JPH0774021B2 - Frame for vehicles such as motorcycles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a frame used in a vehicle such as a motorcycle.

[Prior art]

In this type of frame, the connecting portion between the steering head pipe and the main pipe extending from the steering head pipe toward the pivotal support portion of the rear arm is required to have sufficient strength and rigidity. From this, conventionally, the main pipe is formed into a flat rectangular tube whose cross-sectional shape is vertically long in the vertical direction,
It is known that the front end portion connected to the steering head pipe is formed in a large hollow box shape thicker than the rear side.

[Problems to be solved by the invention]

However, in order to enhance the dynamic performance of the vehicle, it is important to reduce the weight of the frame as well as the rigidity, and in the conventional frame described above, in terms of achieving both weight reduction and high rigidity. There was room for improvement.

The present invention has been made under such circumstances, and it is possible to reduce the weight while sufficiently securing the rigidity and strength around the steering head pipe, and moreover, despite the fact that a hole is formed in the steering head pipe. First, the purpose of the present invention is to provide a vehicle frame such as a motorcycle that can prevent water and dust from entering the inside of the steering head pipe and the main pipe and prevent corrosion from the inside of the steering head pipe and the main pipe. And

[Means for solving problems]

To achieve the above object, the present invention provides a steering head pipe that pivotally supports a front fork, and a pair of left and right main pipes that are butt-welded to the peripheral surface of the steering head pipe and extend rearward of the steering head pipe. The main pipes have a hollow rectangular tube shape that is vertically long in the axial direction of the steering head pipe, and the longitudinal dimension of at least the front end portion of the main pipes connected to the steering head pipe is set to the steering head pipe. It is premised on a vehicle frame, such as a motorcycle, which is formed to have an axial length substantially equal to that of the vehicle.

Then, a plurality of reinforcing plates connected to the steering head pipe are welded across the front end portion of the main pipe, and these reinforcing plates cooperate with the main pipe to form a hollow box-shaped part connected to the steering head pipe. Along with the formation of the steering head pipe, the steering head pipe passes through the center of the steering head pipe, and is located on both left and right sides of the center line of the vehicle body extending in the front-rear direction, within the range of the box-shaped portion. A plurality of lightening holes to be opened are formed, and these lightening holes are formed at positions such that a continuous portion extending over the entire length of the steering head pipe is left behind on the rear surface of the steering head pipe intersecting with the vehicle body center line. It is characterized by being arranged.

[Action]

According to this configuration, the lightening hole formed in the steering head pipe is not located at the welded joint portion between the main pipe and the steering head pipe, and the joint area and weld length of both are equal to those of the past. Can be secured.

Moreover, the lightening holes are distributed to the left and right sides of the center line of the vehicle body passing through the center of the steering head pipe, and a continuous portion over the entire length is left on the rear surface of the steering head pipe located between these lightening holes. Since the continuous portion functions as a kind of backbone because it is arranged in a position, even when a longitudinal load is applied to compress the steering head pipe in the axial direction through the front fork during braking, for example, the continuous portion is Will counter the vertical load.

Therefore, it is possible to remove the useless meat of the steering head pipe as much as possible while sufficiently ensuring the rigidity and strength of the connecting portion between the steering head pipe and the main pipe, and the weight of the frame can be reduced accordingly.

Further, according to the above configuration, the lightening hole is covered from the outside by the main pipe and the reinforcing plate, so that foreign matters such as water and dust are inside the steering head pipe, the main pipe and the box portion through the lightening hole. Intrusion can be prevented in advance.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings applied to a motorcycle.

In the figure, reference numeral 1 is a frame made of aluminum alloy, and a front fork 3 is pivotally supported on a steering head pipe 2 (hereinafter referred to as a head pipe) vertically installed at the front end thereof. A main frame structure 4 extending rearward is connected to the head pipe 2, and the main frame structure 4 of the present embodiment has a side view between the head pipe 2 and a bracket 6 pivotally supporting the rear arm 5. It has a pair of left and right main pipes 7, 7 that are connected in a substantially straight line. As shown in FIG. 3, the main pipes 7, 7 are made by abutting and welding a pair of frame materials 7a, 7b having a U-shaped cross section from the left and right directions. It is formed in a flat rectangular tube shape that is vertically long in the direction. And
The longitudinal dimension of the front end portions of the main pipes 7, 7 is formed to be substantially equal to the axial length of the head pipe 2, and the front end opening portions of the main pipes 7, 7 are butted against the peripheral surface of the head pipe 2. .

