JPH0584278B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement of an anti-nose dive mechanism of a front fork for a motorcycle.

(Prior Art) In a motorcycle, when braking, the center of gravity shifts due to inertia, and the load sharing ratio applied to the front fork increases, causing the front fork to sink.

Therefore, various devices (anti-nose dive devices) have been proposed that detect the braking action and increase the compression side damping force of the front fork to prevent sinking (anti-nose dive device).
(See Publication No. 20385).

In Fig. 6, 1 is an outer tube, 2 is an inner tube, and 3 is a hollow rod integrated with outer tube 1. During pressure side operation when inner tube 2 enters, the hydraulic oil in the lower oil chamber A is equal to the amount of intrusion volume of inner tube 2. Via oil lines 4 and 5,
The oil flows into the oil reservoir chamber B inside the inner tube 2.

In order to regulate the flow of this hydraulic oil during braking, an AND valve 7 (anti-nose dive valve) is installed inside the valve housing 6. Pressed valve seat 10
sit down.

The solenoid 8 is connected to a power source 13 via a switch 12 linked to a brake lever 11, and is energized when the switch 12 is turned on during braking.

During normal driving, the AND valve 7 is held at the initial position (open position) by the return spring 14, and the front fork absorbs vibrations from the road surface to maintain a soft ride.

On the other hand, during braking, the AND valve 7 is pushed down by the excitation force of the solenoid 8 and the valve seat 1
0, thereby blocking the flow of pressure-side hydraulic oil and preventing the front fork from sinking.

At this time, when the pressure of the pressure-side hydraulic oil rises above a predetermined value, the valve seat 10 is displaced downward while compressing the relief spring 15 to open the oil passage.
In other words, when the pressure increases excessively, such as when the vehicle is pushed up from the road surface while braking, the system prevents the front forks from locking up.

(Problems to be Solved by the Invention) By the way, in the case of such an anti-nose dive mechanism, as described above, the relief action of the valve seat 10 that responds to the internal pressure of the front fork is used to reduce the pressure during braking. Although it is designed to adjust the damping force, there is a delay in the response of the relief operation when the wheels are pushed up due to irregularities on the road surface during braking, so it is not possible to sufficiently absorb and alleviate the impact in a responsive manner. The problem was that the relief operation was often ineffective, especially in response to small shocks, and the ride was not comfortable.

On the other hand, in the front fork, by changing the compression side damping force according to the stroke position, it is possible to increase the damping force when the load is large and prevent bottoming out, without impeding the ride comfort in normal conditions. required.

For this purpose, there is a device that detects the stroke position and increases the opening pressure of the compression side damping valve.
It is impossible to attach such a damping force adjustment device to the front fork together with the anti-nose dive mechanism due to space constraints, and it has been difficult to put it into practical use.

The present invention aims to solve these problems simultaneously.

(Means for Solving the Problems) Therefore, the first invention provides an anti-nose dive mechanism for a front fork in which an anti-nose dive valve that closes during braking is interposed in a passage through which hydraulic oil flows when the front fork is operated on the pressure side. A valve housing that forms part of the passage has an armature that is driven against a relief spring by a solenoid that is energized during braking, and an acceleration-sensitive spool that is coaxially arranged with the armature, and is slidably installed inside the valve housing. At the same time, a valve seat is provided through which this spool is inserted, and a valve is provided on the spool to be seated from below the front fork on this valve seat, and the spool is arranged so that its sliding bearing portion is located upstream of the valve seat. provided in the housing, a portion above the sliding bearing protrudes into the solenoid provided outside the passage, and a lower end disposed within the passage downstream of the valve seat; A sealing means is interposed in the sliding bearing portion to prevent internal pressure from acting on the upper portion of the spool.

Further, a second invention is a front fork anti-nose dive mechanism in which an anti-nose dive valve that closes during braking is interposed in a passage through which hydraulic oil flows when the front fork is operated on the pressure side. , an armature that is driven against a return spring by a solenoid that is energized during braking, and an acceleration-sensitive spool that is coaxially arranged with this armature are slidably installed inside, and a valve seat that this spool passes through is installed. a valve seated on the valve seat from below the front fork is provided on the spool, and the spool is provided on the valve housing so that its sliding bearing portion is upstream of the valve seat, and The upper portion of the spool protrudes into the solenoid provided outside the passage, while the lower end of the spool is disposed in the passage downstream of the valve seat, and the upper portion of the spool is attached to the sliding bearing portion. A sealing means is provided to prevent internal pressure from acting on the valve seat, and the sliding bearing diameter is set larger than the valve seat diameter.

(Function) According to the first invention, during braking, the acceleration sensitive spool senses the upthrust acceleration and causes the spool itself to be relatively displaced, so even if the anti-nose dive valve does not open and the upthrust is small, the spool will not be displaced. This can effectively prevent the "lumpy" feeling caused by a series of small thrusts from being transmitted.

