EXHAUST SYSTEM FOR A TRACTOR

Description

[0001] The invention relates to an exhaust system with a multi-part heat shield for a tractor.

[0002] It is common practice for tractor exhaust systems to be equipped with multi-part heat shields. For example, see DE102011003498A1, US2015 / 167528A1, or JP6707489B2. For example, a first shield section surrounds an exhaust aftertreatment unit, while another shield section surrounds an exhaust tailpipe of the exhaust system. Crop residue can accumulate in the transition area between the shield sections and impair the function of the heat shield.

[0003] The object of the present invention is therefore to provide improved protection for the heat shield against undesirable influences. This object is achieved by an exhaust system having the features of patent claim 1.

[0004] Further advantageous embodiments of the exhaust system according to the invention emerge from the subclaims.

[0005] According to claim 1, an exhaust system for a tractor includes a multi-part heat shield. Along an axial direction, the heat shield includes at least a first shield part and a second shield part. The first shield part surrounds an aftertreatment unit for the aftertreatment of exhaust gases from the tractor. The second shield part surrounds an exhaust tailpipe of the exhaust system at a radial distance. A radial gap is formed between the two aforementioned shield parts, which is sealed by a gasket.

[0006] The seal effectively prevents crop residues or other particles from penetrating any area within the heat shield. Consequently, crop residues and other foreign matter cannot accumulate in the transition area between the two shield sections. This reliably prevents undesirable effects on the heat shield (e.g., temperature increases, mechanical deformation).

[0007] Individual components of the heat shield or the shield parts can be made of different materials. For example, the first and / or second shield parts are made of plastic.

[0008] The aftertreatment unit is preferably a catalyst for exhaust gas aftertreatment in diesel engines, in particular an SCR (Selective Catalytic Reduction) catalyst. The aftertreatment unit reduces the emission of harmful exhaust gas components. For example, the emitted nitrogen oxides (NOx) are reduced using selective catalytic reduction (SCR) systems.

[0009] The seal is preferably made of an elastic material to support a stable sealing function.

[0010] In particular, the seal is made of silicone. This ensures a long service life and durability, even when exposed to significant temperature fluctuations in the exhaust system area and other substances such as oil and / or fuel.

[0011] The heat shield is preferably designed such that the radial gap is located between an opening in the first shield part and an opening in the second shield part. This facilitates a simple design of the seal and its stable positioning on the heat shield. The two openings are preferably of different sizes. Along the axial direction of the exhaust tailpipe, the two openings can be located in the same plane or in different planes, depending on the design of the heat shield.

[0012] In a preferred embodiment, the opening of the first shield part is larger than the opening of the second shield part. With this design, if the two shield parts are installed consecutively, the seal can be pre-installed in the area of ​​the opening of the first shield part for easy installation before the second shield part is installed and positioned on the exhaust tailpipe.

[0013] The seal preferably has a movable and in particular elastic sealing lip, which delimits an axial sealing opening for receiving the second shield part. The seal is dimensioned such that the sealing opening in an initial position is smaller than a cross-section of an outer wall of the second shield part. During assembly, the second shield part is inserted into the sealing opening, which (particularly due to the elastic properties of the seal) results in the seal automatically assuming a sealing position in which the sealing lip rests against the outer wall of the second shield part. This assembly results in a type of self-locking of the seal to the heat shield without any additional fastening means, specific tools and / or additional assembly steps.

[0014] Furthermore, the seal is preferably designed as a self-contained ring seal. This supports easy installation of the seal and facilitates a uniformly stable sealing effect in the circumferential direction of the heat shield.

[0015] In an alternative embodiment, the seal, in an initial position, has two free ends arranged in the circumferential direction of the heat shield, which, in a sealing position of the seal, are arranged adjacent to one another or overlapping in the circumferential direction. This allows the seal to be positioned on the heat shield in the manner of a sleeve, making installation very easy. A mechanically stable fit of the sleeve-like seal on the heat shield can be further supported by securing the two aforementioned free ends of the seal to one another using suitable fixing means (e.g., releasable locking elements, Velcro strips).

