Exhaust purification equipment

Abstract

An exhaust purification apparatus comprising: a contacting device which brings a reducing agent into contact with exhaust gas discharged from an internal combustion engine; and a catalytic device which is connected to the contacting device, is in communication with the contacting device, and has a catalyst that has an axis extending in a first direction and facilitates the reaction between the reducing agent and nitrogen oxide in the exhaust gas, wherein the contacting device has an injection part which injects the reducing agent into the exhaust gas, and a tubular connection part which extends substantially parallel to the first direction and which connects the injection part and the catalytic device.

Description

[Technical field]

[0001] The present invention relates to an exhaust gas purification device. [Background technology]

[0002] A selective catalytic reduction (SCR) system is known as a conventional technology in which urea water is injected into the exhaust gas passageway and thermally decomposed to generate ammonia, which is then mixed with the exhaust gas to reduce nitrogen oxides (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6077665 Summary of the Invention [Problem to be solved by the invention]

[0004] In the device described in Patent Document 1, it is necessary to arrange an injector for urea water in the axial direction of the catalyst and the filter, and further to extend an overflow pipe vertically, which imposes significant design constraints. [Means for solving the problem]

[0005] In one aspect, the present invention provides an exhaust purification device comprising: a contact device that brings a reducing agent into contact with exhaust gas discharged from an internal combustion engine; and a catalytic device connected to the contact device, the catalytic device having an axis extending in a first direction and having a catalyst that promotes a reaction between nitrogen oxides in the exhaust gas and the reducing agent, the contact device having an injection portion that injects the reducing agent into the exhaust gas, and a tubular connecting portion that connects the injection portion to the catalytic device and extends approximately parallel to the first direction. Effect of the Invention

[0006] According to the present invention, it is possible to provide an exhaust gas purification device with fewer design restrictions. [Brief description of the drawings]

[0007] [Figure 1] 1A and 1B are schematic diagrams of a purification device according to a first embodiment, showing a configuration including a DOC device and a DPF device, and a configuration in which the DOC device and the DPF device are omitted. [Diagram 2] FIG. 2A is a perspective view and FIG. 2B is a cross-sectional view of a contact device and a DPF device according to the first embodiment. [Diagram 3] FIG. 3A is a cross-sectional view taken along line III-III in FIG. 2, and FIG. 3B is a diagram showing the arrangement of an SCR catalyst device, a DPF device, and an overflow pipe. [Figure 4] 4A is a perspective view, FIG. 4B is a cross-sectional view, and FIG. 4C is a cross-sectional view taken along line IVc of a contact device and a DPF device according to a first modified example. [Diagram 5] 5 is a cross-sectional view taken along line VV in FIG. 4. [Figure 6] 6A is a perspective view of a contact device and a DPF device according to a second modified example, FIG. 6B is a cross-sectional view, FIG. 6C is a cross-sectional view taken along line VIc, and FIG. 6D is a cross-sectional view taken along line VId. [Figure 7] 13A and 13B are a perspective view and a cross-sectional view of a contact device and a DPF device according to a third modified example. [Figure 8] 1A is a top view, FIG. 1B is a side view, and FIG. 1C is a top view showing a configuration in which a DOC device and a DPF device are omitted, showing an outline of a purification device according to a second embodiment. [Figure 9] 9A is a perspective view showing a contact device and a catalytic device according to a second embodiment, FIG. 9B is a cross-sectional view, and FIG. 9C is a cross-sectional view taken along line IXc-IXc. [Figure 10] 11A is a perspective view showing a contact device and an SCR catalyst device according to a second embodiment, FIG. 11B is a cross-sectional view, and FIG. 11C is a cross-sectional view taken along line Xc-Xc. [Figure 11] FIG. 6 is a schematic diagram of a purification device according to a second embodiment. [Figure 12] FIG. 1 is a cross-sectional view showing the arrangement of a DPF and an overflow pipe in the prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] First Embodiment A purification device 1 which is a first embodiment of an exhaust purification device will be described below with reference to Figures 1 to 3. The purification device 1 is a device that performs selective catalytic reduction (SCR), that is, injects urea water into exhaust gas and reduces nitrogen oxides in the exhaust gas using ammonia as a reducing agent.

