Exhaust Manifold
In an exhaust manifold, a plurality of branch pipes is bent downward from a head flange to form like an L-letter shape, where exhaust-gas upstream side end portions of the pipes are connected with an engine through the head flange and exhaust-gas downstream side end portions thereof are connected with a pipe collecting part which is provided with a sensor for detecting a state of exhaust gas. The pipe collecting part has a reduced diameter portion where a length of the pipe collecting part in a longitudinal direction of the head flange is set shorter than that of the pipe collecting part in a thickness direction of the head flange. The sensor is provided on the reduced diameter portion.
The present invention relates to an exhaust manifold which is connected to an engine, especially an exhaust manifold provided with a sensor on a pipe collecting part thereof to detect a state of an exhaust gas passing therethrough.
BACKGROUND OF THE INVENTIONConventional exhaust manifolds with a sensor are disclosed in Japanese Patent Applications Laid-open Publication No. 2003-83061 and No. 10-26037. As shown in
The pipe collecting part 06 has a reduced diameter portion 06d at its intermediate position, where the reduced diameter portion 06d has a circular cross section whose diameter is reduced compared to those of upstream and downstream side end portions thereof. The reduced diameter portion 06d is provided with a sensor 010 for detecting oxygen concentration in the exhaust gas so that a sensing part 010c of the sensor 010 is positioned in the center of a flow of the exhaust gas passing through the reduced diameter portion 06d to obtain high accurate sensing.
DISCLOSURE OF THE INVENTION Problem(s) to be Solved by the InventionThe former conventional exhaust manifold, however, has the following problem.
In the conventional exhaust manifold, all of branch pipes 02 are bent downward from the head flange 01 to form like an L-letter shape, exhaust-gas upstream side end portions of the branch pipes 02 are fixed to the engine E through the head flange 01, and exhaust-gas downstream side end portions thereof are fixed to a vehicle body through a catalytic converter 07 and others. A stress is produced due to the vibrations of the engine E (A direction of the vibration is indicated by an arrow ER around a vertical axis, vertical to a paper surface of this specification, passing through a point OA in
The present invention is made to solve the above-described problem, and an object thereof is to provide an exhaust manifold which can enforce strength of a pipe collecting part without increasing its weight and detect a state of an exhaust gas with high accuracy by a sensor, thereby accelerating a temperature rise of an exhaust gas purifying catalyst to improve an exhaust gas purifying performance.
Means for Solving the ProblemsAccording to an aspect of the present invention, there is provided an exhaust manifold including a head flange, a plurality of branch pipes, and a pipe collecting part. The head flange is fixed to an engine. The plurality of branch pipes is bent downward from the head flange to form like an L-letter shape, where the branch pipes have exhaust-gas upstream side end portions and exhaust-gas downstream side end portions. The exhaust-gas upstream side end portions are connected with the engine through the head flange, and the exhaust-gas downstream side end portions of the branch pipes are connected with the pipe collecting part. The pipe collecting part is provided with a sensor for detecting a state of an exhaust gas. The pipe collecting part has a reduced diameter portion in which a length, of the pipe collecting part, in a longitudinal direction of the head flange is set to be shorter than a length, of the pipe collecting part, in a thickness direction of the head flange. The reduced diameter portion is provided with the sensor.
Preferably, the pipe collecting part has an intermediate portion in which the both surfaces seen from the thickness direction are formed to have an involute curve.
Preferably, the pipe collecting part is formed to have curves at both sides, respectively, so that width lengths of the surfaces seen from the thickness direction become larger from an exhaust-gas upstream side end portion of the pipe collecting part to an exhaust-gas downstream side end portion thereof.
Preferably, the pipe collecting part has two divided bodies, which are separatable in the longitudinal direction along the thickness direction, coupled with each other.
Preferably, the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.
