Bicycle frame structure and motorized bicycle

Abstract

To enhance variability of a setting position of a seat on which a driver sits in a cross direction and load bearing performance of a frame that supports the seat.SOLUTION: This bicycle frame structure is configured such that a reverse Z-shaped frame part 300 of a reverse Z shape in a side view is constituted by a first frame part 301 extending roughly horizontally rearward, a second frame part 302 extending inclinedly upward from the rear end of the first frame part 301 to the front, and a third frame part 303 which extends roughly horizontally from the upper end of the second frame part 302 to the rear and on which a seat 17 is placed, a bridge tube 9 is hung near the intermediate part of the second frame part 302 in a longitudinal direction on a pair of reverse Z-shaped frame parts 300 and 300 spaced apart in a width direction, and the bridge tube 9 is supported by a rear tube 10 inclined upward toward the rear.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a bicycle frame structure and a motorized bicycle. [Background technology]

[0002] A conventional bicycle frame structure is that of Patent Document 1. The frame structure of Patent Document 1 has a head pipe to which an operating handle is attached, two down tubes extending diagonally downward and rearward from the head pipe, and a seat tube extending diagonally upward and rearward from the rear end of the down tube, with a saddle attached to the upper end of the seat tube by inserting a seat post into the seat tube. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-149389 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in the frame structure of Patent Document 1, the saddle on which the rider sits needs to be set on the extension line of the seat tube in order to suppress the load on the joint between the saddle and the seat post. Therefore, the adjustment range of the seat on which the rider sits in the fore-aft direction is very limited, resulting in a structure with low variability in the setting position of the seat on which the rider sits.

[0005] The present invention has been proposed in consideration of the above-mentioned problems, and aims to provide a bicycle frame structure that can increase the variability of the fore-and-aft setting position of the seat on which the rider sits, as well as increase the load-bearing capacity of the frame that supports the seat, and a moped having this bicycle frame structure. [Means for solving the problem]

[0006] The bicycle frame structure of the present invention is characterized in that an inverted Z-shaped frame portion having an inverted Z shape in side view is composed of a first frame portion extending approximately horizontally toward the rear, a second frame portion extending from the rear end of the first frame portion at an upward incline toward the front, and a third frame portion extending approximately horizontally from the upper end of the second frame portion toward the rear and on which a seat is placed, the inverted Z-shaped frame portions being provided in a pair on the left and right with a gap in the width direction, a bridge tube being installed between the left and right inverted Z-shaped frame portions near the longitudinal middle of the second frame portion, and the bridge tube being supported by a rear tube that inclines upward toward the rear. According to this, since the third frame portion on which the seat is placed extends substantially horizontally, it is possible to adjust the seat placement position in the front-rear direction relative to the third frame portion, and the variability of the setting position in the front-rear direction of the seat on which the driver sits can be increased. In addition, by installing a bridge tube between the left and right inverted Z-shaped frame portions and supporting the bridge tube with a rear tube that is inclined upward toward the rear, the load-bearing capacity of the frame supporting the seat can be increased. Furthermore, it is possible to obtain cushioning properties for the seat placed on the third frame portion, and to obtain a comfortable sitting experience for the driver.

[0007] The bicycle frame structure of the present invention is characterized in that the third frame portion is composed of front and rear tubular portions of the seat rail which are formed in an approximately C-shape when viewed from above, and a horizontal tubular portion of the top bridge to whose end the front end of the seat rail is fixed, and a seat support tube is installed between the horizontal tubular portions of the left and right top bridges. According to this, by forming the seat rail into an approximately C-shape when viewed from above and installing a seat support tube between the horizontal cylindrical portions of the left and right top bridges, it is possible to reliably prevent the left and right third frame portions from tipping inward due to the weight of a driver sitting in a seat placed on the third frame portion.

[0008] The bicycle frame structure of the present invention is characterized in that another seat support tube is installed between the front and rear tubular portions of the left and right seat rails. According to this, by installing another seat support tube between the front and rear tubular portions of the left and right seat rails, it is possible to more reliably prevent the left and right third frame portions from collapsing inward due to the weight of a driver sitting in a seat placed on the third frame portion.