[0009] The purification device 1 is mounted on a vehicle 100 equipped with a diesel engine 101, and purifies the exhaust gas of the diesel engine 101. In the following description, the front-rear, up-down, left-right directions of the purification device 1 are defined based on the orientation of the vehicle 100 as shown in FIG.

[0010] The purification device 1 mainly includes a DOC device 2 equipped with an oxidation catalyst (DOC: Diesel Oxidation Catalyst), a DPF device 3, a contact device 4, and an SCR catalyst device 5 equipped with an SCR catalyst 51. As shown in FIG. 1(a), the DOC device 2 and the DPF device 3 are arranged side by side in the left-right direction of the vehicle 100. These devices are connected via piping or a housing, and their internal spaces are connected (hereinafter also referred to as communication). Exhaust gas from a diesel engine 101 passes through each device in the order of the DOC device 2, the DPF device 3, the contact device 4, and the SCR catalyst device 5.

[0011] As shown in Fig. 1(b), the purification device 1 may be configured not to include the DOC device 2 and the DPF device 3, but to have a diesel engine 101 and an SCR catalyst device 5 connected via a contact device 4. However, in the following, unless otherwise specified, the explanation will be given on the premise of a configuration including the DOC device 2 and the DPF device 3 (Fig. 1(a)).

[0012] As shown in FIG. 2, the DPF device 3 includes a case 31, a shell 33, and a DPF 34 (Diesel Particulate Filter).

[0013] The case 31 is a housing that houses the shell 33 and the DPF 34, and is a substantially cylindrical member having an axis that extends in the left-right direction.

[0014] The shell 33 is formed in a generally cylindrical shape having an axis extending in the left-right direction. The shell 33 is a cylindrical member having a smaller diameter than the case 31, and is housed inside the case 31. The right end portion of the shell 33 forms a discharge portion 33A having an opening for discharging the exhaust gas that has passed through the DPF 34.

[0015] The DPF 34 is a filter for collecting and removing particulate components in the exhaust gas, and has a cylindrical shape with an axis 34A. The DPF 34 is removably housed inside the shell 33 with the axis 34A facing in the left-right direction.

[0016] The contactor 4 has a function of bringing the exhaust gas discharged from the DPF device 3 into contact with the urea water serving as a reducing agent, and further guiding the exhaust gas toward the SCR catalyst device 5. As shown in FIG. 2, the contactor 4 includes a case 41, an injector 42, an overflow pipe 43, and a plurality of baffle plates 44.

[0017] The case 41 is a housing forming the outer shell of the contact device 4, and is attached so as to cover the right side of the case 31. The inside of the case 41 is formed hollow to guide the exhaust gas. More specifically, the inside of the case 41 is formed with a lower chamber 41A, a middle chamber 41B provided above the lower chamber 41A, and an upper chamber 41C above the middle chamber 41B. These chambers 41A, 41B, and 41C are mutually connected, and as shown by the arrows in FIG. 2, the exhaust gas discharged from the discharge portion 33A can be sequentially guided upward.

[0018] The lower chamber 41A is a chamber through which the exhaust gas discharged from the discharge portion 33A first passes, and is formed on the right side of the case 31 and communicates with the discharge portion 33A.

[0019] The upper chamber 41C is a chamber formed in the upper part of the case 41. In the upper chamber 41C, the urea water is injected into the exhaust gas, and the exhaust gas is guided to the overflow pipe 43.

[0020] The middle chamber 41B is formed between the lower chamber 41A and the upper chamber 41C, and has a function of guiding the exhaust gas from the lower chamber 41A to the upper chamber 41C while adjusting the flow direction of the exhaust gas.

