JP2015224602A - Exhaust pipe of construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of high stress in both end portions of an exhaust pipe and prevent the resonance of the exhaust pipe with an engine.SOLUTION: A construction machine exhaust pipe (5) connecting an engine (3) to an exhaust-gas post-treatment device (4), comprises: a first pipe (8); a second pipe (9); a plurality of bellows (6a, 6b, 6c) disposed between the first pipe (8) and the second pipe (9); and coupling pipes (7) disposed among the bellows (6a, 6b, 6c). The first bellows (6b) is formed such that a peak in an end portion of the first bellows (6b) connected to the first pipe (8) is lower than peaks in the other portions, and the second bellows (6c) is formed such that a peak in an end portion of the second bellows (6c) connected to the second pipe (9) is lower than peak in the other portions.

Description

  The present invention relates to an exhaust pipe of a construction machine.

  For example, a hydraulic excavator, which is a typical example of a construction machine, is provided on a lower traveling body that enables self-propelling, an upper revolving body that enables turning on the lower traveling body, and a front side of the upper revolving body. It is equipped with a working device driven by pressure oil. An engine, a fuel tank, and the like for driving the hydraulic pump are mounted on the rear part of the upper swing body.

  A diesel engine is generally used as an engine of a hydraulic excavator. A diesel engine emits particulate matter (PM), nitrogen oxides (NOx), and the like. Therefore, an exhaust gas aftertreatment device is provided in the exhaust system of the engine. For example, the construction machine described in Patent Document 1 or 2 has a mounting structure in which the exhaust gas aftertreatment device is fixed to the engine via a bracket. In this mounting structure, since the engine and the exhaust gas aftertreatment device are in the same vibration system, there is no fear that a large relative displacement is applied to the exhaust pipe connecting the two. Therefore, for example, as described in Patent Document 2, the engine-side piping and the exhaust gas aftertreatment device are connected by a single bellows.

  However, exhaust gas aftertreatment devices have become larger due to the recent tightening of exhaust gas regulations, and the weight has increased accordingly. As a result, it is difficult to ensure the strength of the bracket in the mounting structure, and a structure in which the engine and the exhaust gas aftertreatment device are separately provided is necessary. With this structure, a bracket for fixing the exhaust gas aftertreatment device to the engine is not required, but the engine and the exhaust gas aftertreatment device are in separate vibration systems, so a large relative displacement is added to the exhaust pipe, There is an actual situation that it is difficult to connect with one bellows. More specifically, in a limited space such as the engine room of a hydraulic excavator, the bellows is required to be short in the axial direction, to withstand internal pressure due to exhaust gas, and to have excellent stretchability. Therefore, the bellows has a multilayer structure in which a plurality of thin plates are stacked. Since this bellows is manufactured by hydraulic forming, the water used in the manufacturing process remains between multiple layers. As a result, when mounted on an actual machine and heated to high temperatures by exhaust gas, the remaining water expands as water vapor and damages the bellows. As a countermeasure, an air hole is usually provided at the end of the bellows. However, if the bellows becomes long, water vapor cannot be completely removed from the air hole, resulting in damage to the bellows. On the other hand, if air holes are provided in the peaks and valleys of the bellows, stress concentration occurs in those portions, which causes damage. Therefore, it is impossible to manufacture a bellows having a long dimension, and there is a limit to the number of peaks. As a result, it is necessary to connect the engine and the exhaust gas aftertreatment device with a plurality of bellows.

US Patent Application Publication No. 2010/0269494 JP 2012-219625 A

  Under such circumstances, a special exhaust pipe is manufactured by directly joining a plurality of bellows by welding or the like to a desired length, and the engine and the exhaust gas aftertreatment device are connected using the special exhaust pipe. Configuration is conceivable. However, since the engine and the exhaust gas aftertreatment device are provided separately, if a large relative displacement due to severe vehicle body vibration is applied to this special exhaust pipe, high stress is generated at both ends thereof. In addition, since the special exhaust pipe is secured by joining the bellows directly, the natural frequency decreases as the length increases. As a result, when resonance occurs due to engine vibration, a large amplitude is generated because the natural frequency is low, and a special exhaust pipe may be damaged due to repeated high stress.