[0009] The bicycle frame structure of the present invention is characterized in that the length of the third frame section in the front-to-rear direction is set to 300 mm to 400 mm. This ensures a sufficient adjustment distance in the front-rear direction for the position of the seat placed on the third frame portion, and ensures that the seat position can be adjusted so that drivers of various sizes can sit in a stable position. In addition, by setting the length of the third frame portion in the front-rear direction to within 400 mm, it is possible to more reliably ensure that the third frame portion is maintained in a substantially horizontally extended state.

[0010] The motor-driven bicycle of the present invention is characterized in that it has a bicycle frame structure in which an inverted Z-shaped frame portion having an inverted Z shape in side view is composed of a first frame portion extending approximately horizontally toward the rear, a second frame portion extending from the rear end of the first frame portion at an upward incline toward the front, and a third frame portion extending approximately horizontally from the upper end of the second frame portion toward the rear and on which a seat is placed, the inverted Z-shaped frame portions being provided in a pair on the left and right with a gap in the width direction, a bridge tube being installed between the left and right inverted Z-shaped frame portions near the longitudinal middle portion of the second frame portion, and the bridge tube being supported by a rear tube inclined upward toward the rear. According to this, since the third frame portion on which the seat is placed extends substantially horizontally, it is possible to adjust the seat placement position in the front-rear direction relative to the third frame portion, and the variability of the setting position in the front-rear direction of the seat on which the driver sits can be increased. In addition, by installing a bridge tube between the left and right inverted Z-shaped frame portions and supporting the bridge tube with a rear tube that is inclined upward toward the rear, the load-bearing capacity of the frame supporting the seat can be increased. Furthermore, it is possible to obtain cushioning properties for the seat placed on the third frame portion, and to obtain a comfortable sitting experience for the driver. Effect of the Invention

[0011] According to the present invention, it is possible to increase the variability of the setting position in the fore-aft direction of the seat in which the driver sits, and to increase the load-bearing capacity of the frame supporting the seat. [Brief description of the drawings]

[0012] [Figure 1] 1 is a side view of a motorized bicycle equipped with a bicycle frame structure according to an embodiment of the present invention; [Diagram 2] 1 is a side view of a main part of a bicycle frame structure according to an embodiment; [Diagram 3] 1 is a plan view of a main portion of a bicycle frame structure according to an embodiment; [Figure 4] 2 is an enlarged front view of a main portion of the bicycle frame structure according to the embodiment; [Diagram 5] FIG. 2 is an enlarged rear view of a main portion of the bicycle frame structure according to the embodiment. [Figure 6] Enlarged cross-sectional view taken along line AA in Figure 3. [Figure 7] 5A to 5C are explanatory diagrams illustrating a welded portion between a down tube and a rear stay in a bicycle frame structure according to an embodiment. [Figure 8] 2 is an enlarged side view of the periphery of an inverted Z-shaped frame portion in the bicycle frame structure according to the embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Embodiment of bicycle frame structure and motorized bicycle] 1 to 6, the bicycle frame structure for the motorized bicycle 1 includes a head pipe 2, a down tube 3 formed of a single tube and extending obliquely downward from the head pipe 2, a pair of left and right rear stays 4,4 fixed to the rear end of the down tube 3, a bottom bridge 5 that is substantially cylindrical and V-shaped in side view and fixed by welding or the like to the rear ends of the rear stays 4, a pair of left and right cylindrical seat stays 6,6 that are fixed by welding or the like to the upper ends of the bottom bridges 5 and extend obliquely upward toward the front, a top bridge 7 that is cylindrical and V-shaped in side view and fixed by welding or the like to the upper ends of the seat stays 6, and a cylindrical seat rail 8 that is fixed by welding or the like to the rear ends of the parts of the top bridges 7 that extend rearward. Each frame that constitutes the bicycle frame structure of this embodiment is preferably made of, for example, stainless steel, aluminum alloy, aluminum, carbon, steel, etc.

