Tank support structure

Abstract

To make a structure for supporting a tank as simple and strong as possible.SOLUTION: A tank support structure includes: a pair of side members 2, 2 extending along a front-back direction of a vehicle 1; a cross member 4 connecting the pair of side members 2, 2; and a tank 10 in which an additive agent for purifying exhaust air is stored. The tank 10 is fixed to a first auxiliary frame 51 protruding forward from the cross member 4 and a second auxiliary frame 52 protruding rearward so as to be supported. A rear end of the first auxiliary frame 51 and a front end of the second auxiliary frame 52 are connected in the front-back direction of the vehicle 1 by a connection part 53 while sandwiching the cross member 4 therebetween.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] This invention relates to a support structure for a tank in a vehicle equipped with a tank for storing additives for purifying exhaust gases. [Background technology]

[0002] One method for purifying nitrogen oxides (NOx) in exhaust gases emitted from diesel engines involves hydrolyzing urea solution (aqueous urea solution) on a catalyst to produce ammonia (NH3), which is then used to selectively reduce and purify the nitrogen oxides in the exhaust gas. Exhaust gas purification devices with this function are called urea selective catalytic reduction systems. Vehicles equipped with urea selective catalytic reduction systems are fitted with a urea solution tank for storing urea solution as an additive.

[0003] A urea water tank includes a tank body for storing urea water, a urea water injection pipe leading to the tank body, an atmospheric release valve for releasing air inside the tank body to the atmosphere, a leveling valve for regulating the liquid level of urea water stored inside the urea water tank, a urea water transport means for sending an appropriate amount of urea water to the catalyst side, and a urea water supply pipe which is the passage for the sent-out urea water (see, for example, Patent Document 1). Furthermore, as a urea water transport means, for example, there is a urea water pump equipped with an outlet for discharging urea water sucked in from an inlet installed in the bottom wall of the tank body to the bottom of the tank body, and an arc-shaped liquid reservoir wall that rises from the bottom wall of the tank body and surrounds the urea water pump (see, for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2017-110620 [Patent Document 2] Japanese Patent Publication No. 2020-192876 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, the applicant of this application has proposed a structure for stably supporting a urea solution tank relative to a vehicle body in Japanese Patent Application No. 2022-059269 (filed March 31, 2022). In this structure, the urea solution tank is supported by either one of the side members and the cross member, with respect to a pair of side members extending along the longitudinal direction of the vehicle body and a cross member positioned towards the rear of the vehicle body. The cross member has a structure comprising a vehicle width direction member connecting the pair of side members, a first auxiliary frame projecting forward from the vehicle width direction member, and a second auxiliary frame projecting backward. The urea solution tank is supported by the cross member via the first and second auxiliary frames.

[0006] In the above-mentioned Japanese Patent Application No. 2022-059269, it is necessary to connect two frames, a first auxiliary frame and a second auxiliary frame, to the cross member. Since the first auxiliary frame and the second auxiliary frame are separate components, there are many components, and the connection work (welding work) must be performed separately, which presents a problem as it is time-consuming.

[0007] Furthermore, as the vehicle moves, the urea tank oscillates up and down and left and right, causing repeated deflection deformation of the first and second auxiliary frames. If this deflection deformation is large, under harsh operating conditions such as continuous driving on rough roads over many years, fatigue failure may occur at the connection points (welded points) between the first and second auxiliary frames and the cross member. For this reason, measures are taken to minimize the amount of oscillation (deflection) by providing bracing to support the first and second auxiliary frames from below to the cross member. However, adding bracing also presents the problem of further increasing the number of parts and the amount of work involved.

[0008] Therefore, the objective of this invention is to make the structure supporting the tank in which the additive for purifying exhaust gases is stored as simple and robust as possible. [Means for solving the problem]

[0009] To solve the above problems, this invention provides a support structure for the tank comprising a pair of side members extending along the longitudinal direction of the vehicle, a cross member connecting the pair of side members, and a tank for storing an additive for purifying exhaust gases, wherein the tank is supported by being fixed to a first auxiliary frame projecting forward from the cross member and a second auxiliary frame projecting backward, and the rear end of the first auxiliary frame and the front end of the second auxiliary frame are connected in the longitudinal direction of the vehicle with the cross member in between by a connecting portion (Configuration 1).