  The present invention has been made in view of the above situation, and the purpose of the present invention is to generate high stress at both ends of an exhaust pipe of a construction machine that connects an engine and an exhaust gas aftertreatment device. It is to prevent the exhaust pipe from resonating with the engine at a low natural frequency.

  In order to achieve the above object, the present invention provides an exhaust pipe for a construction machine that connects an engine and an exhaust gas aftertreatment device, the first pipe connected to the engine side, and the exhaust gas after A second pipe connected to the processing apparatus side, a plurality of bellows disposed between the first pipe and the second pipe, and a connecting pipe disposed between the plurality of bellows; Among the plurality of bellows, the first bellows connected to the first pipe has a peak height at the end connected to the first pipe higher than the peak height of the other portion. Of the plurality of bellows, the second bellows connected to the second pipe has a peak height at the other end connected to the second pipe. Forming a shape lower than the height of the mountain, the adjacent bellows of the plurality of bellows are connected to each other. By connecting a pipe, the natural frequency of the exhaust pipe of the construction machine is characterized in that it has to be higher than the case of connecting the bellows adjacent the plurality of bellows directly.

  In the present invention, the height of the peak at one end of the first bellows is formed low, and the height of the peak at one end of the second bellows is similarly formed low. The change in the rigidity of the connection portion of the first bellows and the connection portion of the second pipe and the second bellows is moderated, and the relative position between the engine and the exhaust gas aftertreatment device is greatly changed, so that the exhaust pipe has a large relative displacement. Even if is added, bending deformation can be moderated. As a result, stress concentration at both ends of the exhaust pipe can be avoided.

  Furthermore, according to the present invention, by connecting a plurality of bellows by connecting pipes, in the vibration shape inherent to the exhaust pipe, which is generally called a natural vibration mode, deformation is suppressed by the rigidity of the connecting pipe, and the amplitude of the exhaust pipe Can be suppressed. As a result, the natural frequency of the exhaust pipe can be increased, and resonance in the low frequency range with the engine can be prevented. Therefore, according to the present invention, it is possible to prevent an unexpected situation that the exhaust pipe is suddenly damaged, and to extend the service life.

  Further, in the above-mentioned configuration, the present invention is such that the first bellows is formed such that a mountain gradually decreases toward the tip of the end connected to the first pipe, and the second bellows The mountain is formed so as to gradually become lower toward the tip of the end connected to the second pipe.

  According to the present invention, since the bending deformation of the first bellows and the second bellows can be made more gradual, the stress at both ends of the exhaust pipe can be further reduced. As a result, the exhaust pipe can be used for a longer period of time and is highly reliable.

  Moreover, the present invention is characterized in that, in the above configuration, the rigidity of the connecting pipe is higher than the rigidity of the plurality of bellows.

  According to the present invention, in the vibration shape inherent to the exhaust pipe, which is generally called the natural vibration mode, deformation can be suppressed by the rigidity of the connecting pipe and the amplitude of the exhaust pipe can be suppressed. Local stress concentration can be further suppressed. As a result, the life of the exhaust pipe can be extended.

  Further, the present invention is the above configuration, wherein the plurality of bellows, the first piping, the second piping, and the connecting piping are all made of the same stainless steel material, and the thickness of the connecting piping is It is characterized by being thicker than the thickness of each of the plurality of bellows and equal to or thinner than the thickness of the first pipe and the second pipe.

  According to the present invention, the stress at both ends of the exhaust pipe can be reduced, the natural frequency of the exhaust pipe can be increased, and the corrosion resistance can be enhanced by using a stainless steel material. Therefore, it is more suitable as an exhaust pipe applied to a construction machine.

  Further, the present invention is the above configuration, wherein the plurality of bellows is at least three, and among the plurality of bellows, bellows other than the first bellows and the second bellows have a height of a mountain. Are characterized by being formed identically.

