Electric-assist bicycle

Abstract

To provide an electric assist bicycle that can suppress stress concentration at the connection point between the main pipe and the bracket. [Solution] The electric assist bicycle 10 comprises a drive unit 38, a main pipe 16, and a bracket 14. The bracket 14 includes side plate portions 50a, 50b for clamping the drive unit 38, and a front plate portion 52 that connects the front edges of the side plate portions 50a, 50b and to which the main pipe 16 is connected. The front plate portion 52 has a protrusion 52 that projects at least forward. The connection angle C of the front plate portion 52 with respect to the side plate portions 50a, 50b is set to be greater than 90 degrees and less than 180 degrees. Preferably, the connection angle C is set to be greater than 90 degrees and less than 135 degrees, and more preferably, the connection angle C is set to be 100 degrees.

Description

Technical Field

[0001] This invention relates to an electric assist bicycle, and more particularly to an electric assist bicycle including a bracket that is connected to a main pipe and sandwiches a drive unit.

Background Art

[0002] An example of this type of prior art is disclosed in Patent Document 1. The frame for an electric bicycle disclosed in Patent Document 1 includes a bracket including a front wall portion and a down tube having an opening edge portion at one end side in the longitudinal direction. The opening edge portion of the down tube is connected to the front wall portion of the bracket so that the down tube extends from the bracket. The front wall portion has an opening provided to draw out wiring in the down tube backward, and a through portion provided separately from the opening to discharge water in the down tube. The through portion is located in a portion of the front wall portion surrounded by the opening edge portion of the down tube.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The frame for an electric bicycle disclosed in such Patent Document 1 aims to enhance the water drainage property in the down tube while suppressing a decrease in the strength of the down tube, but there is no description regarding suppressing stress concentration at the connection portion between the down tube and the bracket.

[0005] Therefore, the main object of this invention is to provide an electric assist bicycle capable of suppressing stress concentration at the connection portion between the main pipe and the bracket.

Means for Solving the Problems

[0006] To achieve the above objective, an electric assist bicycle is provided, comprising a drive unit, a main pipe, and a bracket connected to the main pipe and clamping the drive unit, wherein the bracket includes a pair of side plates for clamping the drive unit and a front plate connecting the front edges of the pair of side plates and to which the main pipe is connected, and the front plate has at least a protrusion projecting forward.

[0007] In this invention, the front plate is formed to have a convex portion, and the front plate has a shape that protrudes at least further forward than when it is formed as a flat plate. In other words, the front plate is formed to pass through a region enclosed by a virtual plane connecting the front edges of a pair of side plates and a pair of virtual extension planes that extend the pair of side plates. By forming the front plate as a convex shape instead of a flat shape in this way, it becomes more susceptible to stress, and stress can be borne at the convex portion. Therefore, when the drive unit is clamped by the pair of side plates of the bracket, the stress applied when the drive unit is fastened can also be borne at the convex portion, thus suppressing stress concentration at the connection point between the main pipe and the bracket.

[0008] Preferably, the connection angle of the front panel to the pair of side panels is set to be greater than 90 degrees and less than 180 degrees. In this case, an appropriate protrusion can be formed on the front panel.

[0009] Preferably, the connection angle is set to be greater than 90 degrees and less than 135 degrees. In this case, the protrusion can receive stress without protruding too much.

[0010] More preferably, the connection angle is set to 100 degrees. In this case, the protrusion can receive stress without protruding too much.

[0011] Preferably, the protrusion is formed in the shape of a triangular roof. In this case, the triangular roof-shaped protrusion can typically be easily formed by two flat plate-like members, and stress can be received at the ridge.

[0012] Preferably, the convex portion is formed in a circular arc shape in cross-section. In this case, the convex portion formed in a circular arc shape can receive stress over a surface area.

[0013] More preferably, the front plate portion has multiple protrusions. In this case, stress can be distributed and received at multiple protrusions, i.e., multiple locations on the front plate portion.

[0014] Preferably, the protrusion is formed on at least a portion of the front plate. In this case, the location and size of the protrusion on the front plate can be set as needed.

