JP2012116283A - Connecting structure of steering shaft in front fork bracket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connecting structure of a steering shaft in a front fork bracket which can be sealed at low cost, and can improve the ride quality of a saddle riding vehicle.SOLUTION: This invention is configured so as to connect the front fork bracket 2 to a steering shaft 3 by fitting the lower end of the steering shaft 3 rotatably inserted in the interior of a head pipe 4 through ball bearings 5, 6 into a shaft through-hole 2b formed in a center boss 2a in the middle of the front fork bracket 2 for supporting front forks F, F. In the steering shaft connecting structure of the front fork bracket 2, an annular spacer 8 is provided between the ball bearing 6 and the center boss 2a. A dust seal 9 is provided on the outer periphery of the annular spacer 8 between the ball bearing 6 and the center boss 2a so as to slidably contact with the inner periphery of the head pipe 4.

Description

  The present invention relates to an improvement in a steering shaft connecting structure of a front fork bracket.

  Conventionally, as a steering shaft coupling structure of a front fork bracket, for example, the straddle vehicle is provided in a shaft insertion hole provided in a center boss of a front fork bracket that holds a front fork that supports a front wheel of the saddle vehicle. A connecting structure is known in which a lower end of a steering shaft that is rotatably inserted through a ball bearing is fitted into a head pipe that is connected to the vehicle body, and a front fork bracket is connected to the steering shaft (for example, , See Patent Document 1).

  However, in this connection structure, the gap between the head pipe and the steering shaft is not sealed, so dust or the like may enter the head pipe from the gap. When the dust enters the head pipe in this way, the sand is caught between the ball bearing ball and the inner ring or the outer ring, and the surface of the ball, inner ring and outer ring can be damaged, and resistance to the operation of the ball bearing is reduced. May occur, which may hinder smooth operation of the steering wheel.

JP 2008-290510 A

  Therefore, a notch or a recess is provided on the outer periphery of the center boss of the front fork bracket, a dust seal is attached to the center boss, and the dust seal seals between the head pipe and the front fork bracket so that dust in the head pipe can be obtained. It is also conceivable to prevent the sand intrusion of the ball bearing by preventing the intrusion of the ball.

  However, when a notch or a recess is provided in the center boss, naturally, the front fork bracket needs to be processed such as cutting, and the center boss dust seal mounting site must be inserted into the head pipe. Becomes longer in the axial direction, and the cost increases accordingly.

  In addition, since the boss part becomes longer in the axial direction, the fulcrum of the deflection of the steering shaft will shift upward, and the steering shaft will be difficult to bend, which makes it easier to transmit the vibration on the wheel side to the vehicle side. May be damaged.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a front fork that can be sealed at a low cost and can improve the riding comfort of a saddle-ride vehicle. It is to provide a steering shaft coupling structure of a bracket for a vehicle.

  In order to achieve the above-described object, the problem-solving means of the present invention includes a straddle vehicle in a shaft insertion hole provided in a central boss of a front fork bracket for holding a front fork that supports a front wheel of the straddle vehicle. Steering shaft coupling structure of front fork bracket for fitting the front fork bracket to the steering shaft by fitting the lower end of the steering shaft rotatably inserted through the ball bearing into the head pipe coupled to the vehicle body An annular spacer fitted on the outer periphery of the steering shaft is interposed between the ball bearing on the lower end side of the steering shaft and the center boss, and the ball bearing and the center boss on the outer periphery of the spacer. Dust seal that slidably contacts the inner circumference of the head pipe during Characterized in that it is interposed.

  According to the steering shaft coupling structure of the present invention, it is not necessary to provide a notch or a recess for attaching a dust seal to the outer periphery of the center boss of the front fork bracket, and accordingly, cutting processing to the front fork bracket is reduced accordingly. In addition, the axial length of the center boss can be shortened and the manufacturing cost can be reduced. That is, it is possible to seal between the head pipe 4 and the steering shaft at a low cost.

  In addition, since it can be sealed with a dust seal without increasing the axial length of the center boss, it is possible to prevent the deflection of the steering shaft from being displaced upward, and the steering shaft's bending rigidity is suitable for saddle riding vehicles. It is possible to improve the ride comfort in the vehicle.

It is front sectional drawing in the connection part of the bracket for front forks and the steering shaft which actualized the steering shaft connection structure of one Embodiment. It is a partially expanded side sectional view in the connecting part of the bracket for front forks and the steering shaft in which the steering shaft connecting structure of one embodiment is embodied.

  The present invention will be described below based on the embodiments shown in the drawings. As shown in FIGS. 1 and 2, the steering shaft coupling structure in one embodiment includes a front fork bracket 2 that holds a front fork F that supports a front wheel of a saddle riding vehicle (not shown), and a steering of the saddle riding vehicle. The steering shaft connecting portion 1 of the shaft 3 is embodied.

  As shown in FIG. 1, the front fork bracket 2 is provided with split cylindrical fork bosses 2d and 2e at both ends, and a pair of front forks that support the front wheels of the saddle vehicle with the fork bosses 2d and 2e. The upper ends of F and F are gripped. Further, the front fork bracket 2 includes a cylindrical center boss 2a having a shaft insertion hole 2b at the center thereof, and the lower end of the steering shaft 3 is fitted into the shaft insertion hole 2b. Further, the inner diameter of the shaft insertion hole 2b is set to such a diameter that the steering shaft 3 can be fitted without play, and the lowermost end of the shaft insertion hole 2b is expanded to form an expanded diameter portion 2c.