At the same time, the spool senses the internal pressure of the front fork and is urged in the valve closing direction, providing resistance to the pressure-side flow.Moreover, this internal pressure increases in proportion to the stroke position, so as the vehicle weight increases, Compression damping force can be increased.

In the second invention, the sliding bearing diameter of the spool is set larger than the valve seat diameter, so when the anti-nose dive valve closes during braking, the pressure side hydraulic pressure acts in the closing direction of the spool based on this pressure receiving area difference. Therefore, the burden on the solenoid (valve closing force) can also be reduced.

(Example) Figures 1 to 4 each show an example of the first invention. In FIG. 1, 1 is an outer tube of the front fork Z, 20 is a valve housing, and inside the valve housing 20 is an armature 22 of a solenoid 21 and a separate acceleration-sensitive spool 23.
is inserted and supported by the bearing portion 24 and the valve seat 25 so as to be freely slidable.

An AND valve 26 (anti-nose dive valve) is fitted into the spool 23 so as to be freely slidable.
A relief spring 27 interposed between the tip of the spool 23 and the tip of the spool 23 urges the spool 23 to come into contact with the stepped portion 28 .

The spool 23 is set to a predetermined mass (movable mass), and when the armature 22 is pulled up while compressing the return spring 29 due to the excitation force when the solenoid 21 is energized, the spring force of the spring 30 follows this. Displaced,
AND valve 26 is seated on valve seat 25.

The bearing sliding part diameter D ₁ of the spool 23 is set to be approximately the same as the valve seat diameter D ₂ , and a sealing member 31 is interposed in the bearing part of the spool 23 to release the upper end of the spool 23 to atmospheric pressure. At the same time, the internal pressure of the front fork Z is applied to the lower end of the spool 23, thereby generating thrust in the direction of compressing the return spring 29.

Although the solenoid 21 is not shown, it is connected to a power source via a switch linked to a brake device as in the past, and is energized during braking when the switch is closed.

32 connects the valve seat 25 to the valve housing 2
a spring 3 that elastically holds the stepped portion 33 of 0;
4 shows an adjustment mass detachably attached to the acceleration sensitive spool 23.

During normal driving, the spool 23 is the armature 22
The spring force of the return spring 29 compresses the spring 30 and pushes it down as shown in the left half of the figure.
6 is held in the open position.

In this case, the internal pressure changes depending on the stroke position of the front fork Z. In other words, the oil reservoir chamber is compressed and the internal sealed gas pressure increases in proportion to the stroke amount of the inner tube, so this pressure is applied to the spool 23. This acts to displace the AND valve 26 in the closing direction.

The end surface of the spool 23 that comes into contact with the armature 22 is open to atmospheric pressure, which is lower than the internal pressure of the front fork, so that the spool 23 is pushed up according to the internal pressure until it balances with the biasing force of the return spring 29.

The average stroke position of the front fork decreases when the vehicle weight increases, such as when loading a vehicle, and as the stroke amount of the inner tube increases, the internal pressure increases.
Eventually, the opening degree of the AND valve 26 decreases as the internal pressure increases.

Therefore, in this state, resistance to the flow of hydraulic oil during compression side operation occurs based on the opening degree of the AND valve 26, so the compression side damping force increases as the vehicle body load increases.

Furthermore, when the carrying load is small, the average stroke position of the front fork is upward, so
Since the damping force generated by the AND valve 26 is also small,
A soft ride is ensured.

Note that the balancing conditions for the AND valve 26 at this time are determined as follows.

Ks・Xs＝A ₂・PL＋Kv・_Xv However, Ks: Spring constant of return spring 29 Therefore, the compression amount of the spring 29, that is, the displacement amount Xs of the spool 23 increases according to the internal pressure,
It can be seen that the opening degree of the AND valve 26 decreases accordingly.

On the other hand, during braking, when the armature 22 is pulled up by the excitation force of the solenoid 21, the spool 23 follows this with the spring force of the spring 30, and seats the AND valve 26 on the valve seat 25 as shown in the right half of the figure. .

In this state, the armature 22 and spool 23 have a holding force ΔFs=f+Kv・Xv+A ₂・PL−Ks・Xs (f:
is the excitation force of the solenoid 21).

At this time, when the pressure (PH) on the oil chamber A side rises above the set load of the relief spring 27 due to the nose dive load, the AND valve 26 opens while compressing the relief spring 27. In other words, when the pressure rises excessively, the lock state of the front fork Z is avoided, and the pressure (PH) on the oil chamber A side
This is to control the sinking of the front fork Z with a damping force corresponding to the damping force.