[0015] Preferably, the rear end of the main pipe is connected to the front plate. When the rear end of the main pipe is connected to the front plate, the stress applied when fastening the drive unit to the pair of side plates of the bracket tends to concentrate at the connection point between the rear end of the main pipe and the front plate. However, the protrusion of the front plate can bear this stress, thus effectively suppressing stress concentration at the connection point between the rear end of the main pipe and the front plate.

[0016] More preferably, at least a portion of the rear end of the main pipe is connected to the front plate. In this case, the stress applied to the portion of the rear end of the main pipe connected to the front plate can be effectively suppressed by the protrusion of the front plate.

[0017] Preferably, the shape of the protrusion is made to match the shape of the rear end of the main pipe. In this case, the rear end of the main pipe is connected to the front plate while suppressing stress concentration at the connection point between the rear end of the main pipe and the front plate. [Effects of the Invention]

[0018] According to this invention, stress concentration at the connection point between the main pipe and the bracket can be suppressed. [Brief explanation of the drawing]

[0019] [Figure 1] This is a side view showing an electric assist bicycle according to an embodiment of the present invention. [Figure 2] This is a front perspective view showing a main part of the frame. [Figure 3] This is a perspective view showing a state in which a part of the main part of the frame is disassembled. [Figure 4] This is a side view showing a main part of the frame and a drive unit. [Figure 5] This is a bottom view showing a main part of the frame. [Figure 6] This is a perspective view of a bracket and its vicinity as viewed from below. [Figure 7] This is a view showing front end portions of a pair of side plate portions and a front plate portion of the bracket as viewed from the A direction in FIG. 4. [Figure 8] This is a sectional view taken along the line B-B in FIG. 4. [Figure 9] This is a schematic view showing a modification example of the front plate portion. [Figure 10] This is a schematic view showing a modification example of the front plate portion. [Figure 11] This is a view showing a main part of another embodiment of the present invention.

Mode for Carrying Out the Invention

[0020] [[ID=A]] [[ID=B]]

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, "Fr" indicates the front, "Rr" indicates the rear, "R" indicates the right, "L" indicates the left, "U" indicates the upper, and "Lo" indicates the lower.

[0021] Referring to FIG. 1, an electric assist bicycle 10 according to an embodiment of the present invention includes a frame 12. Referring also to FIGS. 2, 4 and 5, the frame 12 includes a bracket 14, a main pipe 16 corresponding to a down tube, a seat post 18, a pair of seat stays 20, a pair of chain stays 22, a head tube 24, and a front fork 26.

[0022] A main pipe 16 extends diagonally upward and forward from the bracket 14, a seat post 18 extends upward from the bracket 14 at a slight angle to the rear, and a pair of chainstays 22 extend rearward from the bracket 14. A pair of seatstays 20 connect the upper part of the seat post 18 to the rear ends of the pair of chainstays 22. The head tube 24 is connected to the front end of the main pipe 16. The front fork 26 is rotatably inserted into the head tube 24 and is mounted at a slight angle to the rear.

[0023] Returning to Figure 1, a handle stem 28 is attached to the upper end of the front fork 26, and the handle 30 is supported by the handle stem 28. The saddle 32 is supported by the seat post 18. The front wheel 34 is rotatably supported by the lower end of the front fork 26, and the rear wheel 36 is rotatably supported by the rear ends of a pair of chainstays 22.

[0024] The drive unit 38 is held in place by the bracket 14.

[0025] A pair of crank arms 42 are attached to both ends of the crankshaft 40 of the drive unit 38. Pedals 44 are attached to the ends of each crank arm 42. A drive sprocket (not shown) that is linked to the output shaft is attached to the end of the output shaft (not shown) of the drive unit 38. The rear wheel 36 has a rear sprocket (not shown). The drive sprocket and the rear sprocket are connected by a chain (not shown).

[0026] A control unit consisting of a CPU and an inverter device (neither shown) are provided near the bracket 14, and a battery 46 is attached to the seat post 18. Based on instructions from the control unit, the inverter device converts the DC power from the battery 46 into AC power and supplies it to the motor 48 included in the drive unit 38. The motor 48 generates a driving force corresponding to the input AC power. This driving force is transmitted to the drive sprocket via a reduction mechanism (not shown) and an output shaft.