[0010] In contrast to this configuration 1, the connecting portion can be configured (configuration 2) in which it is arranged along the upper surface of the cross member.

[0011] Furthermore, in addition to configuration 1, a configuration (configuration 3) can be adopted in which the first auxiliary frame and the second auxiliary frame are set to have different widths in the width direction of the vehicle.

[0012] Furthermore, in addition to configuration 3, a configuration (configuration 4) can be adopted in which one of the first auxiliary frame and the second auxiliary frame has a greater width in the vehicle width direction than the other, and the connecting portion is set to gradually decrease in width in the vehicle width direction from one side to the other side.

[0013] Furthermore, a configuration (configuration 5) can be adopted in which, compared to configuration 1, the first distance from the first fixing point that secures the first auxiliary frame and the tank to the front end of the cross member and the second distance from the second fixing point that secures the second auxiliary frame and the tank to the rear end of the cross member are set to be different from each other.

[0014] Furthermore, in addition to configuration 1, a configuration (configuration 6) can be adopted in which the first auxiliary frame and the second auxiliary frame are positioned so that one is further outward in the width direction of the vehicle than the other.

[0015] Furthermore, for Configuration 6, the connecting portion may adopt a configuration (Configuration 7) including a first portion extending along the longitudinal direction of the vehicle from the other end in the longitudinal direction of one vehicle, a second portion extending along the longitudinal direction of the vehicle from one end in the longitudinal direction of the other vehicle, and a third portion connecting the first portion and the second portion at the shortest distance and inclined with respect to the longitudinal direction of the vehicle.

[0016] Furthermore, for the above Configuration 1, a configuration in which a plurality of configurations selected from Configurations 2 to 7 are added may be adopted. At that time, the number of configurations selected from Configurations 2 to 8 may be any of 2 to 6.

[0017] In each aspect consisting of any of the above combinations, the tank is fixed to the side member, and the first fixing point for fixing the first auxiliary frame and the tank is arranged between the second fixing point for fixing the second auxiliary frame and the tank and the third fixing point for fixing the side member and the tank in the vehicle width direction. A configuration (Configuration 8) can be adopted.

[0018] Also, in each aspect consisting of any of the above combinations, the tank is fixed to the side member, the first fixing point for fixing the first auxiliary frame and the tank is arranged between the second fixing point for fixing the second auxiliary frame and the tank and the third fixing point for fixing the side member and the tank in the vehicle width direction, and the second fixing point and the third fixing point are arranged at overlapping positions in the vehicle longitudinal direction. A configuration (Configuration 9) can be adopted.

Advantages of the Invention

[0019] According to this invention, the structure for supporting the tank can be made as simple and strong as possible.

Brief Description of the Drawings

[0020] [Figure 1] Bottom view of the vehicle according to an embodiment of this invention [Figure 2]Plan view of the urea water tank and its accessories mounted on the vehicle shown in Figure 1. [Figure 3] Cross-sectional view of the urea water tank in Figure 2. [Figure 4] Bottom view showing the mounting structure of the urea water tank to the vehicle. [Figure 5] Enlarged cross-sectional view of key parts showing the mounting structure of the urea water tank to the vehicle. [Figure 6] Perspective view of a urea water tank [Figure 7] Perspective view showing the relationship between the urea tank and the vehicle frame. [Figure 8A] Plan view of the auxiliary frame fixed to the cross member [Figure 8B] Front view (Figure 8A) [Figure 9] Cross-sectional view showing the relationship between the urea tank and the vehicle frame. [Figure 10A] Perspective view showing the relationship between the cross member and the auxiliary frame. [Figure 10B] Perspective view showing the relationship between the cross member and the auxiliary frame. [Modes for carrying out the invention]

[0021] Embodiments of this invention will be described based on the drawings. Vehicle 1 is equipped with a diesel engine and a urea selective catalytic reduction (urea SCR) system to purify nitrogen oxides in the exhaust gas emitted from the engine. The urea selective catalytic reduction system is a system in which urea water is injected as an additive into the exhaust pipe 7 through which the exhaust gas passes, and ammonia produced by the hydrolysis of the urea water is used as a reducing agent to reduce nitrogen oxides on the catalyst and discharge them. This system is applicable to vehicles equipped with diesel engines or lean-burn engines where nitrogen oxide emissions are a problem.

