JP4034102B2 - Front fork - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a front fork that is mounted on a front wheel side of a two-wheeled vehicle and absorbs road surface vibrations input to the front wheel.
[0002]
[Prior art]
There have been various proposals for a front fork that is mounted on the front wheel side of a motorcycle and absorbs road surface vibrations that are input to the front wheel. Among them, a set damping force is generated when the front fork is retracted. There is a proposal to ensure that.
[0003]
That is, in the front fork shown in FIG. 5, the inner tube 2 that is the axle side tube is inserted into the outer tube 1 that is the vehicle body side tube under the arrangement of the suspension spring S so that the inner tube 2 can be projected and retracted. It is assumed that the lower end side of the piston rod 4 suspended from the shaft core portion of the outer tube 1 is inserted into the cylinder 3 standing upright so as to be able to protrude and retract.
[0004]
At this time, although not shown, the upper end of the suspension spring S is locked to the upper end side of the outer tube 1, and the lower end of the suspension spring S is received by a head portion 3 a that closes the upper end opening of the cylinder 3. It is assumed that it is carried under the presence of a free piston 6 that also serves as
[0005]
The front fork defines an extension side oil chamber R1 and a compression side oil chamber R2 in the cylinder 3 with a piston portion 5 connected to the lower end of the piston rod 4, and the extension side oil chamber R1 and the pressure side oil chamber R2. The chamber R2 communicates with each other via the piston portion 5, and the compression side oil chamber R2 communicates with a reservoir chamber R defined outside the cylinder 3.
[0006]
At this time, although not shown in the drawing, the piston portion 5 is provided with an expansion side damping valve that operates during the extension operation and a suction valve or a back pressure valve that operates during the contraction operation. It is assumed that the set extension side damping force is generated by the oil from the chamber R1 passing through the extension side damping valve and flowing into the compression side oil chamber R2.
[0007]
Incidentally, during the contraction operation of the front fork, the expansion side oil chamber R1 is replenished with oil from the compression side oil chamber R2 via the suction valve or the back pressure valve.
[0008]
Although not shown in the drawing, a base valve portion having a pressure side damping valve that operates during contraction operation and a suction valve that operates during extension operation is disposed at the lower end portion of the cylinder 3, and when the front fork is contracted. The oil from the pressure side oil chamber R2 passes through the pressure side damping valve and flows out into the reservoir chamber R, so that a set pressure side damping force is generated.
[0009]
Incidentally, when the front fork is extended, the oil that is insufficient in the compression side oil chamber R2 is replenished from the reservoir chamber R via the suction valve in the base valve portion.
[0010]
By the way, this front fork is free in order to ensure the hydraulic pressure in the cylinder 3 during the expansion and contraction operation that supports the lower end of the suspension spring S while being disposed in the oil in the reservoir chamber R and the inner tube 2 protrudes and retracts with respect to the outer tube 1. It has a piston 6.
[0011]
At this time, the free piston 6 is formed in an annular shape, and the inner periphery has a gap a on the outer periphery of the piston rod 4 while the outer periphery is in sliding contact with the inner periphery of the inner tube 2. opposite It is configured to be brought into sliding contact with the outer periphery of the cylindrical guide rod 7 and to rise against the urging force of the suspension spring S.
[0012]
As a result, the reservoir chamber R is apparently divided into a reservoir chamber R portion below the free piston 6 and a reservoir chamber r portion above the free piston 6. Although not shown, an air chamber is defined in the reservoir chamber r portion with the oil level as a boundary.
[0013]
On the other hand, the cylindrical guide rod 7 has a bearing member 8 that allows the piston rod 4 to pass through to the lower end side that closes the opening end of the cylinder 3, and oil from the reservoir chamber R is in sliding contact with the outer periphery of the piston rod 4. 3 is provided with a check seal 9 that allows the gas to flow into 3 but prevents its backflow.
[0014]
And this cylindrical guide rod 7 has the through-hole 7a which accept | permits the communication of the inner and outer peripheral side in the vicinity of the upper end, and when the lower side of the free piston 6 rising to this through-hole 7a communicates, It is assumed that the oil below the free piston 6, that is, the reservoir chamber R portion flows out to the reservoir chamber r portion through the through hole 7a and the gap a.