[0027] When the drive unit 38 receives pedaling force input from the pedal 44, it generates a drive assist output corresponding to the pedaling force using the motor 48 to supplement the pedaling force. The drive sprocket rotates in conjunction with the rotation of the crank arm 42 and also receives output from the motor 48. In other words, the drive unit 38 transmits the pedaling force from the pedal 44 and crank arm 42 and the output from the motor 48 to the drive sprocket. The power transmitted to the drive sprocket is then transmitted to the rear wheel 36 via the chain.

[0028] Here, we will describe in detail the configuration of bracket 14 and its vicinity.

[0029] Referring to Figure 3, the bracket 14 includes a pair of side plate portions 50a, 50b, a front plate portion 52, cross members 54, 56, and a plate-shaped portion 58.

[0030] The pair of side plates 50a and 50b are plate-shaped members for clamping the drive unit 38 and are spaced apart from each other in the vehicle width direction. The side plates 50a and 50b extend at least in the front-rear direction. In this embodiment, the side plates 50a and 50b are formed in a substantially inverted V shape when viewed from the side. The side plate 50a has a plurality (three in this embodiment) of through holes 60a, and similarly, the side plate 50b has a plurality (three in this embodiment) of through holes 60b.

[0031] Referring also to Figures 6 and 7, the front plate portion 52 includes a first piece 52a provided on the front edge of the side plate portion 50a so as to bend inward relative to the side plate portion 50a, and a second piece 52b provided on the front edge of the side plate portion 50b so as to bend inward relative to the side plate portion 50b, and is obtained by combining and connecting the first piece 52a and the second piece 52b. In this way, the front plate portion 52 is provided so as to bend inward relative to each side plate portion 50a, 50b, and connects the front edges of the pair of side plate portions 50a, 50b. In this embodiment, the front plate portion 52 is bent at a slight angle so as to form an obtuse angle rather than a right angle with respect to each side plate portion 50a, 50b. As a result, the front plate portion 52 has a convex portion 52c. The convex portion 52c protrudes at least forward, and in this embodiment, it protrudes diagonally upward and forward. In other words, the front plate portion 52 is formed so as to pass through a region S enclosed by a virtual plane F connecting the front edges of a pair of side plate portions 50a and 50b, and a pair of virtual extension surfaces E1 and E2 that extend the pair of side plate portions 50a and 50b. Furthermore, the convex portion 52c is formed to bend at the center of the width direction of the front plate portion 52. That is, the cross-sectional shape of the front plate portion 52 is formed to be convex toward the front of the vehicle at its center in the width direction. Preferably, the shape of the convex portion 52c (front plate portion 52) matches the shape of the rear end of the main pipe 16. In addition, the front plate portion 52 has an elongated through-hole 52d for passing wiring (not shown).

[0032] In this embodiment, the side plate portion 50a and the first piece 52a are formed integrally beforehand and consist of a sheet metal member 62a. Similarly, the side plate portion 50b and the second piece 52b are formed integrally beforehand and consist of a sheet metal member 62b. The sheet metal members 62a and 62b are connected to each other. The sheet metal members 62a and 62b are joined to each other, for example, by welding. That is, the first piece 52a and the second piece 52b are joined to each other, for example, by welding.

[0033] Both cross members 54 and 56 are formed in a hollow cylindrical shape. Cross member 54 extends in the vehicle width direction and connects the approximate center portions of the side plate portions 50a and 50b. Cross member 54 and side plate portions 50a and 50b are joined, for example, by welding. Cross member 56 extends in the vehicle width direction and connects the rear ends of the side plate portions 50a and 50b. Cross member 56 and side plate portions 50a and 50b are joined, for example, by welding.

[0034] The plate-like portion 58 is formed in a roughly rectangular shape and is provided so as to span across the pair of side plate portions 50a, 50b in the region enclosed by the pair of side plate portions 50a, 50b and the cross members 54, 56. The plate-like portion 58 and the side plate portions 50a, 50b are joined together, for example, by welding.

[0035] Multiple fastening members (three in this embodiment) are attached to such a bracket 14 to connect the side plate portions 50a and 50b. Each fastening member includes, for example, a bolt and a nut, and is inserted through the corresponding through holes 60a and 60b to attach to the side plate portions 50a and 50b. The drive unit 38 is supported by these fastening members and is also held between the pair of side plate portions 50a and 50b (see Figure 4). In this embodiment, the drive unit 38 is suspended from the bracket 14 via the three fastening members. Therefore, the bracket 14 can be called a suspension bracket.

