason, a backwash device for regenerating the particulate filter in the over-collection state, and a regenerating device such as a particulate combustion device have been developed. The exhaust filter device is equipped with a detector that detects the exhaust pressure of the engine that rises when the particulate filter reaches an excessive collection state, and these regenerators are operated based on the detection output of the exhaust pressure detector. The curate filter is configured to determine whether the curate filter is in an over-collection state and operate when necessary.

A general exhaust pressure detector comprises a detector main body and a cap for mounting the main body to a bracket, and a male screw portion is formed on the body portion of the detector body, and a pressure detecting portion is provided at the tip of the body portion. Is formed. On the other hand, the cap is configured to attach the exhaust pressure detector to a predetermined bracket by being screwed into the male screw portion. Since engine exhaust pulsates, an exhaust pressure detector is connected via a hose that communicates with the engine exhaust passage to damp the pulsation, and a hollow hose mounting part for mounting the hose is attached to the cap with a male thread. Are continuously formed. Part of the engine exhaust enters the hose from the exhaust path to dampen the pulsation, and the exhaust pressure is detected by the pressure detection part formed at the tip of the male screw part that is continuous with the hose mounting part. There is.

[0005]

However, depending on the vehicle or equipment to which the exhaust pressure detector is attached, it may not be possible to provide a hose having a length long enough to damp pulsation, and even if the hose is relatively short. It is desired to have an exhaust pressure detector capable of sufficiently damping pulsation. On the other hand, when the hose is short, the exhaust gas penetrates into the surroundings of the pressure detection unit, and the particulates in the exhaust gas adhere to the pressure detection unit to make the detection sensitivity dull. In addition, a general exhaust pressure detector uses natural rubber as a component of the pressure detection unit and detects the exhaust pressure by measuring the amount of deformation of the rubber due to the exhaust pressure, thus suppressing deterioration of the rubber. In order to secure reliability for a relatively long period, it is preferable to avoid the exhaust pressure detector itself from being exposed to high temperature. An object of the present invention is to dampen exhaust pulsations in an engine,
Does not adhere to the pressure detection part of the particulate,
Another object of the present invention is to provide an exhaust pressure detector that does not easily transfer exhaust heat to the pressure detection unit.

[0006]

The invention according to claim 1 is
As shown in FIGS. 1 and 2, the bracket mounting portion 2 is provided at the base end.
2a having a male threaded portion 22b on the body and a pressure sensing portion 22d at the tip of the body, and a detector body 22 having a female threaded portion 23a screwed to the male threaded portion 22b A hose 1 which is attached to the bracket 16 together with the portion 22a and has a cap 23 in which a hollow hose mounting portion 23b is formed continuously from 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 engine to which 4 is connected. The characteristic configuration is that a reduced diameter portion 23d is provided at the tip opening of the hose attachment portion 23b, and an outer diameter smaller than the inner diameter d1 of the hose attachment portion 23b and larger than the inner diameter d2 of the reduced diameter portion 23d inside the hose attachment portion 23b. A columnar body 27 having D and exposing carbon on the surface is provided facing the pressure detection portion 22d so as to have a predetermined gap W with the pressure detection portion 22d in a screwed state of the cap.

In the invention according to claim 1, the hose 14
The pulsation transmitted to the exhaust pressure detector 21 via the air reaches the pressure detecting portion 22d via the air or gas present 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 between them is extremely small, the pulsation reaches the pressure detecting portion 22d in a state in which the pulsation is remarkably attenuated. On the other hand, since the columnar body 27 has the outer diameter D larger than the inner diameter d2 of the reduced diameter portion 23d, it does not come out from the hose mounting portion 23b and has a predetermined gap W with the pressure detecting portion 22d, so that the columnar body 27 directly applies pressure. The detection unit 22d does not come into contact with the detection unit 22d to cause an error in the detection output.

