JP2003307245A - Spring force regulating structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable not only the regulation of a given spring force but also the reduction of a part cost, and the reduction of the number of processes to reduce a manufacturing cost. <P>SOLUTION: A cap 11 to close the upper end opening of a tube 2 on a car body side is formed in a shape of a bottomed cylinder and set in a pump housing and contained in the pump housing and a piston 12 to partition a subair chamber A1 communicating with an air chamber A in the tube 2 on the car body side contained in the pump housing is moved forward and backward as it is rotated to widen and narrow the subair chamber A1. The tip of an output rod 13 protruded from the lower end of the piston 12 is brought into contact with a spring seat 14, locking the upper end of a suspension spring S, in the tube 2 on the car body side as it is extended through the bottom 11a of the cap 11 and situated facing the air chamber A in the tube 2 on the car body side. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spring force adjusting structure, and more particularly to an improvement of a spring force adjusting structure capable of adjusting a spring force for urging a front fork in an extension direction.

[0002]

2. Description of the Related Art A front fork mounted on the front wheel side of a two-wheeled vehicle and absorbing road surface vibrations input to the front wheel is capable of adjusting the spring force for urging the front fork in the extension direction. It is preferably set, so
There are several proposals in the past.

Among them, for example, JP-A-56-430.
In the proposal disclosed in Japanese Patent Publication No. 75, as shown in FIG. 3, the operation rod D screwed to the upper end of the vehicle body side tube 2 forming the front fork is rotated to be housed in the vehicle body side tube 2. The upper end of the suspension spring S mounted is moved up and down.

That is, in the above proposal, the free piston F is slidably accommodated in the upper end side of the vehicle body side tube 2, and the free piston F locks the upper end of the suspension spring S and the above-mentioned structure. It is assumed that the turning operation of the operating rod D raises and lowers the inside of the vehicle body side tube 2 in the axial direction.

Therefore, according to the above-mentioned proposal, the spring force of the suspension spring S can be adjusted by raising and lowering the free piston F, and the air chamber A below the free piston F and having the oil surface O as a boundary is provided. Since it is almost defined, the volume in the air chamber A can be widened and narrowed, and therefore, the air spring force can also be adjusted in height.

However, in the above proposal, the spring force can be adjusted by raising and lowering the free piston F which is slidably accommodated on the upper end side in the vehicle body side tube 2. In order to smoothly move up and down the free piston F and to avoid damage to a seal (not shown) provided on the outer circumference of the free piston F, the inner circumference of the vehicle body side tube 2 is slid. It is necessary to finish the moving surface.

Therefore, in the above proposal, in the manufacture of the front fork, the free piston F with a seal as a component is required, and the sliding surface on the inner circumference of the vehicle body side tube 2 at the time of processing. There is a problem that finishing is indispensable and the manufacturing cost cannot be reduced accordingly.

The present invention was devised in view of the above-mentioned circumstances, and it is an object of the present invention to realize a predetermined spring force adjustment, reduction of parts cost, and man-hours for processing. The purpose of the present invention is to provide a spring force adjusting structure which is suitable for expecting an improvement in versatility of a front fork by enabling reduction in manufacturing cost by reducing

[0009]

In order to achieve the above object, the structure of the spring force adjusting structure according to the present invention is basically arranged such that the vehicle body side tube is inserted into and retractable from the axle side tube. A guide pipe is erected on the axial center of the side tube, and a suspension spring is arranged between the upper end of this guide pipe and the upper end of the vehicle body side tube to keep the oil level inside the vehicle body side tube communicating with the inside of the guide pipe. In the front fork that defines the air chamber that serves as a boundary, a cap that closes the upper end opening of the vehicle body side tube is formed in a cylindrical shape with a bottom and set in the pump housing, and is also housed in this pump housing. The piston that defines the sub air chamber that communicates with the air chamber in the vehicle body side tube moves forward and backward while rotating in the pump housing to widen and narrow the sub air chamber, and to project at the lower end of the piston. That the output rod and made by contacting the spring receiver for locking the upper end of the suspension spring while the congregation to the air chamber in the body-side tube through the bottom of the cap tip in the vehicle body side tube.

Therefore, by advancing and retracting the piston in the pump housing, the air in the sub air chamber is supplied to the air chamber in the vehicle body side tube, or the air in the air chamber is sucked into the sub air chamber, and the air spring force in the air chamber is increased. The height of the spring can be adjusted, and the spring force of the suspension spring can be adjusted by raising and lowering the spring retainer that locks the upper end of the suspension spring in the tube on the vehicle body side by advancing and retracting the output rod by advancing and retracting the piston.

At this time, when the spring receiver is formed of a plate-shaped member, the occupied volume can be reduced and the weight of parts can be reduced as compared with the case where the spring receiver is formed of a free piston with a seal. Therefore, the cost of parts can be reduced.

In the above structure, more specifically, it is assumed that the output rod projecting from the lower end of the piston has a thread on the outer circumference and the output rod is screwed to the bottom of the pump housing. .