[0021] The injector 42 is a device fixed to the upper end of the case 41, and has a function of injecting the urea water to the left into the upper chamber 41C. The injector 42 is located above the overflow pipe 43, and injects the urea water above the overflow pipe 43.

[0022] The overflow pipe 43 is a tubular member extending in the left-right direction, and has a substantially elliptical cross section that is flattened vertically as shown in Fig. 3. The overflow pipe 43 is provided so as to extend leftward from the upper portion of the case 41 as shown in Fig. 2(b), and has the function of guiding exhaust gas to the SCR catalytic device 5.

[0023] A right end portion of overflow pipe 43 is disposed inside upper chamber 41C. An opening 43C is formed in the upper surface of the right end portion of overflow pipe 43, and the inside of overflow pipe 43 and upper chamber 41C communicate with each other via opening 43C. As shown in FIG. 2(b), a gap is formed between the outer periphery of overflow pipe 43 and the inner surface of case 41 in upper chamber 41C.

[0024] Baffle plate 44 is a plate-like member extending in the front-rear and up-down directions, and is fixed to the upper part of case 41. A plurality of baffle plates 44 are arranged side by side in the left-right direction above opening 43C. The lower end of baffle plate 44 is located inside overflow pipe 43, and forms a gap with the inner surface of overflow pipe 43 (FIG. 3).

[0025] The SCR catalyst device 5 is connected to the overflow pipe 43. The SCR catalyst device 5 receives exhaust gas from the overflow pipe 43 and has a function of promoting the reduction reaction of nitrogen oxides by ammonia using the SCR catalyst 51. The SCR catalyst 51 is a cylindrical member (FIG. 3(b)) having an axis 51A extending horizontally.

[0026] As described above, overflow pipe 43 is disposed so as to be parallel to axis 51A and axis 34A. However, including in the following modified examples and embodiments, the direction in which overflow pipe 43 extends may be within an angular range of ±5 degrees with respect to at least one of axis 51A and axis 34A ( FIG. 3( b ), the upper side is positive). Similarly, including in the following modified examples and embodiments, the direction in which overflow pipe 43 extends may be not only horizontal, but also within an angular range of ±5 degrees with respect to the horizontal direction.

[0027] In this specification, overflow pipe 43 is described as being "substantially parallel" to axis 51A or axis 34A when the absolute value of the angle that overflow pipe 43 forms with axis 51A or axis 34A is 5 degrees or less. Overflow pipe 43 may form an angle with axis 51A or axis 34A in a direction other than up and down, such as the horizontal direction. Also, when the direction in which overflow pipe 43 extends is within an angle range of ±5 degrees with respect to the horizontal direction, it is described as being "substantially horizontal."

[0028] (Exhaust gas purification) The purification of exhaust gas in the purification device 1 will be described below. The DOC device 2 oxidizes nitrogen oxides (NOx) in the exhaust gas. The exhaust gas then passes through the DPF device 3, during which the DPF 34 collects and removes particulate matter in the exhaust gas. The exhaust gas is discharged from the right end face of the DPF 34, passes through the discharge section 33A, and enters the contact device 4.

[0029] The exhaust gas that has entered the contact device 4 passes through the lower chamber 41A, the middle chamber 41B, and the upper chamber 41C in that order. Inside the upper chamber 41C, the exhaust gas flows around the outside of the overflow pipe 43 and enters the inside of the overflow pipe 43 through the opening 43C. At this time, the exhaust gas flows along the outer periphery of the overflow pipe 43, creating two symmetrical swirling flows (hereinafter referred to as "swirling flows"), and while maintaining these swirling flows, the exhaust gas advances inside the overflow pipe 43 toward the SCR catalytic device 5 (FIGS. 2(b) and 3). The baffle plate 44 and the overflow pipe 43 are heated from the inside and outside of the pipe by the moving exhaust gas.