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

A second aspect of the present invention is the exhaust pressure detector for an engine according to the first aspect of the present invention, wherein the columnar body 27 is a solid carbon body or a hollow body whose both ends are sealed. In the invention according to the second aspect, a relatively large amount of particulates can be adsorbed, and the particulates in the exhaust can be effectively prevented from adhering to the pressure detection unit 22d. The invention according to claim 3 is the invention according to claim 1, which is an exhaust gas pressure detector for an engine, wherein the columnar body 27 is a ceramic columnar body whose surface is covered with a carbon layer. In the invention according to claim 3, the columnar body can be obtained at a relatively low cost. The invention according to claim 4 is claim 1
The invention according to any one of 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 the tip opening portion of 3b in a range excluding the lower portion of the tip opening portion. In the invention according to claim 4, the columnar body 2 is provided without attenuating the pressure of exhaust gas transmitted through the hose 14.
7 can be effectively prevented from slipping out of the hose mounting portion 23b.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described. As shown in FIG. 3, the engine is provided with an exhaust pipe 11 which is an exhaust passage, and an exhaust filter device 12 is provided in the middle of the exhaust pipe. The exhaust filter device 12 is
A columnar particulate filter 12a that actually collects particulates, and a particulate filter 12
This particulate filter 12 is coaxial with the central axis of a.
The holding tube 12b for holding a and the holding plates 12c, 12c respectively inserted into both ends of the holding tube 12b so as to hold the both ends of the particulate filter 12a are provided, and these holding plates 12c, 12c are Housing tube 1
Lids 12d, 12d provided by welding to both ends of 2b
It is held down by. An exhaust outlet 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 an exhaust pressure detector 21 is attached to the bracket 16 to connect the hose 14
The other ends of are connected.

As shown in FIG. 1, the exhaust pressure detector 21 comprises a detector main body 22 and a cap 23 for attaching the main body 22 to the bracket 16. The detector main body 22 has a bracket mounting portion 22a formed at the base end, and the male screw portion 2 formed on the body portion.
2b is formed. The bracket mounting portion 22a is formed with a seating surface 22c facing one surface of the bracket 16, and its outer diameter is formed into a hexagonal shape capable of fixing its rotation by a tool such as a spanner. The male screw portion 22b is formed so as to project from the center of the seat surface 22c, and a pressure detecting portion 22d that actually senses the exhaust pressure is formed at the tip of the male screw portion 22b that is the body portion. A mounting hole 16a having a diameter slightly larger than that of the male screw portion 22b is formed in the bracket 16, and the male screw portion 22b is inserted into the mounting hole 16a from its tip via a ring-shaped packing 24.

On the other hand, the cap 23 is formed with a female screw portion 23a which is screwed into the male screw portion 22b of the detector main body 22,
Male screw part 2 inserted in mounting hole 16a of bracket 16
It is screwed to 2b via a ring-shaped packing 24. In this way, by screwing the female screw portion 23a into the male screw portion 22b, the end edge of the cap 23 is fixed to the seat surface 2 of the detector main body 22.
3c and the bracket 16 around the mounting hole 16a, and the bracket 1 together with the bracket mounting portion 22a.
6 is attached. In addition, a hollow hose mounting portion 23b is formed on the cap 23 continuously with the female screw portion 23a. A large diameter portion 23c for hose locking that bulges outward is formed at the tip of the hose mounting portion 23b, and the other end of the hose 14 is tightened from the surroundings by a fixing band 26 while being fitted into the hose mounting portion 23b. Are connected.

As shown in FIGS. 1 and 2, a reduced diameter portion 23d is provided at the tip opening of the hose mounting portion 23b. The reduced diameter portion 23d in this embodiment is the hose attachment portion 2
The reduced diameter portion 23d is provided in 75% of the entire circumference because it is provided outside the range of 90 degrees from the center in the lower portion of the tip opening portion in 3b. The range in which the reduced diameter portion 23d is provided is not limited to this 75%, but 6
It is preferably in the range of 5% to 90%. Inside the hose mounting portion 23b, the outer diameter D (FIG. 2) is smaller than the inner diameter d1 of the hose mounting portion 23b by 20 μm to 1 mm and the reduced diameter portion 23d.
The columnar body 27 having an outer diameter 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 of No. 3 is screwed into the male screw portion 22b, the female screw portion 23a is inserted into the hose mounting portion 23b in advance, and in this state, the female screw portion 23a is screwed into the male screw portion 22b.
7 is provided inside the hose mounting portion 23b. A carbon solid body having carbon exposed on its surface is used for the columnar body 27 in this embodiment, and the columnar body 27 is 20 μm to 1 mm from the pressure detecting portion 22 d when the cap 23 is screwed.
Is adjusted to have a gap W (FIG. 1).