[0036] Furthermore, the rear end of the main pipe 16 is connected to the bracket 14. The bracket 14 and the main pipe 16 are joined together, for example, by welding.

[0037] Referring also to Figure 8, the main pipe 16 is formed in a cylindrical shape with a rear end opening 64. This allows wiring to be passed through the main pipe 16 and pulled out to the rear. The rear end of the main pipe 16 is connected to the front plate portion 52 of the bracket 14 in contact with it. At this time, the rear end of the main pipe 16 is positioned to surround the through hole 52d. That is, the rear end opening 64 of the main pipe 16 is positioned to align with the through hole 52d, and the rear end of the main pipe 16 is covered by the front plate portion 52. The front plate portion 52 of the bracket 14 is tilted backward without extending vertically and is connected to the rear end of the main pipe 16 so as to be approximately perpendicular to the axial direction of the main pipe 16. The front plate portion 52 and the main pipe 16 are joined, for example, by welding. In this way, the main pipe 16 is connected to the front plate portion 52. Note that in Figure 8, the drive unit 38 is omitted from the illustration for the sake of simplicity.

[0038] The lower end of the seatpost 18 is connected to the crossmember 54. The crossmember 54 and the seatpost 18 are joined, for example, by welding. A reinforcing member 66 is attached so as to extend from the rear upper surface of the main pipe 16 to the lower front surface of the seatpost 18. The reinforcing member 66 and the main pipe 16 and seatpost 18 are joined, for example, by welding.

[0039] The front ends of a pair of chainstays 22 are connected to the cross member 56. The front ends of the pair of chainstays 22 are also connected to each other by a reinforcing member 68 attached to the cross member 56. The reinforcing member 68, the cross member 56, and the pair of chainstays 22 are joined together, for example, by welding.

[0040] In this electric assist bicycle 10, the front plate portion 52 is formed to have a convex portion 52c, and the front plate portion 52 has a shape that protrudes at least further forward than when it is formed as a flat plate. In other words, the front plate portion 52 is formed to pass through a region S enclosed by a virtual plane F that connects the front edges of a pair of side plate portions 50a, 50b, and a pair of virtual extension surfaces E1, E2 that extend the pair of side plate portions 50a, 50b. By forming the front plate portion 52 as a convex shape instead of a flat shape, it becomes more susceptible to stress, and stress can be received at the convex portion 52c. Therefore, when the drive unit 38 is clamped by the pair of side plate portions 50a, 50b of the bracket 14, the stress applied when fastening the drive unit 38 can also be borne by the convex portion 52c, thus suppressing stress concentration at the connection point between the main pipe 16 and the bracket 14. In particular, stress can be received at the area enclosed by P1 and P2 in Figure 5.

[0041] When the rear end of the main pipe 16 is connected to the front plate portion 52, the stress applied when fastening the drive unit 38 to the pair of side plates 50a and 50b of the bracket 14 tends to concentrate at the connection point between the rear end of the main pipe 16 and the front plate portion 52. However, since the protrusion 52c of the front plate portion 52 can bear this stress, the concentration of stress at the connection point between the rear end of the main pipe 16 and the front plate portion 52 can be effectively suppressed.

[0042] By matching the shape of the protrusion 52c to the shape of the rear end of the main pipe 16, the rear end of the main pipe 16 can be connected to the front plate portion 52 smoothly, while suppressing stress concentration at the connection point between the rear end of the main pipe 16 and the front plate portion 52.

[0043] The front panel may be formed as shown in Figure 9. Figure 9 is a schematic view from direction A in Figure 4.

[0044] The front plate portion 70 shown in Figure 9(a) has a triangular roof-shaped protrusion 70a. In this case, the triangular roof-shaped protrusion 70a can be easily formed by two flat plate members 70b and 70c, and stress can be received at the ridge portion 70d.

[0045] The front plate portion 72 shown in Figure 9(b) has a convex portion 72a with a circular arc cross-section. In this case, the convex portion 72a, which is formed with a circular arc cross-section, can receive stress over a surface area.

[0046] The front plate portion 74 shown in Figure 9(c) has a convex portion 74a with a shape obtained by dividing an oval into approximately two parts along its major axis. In this case, the convex portion 74a can receive stress over a surface area.