[0030] Since the middle chamber 41B is located below the upper chamber 41C and the overflow pipe 43, when the exhaust gas moves from the middle chamber 41B, the exhaust gas moves in a direction intersecting the direction in which the overflow pipe 43 extends. Therefore, the flow speed of the exhaust gas is unlikely to decrease, and a swirling flow can be efficiently generated. The ammonia and urea water are easily mixed and stirred with the exhaust gas.

[0031] At the same time, urea water is injected from the injector 42 into the upper chamber 41C. The urea water hits the baffle plate 44 and enters the inside of the overflow pipe 43 from the opening 43C together with the exhaust gas. The urea contained in the urea water is heated by the baffle plate 44 or the overflow pipe 43 to generate ammonia. The swirling flow of the exhaust gas mixes and agitates the ammonia and the exhaust gas.

[0032] Since the exhaust gas moves around the overflow pipe 43, the overflow pipe 43 is easily heated, and ammonia is easily generated by heating the urea water. That is, the urea water attached to the inside of the overflow pipe 43 is efficiently heated, and ammonia can be easily generated. In addition, the risk that the urea water will remain inside the overflow pipe 43 without generating ammonia and cause urea crystals to form and solidify is reduced.

[0033] The exhaust gas that has passed through the overflow pipe 43 reaches the SCR catalytic device 5. In the SCR catalytic device 5, the reduction of nitrogen oxides in the exhaust gas by ammonia is promoted by the SCR catalyst 51. As a result, the nitrogen oxides in the exhaust gas are reduced to nitrogen.

[0034] <First Modification> The shape and dimensions of the middle chamber are not limited to those shown in Figures 2 and 3, and may be various. A contact device 104 according to a first modified example is shown in Figure 4. In the following, devices, members, etc. having the same configuration as in the first embodiment are given the same reference numbers as in the first embodiment, and descriptions thereof will be omitted.

[0035] The contact device 104 includes a case 141. A middle chamber 141B formed in the case 141 is located between the overflow pipe 43 and the case 31, and is formed to extend in the left and right directions. The left and right length of the middle chamber 141B is approximately the same as the left and right length of the opening 43C.

[0036] Since the middle chamber 141B is located below the upper chamber 41C and the overflow pipe 43, when the exhaust gas moves from the middle chamber 141B to the upper chamber 41C, it moves in a direction approximately perpendicular to the overflow pipe 43, i.e., directly upward, as shown by the arrows in Figures 4 and 5.

[0037] Since the exhaust gas moves around the overflow pipe 43 over a wide area, the overflow pipe 43 is easily heated, and ammonia is easily generated by heating the urea water. That is, the urea water attached to the inside of the overflow pipe 43 is efficiently heated, and ammonia can be easily generated. In addition, the risk of the urea water remaining inside the overflow pipe 43 without generating ammonia, which may cause urea crystals to form and solidify, is reduced.

[0038] Since the exhaust gas moves in a direction intersecting, preferably perpendicular to, the overflow pipe 43, the flow velocity of the exhaust gas is unlikely to decrease, and a swirling flow can be efficiently generated. Mixing and stirring of the ammonia and urea water with the exhaust gas becomes easy.

[0039] <Second Modification> A contact device 204 according to a second modification is shown in Fig. 6. In a case 241 of the contact device 204, a flow path 241D provided radially outward of the case 31 is formed in addition to a lower chamber 41A, a middle chamber 241B, and an upper chamber 41C.

[0040] The middle chamber 241B is a space formed to extend in the left-right direction, and is located at a position other than the upper side, such as the front or rear side, of the case 31. The middle chamber 241B is also formed below the axis 34A. Since the middle chamber 241B is not located above the case 31, the height dimension of the contact device 204 can be made smaller than that of the contact device 104 of the first modified example.

[0041] Flow path 241D is a space formed between the outer circumferential surface of case 31 and the inner circumferential surface of case 241, and connects middle chamber 241B and upper chamber 41C.