[0022] As shown in Figure 1, the body structure of Vehicle 1 is a structure in which the body is attached to a frame that has two side members 2,2 extending in the longitudinal direction of Vehicle 1 (hereinafter simply referred to as the longitudinal direction) and a cross member 4 connecting the side members 2,2 in the width direction of Vehicle 1 (hereinafter referred to as the vehicle width direction). The side members 2,2 are located below the floor from the front to the rear of Vehicle 1 and are spaced apart in the vehicle width direction. Multiple cross members 4 are provided along the longitudinal direction. Floor panels, which constitute part of the body, are fixed to the upper surfaces of the side members 2,2.

[0023] Figure 1 is a schematic bottom view of the vehicle from below. In Figure 1, only one cross member 4 located behind the axle (drive shaft) 5 positioned between the left and right rear wheels 3,3 is shown, and the other cross members 4 are not shown. Also, only the portion of the side members 2,2 that is at least towards the rear of the vehicle 1 is shown. In this embodiment, a differential is positioned between the left and right axles 5,5, and the propeller shaft and transmission are connected to the differential in order toward the front. In this embodiment, the rear wheels 3,3 are drive wheels, but in some cases the front wheels are not drive wheels.

[0024] An emergency tire wheel 6 (hereinafter referred to as spare tire 6) is housed under the floor near the rear of vehicle 1. The spare tire 6 is detachably suspended and fixed to the cross member 4 located behind the drive shaft 5, as shown in Figure 1, via predetermined fasteners (e.g., bolts and nuts). In some cases, this spare tire 6 can be raised and lowered by winding up and down a chain.

[0025] Furthermore, as shown in Figure 1, an exhaust pipe 7 extending from the engine is located under the floor of the vehicle 1. Along the direction of exhaust gas flow, the exhaust pipe 7 is equipped with an exhaust gas purification device 60 consisting of urea selective catalytic reduction, and a muffler (silencer) 8, etc. The muffler 8 and the opening 9 at the end of the exhaust pipe 7 are each positioned closer to one of the side members 2 (in this embodiment, the right side member 2 in the vehicle width direction) than the centerline in the vehicle width direction of the vehicle 1. Here, the exhaust gas purification device 60 is part of the aforementioned urea selective catalytic reduction system. A nozzle (not shown) for injecting urea water is provided inside the exhaust pipe 7 (including inside the exhaust gas purification device 60). The nozzle for injecting urea water is generally located upstream of the exhaust gas purification device 60, but its injection position is selected appropriately according to the specifications.

[0026] Furthermore, vehicle 1 is equipped with a urea water tank 10 (hereinafter referred to as tank 10) that stores a certain amount of urea water in order to supply urea water into the exhaust pipe 7.

[0027] The tank 10 may be made of a metal with excellent corrosion resistance, such as stainless steel, or a molded product made of a resin such as polyethylene or polypropylene, or glass fiber reinforced plastic (FRP). Alternatively, it may be made by integrally molding multiple molded components using well-known methods such as welding, bonding, or fusion.

[0028] As shown in Figures 1 and 2, the tank 10 comprises a tank body 11 having a hollow section inside, and a plurality of brackets 20 protruding laterally from the tank body 11. In this embodiment, the tank body 11 is formed by joining an upwardly opening concave lower member 15 and a downwardly opening concave upper member 16 to create a hollow tank body 11 (see Figure 6). The brackets 20 are provided on the upper member 16. As shown in Figures 4 and 5, the tank 10 is detachably attached to the underside of the floor panel by fastening the brackets 20 to the vehicle member (frame F) with fastening means A such as bolts and nuts.