[0047] The front plate portion 76 shown in Figure 9(d) has two curved protrusions 76a and 76b. By having multiple protrusions 76a and 76b in the front plate portion 76, stress can be distributed and received at multiple points on the front plate portion 76, i.e., multiple points on the front plate portion 76.

[0048] The front plate portion 78 shown in Figure 9(e) has two triangular roof-shaped protrusions 78a and 78b. By having multiple protrusions 78a and 78b in this way, the front plate portion 78 can distribute and receive stress at multiple points on the front plate portion 78, i.e., multiple locations on the front plate portion 78.

[0049] The front plate portion 80 shown in Figure 9(f) has a protruding portion 80a in the center. In this case, the protruding portion of the protruding portion 80a can bear stress.

[0050] The front plate portion 82 shown in Figure 9(g) has a trapezoidal protrusion 82a. In this case, stress can be received near the upper end of the protrusion 82a.

[0051] The front plate portion 84 shown in Figure 9(h) has two triangular roof-shaped protrusions 84a and 84b, and a recess 84c whose depth reaches the space between the pair of side plate portions 50a and 50b. By having multiple protrusions 84a and 84b in the front plate portion 84, stress can be distributed and received at multiple points on the front plate portion 84, i.e., multiple points on the front plate portion 84.

[0052] As described above, the front plate portion has a protrusion that extends forward of the vehicle. Furthermore, the front plate portion is not limited to being formed in a convex shape as a whole, but may have a recess in part, or may have multiple protrusions.

[0053] Furthermore, the connection angle C of the front plate portion to the pair of side plates 50a and 50b is set to be greater than 90 degrees and less than 180 degrees (see Figures 9(a) to 9(h)). The connection angle C corresponds to the angle of the "shoulder portion" formed by the side plates 50a (50b) and the front plate portion (see Figure 9(a)). Therefore, the angle of each shoulder portion is set to be greater than 90 degrees and less than 180 degrees, i.e., obtuse. In this case, an appropriate protrusion can be formed on the front plate portion.

[0054] Preferably, the connection angle C (angle of each shoulder) of the front plate portion to the pair of side plate portions 50a, 50b is set to be greater than 90 degrees and less than 135 degrees (see Figures 9(a), 9(e), and 9(h)). In this case, stress can be received at the protrusion without the protrusion being made to protrude too much.

[0055] More preferably, the connection angle C (angle of each shoulder) of the front plate portion to the pair of side plate portions 50a, 50b is set to 100 degrees (see Figure 9(a)). In this case, the protrusions can receive stress without protruding too much.

[0056] The connection angle C of the front panel to the side panel 50a(50b) refers to the angle between the side panel 50a(50b) and the front panel. When the front panel is connected to the side panel 50a(50b) in a curved manner, a virtual extension line E of the front panel is formed, and the tangent line T of the connection between the side panel 50a(50b) and the front panel is found. The angle between the tangent line T and the side panel 50a(50b) is defined as the connection angle C (see Figures 9(b), 9(c), and 9(d)). The same applies when the side panel is connected to the front panel in a curved manner. That is, a virtual extension line of the side panel is formed, and the tangent line of the connection between the side panel and the front panel is found. The angle between this tangent line and the front panel is defined as the connection angle C.

[0057] Furthermore, the protrusions may be formed as shown in Figure 10. Figure 10 is a schematic diagram showing the upper surface of the front plate.

[0058] The front plate portion 86 shown in Figure 10(a) includes, but is not limited to, a protrusion 86a formed from the upper end to the lower end (from the rear end to the front end). As shown in Figure 10(b), a protrusion 88a may be formed in the center of the front plate portion 88, as shown in Figure 10(c), a protrusion 90a may be formed on the lower end (front end) side of the front plate portion 90, and as shown in Figure 10(d), a protrusion 92a may be formed on the upper end (rear end) side of the front plate portion 92. Thus, the protrusion only needs to be formed on at least a part of the front plate portion.

[0059] In this case, the location and size of the protrusions formed on the front panel can be set as needed.