The engine exhaust pressure detector 21 thus constructed detects the engine exhaust pressure via the hose 14. Exhaust gas flowing through the exhaust pipe 11, which is 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. Although the pulsation transmitted to the exhaust pressure detector 21 reaches the pressure detecting portion 22d through the air or gas present in the gap between the inner surface of the hose mounting portion 23b and the outer surface of the columnar body 27,
Since the gap between them is extremely small, the pulsation reaches the pressure detection unit 22d in a state of being significantly damped. Therefore, the exhaust pressure detector 21 can detect the exhaust pressure in a state where there is relatively little fluctuation. In this case, the columnar body 27 has the reduced diameter portion 23.
Since the outer diameter is larger than the inner diameter of d, it does not come out from the hose mounting portion 23b, and the pressure detection portion 22d and 20 μm-
Since the gap W has a width of 1 mm, the columnar body 27 does not directly contact the pressure detection portion 22d to cause an error in the detection output.

Further, 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. Therefore, the exhaust gas flows from the hose 14 to the hose mounting portion 23.
It does not enter b and be discharged to the outside. Therefore, the exhaust gas does not enter the surroundings of the pressure detection portion 22d through the hose 14, and even if the exhaust gas reaches the hose attachment portion 23b, the particulates in the exhaust gas will not reach the surface of the columnar body 27. The exposed carbon is not adsorbed, and the particulate matter in the exhaust gas does not adhere to the pressure detecting portion 22d and the detection sensitivity is not lowered. Further, since carbon has a relatively low heat transfer coefficient, the columnar body 27 in which carbon is exposed also functions as a heat insulating material, and even if relatively high temperature exhaust gas enters the hose, its temperature is directly detected by the pressure detecting portion 22d. Is prevented, and 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 can be ensured for a relatively long period of time.

In the above-described embodiment, the columnar body 27 made of solid carbon is used, but 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 coated with a carbon layer having a thickness of 2 to 100 μm. Even such a columnar body in which carbon is exposed on the surface 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 exhausted. The pulsation can be sufficiently attenuated. Also, since the columnar body has an outer diameter larger than the inner diameter of the reduced diameter portion, it does not come out from the hose mounting part and has a predetermined gap with the pressure detection part, so the columnar body directly contacts the pressure detection part and outputs Does not cause an error. Also, since carbon is exposed on the surface of the columnar body, even if exhaust gas enters the hose attachment part, the particulate matter in the exhaust gas is adsorbed by the carbon exposed on the surface, and the particulate matter in the exhaust gas detects the pressure. It can be prevented from adhering to the part. Furthermore, because carbon has a relatively low heat transfer coefficient,
The columnar body in which carbon is exposed also functions as a heat insulating material, preventing the temperature from being directly transmitted to the pressure detection unit even if relatively high temperature exhaust gas enters the hose. It is possible to secure reliability for a very long term.

[Brief description of drawings]

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

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

FIG. 3 is a view showing a mounting state of the detector.

[Explanation of symbols]

11 exhaust passage 14 hose 16 brackets 21 Exhaust pressure detector 22 Detector body 22a Bracket mounting part 22b Male thread 22d Pressure detector 23 Cap 23a Female thread part 23b Hose mounting part 23d reduced diameter part 27 columns d1 Inner diameter of hose mount d2 Inner diameter of reduced diameter part D Column outer diameter W predetermined gap

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Claims (4)

(57) [Claims] 1. A detector body (22) having a bracket mounting portion (22a) at a base end thereof, a male screw portion (22b) at a body portion, and a pressure detection portion (22d) at a tip end of the body portion. , The male screw part (22
(b) has a female threaded portion (23a) that is screwed onto the bracket (16) together with the bracket mounting portion (22a) in a threaded state, and is a hollow hose mounting portion that is continuous with the female threaded portion (23a). 23b) formed with a cap (23), the hose mounting portion (23b) is connected to a hose (14) communicating with the exhaust passage (11) of the engine exhaust pressure detector of the engine, A reduced diameter portion (23d) is provided at the tip opening of the mounting portion (23b), and the hose mounting portion (23b) is provided inside the hose mounting portion (23b).
Columnar body (27) having an outer diameter (D) smaller than the inner diameter (d1) 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 so as to face (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 whose both ends are 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 covered with a carbon layer. 4. The exhaust pressure of the engine according to claim 1, wherein a reduced diameter portion (23d) is provided in a tip opening portion of the hose mounting portion (23b) in a range excluding a lower portion of the tip opening portion. Detector.