[0029] Furthermore, as shown in Figures 3 and 4, the tank 10 is provided with a urea water transport means (pump unit) 12 that delivers urea water using a driving force such as a motor. Reference numeral 12a in Figure 3 is the pump body 12a that constitutes the urea water transport means 12, and reference numeral 12b is a heater 12b that heats the temperature of the urea water to be delivered to an appropriate predetermined temperature. Through the action of the pump body 12a, the urea water is delivered from the discharge port 12c provided in the bottom wall of the tank body 11 to the exhaust pipe 7 side via the urea water supply pipe 36. In a plan view of the tank 10, the pump body 12a, heater 12b, and discharge port 12c are surrounded by an arc-shaped first liquid reservoir wall 13a rising from the bottom wall of the tank body 11, and a second liquid reservoir wall 13b projecting laterally from the first liquid reservoir wall 13a. The urea solution is guided to the central pump body 12a through an arc-shaped passage formed between the first liquid reservoir wall 13a and the second liquid reservoir wall 13b, etc.

[0030] A cover (not shown) is attached to the lower part of the tank body 11 as a protective member, so as to cover part or all of the urea water transport means 12 and the tank body 11. Preferably, the cover has a certain degree of heat insulation to protect the tank 10 from impact and to prevent excessive temperature rise of the urea water.

[0031] As shown in Figure 2, a urea solution injection pipe 31, a leveling pipe 32, and a vent pipe 33 are connected to the top of the tank 10. The urea solution injection pipe 31 is drawn out from an inlet 31c provided at the front end of the connection part 11a of the tank 10 and serves as a passage to guide urea solution, which has been replenished from the outside through the inlet 31b of the urea solution filler 31a provided at some location on the vehicle 1, into the tank body 11. The leveling pipe 32 is a passage that releases air inside the tank 10 to the urea solution filler 31a side when urea solution is replenished. The vent pipe 33 is a passage that releases gas inside the tank 10 to the atmosphere when the pressure inside the tank 10 increases. An atmospheric release valve is provided in the middle of the vent pipe 33 to open and close the passage. The atmospheric release valve is opened when the internal pressure of the tank 10 exceeds a set pressure. In Figure 2, reference numeral 34 indicates a signal cable 34 and reference numeral 35 indicates a power cable 35.

[0032] As shown in Figures 2 and 3, the tank body 11 is enclosed on all four sides in a plan view by an outer wall 14a facing the side member 2, an arc-shaped inner wall 14b facing the spare tire 6, a front wall 14c that closes the front side of the vehicle 1, and a rear wall 14d that closes the rear side of the vehicle 1. The tank body 11 also includes an expanded section 11c where the urea water transport means (pump section) 12 is located, that is, where the pump section 12 that sends urea water toward the exhaust pipe 7 is located, and connecting sections 11a and 11b that extend from the expanded section 11c toward the front side of the vehicle 1 to the urea water inlet 31c from the outside. The expanded section 11c is wider in the vehicle width direction than the connecting sections 11a and 11b, and constitutes a large space that can accommodate the urea water transport means (pump section) 12. Furthermore, the extension section 11c is formed towards the rear of the tank 10 to facilitate the flow of urea solution when the vehicle 1 is tilted on an uphill slope. In addition, to secure this large space, the extension section 11c utilizes a large space behind the center O of the spare tire 6, which is circular in plan view (see Figure 1). The center O of the spare tire 6 is the center position of the wheel of the spare tire 6.

[0033] The structure for fixing the tank 10 to the vehicle 1 will be described.

[0034] As described above, the vehicle 1 comprises a pair of side members 2,2 extending along the front-rear direction and a cross member 4 connecting the side members 2,2 in the vehicle width direction. The tank 10 is supported by one of the side members 2 to the side of the spare tire 6 and is also supported by the cross member 4 connecting the two side members 2,2 via an auxiliary frame 50. As shown in Figure 4, the cross member 4 mainly consists of a vehicle width direction member 40 that connects the side members 2,2, and the auxiliary frame 50 is fixed to this vehicle width direction member 40. The auxiliary frame 50 functions as an auxiliary bracket that supports the tank 10.