Therefore, it is not necessary to set a portion for screwing the output rod to a portion other than the pump housing, and even in the pump housing, a screw thread matching the screw thread of the output rod is airtight. It suffices if it is formed without the need for consideration.

The stop ring fitted on the tip of the output rod is locked to the bottom of the pump housing to prevent the piston from coming out of the pump housing, or in the vicinity of the opening end of the pump housing. It is assumed that the piston is prevented from coming out of the pump housing by being locked with the stop ring fitted to the inner circumference of the piston.

Therefore, it is possible to provide a stopper mechanism having a predetermined function without causing an increase in the number of mischievous parts and an increase in the number of processing steps.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the illustrated embodiments. The front fork in which the spring force adjusting structure according to the present invention is embodied is basically the same as that shown in FIG. It has the same structure as the front fork in which the conventional spring force adjusting structure shown in FIG.

To explain briefly, this front fork is inserted in the axle side tube 1 so that the lower end side of the vehicle body side tube 2 can be retracted and retracted in a liquid tight state, and the axle 1 of the axle side tube 1 extends from the bottom 1a of the axle side tube 1. The guide pipe 3 is erected on the core, and the upper end head portion 3a of the guide pipe 3
A suspension spring S is disposed between the vehicle body side tube 2 and the upper end side of the vehicle body side tube 2, and an air chamber A having an oil level O as a boundary is defined in a reservoir chamber R in the vehicle body side tube 2 communicating with the inside of the guide pipe 3. It is supposed to be done.

By the way, in this front fork, the piston 4 at the lower end of the vehicle body side tube 2 is in sliding contact with the outer periphery of the guide pipe 3, and the extension side oil chamber R1 and the pressure side oil chamber R2 are provided on the outer peripheral side of the guide pipe 3. Will be defined.

In this front fork, the extension side oil chamber R1 communicates with the inside of the guide pipe 3 through the orifice 3b opened near the upper end of the guide pipe 3, and the pressure side oil chamber R2 is guided. The inside of the guide pipe 3 is communicated with via a communication hole (not shown) opened at the lower end of the pipe 3.

On the other hand, in the spring force adjusting structure according to the present invention, as shown in FIG. 1, a cap 11 for closing the upper end opening of the vehicle body side tube 2 by screwing is formed in a cylindrical shape with a bottom. Set on the pump housing,
A piston 12, which is housed in the pump housing and defines a sub air chamber A1 that communicates with the air chamber A in the vehicle body side tube 2 through a communication hole 11a that is opened in the pump housing, rotates inside the pump housing. It is assumed that the sub air chamber A1 is widened and narrowed by moving forward and backward while moving.

Therefore, by moving the piston 12 back and forth in the pump housing, the air in the sub air chamber A1 is supplied to the air chamber A in the vehicle body side tube 2, or the air in the air chamber A is sucked into the sub air chamber A1. As a result, the height of the air spring force in the air chamber A can be adjusted.

In the spring force adjusting structure according to the present invention, the output rod 13 projecting from the lower end of the piston 12 penetrates the tip of the output rod 13 through the bottom portion 11b of the cap 11 formed to have a relatively large thickness. It is assumed that the spring support 14 that locks the upper end of the suspension spring S in the vehicle body side tube 2 is brought into contact with the air chamber A in the side tube 2 while being brought into contact therewith.

At this time, as shown in the drawing, the output rod 13 has a thread 13a on the outer periphery thereof, and the output rod 13 is provided at the bottom 11 of the pump housing.
It is supposed to be screwed to b.

Therefore, it is not necessary to set a portion for screwing the output rod 13 to a portion other than the pump housing, and even in the pump housing, a screw thread matching the screw thread 13a of the output rod 13. That is, it is sufficient to form the thread 11c on the bottom portion 11b of the pump housing without considering the airtightness.

By the way, in the above output rod 13, the stop ring 15 fitted to the tip end is locked to the bottom portion 11b of the pump housing to prevent the piston 12 from coming out of the pump housing. I am trying.

Therefore, in the case of the stopper mechanism using the stop ring 15, it is possible to expect the predetermined stopper function to be exhibited without causing an increase in the number of mischievous parts and an increase in the number of processing steps.

From the above, in the spring force adjusting structure according to the present invention, the output rod 13 advances and retracts as the piston 12 moves back and forth in the pump housing, and as a result, the spring bearing that locks the upper end of the suspension spring S is received. 14 is the body side tube 2
By going up and down inside, the spring force of the suspension spring S can be adjusted in height.

At this time, the spring receiver 14 is made up of a plate-shaped body in the drawing, and therefore the spring receiver 14 is provided with a seal as in the case disclosed in the above-mentioned publication. Compared with the case of the free piston F (see FIG. 3), the volume occupied by the spring bearing 14 can be reduced, the weight of parts can be reduced, and
It is possible to reduce the cost of parts.

In particular, since the spring bearing 14 is formed to be so-called thin, the lifting stroke of the spring bearing 14 can be set large correspondingly, and therefore, the spring force can be adjusted freely. There are advantages.