  According to the present invention, the bellows other than the bellows at both ends have the same peak height, so that even if a large relative displacement is applied to the exhaust pipe, the relative displacement can be further absorbed.

  Moreover, the present invention is characterized in that, in the above configuration, the plurality of bellows is at least three, and the plurality of bellows are all configured in the same shape.

  According to the present invention, since all the plurality of bellows have the same shape, it is possible to reduce the number of parts and the manufacturing cost.

  Further, the present invention is characterized in that, in the above configuration, a plurality of outer blades are provided to cover each of the plurality of bellows.

  According to the present invention, the bellows can be protected from dirt and the like by the outer blade, and the damping effect of the exhaust pipe can be enhanced by friction caused by contact with the outer blade.

  Further, the present invention is characterized in that, in the above-described configuration, one outer blade that covers the plurality of bellows as a whole is provided.

  According to the present invention, the bellows can be protected from dirt and the like by the outer blade, and the damping effect of the exhaust pipe can be enhanced by friction caused by contact with the outer blade. Moreover, since a plurality of bellows can be entirely covered with one outer blade, there is an advantage that the outer blade can be easily attached.

  According to the present invention, in an exhaust pipe of a construction machine that connects between an engine and an exhaust gas aftertreatment device, it is possible to prevent high stress from being generated at both ends, and to resonate with the engine in a low frequency range. Can be prevented. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is a side view of a hydraulic excavator to which an exhaust pipe of a construction machine according to the present invention is applied. It is a top view which shows the inside of the upper revolving body of the hydraulic shovel shown in FIG. It is a perspective view which shows the structure of the engine of the hydraulic shovel shown in FIG. 1, and its circumference | surroundings. 1 is an overall configuration diagram of an exhaust pipe according to a first embodiment of the present invention. It is a figure which shows the deformation | transformation state of an exhaust pipe when a relative displacement is added. It is a whole block diagram of the exhaust pipe which concerns on 2nd Embodiment of this invention. It is a whole block diagram of the exhaust pipe which concerns on 3rd Embodiment of this invention. It is a whole block diagram of the exhaust pipe which concerns on 4th Embodiment of this invention. It is a whole block diagram of the exhaust pipe which concerns on 5th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a side view of a hydraulic excavator to which an exhaust pipe according to the present invention is applied, FIG. 2 is a top view showing the inside of an upper swing body of the hydraulic excavator shown in FIG. 1, and FIG. 3 is a hydraulic pressure shown in FIG. It is a perspective view which shows the structure of the engine of a shovel, and its periphery.

  As shown in FIGS. 1 to 3, a hydraulic excavator 1 that is a typical example of a construction machine includes a lower traveling body 2 b that enables self-running, and an upper revolving body 2 a that is pivotable with respect to the lower traveling body 2 b. And a working device 2c provided on the front side of the upper swing body 2a and driven by pressure oil from a hydraulic pump (not shown).

  The work device 2c is for performing excavation work, and includes a boom 2c-1, an arm 2c-2, and a bucket 2c-3. The boom 2c-1, arm 2c-2, and bucket 2c-2 are driven by a boom cylinder 2c-4, an arm cylinder 2c-5, and a bucket cylinder 2c-6 as hydraulic actuators, respectively. In addition, an engine 3 for driving a hydraulic pump (not shown), an exhaust gas aftertreatment device 4 for purifying exhaust gas, a fuel tank (not shown), and the like are provided at the rear part of the upper swing body 2a.

  As shown in FIGS. 2 and 3, the engine 3 and the exhaust gas aftertreatment device 4 are connected by an exhaust pipe 5. The exhaust pipe 5 is configured to be able to absorb the change when the relative position between the engine 3 and the exhaust gas aftertreatment device 4 changes. That is, the exhaust pipe 5 has flexibility. Since the engine 3 and the exhaust gas aftertreatment device 4 are installed separately, they are separate vibration systems.