EFFECT OF THE INVENTIONIn the exhaust manifold of the present invention, the plurality of branch pipes is bent downward from the head flange to form the L-letter shape. The exhaust-gas upstream side end portions are connected with the engine through the head flange, and the exhaust-gas downstream side end portions of the branch. pipes are connected with the pipe collecting part. The pipe collecting part is provided with the sensor for detecting the state of the exhaust gas. The pipe collecting part has a reduced diameter portion in which the length of the pipe collecting part in the longitudinal direction of the head flange is shorter than the length of the pipe collecting part in the thickness direction of the head flange, and the reduced diameter being provided with the sensor.
Therefore, the exhaust manifold of the invention can increase its strength without increasing the weight of the pipe collecting part. This can improve its exhaust gas purifying performance by promoting the rise in temperature of an exhaust gas purifying catalyst. In addition, it can detect the state of the exhaust gas with high accuracy.
In the invention, the pipe collecting part has the intermediate portion in which the both surfaces seen from the thickness direction are formed to have the involute curve. Therefore, it facilitates dispersion of the stress acting on the surfaces, thereby increasing the strength of the reduced diameter portion.
In the invention, the pipe collecting part is formed to have the curves at both sides, respectively, so that width lengths of the surfaces seen from the thickness direction become larger from the exhaust-gas upstream side end portion of the pipe collecting part to the exhaust-gas downstream side end portion thereof. Therefore, this can ensure the pipe collecting part 6 to bear the stress acting on the surfaces.
In the invention, the pipe collecting part has the two divided bodies, which are separatable in the longitudinal direction along the thickness direction, coupled with each other. Therefore, the pipe collecting part 6 can be manufactured easily and low costs.
In the invention, the sensor has the holding portion which is fixed on the one of the surfaces seen from the longitudinal direction through the boss member provided thereon. Therefore, strength of the surface provided with the holding portion and the boss member can be increased, a projecting amount of the oxygen sensor from the pipe collecting part being reduced, and the oxygen sensor being avoided from possible interference with other portions/parts.
The objects, features and advantages of the present invention will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:
- EM exhaust manifold
- 1 head flange
- 1a insertion hole
- 2, 3, 4, 5 branch pipe
- 6 pipe collecting part
- 6a, 6b divided body
- 6c exhaust-gas upstream side end portion
- 6d reduced diameter portion
- 6e opening portion
- 6f exhaust-gas downstream side end portion
- 7 catalytic converter
- 8 catalyst carrier
- 9 flange portion
- 10 oxygen sensor
- 10a wiring
- 10b holding portion
- 10c sensing part
- 11 boss member
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
EmbodimentThe embodiment of the present invention will be described.
First the entire construction of the exhaust manifold EM of the embodiment will be described.
As shown in
The head flange 1 is formed like a plate and is fixed on one of side surfaces of a not-shown cylinder head of a not-shown engine.
The branch pipes 2 to 5 are projected in a lateral direction of the engine from the head flange 1 so that they are bent downward therefrom to form like an L-letter shape.
As shown in
An exhaust-gas downstream side end portion 6f of the pipe collecting part 6 is connected with an exhaust-gas side upstream side end portion of the catalytic converter 7 which contains a catalyst carrier 8.
An exhaust-gas downstream side end portion of the catalytic converter 7 is provided with a flange portion 9 for fixing a not-shown downstream side exhaust pipe.
As shown in
As shown in
An opening of the exhaust-gas downstream side end portion 6f of the pipe collecting part 6 is expanded in diameter so as to receive an exhaust-gas upstream side end portion of the catalytic converter 7.
The pipe collecting part 6 is formed to have an outer shape described below. As shown in
As shown in
At least the head flange 1, the branch pipes 2 to 5, the pipe collecting part 6 and the catalytic converter 7 are made of metal like stainless. Thus constructed exhaust manifold EM is connected with the cylinder head of the engine through the head flange 1, and the flange portion 9 of the catalytic converter 8 is connected with the downstream side exhaust pipe attached to the vehicle body when they are mounted on the vehicle body.
Next the operation of the exhaust manifold EM of the embodiment will be described.
Before that, the problem of the conventional exhaust manifold will be explained below.