[0042] As shown by the arrows in Figures 6(b) and (c), the exhaust gas moves diagonally downward from the lower chamber 41A and enters the middle chamber 241B. The exhaust gas then splits into two streams and passes through the flow passage 241D, creating an upward flow before flowing into the upper chamber 41C (Figure 6(d)). The exhaust gas flows into the overflow pipe 43 while creating a swirling flow in the upper chamber 41C.

[0043] The movement of exhaust gas inside upper chamber 41C and the injection of urea water are the same as those in the first embodiment. That is, even with this configuration, it is possible to obtain the same effects as those in the first embodiment while suppressing the height of the device.

[0044] <Third Modification> A DPF device 303 and a contact device 304 according to a third modification are shown in Fig. 7. The DPF device 303 has a case 31, a shell 133, a DPF 34, and a gasket 135. A gap between the outer peripheral surface of the shell 133 and the inner peripheral surface of the case 31 is sealed by the gasket 135 to prevent leakage of exhaust gas. In addition, the contact device 304 has a case 341.

[0045] The shell 133 is a substantially cylindrical member, and a right end surface of the shell 133 contacts the case 341. In the exhaust portion 133A, a plurality of openings 133B are formed lined up in the circumferential direction and penetrating the side wall of the shell 133. The exhaust gas can flow radially outward of the shell 133 through the plurality of openings 133B.

[0046] A lower chamber 341A is formed radially outward from the shell 133, and is defined by the outer peripheral surface of the shell 133 and the inner peripheral surface of the case 341. The lower chamber 341A is formed to be annular when viewed in the left-right direction, unlike the lower chamber 41A of the first embodiment. The lower chamber 341A communicates with the middle chamber 41B at its upper portion.

[0047] The exhaust gas discharged from the discharge section 133A is guided to the lower chamber 341A, the middle chamber 41B, and the upper chamber 41C, and moves upward. Thereafter, similar to the first embodiment and the first modification, the exhaust gas that has moved upward flows into the overflow pipe 43 while creating a swirling flow in the upper chamber 41C.

[0048] Even with this configuration, it is possible to shorten the left-right lengths of the DPF device 303 and the contact device 4 and to provide a compact configuration. In particular, since the right end of the shell 133 can be brought into contact with the case 341, the left-right dimension of the case 341 can be reduced.

[0049] In the first embodiment, the overflow pipe 43 is arranged so that its extension direction is approximately parallel to the axial direction of the DPF 34, but as shown in the second embodiment described below, it may be arranged so that its extension direction is approximately parallel to the axial direction or the SCR catalyst 51.

[0050] <Second embodiment> A purification device 401 according to the second embodiment will be described below. In the following, devices, members, etc. having the same configuration as those in the first embodiment will be given the same reference numerals as those in the first embodiment, and descriptions thereof will be omitted.

[0051] As shown in FIG. 8, the purification device 401 mainly includes a DOC device 2, a DPF device 3, a contact device 404, and an SCR catalyst device 5 having an SCR catalyst 51.

[0052] As shown in Fig. 8(c), the purification device 401 may be configured not to include the DOC device 2 and the DPF device 3, and the diesel engine 101 and the SCR catalyst device 5 may be connected via the contact device 4. However, in the following, unless otherwise specified, the description will be given on the premise that the configuration includes the DOC device 2 and the DPF device 3 (Figs. 8(a) and (b)). The DPF device 3 and the contact device 404 are disposed with a gap between them in the front-rear direction.

[0053] The SCR catalytic device 5 is fixed to the chassis of the vehicle 100. The SCR catalyst 51 of the SCR catalytic device 5 is formed in a cylindrical shape and has an axis 51A that extends in the front-rear direction and horizontally or approximately horizontally (FIGS. 8 and 9). The SCR catalytic device 5 receives a supply of exhaust gas from the contact device 404, and promotes the reduction reaction of nitrogen oxides by the SCR catalyst 51.