  On the other hand, as shown in FIGS. 1 and 2, the steering shaft 3 is rotatably inserted through ball bearings 5 and 6 in a head pipe 4 connected to a vehicle body of a saddle riding vehicle not shown. The lower end is fitted into the shaft insertion hole 2b of the front fork bracket 2 described above. That is, the upper and lower ends of the steering shaft 3 are respectively supported by the ball bearings 5 and 6 and are rotatably inserted into the head pipe 4, and further below the mounting position of the ball bearing 6 on the lower end side of the steering shaft 3. A front fork bracket 2 is fitted on the side.

  An annular groove 3a is formed at the lower end of the steering shaft 3, and a snap ring 7 is attached to the annular groove 3a. The snap ring 7 has an outer diameter that can be accommodated in the enlarged diameter portion 2c formed in the shaft insertion hole 2b of the center boss 2a. After the steering shaft 3 is fitted into the shaft insertion hole 2b, the annular groove When the snap ring 7 is attached to 3a, the snap ring 7 comes into contact with the center boss 2a of the front fork bracket 2 and the steering shaft 3 tends to come out upward from the shaft insertion hole 2b of the front fork bracket 2. It functions as a retainer that prevents this.

  In this embodiment, the enlarged diameter portion 2c is provided so that the snap ring 7 is accommodated in the enlarged diameter portion 2c, and the snap ring 7 is expanded in diameter and is likely to come off from the annular groove 3a. The inner periphery of the enlarged diameter portion 2c interferes with the snap ring 7, and the snap ring 7 is prevented from coming off from the annular groove 3a. If it is not necessary to prevent the snap ring 7 from coming off, the snap ring 7 may be brought into contact with the lower end of the center boss 2a without providing the enlarged diameter portion 2c.

  An annular spacer 8 fitted to the outer periphery of the steering shaft 3 is interposed between the ball bearing 6 fitted to the lower end side of the steering shaft 3 and the center boss 2 a of the front fork bracket 2. ing. The outer diameter of the spacer 8 is set to be smaller than the outer diameter of the lower end of the inner ring 6 a fitted to the outer periphery of the steering shaft 3 of the ball bearing 6, and smaller than the outer diameter of the upper end of the center boss 2 a of the steering shaft 2. It is set.

  Further, an annular dust seal 9 is interposed on the outer periphery of the spacer 8 between the ball bearing 6 on the lower end side and the center boss 2 a of the front fork bracket 2. The dust seal 9 includes an annular fitting portion 9a fitted to the outer periphery of the spacer 8, and an annular seal lip 9b extending from the upper end of the fitting portion 9a to the outer periphery.

  The fitting portion 9a is fitted to the outer periphery of the spacer 8, and is sandwiched between the inner ring 6a of the ball bearing 6 and the center boss 2a of the front fork bracket 2, and is positioned in the radial direction and the axial direction so as to be steered. 3 is fixed. Further, the seal lip 9b is in sliding contact with the inner periphery of the head pipe 4, and the dust seal 9 prevents entry of dust, water, etc. into the head pipe 4. As described above, the dust seal 9 is arranged on the lower end opening side of the head pipe 4 from the ball bearing 6, so that the ball bearing 6 is not exposed to dust and prevents the sand of the ball bearing 6 from being caught. is doing.

  As described above, the steering shaft coupling structure is configured. According to this steering shaft coupling structure, it is necessary to provide a notch or a recess for mounting the dust seal 9 on the outer periphery of the center boss 2a of the front fork bracket 2. Therefore, it is possible to reduce the cutting process on the front fork bracket 2 and to reduce the axial length of the center boss 2a, thereby reducing the manufacturing cost. That is, the gap between the head pipe 4 and the steering shaft 3 can be sealed at a low cost.

  Further, since the center boss 2a can be sealed with the dust seal 9 without increasing the axial length thereof, the deflection of the steering shaft 3 can be prevented from being displaced upward, and the bending rigidity of the steering shaft can be reduced. It is possible to improve the ride comfort in the vehicle.

  In the above description, the center boss 2a is set longer than the vertical length in the other part of the front fork bracket 2. However, it may be set to the same length, and one of the upper end and the lower end of the center boss 2a. Alternatively, both may be flush with other parts of the front fork bracket 2.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

The present invention can be used for a connecting portion between a steering shaft and a front fork bracket in a saddle-ride vehicle.

DESCRIPTION OF SYMBOLS 1 Steering shaft connection part 2 Front fork bracket 2a Center boss 2b Shaft insertion hole 2c Expanded diameter part 2d, 2e Fork boss 3 Steering shaft 3a Annular groove in steering shaft 4 Head pipe 5, 6 Ball bearing 6a Inner ring 7 in ball bearing Snap Ring 8 Spacer 9 Dust seal 9a Fitting portion 9b in dust seal Seal lip F in dust seal Front fork

Claims (1)

A shaft insertion hole provided in the center boss of the front fork bracket that holds the front fork that supports the front wheel of the saddle vehicle rotates through a ball bearing in the head pipe connected to the vehicle body of the saddle vehicle. In the steering shaft coupling structure of the front fork bracket, in which the lower end of the steering shaft that is freely inserted is fitted to couple the front fork bracket to the steering shaft, the ball bearing on the lower end side of the steering shaft and the center boss An annular spacer that is fitted to the outer periphery of the steering shaft is interposed, and a dust seal that is an outer periphery of the spacer and that is in sliding contact with the inner periphery of the head pipe is interposed between the ball bearing and the center boss. Front fork bracket Steering shaft coupling structure.

Images