In the conventional exhaust manifold, each branch pipe 02 of the exhaust manifold EM is formed to bend from the head flange 01 like the L-letter shape, the exhaust-gas upstream side end portion thereof being fixed to the engine through the head flange 01, and the exhaust-gas downstream side end portion thereof being fixed to the vehicle body through the catalytic converter 07 and others. Therefore, a stress is produced due to the thermal expansion and contraction of each branch pipe and also due to the vibrations of the engine, thereby acting on the whole exhaust manifold to be folded like the L-letter shape. In order to avoid this folding, the pipe collecting part 06 requires to be enforced in strength thereof by increasing the thickness of the pipe collecting part 06. This increase in the thickness causes the problems in that the temperature rise in the exhaust gas purifying catalyst is delayed due to the increase in its mass and thermal capacity.
On the other hand, in the exhaust manifold EM of the embodiment, the reduced diameter part 6c of the pipe collecting part 6 is not formed in such a way that the lengths of the surfaces, parallel to the surface extending along which the branch pipes 2 to 5 are bent, are reduced in diameter. This can ensure the pipe collecting part 6 to have the strength enough to bear the stress due to the thermal expansion and contraction of the branch pipes 2 to 5 and due to the vibration of the engine, without increasing the thickness of the pipe collecting part 6.
In addition, in the exhaust manifold of the embodiment, the reduced diameter portion 6d is formed so that the lengths of the surfaces, orthogonal to the surfaces along which the branch pipes 2 to 5 are bent, are set to be shorter than the length of the latter surface, and the oxygen sensor 10 is provided on the reduced diameter portion 6d. This enables the oxygen sensor 10 to detect the state of the exhaust gas with high accuracy, because the sensing part 10c of the oxygen sensor 10 can be positioned in the center of a flow of the exhaust gas passing the reduced cross section of the pipe collecting part 6.
Next the advantages of the exhaust manifold EM of the embodiment will be described.
As described above, in the exhaust manifold EM of the embodiment, the plurality of branch pipes 2 to 5 is formed to bend from the head flange 1 like the L-letter shape, the exhaust-gas upstream side end portions of the branch pipes 2 to 5 are connected with the engine through the head flange 1, and the exhaust-gas downstream side end portions thereof are connected with the pipe collecting part 6, which is provided with the oxygen sensor 10 for detecting the state of the exhaust gas. The reduced diameter portion 6d of the pipe collecting part 6 is formed so that lengths of the surfaces, orthogonal to the surfaces along which the branch pipes 2 to 5 are bent like the L-letter shape, are set to be shorter than those of the latter surfaces. The reduced diameter portion 6d is provided with the oxygen sensor 10. Therefore, the exhaust manifold EM of the embodiment can increase its strength without increasing the weight of the pipe collecting part 6. This can improve its exhaust gas purifying performance by accelerating the temperature rise in the catalyst carrier (an exhaust gas purifying catalyst) 8 in the catalytic converter 7. In addition, the oxygen sensor 10 can detect the state of the exhaust gas with high accuracy because it is located in the center of the flow of the exhaust gas passing through the reduced diameter portion 6d.
The both surfaces, seen from the longitudinal direction LN, of the reduced diameter portion 6 are formed like the involute curve. The involute curved surfaces facilitate dispersion of the stress acting on the surfaces, thereby increasing the strength of the reduced diameter portion 6d.
The both surfaces, seen from the thickness direction LT, of the pipe collecting part 6 is formed to have the curve at their side edge portions so that longitudinal directional (width) lengths of the surfaces are set to be larger from the exhaust-gas upstream side end portion to the exhaust-gas downstream side end portion. This profile can ensure the pipe collecting part 6 to bear the stress acting on the surfaces.
The pipe collecting part 6 consists of the two divided bodies 6a and 6b, which are firstly separated in the longitudinal direction LN along the thickness direction LT and then are coupled with each other. Therefore, the pipe collecting part 6 can be manufactured easily and at low costs.
The oxygen sensor 10 is provided so that the holding portion 10b is placed on one of the surfaces seen from the longitudinal direction LN, via the cylindrical boss member 11. Therefore, the cylindrical boss portion 11 and the holding portion 10b can increase the strength of the surface provided therewith. In addition, they can reduce a projecting amount of the oxygen sensor 10 from the pipe collecting part 6, and can avoid the oxygen sensor 6 from possible interferences with other portions/parts.