[0014] The down tube 3 is a cylindrical single frame made up of a downward extension portion 31 extending obliquely downward from the head pipe 2, a curved portion 32 formed at the lower end of the downward extension portion 31, and a horizontal portion 33 extending approximately horizontally rearward from the curved portion 32, and the upper end portion of the downward extension portion 31 is fixed to the head pipe 2 by welding or the like. From the viewpoint of improving manufacturing efficiency, the down tube 3 in the illustrated example is formed by combining a pair of left and right halves 34, 34 and fixing the halves 34, 34 to each other by welding or the like.

[0015] A pair of left and right rear stays 4,4 are fixed to the rear end of the horizontal portion 33 of the down tube 3. In this embodiment, the rear stay 4 is formed in a square pipe shape over its entire length, and has a front tubular portion 41 and a rear tubular portion 43 extending in the front-to-rear direction, and an inclined tubular portion 42 inclined so as to expand outward toward the rear, with the inclined tubular portion 42 formed from the rear end of the front tubular portion 41 via a bent portion, and the rear tubular portion 43 formed from the rear end of the inclined tubular portion 42 via a bent portion. The pair of left and right rear stays 4,4 are provided so as to expand rearward in a Y shape in a plan view, and are fixed by welding to the rear end of the horizontal portion 33 of the down tube 3 (see FIG. 7).

[0016] The square pipe-shaped front tubular portions 41, 41 of the pair of left and right rear stays 4, 4 are formed in a rectangular cross section, and the rear end of the horizontal portion 33 of the down tube 3 is also formed in a rectangular cross section. The front tubular portions 41, 41 of each rear stay are overlapped in the left-right direction, and are welded to each other at a weld seam W1 at the front ends of the contact surfaces of the front tubular portions 41, 41, and in this state are fitted inside the rear end of the horizontal portion 33 of the down tube 33. The front tubular portions 41, 41 of the pair of left and right rear stays 4, 4, which are overlapped and fitted inside the rear end of the down tube 3, are welded to the rear end of the down tube 3, and are welded all around the entire circumference of the rear end of the down tube 3 at a weld seam W2 (see FIG. 7).

[0017] One end of a bottom bridge 5, which is V-shaped in side view and substantially cylindrical, is fixed by welding or the like to the rear end of a rear tubular portion 43 extending substantially horizontally toward the rear of the rear stay 4, and the lower end of a seat stay 6 is fixed by welding or the like to the other end of the bottom bridge 5, so that the rear tubular portions 43 of the left and right rear stays 4 and the seat stays 6 are connected by the bottom bridge 5, which is V-shaped in side view. The straight seat stays 6 extend obliquely upward toward the front. The inclination angle of the seat stays 6 with respect to the horizontal is preferably, for example, 50° to 60°.

[0018] One end of a cylindrical top bridge 7, which is V-shaped in side view, is fixed to the upper end of the seat stay 6 by welding or the like, and a front end of a seat rail 8 is fixed to an end of a horizontal cylinder portion 71, which is the other end of the top bridge 7, by welding or the like, so that the left and right seat stays 6 and the seat rail 8 are connected by the top bridge 7, which is V-shaped in side view. In this embodiment, the seat rail 8 is formed in a substantially U-shape in plan view, and one end of the seat rail 8 is fixed to the other end of the left top bridge 7 by welding or the like, and the other end of the seat rail 8 is fixed to the other end of the right top bridge 7 by welding or the like. A seat 17, which is substantially L-shaped in side view, is attached to the upper side of the seat rail 8 so as to be placed thereon.

[0019] The rear tubular portion 43 extending substantially horizontally toward the rear of the rear stays 4 connected via the bottom bridge 5 and top bridge 7, the seat stays 6, and the seat rails 8 form an inverted Z-shaped frame in side view, which is provided to protrude to the left and right. A bridge tube 9 is installed between the left seat stay 6 and the right seat stay 6 near the longitudinal middle of the seat stays 6, and both ends of the bridge tube 9 are fixed to the left seat stay 6 and the right seat stay 6, respectively, by welding or the like.