[0015]
Therefore, in the above-described front fork, since the free piston 6 is provided in the reservoir chamber R when the inner tube 2 is extended and retracted relative to the outer tube 1, the cylinder 3 is disposed below the free piston 6. The hydraulic pressure in the reservoir chamber R portion on the outer peripheral side is ensured.
[0016]
That is, the reservoir chamber R portion is always in a pressurized state by the free piston 6 urged from the back side by the suspension spring S during the expansion and contraction operation of the front fork. In other words, the pressure is higher than that of the reservoir chamber r portion, that is, the reservoir chamber r portion communicating with the air chamber with the oil surface as a boundary.
[0017]
Therefore, the hydraulic pressure in the pressure side oil chamber R2 in the cylinder 3 communicating with the reservoir chamber R portion and the extension side oil chamber R1 communicating with the pressure side oil chamber R2 is guaranteed by the influence of pressurization in the reservoir chamber R portion. It will be.
[0018]
Therefore, for example, during the contraction operation of the front fork, the expansion side oil chamber R1 does not become negative pressure, and does not cause a vacuum phenomenon in the expansion side oil chamber R1, and therefore, the expansion side oil chamber R1 There will be no shortage of oil.
[0019]
As a result, when the front fork is reversed and extended, no oil shortage is caused in the expansion side oil chamber R1, and therefore the oil is generated when the oil passes through the expansion side damping valve disposed in the piston portion 5. The extension side damping force is generated as set.
[0020]
[Problems to be solved by the invention]
However, in the front fork having the free piston 6 in the reservoir chamber R described above, there is a possibility that it may be pointed out that there is a problem that requires time for assembling work.
[0021]
That is, when the front fork is assembled, the suspension spring S is inserted after the free piston 6 is dropped into a so-called predetermined position, and the free piston 6 is fixed to the head portion 3a of the cylinder 3 by the urging force of the suspension spring S. Trying to sit down.
[0022]
At this time, the required amount of oil is injected into the front fork, but the front fork before assembly is in the most extended state. Therefore, as shown by the broken line in FIG. When the free piston 6 is dropped from this state when it is in the middle portion in the longitudinal direction of the cylindrical guide rod 7, air is shown below the free piston 6 with the oil level O as a boundary, as shown by a solid line in the figure. Will be contained.
[0023]
Since the front fork cannot be assembled in a state where the air is contained, the operation of releasing the air to the outside, that is, after the free piston 6 is dropped, the suspension spring S is inserted or suspended. The operation of causing the inner tube 2 to protrude and retract with respect to the outer tube 1 without inserting the spring S is repeated, and the work of releasing the air remaining below the free piston 6 to the outside is required.
[0024]
As a result, in the assembly work of the front fork having the free piston 6, it is essential to repeat the operation of moving the inner tube 2 in and out of the outer tube 1 before final assembly. There is a problem that requires time and effort.
[0025]
The present invention was devised in view of such a current situation. The object of the present invention is to provide a free piston so that a predetermined function can be exhibited. Because it has a piston, it takes time to assemble Don't need Thus, it is to provide a front fork that is optimal for expecting improvement in its versatility.
[0026]
[Means for Solving the Problems]
In order to achieve the above-described object, the front fork according to the present invention basically has a lower end of a piston rod suspended from the axial core portion of the outer tube in a cylinder standing on the axial core portion of the inner tube. The extension side oil chamber and the compression side oil chamber are defined in the cylinder by a piston portion continuously connected to the tip of the piston rod, and the extension side oil chamber and the compression side oil chamber are defined in the cylinder. Are communicated with each other via the piston portion, and the pressure side oil chamber is communicated with a reservoir chamber defined outside the cylinder, and the lower end of the suspension spring is supported while being distributed in the oil in the reservoir chamber. In the front fork having a free piston that ensures the hydraulic pressure inside, the free piston carries the lower end of the suspension spring and slidably contacts the inner periphery of the inner tube; And it consists of an inner circumference side member in sliding contact with the inner periphery of the outer peripheral side member to the outer periphery of the piston rod while fitted in separable from below the outer peripheral side of.