On the peripheral surface of the head pipe 2, guide walls 8,8 for guiding the abutting position of the main pipes 7,7 are provided so as to project along the axial direction. The guide walls 8,8 are the main pipes 7,8. It is introduced into the front end opening of 7 and is superposed on the inner surface of the outer part thereof. The main pipes 7, 7 are fixed by continuously welding the range from the outer edge of the front end opening to the upper and lower edges to the peripheral surface of the head pipe 2. Immediately after the head pipe 2, it is expanded in the left-right direction and extends rearward.

An upper reinforcing plate 9 and a lower reinforcing plate 10 each having a substantially triangular shape are overlapped and welded to the upper and lower surfaces of the front ends of the main pipes 7, 7. The upper and lower reinforcing plates 9 and 10 straddle between the front end portions of the main pipes 7 and 7, and their front edge portions are butt-welded to the peripheral surface of the head pipe 2. A rear reinforcing plate 11 is welded between the rear edge portions of the upper and lower reinforcing plates 9 and 10. The left and right edges of the rear reinforcing plate 11 are connected to the main pipe 7,
It is welded to the inner surface of 7.

Therefore, the front end portion of the main frame structure 4 has the main pipes 7,7 and the upper and lower and rear reinforcing plates 9,10,11.
It is assembled into a hollow box shape by this box shape part
The front end of 12 is connected to the head pipe 2.

By the way, on the peripheral surface of the head pipe 2, a vehicle body center line passing through the center of the head pipe 2 and extending in the front-rear direction.
Located on the left and right sides of X ₁ -X ₁ , for example, 3 lightening holes 13
Are bored at intervals in the axial direction. These lightening holes 13 are made by machining after the head pipe 2 is cast and formed, and are opened within a range surrounded by the hollow box-shaped portion 12. That is, the lightening holes 13 ... Are provided at positions outside the welded joints of the main pipes 7, 7 and the upper and lower reinforcing plates 9, 10 and the head pipe 2, and approximately half of them are provided in the main pipes 7, 7. In addition to being opened inside, the other half is opened in the space portion surrounded by the inner side surfaces of the main pipes 7, 7 and the upper and lower and rear reinforcing plates 9, 10, 11. Then, as shown in FIG.
Since lightening holes 13 ... are disposed distributedly to the left and right sides of the vehicle body center line X ₁ -X _1, the rear surface of the head pipe 2 crossing the vehicle body center line X ₁ -X _1, the head pipe 2 Is formed with a continuous portion 2a extending linearly over the entire length of the.
The continuous portion 2a faces the internal space of the box-shaped portion 12.

In addition, left and right down tubes 14 are installed between the front end lower surface of the main pipes 7, 7 and the bracket 6, and an engine 15 is mounted between the down tubes 14 and the main pipes 7, 7. There is.

According to such a configuration, the lightening holes 13 formed in the peripheral surface of the head pipe 2 are opened within the range surrounded by the left and right main pipes 7, 7 and the upper and lower reinforcing plates 9, 10. The lightening holes 13 ... Are not located on the welded joint between the main frame structure 4 and the head pipe 2,
It is possible to secure the joint area and welding length of both of them as in the past.

Further, the lightening holes 13 ... Are distributed to the left and right sides of the vehicle body center line X ₁ -X ₁ passing through the center of the head pipe 2, and are formed on the rear surface of the head pipe intersecting the vehicle body center line X ₁ -X _1. Since the continuous portion 2a is arranged at such a position as to leave the continuous portion 2a over the entire length, the continuous portion 2a functions as a kind of backbone. Therefore, for example, even when a vertical load for axially compressing the head pipe 2 is applied through the front fork 3 during braking, the continuous portion 2a opposes the vertical load.