It is understood that the invention is not limited to the above-described embodiment but that various changes and/or modifications may be made without departing from the spirit and/or the scope of the present invention. For example, the oxygen sensor 10 is provided on the one surface, seen from the longitudinal direction LN, of the reduced diameter portion 6d of the pipe collecting part 6 in the embodiment, while it may be provided on the other surface of the reduced diameter portion 6d.
The sensor of the present invention is not limited to the oxygen sensor, and it may employ a sensor for detecting a state of the exhaust gas, for example, a temperature sensor for detecting a temperature of the exhaust gas.
In the embodiment, the pipe collecting part 6 is manufactured by the two divided bodies 6a and 6b being coupled with each other, while it may be made of one pipe by using press working, spinning or the like.
INDUSTRIAL AVAILABILITYThe exhaust manifold EM of the present invention is applicable to exhaust manifolds of various engines, including transversely mounted engines and longitudinally mounted engines, as long as the engines use an exhaust manifold for discharging exhaust gas therethrough.
Claims
1. An exhaust manifold comprising:
- a head flange fixed to an engine;
- a plurality of branch pipes which is bent downward from the head flange to form like an L-letter shape, the branch pipes having exhaust-gas upstream side end portions and exhaust-gas downstream side end portions where the exhaust-gas upstream side end portions are connected with the engine through the head flange; and
- a pipe collecting part connected with the exhaust-gas downstream side end portions of the branch pipes, the pipe collecting part being provided with a sensor for detecting a state of an exhaust gas, wherein
- the pipe collecting part has a reduced diameter portion in which a length, of the pipe collecting part, in a longitudinal direction of the head flange is set to be shorter than a length, of the pipe collecting part, in a thickness direction of the head flange, the reduced diameter portion being provided with the sensor.
2. The exhaust manifold according to claim 1, wherein
- the pipe collecting part has an intermediate portion in which the both surfaces seen from the thickness direction are formed to have an involute curve.
3. The exhaust manifold according to claim 3, wherein
- the pipe collecting part is formed to have curves at both sides, respectively, so that width lengths of the surfaces seen from the thickness direction become larger from an exhaust-gas upstream side end portion of the pipe collecting part to an exhaust-gas downstream side end portion thereof.
4. The exhaust manifold according to claim 3, wherein
- the pipe collecting part has two divided bodies, which are separatable in the longitudinal direction along the thickness direction, coupled with each other.
5. The exhaust manifold according to claim 5, wherein
- the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.
6. The exhaust manifold according to claim 2, wherein
- the pipe collecting part has two divided bodies, which are separatable in the longitudinal direction along the thickness direction, coupled with each other.
7. The exhaust manifold according to claim 6, wherein
- the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.
8. The exhaust manifold according to claim 2, wherein
- the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.
9. The exhaust manifold according to claim 1, wherein
- the pipe collecting part is formed to have curves at both sides, respectively, so that width lengths of the surfaces seen from the thickness direction become larger from an exhaust-gas upstream side end portion of the pipe collecting part to an exhaust-gas downstream side end portion thereof.
10. The exhaust manifold according to claim 9, wherein
- the pipe collecting part has two divided bodies, which are separatable in the longitudinal direction along the thickness direction, coupled with each other.
11. The exhaust manifold according to claim 10, wherein
- the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.
12. The exhaust manifold according to claim 9, wherein
- the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.
13. The exhaust manifold according to claim 1, wherein
- the pipe collecting part has two divided bodies, which are separatable in the longitudinal direction along the thickness direction, coupled with each other.
14. The exhaust manifold according to claim 13, wherein
- the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.
14. The exhaust manifold according to claim 1, wherein
- the sensor has a holding portion which is fixed on one of the surfaces seen from the longitudinal direction through a boss member provided thereon.
Type: Application
Filed: Jan 16, 2007
Publication Date: May 21, 2009
Inventor: Kazuya Uchida (Tokyo)
Application Number: 12/087,272
International Classification: F01N 7/10 (20060101);