[0054] As shown in FIG. 9, the contact device 404 includes a case 441, an injector 442, an overflow pipe 443, a plurality of baffle plates 444, and piping 445.

[0055] The case 441 is a generally cylindrical member extending in the front-rear direction and is connected to the exhaust portion 33A to receive the supply of exhaust gas. The case 441 has a function of bringing the exhaust gas into contact with the urea water therein, similar to the upper chamber 41C in the first embodiment and the like.

[0056] The injector 442 is fixed to the upper front end of the case 441. The injector 442 has a function of injecting urea water rearward toward the inside of the case 441. The injector 442 is located above the overflow pipe 443, and injects urea water upward of the overflow pipe 443.

[0057] The overflow pipe 443 is a generally horizontal pipe extending in the front-rear direction that connects the case 441 and the SCR catalytic device 5, and is formed in a generally elliptical shape in cross section as shown in Fig. 9(c) . The axis of the overflow pipe 43 coincides with the axis 51A.

[0058] The front end of overflow pipe 443 is disposed inside case 441. An opening 443C is formed in the upper surface of the front end of overflow pipe 443, and overflow pipe 443 and case 441 communicate with each other via opening 443C. As shown in Figures 9(b) and (c), within case 441, a gap is formed between the outer peripheral surface of overflow pipe 443 and the inner surface of case 441.

[0059] Baffle plate 444 is a plate-like member extending in the left-right and up-down directions, and is fixed to the inner upper surface of case 441. A plurality of baffle plates 444 are arranged in a front-to-back arrangement above opening 443C. The lower end of baffle plate 444 is located inside overflow pipe 443, and forms a gap with the inner surface of overflow pipe 443 (FIG. 9(c)).

[0060] Piping 445 connects case 441 and exhaust unit 33A, and has a function of guiding exhaust gas from exhaust unit 33A to case 441. In other words, the rear end of pipe 445 extends in a direction intersecting the direction in which overflow pipe 443 extends, preferably at a right angle.

[0061] The connection direction between pipe 445 and case 441 can be various. For example, as shown in Fig. 9, the rear end of pipe 445 can be bent upward and connected to case 441. In this case, the exhaust gas moves upward, goes around the outside of overflow pipe 443, and moves into overflow pipe 443 through opening 443C.

[0062] 10, the rear end of the pipe 445 can be extended in the left-right direction and connected to the case 441. When such a connection method is adopted, it is also possible to install the SCR catalyst 51 so that the axis 51A extends in the left-right direction, for example, as shown in FIG.

[0063] In this case, it is preferable that the length of the gap provided between pipe 445 and the inner surface of case 441 is narrower on the side connected to pipe 445 (L2 in FIG. 10(c)) than on the opposite side (L3). This is to adjust the pressure loss caused by the difference in path length and make the flow rate, flow velocity, or magnitude of the swirling flow of the exhaust gas closer to symmetry. The exhaust gas moves horizontally, goes around the outside of overflow pipe 443, and moves into the inside of overflow pipe 443 through opening 443C.

[0064] It is desirable that piping 445 is connected so as to intersect with the extending direction of overflow pipe 43, but if there are design constraints, the rear end of piping 445 does not have to extend in a direction intersecting overflow pipe 443. It is also possible to configure the rear end of piping 445 to extend in the same direction as overflow pipe 443 and be connected to case 441.

[0065] (Exhaust gas purification) The principle of exhaust gas purification in the purification device 401 is the same as that of the purification device 1 of the first embodiment. That is, the DOC device 2 oxidizes nitrogen oxides (NOx) in the exhaust gas, and then the exhaust gas passes through the DPF device 3. At that time, the DPF 34 collects and removes particulate components in the exhaust gas. The exhaust gas is discharged from the DPF 34 and flows into the pipe 445 of the contact device 4.