[0020] That is, in the bicycle frame structure of this embodiment, as shown in Fig. 8, an inverted Z-shaped frame portion 300 having an inverted Z shape in a side view is made up of a first frame portion 301 extending rearward substantially horizontally, a second frame portion 302 extending forward from the rear end of the first frame portion 301 at an inclination upward, and a third frame portion 303 extending rearward substantially horizontally from the upper end of the second frame portion 302 and on which the seat 17 is placed and attached, and a pair of left and right inverted Z-shaped frame portions 300 are provided with a gap in the width direction. The bridge tube 9 is fixed between the left and right inverted Z-shaped frame portions 300, 300 near the longitudinal middle of the second frame portion 302 (see Figs. 3 to 5 and 8).

[0021] In this embodiment, the first frame portion 301 is composed of the rear stay 4 and the horizontal tube portion 51 of the bottom bridge 5, which extends substantially horizontally, the second frame portion 302 is composed of the inclined tube portion 52, which extends obliquely upward toward the front of the bottom bridge 5, the seat stay 6, and the inclined tube portion 72, which extends obliquely downward toward the rear of the top bridge 7, and the third frame portion 303 is composed of the horizontal tube portion 71 of the top bridge 7, which extends substantially horizontally, and the front and rear tube portions 81 of the seat rail 8, which is formed in a substantially U-shape in plan view, which extend substantially horizontally. The length L of the third frame portion 303 in the front-rear direction is preferably set to 300 mm to 400 mm, and more preferably set to 350 mm to 400 mm (see FIG. 8).

[0022] Between the horizontal portion 33 of the down tube 3 and the bridge tube 9, there is provided a rear tube 10 which extends at an incline upward toward the rear, and the lower end of the rear tube 10 is fixed to the horizontal portion 33 of the down tube 3 by welding or the like, and the upper end of the rear tube 10 is fixed to the bridge tube 9 near the midpoint of the bridge tube 9 by welding or the like. In other words, the bridge tube 9 is supported by the rear tube 10. In the illustrated example, the bridge tube 9 is provided so as to penetrate the rear tube 10, and the rear tube 10 and the bridge tube 9 are fixed by welding. The inclination angle of the rear tube 10 with respect to the horizontal is preferably, for example, 50° to 60°.

[0023] Furthermore, the position where the bridge tube 9 is provided and the position where the rear tube 10 is fixed to the bridge tube 9 should be, for example, 250 to 300 mm high from the lowest end of the down tube 3, and the height of the top surface of the seat rail 8 should be 150 to 200 mm from the position where the rear tube 10 is fixed to the bridge tube 9, which is preferable from the standpoint of improving the strength of the bicycle frame structure and ensuring a good rider posture. Furthermore, by providing the position where the bridge tube 9 is provided and the position where the rear tube 10 is fixed to the bridge tube 9 near the longitudinal middle part of the seat stay 6 or near the longitudinal middle part of the second frame part 302, cushioning properties can be obtained for the seat rail 8 and the seat 17, and a comfortable seating experience for the rider 100 can be obtained.

[0024] A cylindrical seat support tube 11 is installed between the horizontal cylinder portions 71, 71 extending approximately horizontally in the front-to-rear direction of the left and right top bridges 7, 7, and both ends of the seat support tube 11 are fixed by welding or the like to the horizontal cylinder portions 71, 71 of the left and right top bridges 7, 7. In addition, another cylindrical seat support tube 12 is installed between the front and rear cylinder portions 81, 81 extending approximately horizontally in the front-to-rear direction of the seat rails 8, near the midpoint of the front and rear cylinder portions 81, and both ends of the seat support tube 12 are fixed by welding or the like to the left and right front and rear cylinder portions 81, 81.

[0025] That is, in this embodiment, two seat support tubes 11, 12 are installed, and in addition to the installed portion between the inverted Z-shaped frame portions 300 / 300 of the seat rail 8, the shape of the inverted Z-shaped frame portions 300 / 300 arranged with a gap in the width direction is maintained by the seat support tube 11 installed between the inverted Z-shaped frame portions 300 / 300 and another seat support tube 12.