[0016] In a further preferred embodiment, a mechanically stable positioning of the seal on the heat shield is supported by the seal having at least one fixing projection along the circumferential direction of the heat shield, which projection interacts with a fixing recess on the first shield part or on the second shield part. In particular, a plurality of fixing projections are distributed along the circumferential direction of the seal. The seal can also be fixed to at least one fixing recess in the first shield part and to at least one fixing recess in the second shield part by means of correspondingly arranged fixing projections.

[0017] In a further preferred embodiment, a defined sealing position of the seal can be easily achieved in terms of assembly technology by the seal having a circumferential groove, in particular a circumferential annular groove, running in the circumferential direction of the heat shield and opening axially toward the second shield part. During assembly of the exhaust system, this seal can be positioned on the first shield part and then automatically accommodate an axial free end of the second shield part when the latter is installed by surrounding the exhaust tailpipe and being moved axially toward the seal.

[0018] Further preferably, the seal has a radial through-hole for accommodating a sensor. This allows for the inclusion of a sensor functionality on the exhaust system without any design and / or sealing disadvantages. Furthermore, the seal can be dimensioned, if necessary, to effectively seal the sensor on the exhaust system without any additional effort.

[0019] The sensor technology is in particular a NOx sensor, which is required in connection with exhaust gas aftertreatment and must be positioned within the exhaust system.

[0020] The exhaust system according to the invention is advantageously used in diesel engines of tractors. This allows for efficient improvement of exhaust gas aftertreatment in tractors.

[0021] The exhaust system according to the invention is explained in more detail below with reference to the accompanying drawings. Components that are identical or comparable in terms of their function are identified by the same reference numerals. They show: Fig. 1 a schematic side view of components of an exhaust system according to the invention for a tractor, Fig. 2 a side view of components of the exhaust system according to the invention with a seal in a first embodiment, Fig. 3 a perspective view of the seal according to Fig. 2 , Fig. 4 a partial view of the seal according to Fig. 3 with a sensor system arranged thereon, Fig. 5 a sectional side view of components of the exhaust system according to the invention with the seal according to Fig. 2 in its initial position, Fig. 6 a partial representation of the side view according to Fig. 5 with the seal in its sealing position, Fig. 7 a sectional side view of approximately the area of ​​the exhaust system according to Fig. 6 in a further embodiment, Fig. 8 a sectional side view of a section of the seal in a further embodiment, Fig. 9 a perspective view of the exhaust system according to the invention in the area of ​​the first and second shield part with the seal in a further embodiment, and Fig. 10 a perspective view of the area of ​​the exhaust system according to Fig. 9 with the seal in its sealing position.

[0022] Fig. 1 shows schematically a tractor 10 with components of an exhaust system 12. The exhaust system 12 contains an exhaust tailpipe 14, one axial end section 16 of which is fluidically connected to an outlet pipe 18 of a aftertreatment unit 20.

[0023] The aftertreatment unit 20 serves for aftertreating the exhaust gases of an internal combustion engine or diesel engine (not shown here) of the tractor 10. For this purpose, the aftertreatment unit 20 contains, for example, an SCR system or an SCR catalyst, whereby the emitted nitrogen oxides (NOx) are reduced by means of selective catalytic reduction (SCR).

[0024] The illustrated components of the exhaust system 12 are surrounded by a multi-part heat shield 22. The heat shield 22 is constructed in several parts, with parts 26, 28, 30 being shown along an axial direction 24. 26 designates a first shield part, which is designed in the manner of a container and surrounds the aftertreatment unit 20. 28 designates a second shield part, which is tubular and surrounds the exhaust tail pipe 14 at a radial distance. The radial distance runs along a radial direction 32. 30 designates a further shield part, which is tubular and surrounds the outlet pipe 18 or an axial transition region between the aftertreatment unit 20 and the exhaust tail pipe 14 at a radial distance. The further shield part 30, in turn, is surrounded by the second shield part 28 at a radial distance.