[0066] When the exhaust gas moves from the pipe 445 to the case 441, it moves along the direction of the rear end of the pipe 445. That is, in the example of FIG. 9, the exhaust gas moves upward, and in the example of FIG. 10, it moves approximately horizontally. Inside the case 441, the exhaust gas goes around the outside of the overflow pipe 443 and enters the inside of the overflow pipe 443 through the opening 443C. At this time, the exhaust gas creates two swirling flows by going around the outer periphery of the overflow pipe 443, and while maintaining these swirling flows, it proceeds inside the overflow pipe 443 toward the SCR catalyst device 5 (FIGS. 9(b) and 10(b)). The baffle plate 444 and the overflow pipe 443 are heated by the exhaust gas.

[0067] At the same time, in upper chamber 441C, urea water is injected from injector 442. The urea water hits baffle plate 444 and is sent into overflow pipe 443 from opening 443C together with exhaust gas. The urea contained in the urea water is heated by baffle plate 444 or overflow pipe 443 to generate ammonia. The swirling flow of exhaust gas mixes and agitates the ammonia in the exhaust gas.

[0068] The exhaust gas advances in the direction in which the pipe 445 extends, and flows in a direction intersecting the overflow pipe 443. Therefore, the flow speed of the exhaust gas is unlikely to decrease, and a swirling flow can be efficiently generated. Mixing and stirring of the ammonia and urea water with the exhaust gas becomes easy.

[0069] The exhaust gas that has passed through the overflow pipe 443 reaches the SCR catalyst device 5, where the nitrogen oxides in the exhaust gas are reduced to nitrogen.

[0070] <Effects> In each of the above-mentioned embodiments and modified examples, the purification device 1, 401 has a DPF device 3, 303 (corresponding to a filter device) having a DPF 34 that collects particulate components in exhaust gas discharged from a diesel engine 101 (corresponding to an internal combustion engine) and an exhaust section 33A, 133A that discharges exhaust gas that has passed through the DPF 34. The purification device 1, 401 also has a contact device 4, 104, 204, 304, 404 that is connected and communicates with the exhaust section 33A, 133A and brings a reducing agent containing urea into contact with the exhaust gas. The purification device 1, 401 also includes a catalyst device 5 that is connected and communicates with the contact device 4, 104, 204, 304, 404 and has an SCR catalyst that promotes the reaction between nitrogen oxides in the exhaust gas and the reducing agent. The contact device 4 has an injection section (injection device 42, 442 and upper chamber 41C, 441C) that injects a reducing agent into the exhaust gas, and an overflow pipe 43, 443 (corresponding to a connection section) that connects the injection section and the catalytic device 5 and extends parallel or approximately parallel to at least one of the axis 34A and the axis center 51A.

[0071] In the above configuration, the contact device 4, 104, 204, 404 does not necessarily need to be arranged coaxially with the DPF 34. For example, the contact device 4, 104, 204, 304 can be arranged substantially parallel to the DPF 34, the contact device 404 can be arranged below the DPF 34, or substantially parallel to the catalytic converter 5. This reduces restrictions on the design of the device. As is clear from FIG. 1 and other figures, the size of the area in which the purification device 1, 401 can be arranged is limited by the width and chassis size of the vehicle 100. In the above configuration, the device dimensions can be reduced while maintaining the purification performance of the exhaust gas.

[0072] In particular, in the contact devices 4, 104, 204, and 304, the horizontal projection dimension (shown as L1 in FIG. 2) from the end of the case 31 can be reduced, thereby reducing the horizontal dimension. Therefore, the contact devices 4, 104, 204, and 304 can be installed even in vehicles 100 with a narrow width (FIG. 1, etc.).

[0073] On the other hand, in the conventional technology, there were many design constraints, such as the need to align the overflow pipe OF in the axial direction of the DPF and then extend it perpendicularly as shown in Fig. 12. With the above configuration, the purification device 1, 401 can be designed without such constraints.