“First Embodiment”
Hereinafter, the exhaust pipe 5 according to the first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 4 is an overall configuration diagram of the exhaust pipe 5 according to the first embodiment of the present invention. As shown in FIG. 4, the exhaust pipe 5 according to the first embodiment includes a first pipe 8 connected to the engine 3 side, a second pipe 9 connected to the exhaust gas aftertreatment device 4 side, Three bellows 6a, 6b, 6c arranged between the first pipe 8 and the second pipe 8 and the three bellows 6a, 6b, 6c arranged to connect adjacent bellows. The two connecting pipes 7 are configured.

  The first pipe 8, the second pipe 9, and the bellows 6a, 6b, 6c are all made of stainless steel having excellent heat resistance, corrosion resistance, and wear resistance in consideration of the usage environment. You may comprise with the material of. An example of the axial length of the exhaust pipe 5 is as follows. Each bellows 6a, 6b, 6c is about 100 to 200 mm, the first pipe 8 is about 80 mm, the second pipe 9 is about 150 mm, and the connecting pipe 7 is About 30 mm.

  The 1st bellows 6b connected with the 1st piping 8 is constituted so that the height of a mountain may become low gradually as it goes to the end by the side connected with the 1st piping 8. FIG. Specifically, as shown in FIG. 4 (b), the first bellows 6b has a peak height H1 at the end (the left end in the figure) on the side connected to the connecting pipe 7. On the other hand, at the end portion on the side connected to the first pipe 8 (the end portion on the right side in the figure), the heights of the peaks are H2 and H3, and the height of the peaks gradually increases toward the tip side. It is formed to be low.

  The 2nd bellows 6c connected with the 2nd piping 9 is comprised so that the height of a mountain may become low gradually as it goes to the edge part by the side connected with the 2nd piping 9. As shown in FIG. Since the second bellows 6c has the same configuration as the first bellows 6b, description thereof is omitted here. On the other hand, the bellows 6a located in the center is formed with H1 having the same mountain height over the entire length.

  Further, the thickness T1 of the connecting pipe 7 is equal to or thinner than the thickness T2 of the first pipe 8 and the second pipe 9 (T1 ≦ T2). Further, the thickness T1 of the connecting pipe 7 is made larger than the thickness T3 of the bellows 6a, 6b, 6c (T1> T3), and the rigidity of the connecting pipe 7 is made higher than that of the bellows 6a, 6b, 6c. That is, in the present embodiment, the relationship between the thickness of each of the first pipe 8, the second pipe 9, the bellows 6a, 6b, 6c, and the connecting pipe 7 is the first pipe 8, the second pipe 9 ≧ the connecting pipe. 7> Bellows 6a, 6b, 6c.

  Since the exhaust pipe 5 configured in this manner is provided with two connecting pipes 7 between the bellows 6a, 6b, 6c, the vibration shape unique to the exhaust pipe can suppress deformation due to the rigidity of the connecting pipe 7. Therefore, the natural frequency is higher than that in the case where the exhaust pipe is configured by directly joining the bellows 6a, 6b, 6c by welding or the like. Incidentally, in the hydraulic excavator 1, the engine speed changes in the range of, for example, 800 rpm to 1900 rpm. Therefore, the exhaust pipe 5 is designed so that at least its natural frequency does not resonate with the steady rotational speed of the engine 3.

  Next, a case where a large relative displacement is applied to the exhaust pipe 5 due to intense body vibration of the excavator 1 will be described. FIG. 5 is a view showing a deformed state of the exhaust pipe 5 when the relative displacement D is applied to the exhaust pipe 5. As shown in FIG. 5, when a large relative displacement D is applied to the exhaust pipe 5, the bellows 6a, 6b, 6c are deformed, and the exhaust pipe 5 is deformed in the vertical direction of FIG. As shown in FIG. 5, the deformation amount of the central bellows 6a is smaller than the deformation amounts of the bellows 6b and 6c on both sides.