[0026] A cylindrical handle post 13 is provided above the head pipe 2 and is fixed to the head pipe 2 by fitting, welding or the like, and a cylindrical operating handle 14 is provided at the upper end of the handle post 13. That is, the operating handle 14 is attached to the head pipe 2 via the handle post 13. An operating unit 15 is provided at the grip portion at the tip of the operating handle 14, with which the rider 100 operates the motorized bicycle 1 to drive, stop, decelerate, accelerate, etc. A front fork 16 is provided below the head pipe 2 and is fixed to the head pipe 2 by fitting, welding or the like, and a front wheel 20 is rotatably supported at the lower end of the front fork 16.

[0027] A rear wheel 21 is rotatably supported at a bent portion of the bottom bridge 5, and a motor device 18 is provided to control and operate the rear wheel 21, such as by driving, stopping, decelerating, and accelerating. The motor device 18 and the operating unit 15 are connected by a connection wire that is routed through the inside of the operating handle 14, the handle post 13, the head pipe 2, the down tube 3, and the rear stay 4 (not shown).

[0028] Foot rest portions 22, 22 that locally protrude to the left and right are attached to the down tube 3 in the range from the bent portion 32 to the front of the rear end of the horizontal portion 33, and in the illustrated example, the foot rest portions 22, 22 that locally protrude to the left and right are attached to the horizontal portion 33 near the bent portion 32. Each foot rest portion 22 is composed of a locking rod 221 that is inserted into a through hole in the down tube 3 and fixed by welding or the like around the periphery of the through hole, an upper foot rest half 222 that is provided above the locking rod 221 and engages with and is fixed to the locking rod 221, a lower foot rest half 223 that is provided below the locking rod 221 and engages with the upper foot rest half 222 and is fixed to the upper foot rest half 222 by bolting or the like, and a foot rest plate 224 that is placed on the upper side of the upper foot rest half 222 and fixed.

[0029] Furthermore, the left and right footrests 22·22 are each positioned within a range from within 20% of the length of the wheelbase H on the front side of the midpoint M to within 20% of the length of the wheelbase H on the rear side of the midpoint M, based on the midpoint M of the line segment connecting the front wheel axle 201 of the front wheel 20 and the rear wheel axle 211 of the rear wheel 21, and are positioned within the footrest placement setting area R in Figure 2.

[0030] According to this embodiment, since the third frame portion 303 on which the seat 17 is placed extends substantially horizontally, it is possible to adjust the position of the seat 17 in the front-rear direction relative to the third frame portion 303, and the variability of the setting position of the seat 17 in the front-rear direction on which the driver 100 sits can be increased. In addition, by installing a bridge tube 9 between the left and right inverted Z-shaped frame portions 300 and supporting the bridge tube 9 with the rear tube 10 inclined upward toward the rear, the load-bearing capacity of the frame supporting the seat 17 can be increased. Furthermore, cushioning of the seat 17 placed on the third frame portion 303 can be obtained, and a comfortable sitting experience for the driver 100 can be obtained.

[0031] Also, by forming the seat rails 8 into a generally U-shape in plan view and installing a seat support tube 11 between the horizontal cylinder portions 71 of the left and right top bridges 7, it is possible to reliably prevent the left and right third frame portions 303 from tipping inward due to the weight of the driver 100 sitting in the seat 17 placed on the third frame portion 303. Furthermore, by installing another seat support tube 12 between the front and rear cylinder portions 81 of the left and right seat rails 8, it is possible to more reliably prevent the left and right third frame portions 300 from tipping inward due to the weight of the driver 100 sitting in the seat 17 placed on the third frame portion 303.

[0032] Furthermore, by setting the fore-aft length L of the third frame portion 303 preferably to 300 mm to 400 mm, and more preferably to 350 mm to 400 mm, a sufficient adjustment distance in the fore-aft direction for the position of the seat 17 placed on the third frame portion 303 can be secured, thereby ensuring that the seat position can be adjusted reliably so that drivers 100 of various sizes can be seated in a stable posture, and also ensuring more reliably that the third frame portion 303 is maintained in an approximately horizontally extended state.