[0035] As shown in Figures 7, 8A, and 8B, the auxiliary frame 50 has a first auxiliary frame 51 that protrudes forward from the vehicle width direction member 40 and a second auxiliary frame 52 that protrudes rearward from the vehicle width direction member 40. The tank 10 also has mounting parts for fixing to the vehicle 1, including a first mounting part 21 fixed to the first auxiliary frame 51, a second mounting part 22 fixed to the second auxiliary frame 52, and a third mounting part 23 fixed to the side member 2 (see Figures 2, 4, and 6). The first mounting part 21, the second mounting part 22, and the third mounting part 23 are integrally formed with the tank body 11. The tank 10 is fixed with the first mounting part 21 to the first auxiliary frame 51, the second mounting part 22 to the second auxiliary frame 52, and the third mounting part 23 to either side of the side member 2 (in this embodiment, the left side member 2 in the vehicle width direction). As a result, the tank 10 is supported below the cross member 4.

[0036] Hereinafter, the fixing point between the first auxiliary frame 51 and the first mounting portion 21 will be referred to as the first fixing point, the fixing point between the second auxiliary frame 52 and the second mounting portion 22 will be referred to as the second fixing point, and the fixing point between the side member 2 and the third mounting portion 23 will be referred to as the third fixing point. At each of the first, second, and third fixing points, the tank 10 is fixed to the vehicle body frame F (corresponding to the first auxiliary frame 51, the second auxiliary frame 52, and the side member 2) by well-known fixing means such as bolts and nuts, as shown in Figure 4. Here, the first fixing point, second fixing point, and third fixing point refer to the respective mounting portions of the first mounting portion 21, the second mounting portion 22, and the third mounting portion 23, the portion of the frame F that is in contact with each mounting portion, and the portion where the fixing means such as bolts and nuts are located. Figure 5 shows an example of the fixing structure at each fixing point. In this embodiment, the frame F corresponds to the fixing member 51c (see Figures 9 and 10A) in the first auxiliary frame 51, the fixing member 52c (see Figures 9, 10A, and 10B) in the second auxiliary frame 52, and the fixing member 2c (see Figure 9) in the side member 2.

[0037] In Figure 5, the upper side of the figure represents the upper side of vehicle 1, and the lower side of the figure represents the lower side of vehicle 1. Holes 21a, 22a, and 23a are formed in the first mounting portion 21, the second mounting portion 22, and the third mounting portion 23, respectively. The lower part of holes 21a, 22a, and 23a is a slightly larger diameter counterbore into which the heads b of bolts 41a, 42a, and 43a used as fixing means A fit, and the upper part of holes 21a, 22a, and 23a is a slightly smaller diameter through hole B into which the shafts a of bolts 41a, 42a, and 43a used as fixing means A fit. The bracket 20 is placed against the lower surface of frame F, and the shafts a of bolts 41a, 42a, and 43a are inserted from bottom to top. At this time, annular collars G and C are interposed between the inner surface of the through hole B and the shafts a of the bolts 41a, 42a, and 43a, and between the inner surface of the hole in the frame F and the shafts a of the bolts 41a, 42a, and 43a, respectively. The tank 10 is fixed to the vehicle 1 by screwing nuts E onto the shafts a of the bolts 41a, 42a, and 43a from the upper side of the frame F and tightening them. Since the tank 10 is detachable from the lower part of the vehicle 1 via the fixing means A, work such as replacing the tank is easy.

[0038] As shown in Figures 7, 8A, and 8B, the rear end of the first auxiliary frame 51 and the front end of the second auxiliary frame 52 are connected in the front-rear direction by a connecting portion 53, with the cross member 4 in between.

[0039] The interposition of the connecting portion 53 prevents the first auxiliary frame 51 and the second auxiliary frame 52 from being pulled away (lifting up) from the cross member 4. In other words, by constructing the first auxiliary frame 51, which protrudes forward, and the second auxiliary frame 52, which protrudes backward, as a single integrated member, when the load of the tank 10 is applied, the front and rear members receive a tensile force in the direction away from each other, a so-called tug-of-war situation, allowing the tank 10 to be supported in a balanced manner. This avoids the need to enlarge the members, resulting in a compact and simple member configuration. Furthermore, the interposition of the connecting portion 53 improves the rigidity, strength, and durability of the entire auxiliary frame 50, including the first auxiliary frame 51 and the second auxiliary frame 52.