[0025] Axially in the area of ​​the further shield part 30, the exhaust system 12 has a NOx sensor 34, which extends through the outlet pipe 18. The NOx sensor 34 is connected via a connecting line 36 to a control unit (not shown here), which, for example, determines the nitrogen oxide content in the exhaust gas, monitors the efficiency of the aftertreatment unit 20, and detects any malfunctions.

[0026] A radial gap 38 is formed between the two shield parts 26, 28, which is sealed by a seal 40. In this way, particles such as crop residues or other foreign matter can be reliably prevented from unwanted penetration into areas of the exhaust system 12.

[0027] The two shield parts 26, 28 are preferably manufactured in the broadest sense as approximately cylindrical or rotationally symmetrical components, as for example in Fig. 2 The radial gap 38 then forms an annular gap along a circumferential direction 70 of the heat shield 22, which is closed by a seal 40 ( Fig. 3 ) can be sealed.

[0028] In Fig. 3 a receiving area 42 of the seal 40 with a radial through-opening 44 is visible. The receiving area 42 and its through-opening 44 serve to accommodate the NOx sensor 34 ( Fig. 4 ).

[0029] Based on Fig. 5 It can be seen that the radial gap 38 is formed between an outlet opening 46 of the first shield part 26 and an inlet opening 48 of the second shield part 28 as soon as the shield part 28 has been brought towards the outlet opening 46 in an axial assembly direction 50. The outlet opening 46 is delimited by a radially extending shield edge 52 of the first shield part 26. It can thus be seen that the outlet opening 46 is larger than the inlet opening 48 and, after assembly of the second shield part 28, the radial gap 38 sealed by the seal 40 is formed between the two openings 46, 48.

[0030] After assembly of the two shield parts 26, 28, the two openings 46, 48 do not necessarily have to be arranged in the same plane along the axial direction 24. Regardless of the axial relative arrangement of the two openings 46, 48, the gap 38 formed between them is filled and sealed by a correspondingly shaped seal 40.

[0031] The seal 40 according to Fig. 5 is clamped to the radial shield edge 52 with two differently shaped clamping legs 54. The seal 40 has an elastic and axially and radially movable sealing lip 56. A radially inner lip-free end 58 of the sealing lip 56 defines an axial sealing opening 60 for receiving the second shield part 28.

[0032] Preferably, the entire seal 40 is made of an elastic material (e.g., silicone).

[0033] In its initial position according to Fig.3 or Fig. 5 The sealing opening 60 is smaller than a cross-section of an outer wall 62 of the second shield part 28. During assembly, the second shield part 28 is pushed axially downward in the assembly direction 50, thereby pressing the radially inner lip-free end 58 radially outward. This leads to a radially outer lip-free end 64 of the sealing lip 56 being pivoted radially inward and sealingly abutting the outer wall 62 of the second shield part 28 ( Fig. 6 ). The radially inner lip-free end 58 also lies sealingly against the outer wall 62. Consequently, a sealing position of the seal 40 is automatically achieved during assembly of the second shield part 28.

[0034] In Fig. 7 a further embodiment of the first shield part 26 with a further embodiment of the seal 40 can be seen. The first shield part 26 has an axially extending shield edge 66. A simple sealing of the gap 38 in terms of assembly technology is possible, for example, in such a way that the seal 40, which is again designed as a self-contained annular seal along the circumferential direction 70, rests with a sealing lip 68 against the outer wall 62 of the second shield part 28. During an assembly movement of the second shield part 28 along the assembly direction 50, the two differently shaped clamping legs 54 of the seal 40 then automatically engage around the area of ​​the shield edge 66 in the manner of a latch. This automatically achieves a stable fit of the seal 40 on the first shield part 26 with the desired sealing of the radial gap 38.