[0033] [Scope of the invention disclosed herein] The inventions disclosed in this specification include, in addition to the inventions and embodiments listed as inventions, those specified by changing partial contents of these to other contents disclosed in this specification, those specified by adding other contents disclosed in this specification to these contents, or those specified by deleting partial contents of these to the extent that partial effects can be obtained, and specifying them as a higher-level concept. The inventions disclosed in this specification also include the following modified examples and added contents.

[0034] For example, the materials of each frame constituting the bicycle frame structure of the present invention may be any suitable material within the spirit and scope of the present invention, and it is possible to use, for example, carbon, etc. Also, in the above embodiment, the pair of left and right halves 34, 34 are made of metal and fixed to each other by welding or the like to form the down tube 3, but the down tube 3 may also be formed by bending a metal tube, for example. Also, the bicycle frame structure of the present invention is suitable for use in a motorized bicycle that travels at a low speed of 20 km / h or less, but can be used for any suitable motorized bicycle or bicycle. [Industrial Applicability]

[0035] The present invention can be used as a motorized bicycle that travels at low speeds and as a bicycle frame structure. [Explanation of symbols]

[0036] 1...motorcycle 2...head pipe 3...down tube 31...downward extension 32...curved portion 33...horizontal portion 34...half body 4...rear stay 41...front tube portion 42...inclined tube portion 43...rear tube portion 5...bottom bridge 51...horizontal tube portion 52...inclined tube portion 6...seat stay 7...top bridge 71...horizontal tube portion 72...inclined tube portion 8...seat rail 81...front and rear tube portions 9...bridge tube 10...rear tube 11, 12...seat support tube 13...handle post 14...operating handle 15...operating portion 16...front fork 17...seat 18...motor device 20...front wheel 201...front wheel axle 21...rear wheel 211...rear wheel axle 22...foot rest portion 221...retaining bar 222...upper foot rest half body 223...lower foot rest half body 224: Foot rest 100: Driver 300: Inverted Z-shaped frame section 301: First frame section 302: Second frame section 303: Third frame section W1, W2: Welded section M: Midpoint of line segment connecting front and rear axles H: Wheelbase R: Foot rest placement setting area L: Front-rear length of third frame section

Claims

1. a first frame portion extending rearward substantially horizontally, a second frame portion extending forward from a rear end of the first frame portion at an upward incline, and a third frame portion extending rearward substantially horizontally from an upper end of the second frame portion and on which a seat is placed, forming an inverted Z-shaped frame portion having an inverted Z shape in a side view; The inverted Z-shaped frame portions are provided in a pair on the left and right sides with a gap in the width direction, a bridge tube is provided between the left and right inverted Z-shaped frame portions near a longitudinal intermediate portion of the second frame portion; A bicycle frame structure, characterized in that the bridge tube is supported by a rear tube that slopes upward toward the rear.

2. The third frame portion is composed of front and rear tubular portions of a seat rail formed in a generally U-shape in a plan view, and a horizontal tubular portion of a top bridge to which a front end of the seat rail is fixed, 2. The bicycle frame structure according to claim 1, wherein a seat support tube is disposed between said horizontal cylinder portions of said left and right top bridges.

3. 3. The bicycle frame structure according to claim 2, wherein another seat support tube is installed between the front and rear tubular portions of the left and right seat rails.

4. 4. A bicycle frame structure as claimed in claim 1, wherein the third frame portion has a length in the front-rear direction set to 300 mm to 400 mm.

5. a first frame portion extending rearward substantially horizontally, a second frame portion extending forward from a rear end of the first frame portion at an upward incline, and a third frame portion extending rearward substantially horizontally from an upper end of the second frame portion and on which a seat is placed, forming an inverted Z-shaped frame portion having an inverted Z shape in a side view; The inverted Z-shaped frame portions are provided in a pair on the left and right sides with a gap in the width direction, a bridge tube is provided between the left and right inverted Z-shaped frame portions near a longitudinal intermediate portion of the second frame portion; A motorized bicycle comprising a bicycle frame structure in which the bridge tube is supported by a rear tube that is inclined upward toward the rear.

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