[0027]
Therefore, when assembling the front fork, the inner peripheral body constituting the free piston is first dropped, and after confirming that the inner peripheral body has submerged in the oil, the free piston is also configured. By dropping the outer peripheral side body to be performed, the free piston can be accommodated at a predetermined position without enclosing air below the free piston.
[0028]
In the above configuration, more specifically, the head member that closes the upper end opening of the cylinder under the insertion of the piston rod carries the outer peripheral body of the free piston and communicates with the outside of the cylinder through the through hole. It has a recess that allows the inner periphery side body that is separated from the outer periphery side body that constitutes the free piston to fall, and when the inner periphery side body is exposed to the recess, the inner periphery side body and the outer periphery side body Assume that a passage is formed between them.
[0029]
Therefore, when the free piston is seated on the head member, and when the pressure above the free piston is abnormally high compared to the position below the free piston, the outer peripheral body constituting the free piston is While being supported by the head member and not being able to descend any further, the inner peripheral body constituting this free piston can be lowered so as to fall into the recess formed in the head member. A passage is formed between the outer peripheral side body and the inner peripheral side body of the free piston.
[0030]
As a result, the hydraulic pressure above the free piston is released to the lower side of the free piston through the passage, and at this time, the recess for allowing the inner peripheral body to reside is outside the head member through the through hole. Since it communicates with the reservoir chamber, the hydraulic pressure released from the upper side to the lower side of the free piston is released to the reservoir chamber.
[0031]
In addition, a free piston that rises at the lower end of the spring guide that prevents buckling of the suspension spring that is interposed at the upper end side of the piston rod and contracts Opposite with a gap In some cases, it is assumed that the lower side of the free piston is set to communicate with the upper side of the free piston through a bypass passage formed in the piston rod.
[0032]
Therefore, when the oil is excessively accumulated below the free piston, the excessive oil is discharged to the upper side of the free piston, so that the oil below the free piston is eliminated. It will be.
[0033]
Further, when the raised free piston comes into contact with the lower end of the spring guide, which prevents buckling of the suspension spring interposed and contracted at the upper end side of the piston rod, it exceeds that of the inner peripheral side body constituting this free piston. It is assumed that the outer peripheral side body constituting the free piston is set so as to be further lifted by being separated from the inner peripheral side body.
[0034]
Therefore, when the free piston is brought into contact with the lower end of the spring guide due to abnormally high pressure below the free piston, the inner peripheral body constituting the free piston can be brought into contact with the lower end of the spring guide and can be further raised. On the other hand, when the outer peripheral side body constituting the free piston is separated from the inner peripheral side body, a passage is formed between the outer peripheral side body and the inner peripheral side body.
[0035]
As a result, the high pressure below the free piston is released above the free piston through this passage, and the high pressure below the free piston is eliminated accordingly.
[0036]
Further, a check seal that allows the inner circumferential side body of the free piston to pass downward from the upper side of the inner circumferential side body but prevents passage of oil from the lower side of the inner circumferential side body is provided. Suppose you have it.
[0037]
Therefore, when the free piston moves up and down in a normal hydraulic environment, oil from above the free piston passes between the inner periphery of the check seal and the outer periphery of the piston rod and flows into the lower portion of the free piston. At this time, the oil between the check seal and the piston rod functions as a lubricating oil.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below on the basis of the illustrated embodiment. The front fork according to the present invention basically has the same configuration as the conventional front fork described above.
[0039]
Therefore, in the place shown in the following, where the structure is the same as that of the conventional front fork described above, the same reference numerals are given in the drawing, and detailed explanations thereof will be given unless necessary. In the following, the description will focus on the features of the present invention.
[0040]
That is, in the front fork according to the present invention, as shown in FIG. 1, an outer peripheral side body 61 slidably contacting the inner periphery of the inner tube 2 while the free piston 6 supports the lower end of the suspension spring S, and the outer peripheral side An inner peripheral body 62 is slidably contacted with the outer periphery of the piston rod 4 while being detachably fitted to the inner periphery of the body 61 from below the outer peripheral body 61.
[0041]
At this time, the outer peripheral side body 61 and the inner peripheral side body 62 constituting the free piston 6 are each formed in an annular shape, and are integrated when the inner peripheral side body 62 is fitted to the outer peripheral side body 61 from below. It is going to be made.