[0040] Furthermore, by constructing the first auxiliary frame 51 and the second auxiliary frame 52 as a single integrated component, the load from the tank 10 acts on the auxiliary frame 50 in a state that is close to equilibrium between the front and rear. This reduces the load on the joints (welded parts) to the vehicle width direction members 40, which tend to be weak points from a durability standpoint. As a result, members such as "braces" that support the cantilevered first auxiliary frame 51 and the second auxiliary frame 52 from below in an oblique direction can be miniaturized or omitted, enabling weight reduction of the components and cost reduction.

[0041] In this embodiment, the vehicle width direction member 40 is a hollow member with a rectangular cross-section, consisting of an upper surface member and a lower surface member that are parallel to each other, a front surface member that connects them vertically at the front, and a rear surface member that connects them vertically at the rear. The auxiliary frame 50 is fixed to the vehicle width direction member 40 by welding to the minimum necessary extent. As described above, by constructing the first auxiliary frame 51 and the second auxiliary frame 52 as a single unit, it is possible to reduce the number of welding points and welding areas compared to conventional designs.

[0042] Specifically, the auxiliary frame 50 is provided with contact members 51a and 52a at the rear end of the first auxiliary frame 51 and the front end of the second auxiliary frame 52, respectively, which abut against the front and rear members of the vehicle width direction member 40. The contact members 51a and 52a are plate-shaped members that protrude from each side (the surface facing the vehicle width direction) of the first auxiliary frame 51 and the second auxiliary frame 52 toward both sides in the vehicle width direction. These contact members 51a and 52a are fixed to the front and rear members of the vehicle width direction member 40 by welding. Reference numerals 51b and 52b shown in Figures 10A and 10B indicate fillet weld beads formed along the vertically protruding edges of the contact members 51a and 52a. The shape of the beads 51b and 52b is more preferably a V-shape, where the distance between them widens as they extend downwards, as shown in Figures 10A and 10B. Furthermore, the type of welding is optional, and spot welding or other methods may be used instead of fillet welding.

[0043] Furthermore, if necessary, the connecting portion 53 may be fixed to the upper surface member of the vehicle width direction member 40 using spot welding, fillet welding, or the like. In addition, the fixing structure of the auxiliary frame 50 to the vehicle width direction member 40 may be replaced with, or in addition to, welding, other joining structures such as bolts and nuts.

[0044] In this embodiment, the connecting portion 53 is positioned to straddle the upper part of the cross member 4, so that the load of the tank 10 acting on both the front-rear and rear-facing sides of the cross member 4 can be received by the connecting portion 53 supported by the cross member 4. This reduces the load on the auxiliary bracket 50 as a whole. However, depending on the load conditions, the connecting portion 53 may be positioned to cross the lower part of the cross member 4 in the front-rear direction.

[0045] Furthermore, as shown in Figure 8A, the first auxiliary frame 51 and the second auxiliary frame 52 are set so that their maximum widths in the vehicle width direction are different from each other. In Figure 8A, the maximum width W1 of the first auxiliary frame 51 is set to be larger than the maximum width W2 of the second auxiliary frame 52. By setting a difference in rigidity between the first auxiliary frame 51 and the second auxiliary frame 52 in this way, the unsprung resonance of the vehicle 1 and the natural frequency of the tank 10 can be shifted, and damage to the members due to resonance can be prevented.

[0046] Furthermore, regarding the point of shifting the unsprung frequency resonance of the vehicle 1 and the natural frequency of the tank 10, as shown in Figure 9, the first distance L4 from the first fixing point 51c that fixes the first auxiliary frame 51 and the tank 10 to the front end of the cross member 4 and the second distance L5 from the second fixing point 52c that fixes the second auxiliary frame 52 and the tank 10 to the rear end of the cross member 4 are set to be different from each other. This makes it possible to suppress the occurrence of the aforementioned resonance even more reliably.