In FIG. 2, it is assumed that the stop ring 15 is fitted on the inner periphery of the pump housing near the open end, and the rear end of the piston 12 is locked to the stop ring 15. Thus, the piston 12 is prevented from coming out of the pump housing.

Therefore, in the case of the embodiment shown in FIG. 1 described above, since the stop ring 15 is present in the so-called oil atmosphere, it can be formed of a material that does not require consideration of rust prevention. In the case of the embodiment shown in FIG. 2, on the other hand, the bottom 11b of the pump housing and the spring bearing 14 are retained when the piston 12 is finally retracted.
It is possible to prevent the gap from appearing between the spring and the spring, which is advantageous in that the lifting stroke of the spring receiver 14 can be set to a large extent.

By the way, even in the embodiment shown in FIG. 2, the same operation as that of the embodiment shown in FIG.

While the cap 11 is set so that the upper end thereof is exposed to the atmosphere in the above description, as shown in phantom diagrams in FIG. 1 and FIG. Of course, the cap 16 may be detachably attached.

[0034]

As described above, according to the first aspect of the present invention, the output rod advances and retracts due to the advance and retreat of the piston in the pump housing, and therefore the spring retainer for locking the upper end of the suspension spring is the tube on the vehicle body side. As a result, the spring force of the suspension spring can be adjusted up and down.

At this time, since the spring receiver is made of a plate-like member, the volume occupied by the spring receiver can be made smaller and the parts can be made smaller than in the case where the spring receiver is made of, for example, a free piston with a seal. It is possible to reduce the weight and the cost of parts.

In particular, since the spring bearing is formed so-called thinly, the lifting stroke of the spring bearing can be set large correspondingly, so that there is an advantage that the spring force can be adjusted freely. is there.

Further, in the invention of claim 2, it is not necessary to set a portion for screwing the output rod projectingly provided on the lower end of the piston to a portion other than the pump housing, and the pump housing is provided. Even if there is, it suffices to form a screw thread that matches the screw thread of the output rod in the bottom portion of the pump housing without considering the airtightness.

Further, in the inventions of claims 3 and 4, it is possible to provide a stopper mechanism which exerts a predetermined function without causing an increase in the number of mischievous parts and an increase in the number of processing steps. Become.

In this case, according to the third aspect of the invention, since the stop ring is present in the so-called oil atmosphere, it is advantageous in that it can be formed of a material that does not consider rust prevention.

Further, according to the invention of claim 4, it is possible to prevent a gap from appearing between the bottom portion of the pump housing and the spring bearing when the piston is finally retracted. This is advantageous in that the lifting stroke of the spring receiver can be set to a large value.

As a result, according to the present invention, not only the predetermined spring force adjustment can be realized, but also the manufacturing cost can be reduced by reducing the parts cost and the processing man-hours, and It is ideal for expecting improvement in versatility.

[Brief description of drawings]

FIG. 1 is a partial vertical sectional view showing an embodiment of a spring force adjusting structure according to the present invention.

FIG. 2 is a view showing another embodiment of the spring force adjusting structure according to the present invention, similar to FIG.

FIG. 3 is a schematic vertical sectional view showing a front fork embodying a conventional spring force adjusting structure.

[Explanation of symbols]

1 axle side tube 1a bottom 2 Body side tube 3 Guide pipe 3a Top head part 3b orifice 4,12 piston 11 cap 11a communication hole 11b bottom 11c, 13a thread 13 Output rod 14 Spring receiver 15 Stoppling 16 rubber cap A air chamber A1 sub air chamber R reservoir chamber R1 Extension side oil chamber R2 pressure side oil chamber S suspension spring

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Claims (4)

[Claims] 1. A vehicle body-side tube is inserted into and retractable from an axle-side tube, a guide pipe is erected at an axial center of the axle-side tube, and a guide pipe is provided between the upper end of the guide pipe and the upper end of the vehicle-body-side tube. In the front fork, where a suspension spring is distributed and an air chamber that defines the oil surface is defined in the vehicle body side tube that communicates with the inside of the guide pipe, a cap that closes the upper end opening of the vehicle body side tube has a bottom. While being formed in a tubular shape and set in the pump housing, a piston that is housed in the pump housing and that defines a sub air chamber that communicates with the air chamber in the vehicle body side tube is rotated in the pump housing. Move back and forth to widen the sub air chamber,
An output rod projecting from the lower end of the piston penetrates the bottom of the cap so that the output rod is exposed to the air chamber in the tube on the vehicle body side, and is brought into contact with a spring receiver that locks the upper end of the suspension spring in the tube on the vehicle body side. Spring force adjustment structure characterized by 2. The spring force adjusting structure according to claim 1, wherein the output rod projecting from the lower end of the piston has a thread on the outer periphery, and the output rod is screwed into the bottom portion of the pump housing. 3. The spring force adjustment according to claim 1, wherein the stop ring fitted to the tip of the output rod is locked to the bottom of the pump housing to prevent the piston from coming out of the pump housing. Construction 4. The spring according to claim 1, wherein the piston is prevented from coming out of the pump housing by locking the piston to a stop ring fitted around the inner periphery of the pump housing near the opening end. Force adjustment structure