  At this time, for example, as shown in part A of FIG. 5, the height of the peak at the left end of the second bellows 6c (the end on the side connected to the second pipe 9) is low. The bending deformation of the left end portion of 6c can be moderated. As a result, the stress concentration on the A part can be reduced. Further, since the connecting pipe 7 has higher rigidity than the bellows 6a, 6b, 6c, deformation in the vibration shape unique to the exhaust pipe can be suppressed, and the amplitude of the exhaust pipe 5 can be suppressed. As a result, the stress at the right end of the bellows 6b and the left end of the bellows 6c are reduced.

  Further, the thickness of the first pipe 8 and the second pipe 9 is equal to or thicker than that of the connecting pipe 7 and the thickness of each bellows 6a, 6b, 6c is made thinner than that of the connecting pipe 7, whereby the exhaust pipe The natural frequency of the exhaust pipe 5 can be increased while increasing the rigidity of both ends of the gas 5 and reducing the stress. As described above, according to the exhaust pipe 5 according to the first embodiment, local stress concentration is reduced, the amplitude in the low frequency range with the engine 3 is large, and severe resonance can be avoided. Therefore, the life of the exhaust pipe 5 can be increased.

“Second Embodiment”
Hereinafter, the exhaust pipe 15 according to the second embodiment of the present invention will be described in detail with reference to the drawings. FIG. 6 is an overall configuration diagram of the exhaust pipe 15 according to the second embodiment of the present invention. The exhaust pipe 15 according to the second embodiment shown in FIG. 6 is different from the first embodiment in the shape of the bellows located in the center. Specifically, in the first embodiment, the bellows 6a (see FIG. 4) located in the center has a structure in which the mountains are the same height over the entire length, but in the second embodiment, the bellows in the center is also The difference is that a bellows 6b is used in which the height of the mountain decreases toward the end.

  In the second embodiment, the exhaust pipe 15 can be formed by using three types of bellows 6b, so that the same operational effects as those of the first embodiment can be obtained, and in addition, common parts can be used. The cost reduction effect by can also be expected. Since other configurations are the same as those of the first embodiment, detailed description thereof is omitted.

“Third Embodiment”
Hereinafter, the exhaust pipe 25 according to the third embodiment of the present invention will be described in detail with reference to the drawings. FIG. 7 is an overall configuration diagram of the exhaust pipe 25 according to the third embodiment of the present invention. The exhaust pipe 25 according to the third embodiment shown in FIG. 7 is different from the first embodiment in that the bellows 6a, 6b, 6c are covered with the outer blade 10, respectively. Since other configurations are the same as those of the first embodiment, detailed description thereof is omitted.

  The outer blade 10 is formed, for example, in a bag shape by weaving a stainless steel wire, and is installed for the purpose of protecting each of the bellows 6a, 6b, 6c. The outer blade 10 is attached by, for example, pressing the end of the outer blade 10 against the first pipe 8 and the connecting pipe 7 with a ring and then joining the ring to the pipe by welding.

  In the third embodiment, in addition to being able to obtain the same operational effects as the first embodiment, the outer blade 10 can protect the bellows 6a, 6b, 6c from dirt and the like. Furthermore, there is an advantage that the damping effect when the exhaust pipe 25 vibrates is increased by the friction caused by the contact between the outer blade 10 and the exhaust pipe 25.

“Fourth Embodiment”
Hereinafter, the exhaust pipe 35 according to the fourth embodiment of the present invention will be described in detail with reference to the drawings. FIG. 8 is an overall configuration diagram of the exhaust pipe 35 according to the fourth embodiment of the present invention. The exhaust pipe 35 according to the fourth embodiment shown in FIG. 8 is different from the third embodiment in that the bellows 6a, 6b, 6c are covered with one outer blade 11. Since other configurations are the same as those of the third embodiment, detailed description thereof is omitted.

  In the fourth embodiment, the attaching operation of the outer blade 11 is easier than in the third embodiment.