[0042]
In other words, the annular rib portion 62a (see FIG. 3) formed to protrude from the outer periphery of the lower end of the inner peripheral body 62 is fitted into the annular groove 61a (see FIG. 3) formed at the inner periphery of the lower end of the outer peripheral body 61. Sometimes, the inner peripheral side body 62 is prevented from separating upward from the outer peripheral side body 61, and the integration of both is realized.
[0043]
Therefore, in this front fork, when assembling, the inner peripheral side body 62 constituting the free piston 6 is first dropped, and it is confirmed that the inner peripheral side body 62 is submerged in the oil. After that, by dropping the outer peripheral side body 61 that also constitutes the free piston 6, the free piston 6 can be accommodated at a predetermined position without containing air below the free piston 6.
[0044]
In addition, since air cannot be contained below the free piston 6 when the front fork is assembled, conventionally, after the free piston 6 is dropped, the operation of causing the inner tube 2 to appear in and out of the outer tube 1 is repeated. Compared with the fact that the work of releasing the air remaining below 6 is required, the present invention does not require the above work.
[0045]
Further, when the front fork is in a stationary state in which it does not expand and contract, as shown by a solid line in FIG. 1, the free piston 6 constitutes the head portion of the cylinder 3 in a so-called integrated state, which will be described later. The head member 31 is seated.
[0046]
Further, when this front fork is expanded and contracted, particularly when it is contracted, as shown in a phantom diagram in FIG. 1, the front fork rises in the inner tube 2 while being integrated. Become.
[0047]
Incidentally, in the free piston 6, a seal 63 is interposed on the outer periphery of the outer peripheral side body 61, so that a so-called sealing property with the inner periphery of the inner tube 2 is ensured.
[0048]
By the way, in this front fork, the head member 31 that closes the upper end opening of the cylinder 3 under the insertion of the piston rod 4 supports the outer peripheral body 61 of the free piston 6.
[0049]
And this head member 31 makes the inner peripheral side body 62 which separates and descends from the outer peripheral side body 61 which comprises the free piston 6 exist outside the cylinder 3, ie, the reservoir chamber R, and the communicating hole 31a. A recess 31b is provided.
[0050]
Therefore, in the head member 31, the free piston 6 is seated on the head member 31, and the upper portion of the free piston 6 is abnormally increased in pressure compared to the lower portion of the free piston 6. 2, the outer peripheral body 61 is supported so that it cannot be lowered any more, while the inner peripheral body 62 is separated from the outer peripheral body 61 and formed on the head member 31. In this case, a passage can be formed between the outer peripheral side body 61 and the inner peripheral side body 62.
[0051]
As a result, the hydraulic pressure above the free piston 6 is released to the lower side of the free piston 6 through this passage, and at this time, the recess 31b in which the inner peripheral side body 62 is present is formed through the through hole 31a. Since it communicates with the reservoir chamber R which is the outside of the head member 31, the hydraulic pressure released downward from above the free piston 6 is released to the reservoir chamber R.
[0052]
Incidentally, in the figure, the sheet member 32 is locked to the upper end of the head member 31, and the outer peripheral side body 61 is seated on the sheet member 32. The outer periphery is brought into sliding contact with the inner periphery of the inner tube 2.
[0053]
In the head member 31, the piston rod 4 is passed through the shaft core portion on the lower end side. At this time, the inner periphery on the lower end side is urged from behind by the backup ring 8 a. The retained bearing member 8 is brought into sliding contact with the piston rod 4.
[0054]
On the other hand, in the illustrated front fork, although not shown in detail, as shown in FIG. 3, a spring guide 10 is interposed on the upper end side of the piston rod 4, and the suspension spring S contracted by the spring guide 10. It is supposed to prevent buckling.
[0055]
When the front fork having the spring guide 10 is contracted with a large stroke, the free piston 6 is placed at the lower end of the spring guide 10 as shown in FIG. Neighboring, that is, facing each other with a gap b However, at this time, as shown in the drawing, the lower side of the free piston 6 is formed on the piston rod 4 and communicates with the upper side of the free piston 6 via the upper and lower through holes 4a and 4b constituting the bypass path. If so.