[0035] In a further embodiment of the seal 40, it has a circumferential groove 72 extending in the circumferential direction 70 and opening axially towards the second shield part 28 ( Fig. 8 ). This seal 40 is preferably already fixed to the first shield part 26 before the second shield part 28 is mounted. For assembly, the second shield part 28 is again moved along the assembly direction 50 until its axial free end 74 is received by the circumferential groove 72. This automatically creates the desired seal of the radial gap 38. The circumferential groove 72 can be provided on various embodiments of the seal 40.

[0036] According to Fig. 9 In contrast to the embodiment according to Fig.3 not designed to be closed along the circumferential direction 70. Rather, the seal 40 has Fig. 9 in an initial position two free ends 76, 78 arranged in the circumferential direction 70, which in the sealing position of the seal 40 according to Fig. 10 are arranged either adjacent to one another or overlapping in the circumferential direction 70. Along the circumferential direction 70, the seal 40 carries a plurality of fixing projections 80, which interact with corresponding fixing recesses 82 on the first shield part 26. This allows the seal 40 to be releasably fixed, e.g., locked, to the first shield part 26.

[0037] For a simple sealing of the radial gap 38 in the embodiment according to Fig. 9 The seal 40 is preferably first releasably fixed to the first shield part 26 by means of the fixing projections 80. Thereafter, the second shield part 28 can be moved along the assembly direction 50 until it interacts with the seal 40. This interaction preferably takes place according to the type of assembly according to Fig. 8 , ie the seal 40 according to Fig. 9 preferably has the circumferential groove 72.

[0038] For the sake of clarity, it should be noted that details disclosed in the drawings are partly schematic and / or not necessarily shown to scale.

Claims

1. Exhaust system (12) having a multi-part heat shield (22) for a tractor (10), wherein, along an axial direction (24), the heat shield (22) comprises - a first shield part (26), which surrounds an aftertreatment unit (20) that subjects exhaust gases to aftertreatment, and - a second shield part (28), which surrounds an exhaust tailpipe (14) with a radial spacing, characterized in that, between the two shield parts (26, 28), there is formed a radial gap (38) which is sealed off by means of a seal (40).

2. Exhaust system according to Claim 1, characterized in that the radial gap (38) is formed between an opening (46) of the first shield part (26) and an opening (48) of the second shield part (28).

3. Exhaust system according to Claim 2, characterized in that the opening (46) of the first shield part (26) is larger than the opening (48) of the second shield part (28).

4. Exhaust system according to one of the preceding claims, characterized in that the seal (40) has a movable sealing lip (56) which delimits an axial seal opening (60) for receiving the second shield part (28), wherein, - in a starting position of the seal (40), the seal opening (60) is smaller than a cross-section of an outer wall (62) of the second shield part (28), and, - in a sealing position of the seal (40), the sealing lip (56) abuts against the outer wall (62) of the second shield part (28).

5. Exhaust system according to one of the preceding claims, characterized in that the seal (40) is in the form of a closed ring seal.

6. Exhaust system according to one of Claims 1 to 4, characterized in that, in a starting position, the seal (40) has two free ends (76, 78) arranged in a circumferential direction of the heat shield (22), which free ends, in a sealing position of the seal (40), are arranged so as to overlap or adjoin one another in the circumferential direction (70).

7. Exhaust system according to one of the preceding claims, characterized in that, along the circumferential direction (70) of the heat shield (22), the seal (40) bears at least one fixing projection (80) which, for releasable fixing of the seal (40), interacts with a fixing cutout (82) in the first shield part (26) or in the second shield part (28).

8. Exhaust system according to one of the preceding claims, characterized in that the seal (40) has a circumferential groove (72) extending in the circumferential direction (70) of the heat shield (22) and open axially towards the second shield part (28), which circumferential groove serves for receiving an axial free end (74) of the second shield part (28).

9. Exhaust system according to one of the preceding claims, characterized in that the seal (40) has a radial passage opening (44) for receiving a sensor arrangement, in particular an NOx sensor arrangement (34).

10. Tractor (10) having an exhaust system (12) according to one of the preceding claims.