[0060] In the above-described embodiment, the front plate portion 52 was obtained by combining and connecting a first piece 52a, which was pre-formed integrally with the side plate portion 50a, and a second piece 52b, which was pre-formed integrally with the side plate portion 50b. However, the embodiment is not limited to this. A single front plate portion may be connected to a pair of side plate portions 50a, 50b, for example, by welding.

[0061] In the above-described embodiment, the side plate portions 50a and 50b are each formed in a substantially inverted V shape in a side view, but are not limited to this. The side plate portion may be separated into a front portion and a rear portion. That is, the side plate portion may include a front portion and a rear portion as separate members. In this case, the front portion and the rear portion may be connected via a cross member 54. In this case, the pair of front portions and front plate portions may be formed integrally in a substantially U shape beforehand.

[0062] In the embodiment described above, the entire circumference (entire surface) of the rear end of the main pipe 16 is connected to the front plate portion 52, but this is not limited to that. It is sufficient if at least a portion of the rear end of the main pipe 16 is connected to the front plate portion.

[0063] For example, as shown in Figure 11, a portion of the rear end of the main pipe 16 may be connected to the front plate portion 94. In this case, the front plate portion 94 is used instead of the front plate portion 52 in the embodiment described above. The front plate portion 94 corresponds to the front plate portion 52 with approximately the lower half (front half) removed, and has a protrusion 94a. The upper rear end 64a of the main pipe 16 is connected to such a front plate portion 94, for example, by welding. In addition, a partition wall 96 extending in the axial direction is provided in the center of the inside of the main pipe 16, and the rear end of the partition wall 96 is connected to the front plate portion 94, for example, by welding. In this way, the closed end face formed by the upper rear end 64a of the main pipe 16 and the rear end of the partition wall 96 is connected to the front plate portion 94, for example, by welding.

[0064] In this case, the stress applied to the portion of the rear end of the main pipe 16 that is connected to the front plate portion 94 can be effectively suppressed by the protrusion 94a of the front plate portion 94.

[0065] In the embodiment described above, the rear end of the main pipe 16 is connected to the front plate portion 52, but the embodiment is not limited to this. The main pipe may pass through the front plate portion. In this case, the outer surface of the main pipe is connected to the front plate portion, for example, by welding.

[0066] In the above-described embodiment, the front plate portion 52 has a through hole 52d, but is not limited thereto. The front plate portion does not have to have a through hole. [Explanation of symbols]

[0067] 10 Electric-assist bicycles 12 frames 14 brackets 16 Main pipe 38 Drive Unit 46 batteries 48 Motor 50a,50b Side plate part 52,70,72,74,76,78,80,82,84,86,88,90,92,94 Front plate part 52c,70a,72a,74a,76a,76b,78a,78b,80a,82a,84a,84b,86a,88a,90a,92a,94a Convex part 64a Upper part of the rear end of the main pipe C connection angle

Claims

1. Drive unit and Main pipe and It comprises a bracket connected to the main pipe and clamping the drive unit, The aforementioned bracket is A pair of side plates for clamping the aforementioned drive unit, It includes a front plate portion that connects the front edges of the pair of side plate portions and to which the main pipe is connected, The front plate portion has at least a protrusion that projects forward, in the electric assist bicycle.

2. The electric assist bicycle according to claim 1, wherein the connection angle of the front plate portion to the pair of side plates portion is set to be greater than 90 degrees and less than 180 degrees.

3. The electric assist bicycle according to claim 2, wherein the connection angle is set to be greater than 90 degrees and less than 135 degrees.

4. The electric assist bicycle according to claim 3, wherein the connection angle is set to 100 degrees.

5. The electric assist bicycle according to claim 1, wherein the convex portion is formed in the shape of a triangular roof.

6. The electric assist bicycle according to claim 1, wherein the convex portion is formed in the shape of a circular arc in cross-section.

7. The electric assist bicycle according to claim 1, wherein the front plate portion has a plurality of the aforementioned protrusions.

8. The electric assist bicycle according to claim 1, wherein the protrusion is formed on at least a part of the front plate portion.

9. The electric assist bicycle according to claim 1, wherein the rear end of the main pipe is connected to the front plate portion.

10. The electric assist bicycle according to claim 9, wherein at least a portion of the rear end of the main pipe is connected to the front plate portion.

11. The electric assist bicycle according to claim 9, wherein the shape of the protrusion matches the shape of the rear end of the main pipe.

Images