[0074] In addition, in each of the above-mentioned embodiments and modified examples, the overflow pipe 43, 443 extends horizontally or approximately horizontally. Since there is no need to extend the overflow pipe vertically as in the conventional technology, there are fewer design constraints on the purification device 1, 401.

[0075] In each of the above-described embodiments and modified examples, the ejection device 42, 442 is disposed above the opening 43C, 443C of the overflow pipe 43, 443.

[0076] Since the injectors 42, 442 are located above the substantially horizontal overflow pipes 43, 443, there is no need to arrange the overflow pipe and the injectors side by side as in the conventional technology. Also, since the injectors 42 are arranged above the openings 43C, 443C and are configured to inject the reducing agent into the upper chamber 41C, the reducing agent flows smoothly into the overflow pipes 43, 443 and is well mixed with the exhaust gas.

[0077] In each of the above-described embodiments and modified examples, the overflow pipe 43 is located above the DPF 34.

[0078] By disposing the overflow pipe 43 above the DPF 34, the horizontal projection dimension of the contact device 4, 104, 204 from the end of the case 31 can be reduced.

[0079] The contact device 4 includes a guide portion (middle chambers 41B, 141B, 241B, flow path 241D, and pipe 445) that guides the exhaust gas from the discharge portion 33A. The guide portion guides the exhaust gas in a direction intersecting with the overflow pipe 43, preferably perpendicular thereto.

[0080] With this configuration, the flow velocity of the exhaust gas is unlikely to decrease, and a swirling flow can be efficiently generated. The ammonia and urea water are easily mixed and stirred with the exhaust gas.

[0081] A cylindrical shell 133 that houses the DPF 34 has an exhaust portion 133A. The exhaust portion 133A is formed with an opening 133B that penetrates a side wall of the shell 133. Exhaust gas can flow radially outward of the shell 133 through the opening 133B.

[0082] By adopting such a configuration, the projection dimension of the contact device 4 can be shortened, and a compact configuration can be achieved. [Explanation of symbols]

[0083] 1, 401 Purification equipment 3. 303 DPF device 4, 104, 204, 304 contact device 5 SCR catalyst device 41, 141, 241, 341 cases 41A, 341A Lower Chamber 41B, 141B, 241B Middle chamber 241D Flow Path 41C, 441C Upper chamber 42, 442 Injection device 43, 443 Overflow pipe 44 Baffle plate

Claims

1. A contact device that brings a reducing agent into contact with exhaust gas discharged from an internal combustion engine; a catalytic converter connected to the contactor, the catalytic converter having an axis extending in a horizontal first direction and including a catalyst for promoting a reaction between nitrogen oxides in the exhaust gas and the reducing agent; The contact device comprises: an injection unit that injects the reducing agent into the exhaust gas; a connecting portion that connects the injection portion and the catalyst device and is a continuous tubular member extending approximately parallel to the first direction, The injection unit has an injection chamber through which the exhaust gas passes, and an injection device that injects the reducing agent into the injection chamber. The connection portion has an end portion with an opening formed thereon, The injector injects the reducing agent above the opening. Exhaust purification device.

2. The exhaust gas purification device further includes a filter device having an axis extending in a second direction and configured to collect particulate matter in the exhaust gas, and a discharge portion configured to discharge the exhaust gas that has passed through the filter to the connection portion, The exhaust purification device according to claim 1 , wherein the connection portion extends substantially parallel to at least one of the first direction and the second direction.

3. The exhaust gas purification device according to claim 2 , wherein the connection portion is located above the filter.

4. 4. The exhaust purification device according to claim 2, wherein the contact device further comprises a guide portion that guides the exhaust gas from the exhaust portion in a direction intersecting a direction in which the connecting portion extends.

5. The filter device further includes a tubular member having the discharge portion and configured to accommodate the filter, The exhaust purification device according to claim 2 , wherein the discharge portion is formed with an opening penetrating a side wall of the tubular member.

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