Body frame for a motorcycle

• US 5,375,677 A
• Filed: 04/30/1992
• Issued: 12/27/1994
• Est. Priority Date: 12/21/1987
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Yamagiwa, Toshio, Horiike, Takeo, Maruoka, Shigehiro, Suzuki, Keiji
• Primary Examiner(s): HILL, MITCHELL
• Application Number:
  US07/876,912
• Time in Patent Office: 971 Days
• Field of Search: 180/219, 180/215, 180/213, 180/311, 180/229, 280/281.1, 280/288.2, 280/288.3
• US Class Current: 180/219
• CPC Class Codes: B62K 11/04 characterised by the engine being between front and rear wheels
• CPC Class Codes: B62K 19/12 having cast members

Abstract

A body frame for a motorcycle including a head pipe for supporting a rotary shaft for a handle, a pair of left and right main body frame elements, connected to the head pipe and extending rearwardly of the head pipe, a pair of left and right engine supporting members, connected to and extending downwardly from the main body frame elements adjacent to said head pipe, and a horizontally extending frame element connecting said left and right main body frame elements to each other at intermediate portions in the longitudinal direction. The engine is supported at least at a lower end portion of the left and right engine supporting members and intermediate portions in the longitudinal direction of the left and right main body frame elements and an upper end portion of a shock absorber is connected to the horizontally extending frame elements. A cast body frame is constructed of a light alloy and assembled by joining a leftward and a rightward divided block formed in shapes being vertically divided at the head pipe portion to each other. The main body frame elements are formed from a tubular member having a rectangular cross section wherein the widths of the opposite side walls are larger relative to the widths of upper and lower walls, and the widths of the side walls gradually vary from a front end portion connected to the head pipe to a rear end portion for forming at least a smaller area between the front end portion to the rear end portion.

Claims

1. A body frame for a motorcycle including a head pipe for supporting a rotary shaft for a handlebar comprising:

a main body frame element connected to said head pipe and extending rearwardly of a motorcycle body; and

a first engine supporting member connected to and extending downwardly from said main body frame element adjacent to said head pipe, an engine being supported at least at a lower end portion of said engine supporting member and at a portion of said main body frame element in the longitudinal direction thereof;

said main body frame element having a hollow sectional area with an increased sectional area adjacent to;

a first connecting portion adjacent to said first head pipe corresponding to a location where a load from a wheel is transmitted to said main body frame element and adjacent to the first engine supporting member, and

second engine supporting portions corresponding to a location where an engine is connected,

said hollow sectional area of said main body frame element is decreased in sectional area relative to the increased sectional area adjacent to said first connection portion and second engine supporting portions at intermediate portions of said main body frame element disposed between the first connecting portion and second engine supporting portions,

said first engine supporting member extending rearwardly at a predetermined acute angle relative to the longitudinal axis of said head pipe, and said main body frame including inner and outer side walls each having a height which gradually varies from said head pipe to said second engine supporting portions for forming a reduced inner and outer side wall height between the first connecting portion and said second connecting portion, and

a second connecting portion of said main body frame element adjacent at one side to the first connecting portion and on another side to said decreased sectional area and adjacent to said first engine supporting member, the second connecting portion having an increased hollow sectional area relative to the decreased sectional area.

2. A body frame for a motorcycle including a head pipe portion and a body frame portion extending rearwardly from said head pipe portion comprising:

divided frames forming said body frame portion, said divided frames being substantially symmetrical and including left and right frame members being formed independent of each other;

said head pipe portion is in an integral relationship in contact with only one of said divided frames and said divided frames are coupled together to form a unitary member.

4. The body frame according to claim 2, and further including a cross member for connecting said divided frames to each other, said cross member being positioned in an integral relationship on at least one of said divided frames.

5. The body frame according to claim 2, and further including a seat frame extending rearwardly from an intermediate upper portion of said body frame portion, a cross member operatively connected to said seat frame, a plurality of stays provided on said seat frame and a mud guard for a rear wheel formed integrally relative to each other, said left and right frame members being divided in a plane along the direction of the length of the body frame and coupled together to form a unitary member.

6. The body frame according to claim 5, and further including a seat frame extending rearwardly from an intermediate upper portion of said body frame and a mud guard for a rear wheel including left and right divided blocks along a dividing plane on a center line of said body frame and said two divided blocks being coupled together to form a unitary member.

7. The body frame according to claim 5, wherein said body frame extends obliquely downwardly and rearwardly in an inverted U-shape from said head pipe and said seat frame extends obliquely upwardly and rearwardly from an intermediate upper portion of said body frame.

3. A body frame for a motorcycle including a head pipe portion and a body frame portion extending downwardly and rearwardly in an inverted U-shape from said head pipe, said body frame portion including left and right frame members coupled to each other comprising:

said head pipe portion being in contact with only one of said left and right frame members;

a cross member formed in an integral relationship with said body frame portion;

a plurality of stays provided on said body frame; and

a dividing plane formed at a front portion of said body frame and bypassing said head pipe portion, the dividing plane being located between the left and right frame members;

said left and right frames being coupled together to form a unitary member.

8. A seat frame for a motorcycle including a front end connected to and extending rearwardly from an intermediate upper portion of a main frame of a motorcycle comprising:

a seat rail disposed on an upper portion of said seat frame;

back stays disposed on said upper portion of said seat frame and positioned adjacent a rear portion thereof;

a cross member secured to said seat rail;

mounting bosses being provided on said seat rail for securing elements thereto;

a mud guard being disposed on an underside of said seat frame for mounting adjacent to a rear wheel of said motorcycle;

said seat rail, back stays, cross member, mounting bosses and mud guard forming a seat frame member, two substantially symmetrical seat frame members being coupled together to form a unitary member.

9. The seat frame according to claim 8, wherein said mud guard forms an upwardly projecting portion in said seat frame.

10. The seat frame according to claim 9, and further including downwardly directed ribs crossing said seat frame and formed in an integral relationship forwardly of said mud guard.

11. A body frame for a motorcycle including a head pipe portion for supporting a rotary shaft for a handlebar comprising:

a main body frame element connected to said head pipe and extending rearwardly of a motorcycle body;

a first engine supporting member connected to and extending downwardly from said main body frame element adjacent to said head pipe, wherein an engine is capable of being supported at least at a lower end portion of said first engine supporting member and at a portion of said main body frame element in the longitudinal direction;

said first engine supporting member being affixed directly to said head pipe portion corresponding to a location where a load from a wheel is transmitted to said main body frame element and extending rearwardly in the direction of said main body frame and projecting downwardly therefrom at an acute angle relative to the longitudinal axis of said head pipe;

said main body frame element having a hollow sectional area with an increased sectional area adjacent to said first engine supporting member affixed to said head pipe portion and a second engine supporting portion, said hollow sectional area of said main body frame element is decreased in sectional area relative to the increased dimension adjacent to said first engine supporting member affixed to said head pipe portion and said second engine supporting portion at intermediate portions of said main body frame element disposed between the first engine supporting member and the second engine supporting portion and said main body frame including inner and outer side walls each having a height which gradually varies from said head pipe to said second engine supporting portion for forming a reduced inner and outer side wall height between the first engine supporting member to said second engine supporting member.