[0047] Furthermore, as shown in Figures 4 and 7, by arranging the first mounting portion 21 and the second mounting portion 22 at different positions relative to the vehicle width direction, the balance of the couple when lateral G (lateral sway) occurs in the tank 10 can be optimized. In other words, it is advantageous to position either the first auxiliary frame 51 corresponding to the first mounting portion 21 or the second auxiliary frame 52 corresponding to the second mounting portion 22 further outward in the vehicle width direction than the other. For example, by positioning the mounting point with greater strength (higher rigidity of the member) further outward in the vehicle width direction than the first auxiliary frame 51 or the second auxiliary frame 52, there is an advantage in that the distribution of front and rear loads is optimized. In this embodiment, the first auxiliary frame 51, which is relatively wider, is located further outward in the vehicle width direction than the second auxiliary frame 52, which is relatively narrower, meaning that the first mounting portion 21, which has relatively greater strength, is located further outward in the vehicle width direction than the second mounting portion 22.

[0048] Furthermore, by combining the above configurations, the support structure of the tank 10 can be made even more stable. Specifically, it is effective to configure either the first auxiliary frame 51 or the second auxiliary frame 52 to be positioned further outward in the vehicle width direction than the other, and to set the maximum width W1 of the member in the vehicle width direction of the one positioned further outward in the vehicle width direction (the first auxiliary frame 51 in this embodiment) to be larger than the maximum width W2 of the member in the vehicle width direction of the other (the second auxiliary frame 52 in this embodiment) (see Figure 8A).

[0049] Furthermore, as described above, it is effective to configure the first auxiliary frame 51 and the second auxiliary frame 52 to be positioned further outward in the vehicle width direction than the other, and to configure the connecting portion 53 such that the width of the member in the vehicle width direction gradually decreases from the side that is positioned further outward in the vehicle width direction (the first auxiliary frame 51 in this embodiment) to the other side (the second auxiliary frame 52 in this embodiment). In Figure 8A, the connecting portion 53 has a width W from the first auxiliary frame 51 side to the second auxiliary frame 52 side. 31 , width W 32 , width W 33 ,width 34In the order of, it gradually narrows (W 31 >W 32 >W 33 >W 34 ). By gradually changing the width of the members of the connecting portion 53 along the front-rear direction in this way, a rigidity difference in the front-rear direction is created in the members of the auxiliary bracket 50, and the occurrence of the above-mentioned resonance can be more reliably suppressed.

[0050] Also, in the configuration of FIG. 8A, the connecting portion 53 includes a first portion 53a that extends rearward along the front-rear direction from the rear end of the first auxiliary frame 51, a second portion 53c that extends forward along the front-rear direction from the front end of the second auxiliary frame 52, and a third portion 53b that connects the rear end of the first portion 53a and the front end of the second portion 53c at the shortest distance and is inclined with respect to the front-rear direction. The aforementioned width W 31 corresponds to the width of the members of the first portion 53a, and the width W 34 corresponds to the width of the members of the second portion 53c. Also, the width W 32 corresponds to the width of the members of the end portion on the first auxiliary frame 51 side of the third portion 53b, and the width 33 corresponds to the width of the members of the end portion on the second auxiliary frame 52 side of the third portion 53b. In the third portion 53b, the width of the members gradually decreases from the first auxiliary frame 51 side toward the second auxiliary frame 52 side (W 32 >W 33 ). Here, the width W 31 and the width W 32 , or the width W 33 and the width 34 may be set equal.

[0051] Here, in the embodiment, as shown in FIG. 4, the first fixing point that fixes the first auxiliary frame 51 and the tank 10 is arranged between the second fixing point that fixes the second auxiliary frame 52 and the tank 10 and the third fixing point that fixes the side member 2 and the tank 10 in the vehicle width direction. That is, the triangle formed by connecting the three fixing points of the first fixing point, the second fixing point, and the third fixing point is an acute triangle in which all three interior angles are less than 90 degrees. Thereby, more stable support of the tank 10 is enabled.