“Fifth Embodiment”
Hereinafter, an exhaust pipe 45 according to a fifth embodiment of the present invention will be described in detail with reference to the drawings. FIG. 9 is an overall configuration diagram of the exhaust pipe 45 according to the fifth embodiment of the present invention. As shown in FIG. 9, the exhaust pipe 45 according to the fifth embodiment is different from the first embodiment in that the two bellows 6 b and 6 c are connected by one connecting pipe 8. As described above, the bellows 6b and the bellows 6c have the same configuration. The exhaust pipe 45 according to the fifth embodiment is suitable when the distance between the engine 3 and the exhaust gas aftertreatment device 4 is short.

  As described above, according to each of the above-described embodiments, it is possible to prevent stress concentration from being locally applied by changing the height of the bellows peak, and by connecting adjacent bellows with a connecting pipe, By increasing the frequency, resonance in the low frequency range with the engine 3 can be avoided, and damage to the exhaust pipe can be prevented.

  Each embodiment of the exhaust pipe described above is an example for explaining the present invention, and is not intended to limit the scope of the present invention only to those embodiments. Those skilled in the art can implement the present invention in various other modes without departing from the spirit of the present invention. For example, the present invention can be applied to construction machines other than hydraulic excavators. Further, for example, in order to increase the rigidity of the connecting pipe 7, a structure using a highly rigid dissimilar metal such as fine ceramics is conceivable. When a material having high rigidity and low mass density such as fine ceramics is used, the natural frequency of the exhaust pipe can be further increased and the weight can be reduced. Further, the number of bellows may be appropriately determined according to the distance between the engine 3 and the exhaust gas aftertreatment device 4.

1 Excavator (construction machine)
2a Upper revolving unit 2b Lower traveling unit 2c Working device 3 Engine 4 Exhaust gas aftertreatment device 5 Exhaust pipe (exhaust pipe of construction machine)
6a Bellows 6b 1st bellows 6c 2nd bellows 7 Connecting piping 8 1st piping 9 2nd piping 10 Outer blade 11 Outer blade 15, 25, 35, 45 Exhaust pipe

Claims (8)

An exhaust pipe for a construction machine that connects an engine and an exhaust gas aftertreatment device,
A first pipe connected to the engine side, a second pipe connected to the exhaust gas aftertreatment device side, and a plurality of bellows disposed between the first pipe and the second pipe And a connecting pipe disposed between the plurality of bellows,
Of the plurality of bellows, the first bellows connected to the first pipe has a shape in which the height of the peak at the end connected to the first pipe is lower than the height of the other peak. And
Of the plurality of bellows, the second bellows connected to the second pipe has a shape in which the height of the crest at the end connected to the second pipe is lower than the height of the other crest. And
By connecting the adjacent bellows of the plurality of bellows with the connecting pipe, the natural frequency of the exhaust pipe of the construction machine is compared with the case of directly connecting the adjacent bellows of the plurality of bellows. An exhaust pipe for a construction machine, characterized by its height. In claim 1,
The first bellows is formed such that the mountain gradually decreases as it goes to the tip of the end connected to the first pipe.
The exhaust pipe of a construction machine, wherein the second bellows is formed such that a mountain gradually becomes lower toward a tip of an end portion on a side connected to the second pipe. In claim 1,
An exhaust pipe for a construction machine, wherein the rigidity of the connecting pipe is higher than the rigidity of each of the plurality of bellows. In claim 1,
The plurality of bellows, the first pipe, the second pipe, and the connecting pipe are all made of the same stainless steel material,
The thickness of the connecting pipe is larger than the thickness of each of the plurality of bellows, and is equal to or thinner than the thickness of the first pipe and the second pipe. Exhaust pipe. In claim 1,
The plurality of bellows is at least three,
Among the plurality of bellows, the bellows other than the first bellows and the second bellows are formed to have the same mountain height. In claim 1,
The plurality of bellows is at least three,
The exhaust pipe for a construction machine, wherein the plurality of bellows are all configured in the same shape. In claim 1,
An exhaust pipe for a construction machine, comprising a plurality of outer blades covering each of the plurality of bellows. In claim 1,
An exhaust pipe for a construction machine, comprising an outer blade that covers the plurality of bellows as a whole.