Therefore, not only the rigidity of the head pipe 2, but also the rigidity and strength of the continuous portion of the head pipe 2 and the main pipes 7, 7 can be sufficiently ensured, and useless meat of the head pipe 2 can be removed. Accordingly, the weight of the frame 1 can be reduced.

Further, according to the above configuration, the lightening holes 13 ... Are opened within the range of the box-shaped portion 12 which is continuous with the head pipe 2, and are opened outward by the main pipes 7, 7 and the upper and lower and rear reinforcing plates 9, 10, 11. Since it is hidden from the head pipe 2, the main pipes 7, 7 and the box-shaped portion 12 through these lightening holes 13 ...
It is possible to prevent foreign matter such as water and dust from entering the interior of the. Therefore, the frame 1 is less likely to be corroded from the inside, and the durability of the frame 1 is improved.

In the embodiment described above, the range from the outer edge of the main pipe to the upper and lower edges is welded to the head pipe, but in some cases, the inner edge of the main pipe is also the wall surface portion between the lightening holes of the head pipe. May be welded to.

Further, the frame according to the present invention is not limited to motorcycles, and can be similarly implemented even in a motorcycle having two rear wheels.

〔The invention's effect〕

According to the present invention described in detail above, since the lightening hole is out of the welded portion of the steering head pipe, the main pipe and the reinforcing plate, the joint area and welding length of these can be sufficiently secured. Moreover, the lightening holes are distributed to the left and right sides of the vehicle body center line that passes through the center of the steering head pipe, and the rear surface of the steering head pipe that intersects the vehicle body center line is left at a position where a continuous portion over the entire length is left. Being arranged, this continuous part functions as a kind of backbone. Therefore, even when a vertical load that axially compresses the steering head pipe is applied through the front fork while the vehicle is traveling, the continuous portion opposes the vertical load.
Therefore, not only the rigidity of the steering head pipe but also the rigidity and strength of the continuous portion of the steering head pipe and the main pipe can be sufficiently ensured, and unnecessary meat of the steering head pipe can be removed. The frame can be made lighter.

Further, since the lightening holes do not have to be directly exposed to the outside of the frame, it is possible to prevent foreign matters such as water and dust from entering the inside of the steering head pipe, the main pipe, and the box-shaped portion through these lightening holes. . Therefore, there is an advantage that the frame is less likely to be corroded from the inside and the durability of the frame is improved.

[Brief description of drawings]

The drawings show one embodiment of the present invention. Fig. 1 is a sectional view of a connecting portion between a steering head pipe and a main frame structure, Fig. 2 is a plan view of the same, and Fig. 3 is III- in Fig. 2.
A sectional view taken along line III, FIG. 4 is a sectional view taken along line IV-IV in FIG. 2, FIG. 5 is a side view of a steering head pipe, and FIG. 6 is a side view of a motorcycle. 2 ... Steering head pipe, 2a ... Continuous part, 3 ...
… Front fork, 7… Main pipe, 9,10,11…
… Reinforcement plate (upper reinforcement plate, lower reinforcement plate, rear reinforcement plate), 12 …… box-shaped part, 13 …… lightening hole.

Claims (1)

[Claims] 1. A steering head pipe that pivotally supports a front fork, and a pair of left and right main pipes that are butt-welded to a peripheral surface of the steering head pipe and extend rearward of the steering head pipe. Is a hollow prismatic shape that is vertically long in the axial direction of the steering head pipe, and at least the longitudinal dimension of the front end portion of the main pipes that is continuous with the steering head pipe is approximately equal to the axial length of the steering head pipe. In a vehicle frame such as a motorcycle formed in the above, a plurality of reinforcing plates connected to the steering head pipe are welded across the front end portion of the main pipe, and these reinforcing plates cooperate with the main pipe to Hollow connecting to the steering head pipe While forming a box-shaped portion, on the peripheral surface of the steering head pipe, located on the left and right sides of the vehicle body center line passing through the center of the steering head pipe and extending in the front-rear direction, Forming a plurality of lightening holes that open within the range, these lightening holes leave a continuous portion that extends over the entire length of the steering head pipe on the rear surface of the steering head pipe that intersects the vehicle body center line. A frame for a vehicle such as a motorcycle, which is arranged in various positions.