[0052] Furthermore, the extension 11c of the tank 10 is wider and heavier than the connecting parts 11a and 11b. For this reason, the front of the tank 10 is supported at one point called the first fixing point, while the rear of the tank 10 is supported at two points, the second fixing point and the third fixing point. In this case, if the second fixing point and the third fixing point are positioned at the same location in the front-rear direction, the stable support of the tank 10 will be further improved. In Figure 4, the bolt 42a of the second fixing point and the bolt 43a of the third fixing point are slightly offset in the front-rear direction, but further stabilization of the support can be expected by perfectly aligning their positions.

[0053] However, in Figure 4, the ranges of the second mounting portion 21 and the third mounting portion 22 overlap in the front-rear direction. That is, the ranges of the second fixing point and the third fixing point overlap in the front-rear direction. Therefore, almost the same effect can be expected as when bolts 42a and 43a are positioned at exactly the same location in the front-rear direction.

[0054] In the above embodiment, the configuration of this invention was described using urea solution as the additive for purifying exhaust gas and a urea solution tank for storing the urea solution as an example. However, this invention can also be applied to tanks for storing additives other than urea solution. Examples of additives other than urea solution include aqueous ammonia solution. [Explanation of Symbols]

[0055] 1 vehicle 2 Side Members 4 Cross Members 10 tanks 20 brackets 21 First bracket 22 Second Bracket 23 Third bracket 40 Vehicle width direction member 50 Auxiliary Frames 51. First auxiliary frame 52 Second Auxiliary Frame 53 Connection part

Claims

1. A pair of side members extending along the front-to-rear direction of the vehicle, A cross member connecting the pair of side members, A tank in which additives for purifying exhaust gases are stored, Equipped with, The tank is supported by being fixed to a first auxiliary frame that protrudes forward from the cross member and a second auxiliary frame that protrudes backward. A tank support structure in which the rear end of the first auxiliary frame and the front end of the second auxiliary frame are connected in the front-rear direction with the cross member in between by a connecting portion.

2. The tank support structure according to claim 1, wherein the connecting portion is arranged along the upper surface of the cross member.

3. The tank support structure according to claim 1, wherein the first auxiliary frame and the second auxiliary frame are set to have different widths in the width direction of the vehicle.

4. The first auxiliary frame and the second auxiliary frame have a greater width in the vehicle width direction than the other. The tank support structure according to claim 3, wherein the connecting portion is set to gradually decrease in width in the vehicle width direction from one side to the other side.

5. The tank support structure according to claim 1, wherein the first distance from a first fixing point that fixes the first auxiliary frame and the tank to the front end of the cross member and the second distance from a second fixing point that fixes the second auxiliary frame and the tank to the rear end of the cross member are set to be different from each other.

6. The tank support structure according to claim 1, wherein one of the first auxiliary frame and the second auxiliary frame is positioned further outward in the width direction of the vehicle than the other.

7. The tank support structure according to claim 6, wherein the connecting portion comprises a first portion extending along the longitudinal direction of one vehicle from the other end in the longitudinal direction of the vehicle, a second portion extending along the longitudinal direction of the other vehicle from the one end in the longitudinal direction of the vehicle, and a third portion connecting the first portion and the second portion at the shortest distance and inclined with respect to the longitudinal direction of the vehicle.

8. The tank is fixed to the side member, The tank support structure according to any one of claims 1 to 7, wherein the first fixing point for fixing the first auxiliary frame and the tank is located in the width direction of the vehicle between the second fixing point for fixing the second auxiliary frame and the tank and the third fixing point for fixing the side member and the tank.

9. The tank is fixed to the side member, The first fixing point for fixing the first auxiliary frame and the tank is located in the width direction of the vehicle between the second fixing point for fixing the second auxiliary frame and the tank and the third fixing point for fixing the side member and the tank. The tank support structure according to any one of claims 1 to 7, wherein the second fixing point and the third fixing point are arranged at overlapping positions in the longitudinal direction of the vehicle.

Images