[0056]
At this time, as shown in the drawing, the upper and lower through holes 4a and 4b have an interval that does not interfere with a check seal 9 described later, and on the other hand, an inner peripheral side body having the check seal 9 on the inner periphery. In 62, a through hole 11a is formed in the holder 11 for preventing the check seal 9 from coming out, and consideration is given so that the lower portion of the free piston 6 can communicate with the bypass passage.
[0057]
The holder 11 is prevented from being pulled out downward by the annular stopper 12 fixed at a predetermined position by caulking at the inner periphery of the lower end of the inner periphery body 62.
[0058]
Therefore, when the oil is excessively accumulated below the free piston 6, the oil pressure naturally increases. However, the excessive oil is allowed to flow out above the free piston 6, and the free piston 6 The oil in the lower part is accumulated too much, that is, the increase in the hydraulic pressure is eliminated.
[0059]
Further, when the front fork having the spring guide 10 is contracted with a large stroke and the hydraulic pressure at this time is abnormally high, as shown in FIG. While being placed in a state where the lower end of the spring guide 10 is in contact with the lower end of the spring guide 10, the outer peripheral side body 61 constituting the free piston 6 is separated from the inner peripheral side body 62 and rises. A passage is formed between 61 and the inner peripheral body 62.
[0060]
As a result, the high pressure below the free piston 6 is released above the free piston 6 through this passage, and the high pressure below the free piston 6 is eliminated accordingly.
[0061]
In the free piston 6 configured as described above, as shown in FIG. 4, the inner peripheral side body 62 constituting the free piston 6 allows passage of oil downward from above, The check seal 9 is provided to prevent the oil from passing upward from below.
[0062]
Therefore, when the free piston 6 moves up and down under a normal hydraulic environment, oil from above the free piston 6 passes between the inner periphery of the check seal 9 and the outer periphery of the piston rod 4 and is below the free piston 6. At this time, the oil between the check seal 9 and the piston rod 4 functions as a lubricating oil.
[0063]
As described above, the front fork in the present invention is set in an inverted type in which the outer tube is the vehicle body side tube and the inner tube is the axle side tube. However, from the intent of the present invention, the outer tube is the axle. The side tube may be set upright and the inner tube as the vehicle body side tube, and the operation and effects in that case are not different.
[0064]
【The invention's effect】
As described above, in the invention of claim 1, it is confirmed that the inner peripheral side body constituting the free piston is first dropped during assembly, and the inner peripheral side body is submerged in the oil. After that, by dropping the outer peripheral side body that also constitutes the free piston, the free piston can be accommodated in a predetermined position without enclosing air below the free piston.
[0065]
And, since air cannot be confined below the free piston when the front fork is assembled, conventionally, after dropping the free piston, the operation of retracting the inner tube with respect to the outer tube is repeated to remain below the free piston. Compared to the fact that the work for releasing the air to be discharged to the outside is required, the above work is not required.
[0066]
When the front fork is in a stationary state where it does not expand and contract, the free piston sits on the cylinder head in a so-called integrated state. Will go up and down.
[0067]
According to the second aspect of the present invention, when the free piston is seated on the head member, and when the pressure on the upper side of the free piston is abnormally increased compared to the lower side of the free piston, While the side body is supported by the head member and cannot be lowered any more, the inner peripheral side body is separated from the outer peripheral side body and can be lowered so as to fall into the recess formed in the head member. At this time, a passage is formed between the outer peripheral side body and the inner peripheral side body.
[0068]
As a result, the hydraulic pressure above the free piston is released to the lower side of the free piston through the passage, and at this time, the recess for allowing the inner peripheral body to reside is outside the head member through the through hole. Since it communicates with the reservoir chamber, the hydraulic pressure released downward from above the free piston is released to the reservoir chamber.
[0069]
In the invention of claim 3, when the oil is excessively accumulated below the free piston, the excessive oil is allowed to flow out above the free piston through the bypass passage, Therefore, the oil below the free piston is excessively accumulated, that is, the increase in the hydraulic pressure is eliminated.
[0070]
Furthermore, in the invention of claim 4, when the free piston is brought into contact with the lower end of the spring guide due to abnormally high pressure below the free piston, the inner end of the spring guide cannot be further raised due to contact with the lower end of the spring guide. The outer peripheral side body rises separately from the peripheral side body. At this time, the high pressure below the free piston is increased above the free piston through the passage formed between the outer peripheral side body and the inner peripheral side body. Therefore, the high pressure under the free piston is eliminated accordingly.
[0071]
Further, in the invention of claim 5, when the free piston moves up and down in a normal hydraulic environment, oil from above the free piston is inserted between the inner periphery of the check seal and the outer periphery of the piston rod. Thus, the oil flows out below the free piston. At this time, the oil between the check seal and the piston rod functions as a lubricating oil.
[0072]
As a result, according to the present invention, it is possible to perform a predetermined function by having a free piston. It is ideal for expecting improved versatility.
[Brief description of the drawings]
FIG. 1 is a partial front view of a front fork according to the present invention, partially broken away.
FIG. 2 is a partial longitudinal sectional view showing a state in which a free piston descends downward and is separated vertically.
FIG. 3 is a partial longitudinal sectional view showing a state in which the free piston is lifted up and separated vertically.
FIG. 4 is a partially enlarged longitudinal sectional view showing a state in which the upper and lower sides of the free piston communicate with each other through a bypass path.
FIG. 5 is a view showing a front fork as a conventional example in the same manner as FIG.
6 is a partial longitudinal sectional view showing a state of a free piston when the front fork shown in FIG. 5 is assembled.
[Explanation of symbols]
1 Outer tube
2 Inner tube
3 cylinders
4 Piston rod
4a, 4b Through-holes constituting bypass path
5 Piston part
6 Free piston
8 Bearing material
8a Backup ring
9 Check seal
10 Spring guide
11 Holder
11a, 31a through hole
12 Annular stopper
31 Head member
31b recess
32 Sheet material
61 outer side
62 Inner circumference side body
63 Seal
R Reservoir chamber
R1 Extension side oil chamber
R2 pressure side oil chamber
S Suspension spring

Claims (5)

  The piston part that is slidably inserted under the suspension spring and the lower end of the piston rod that is suspended from the shaft part of the outer tube is inserted into the cylinder that stands on the shaft part of the inner tube, and is connected to the tip of the piston rod. Thus, an extension side oil chamber and a pressure side oil chamber are defined in the cylinder. The extension side oil chamber and the pressure side oil chamber are communicated with each other via a piston portion, and the pressure side oil chamber is defined outside the cylinder. In a front fork having a free piston that communicates with a reservoir chamber and that is disposed in oil in the reservoir chamber and supports the lower end of the suspension spring to ensure the hydraulic pressure in the cylinder, the free piston is connected to the suspension spring. An outer peripheral side body that is in sliding contact with the inner periphery of the inner tube while carrying the lower end, and an outer periphery of the piston rod while being detachably fitted to the inner periphery of the outer peripheral side body from below the outer peripheral side body. Front fork, characterized in that consists of an inner circumference side member in sliding contact with the   The head member that closes the upper end opening of the cylinder under the insertion of the piston rod carries the outer peripheral body constituting the free piston and is separated from the outer peripheral body constituting the free piston while communicating with the outside of the cylinder through the through hole. A recess is formed to allow the inner peripheral side body to descend and the inner peripheral side body is present in the concave portion, and a passage is formed between the inner peripheral side body and the outer peripheral side body. Front fork according to 1 When the free piston that has risen at the lower end of the spring guide, which is interposed on the upper end side of the piston rod and prevents the buckling of the suspension spring that contracts, faces with a gap, the lower part of this free piston is formed on the piston rod. The front fork according to claim 1, wherein the front fork communicates with the free piston via a bypass.   When the raised free piston comes into contact with the lower end of the spring guide that prevents buckling of the suspension spring that is interposed on the upper end side of the piston rod and contracts, the inner peripheral side body that constitutes the free piston further rises. The outer peripheral side body constituting the free piston is further separated from the inner peripheral side body and further raised, and a passage is formed between the inner peripheral side body and the outer peripheral side body. Listed front forks   The inner peripheral body of the free piston allows passage of oil from the upper side of the inner peripheral body to the piston rod, but prevents passage of oil from the lower side of the inner peripheral body. The front fork according to claim 1, further comprising a check seal.

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