When the wheel is pushed up due to unevenness of the road surface during braking, the valve housing 20 moves upward together with the outer tube 1, while the armature 22 and spool 23 try to remain at that position due to inertia, resulting in a push-up acceleration. When G exceeds the set acceleration α ₀ corresponding to the holding force ΔFs, the armature 22 and the spool 23 move relative to each other in the opening direction, and the AND valve 26 moves toward the valve seat 2.
5 (but the relief spring 27
does not contract) The hydraulic oil from the pressure side oil chamber A is released to the oil reservoir chamber, that is, performs a G cancel action, and as a result, the front fork Z instantaneously contracts to absorb and alleviate the shock.

At this time, the holding force ΔFs is acting on the spool 23, so if the mass (spool 23, armature 22, and adjustment mass 34) is mv, the set acceleration at which the spool 23 starts to open is α ₀ =ΔFs/ It becomes mv.

In other words, when the front fork Z is pushed up during braking, a force acting in the compression direction acts on the front fork Z.
The pressure in the pressure side oil chamber A increases, and this increased pressure is determined by the relief spring 27 mentioned above.
If the closing force of the AND valve 26 is overcome, the AND valve 26 can also open and absorb the impact.

However, when there are continuous small irregularities on the road surface and small and instantaneous thrusts are repeated, the opening pressure of the AND valve 26 may not be reached, or even if the pressure increases, it is instantaneous. The AND valve 26 may not be able to respond.
If the AND valve 26 is made to be able to cope with such a small thrust, the AND valve 26 will be activated early when the pressure in the pressure side oil chamber A increases, such as during sudden braking.
6 opens, making it impossible to effectively prevent sinking during sudden braking.

In other words, it is difficult for the AND valve 26 to simultaneously satisfy the requirements of preventing sinking during sudden braking and absorbing shock during thrusting because the relief setting pressures are different.

On the other hand, if the acceleration-sensitive spool 23 senses the upthrust acceleration and relatively displaces the spool 23 itself, the AND valve 2
Even small thrusts in which the spool 6 does not open can be dealt with by displacing the spool 23, and it is possible to effectively prevent the "lumpy" feeling from being transmitted due to a series of small thrusts.

Incidentally, the acceleration sensitive spool 23 is constructed separately from the armature 22 of the solenoid 21 to prevent malfunctions due to warping, etc., so that even though the solenoid 21 is small, stable AND effect and G cancel effect can be obtained.

In addition, the material of the spool 23 can be selected from non-magnetic materials regardless of the solenoid function, and by adjusting the movable mass mv of the spool 23 by replacing the adjustment mass 34, the set acceleration α at which the spool 23 starts to open can be adjusted. ₀ adjustment is possible.

Note that the adjustment mass 34 and the spring 30 are not necessarily provided, and are provided to increase the degree of freedom in setting the cancel acceleration. Regarding the spring 30, the internal pressure of the spool 23 is applied to the lower end of the spool 23 when the front fork is operating (which is greater than the atmospheric pressure during operation), so the spool 23 receives this internal pressure and is always directed to the solenoid 21 side. Since the spring 30 is biased and comes into pressure contact with the armature 22, it is not necessarily necessary to provide the spring 30; however, the provision of the spring 30 has the advantage of improving the followability of the spool 23 to the armature 22.

By the way, in this example, the front fork Z
The set acceleration α ₀ is adjusted by changing the mounting angle of the anti-nose dive mechanism Y relative to the angle of the anti-nose dive mechanism Y. That is, the anti-nose dive mechanism Y is
As shown in the figure, the axis of the spool 23 is installed so that it is parallel to the operating axis of the front fork Z, and the spool 23 is set so that it is most responsive when it is pushed up in the direction of the operating axis of the front fork Z. be.

In this case, when the vertical thrust acceleration G acts, the axial acceleration of the spool 23 is
Gcosθ (θ: Caster angle of front fork Z)
An acceleration of Gsinθ acts in the direction perpendicular to the axis. If the sliding friction coefficient of the spool 23 is μ, then the relationship is ΔFs+μ・mv・Gsinθ=mv・Gcosθ, and when the acceleration of G=ΔFs/mv(cosθ−μ・sinθ) is exceeded, the spool 23 moves in the opening direction. It will start moving.

Fig. 3 shows another embodiment in which the mounting angle of the anti-nose dive mechanism Y is set so that the spool 23 is most sensitive to vertical thrust acceleration; in this case, the spool 23 is connected to the axle with a predetermined caster angle θ. The anti-nose dive mechanism Z is attached to the front fork Z so that the axis of the spool 23 is perpendicular.

According to this, in the above embodiment, for example, when the caster angle θ=45° and the friction coefficient μ=0.25,
In comparison, the sensitivity of the spool 21 to vertical thrust acceleration G is improved by 1.88 times.

FIG. 4 shows another embodiment of the anti-nose dive mechanism, in which an AND valve 26A is formed with a land portion 36 that is inserted into a port portion 35 of a valve seat 25A with a wrap amount δ.

The drive current of the solenoid 21 is controlled in proportion to the braking force based on a detection signal from a braking force detecting means (not shown).

According to this, since the spool 23 is displaced according to the magnitude of the braking force, the set acceleration of the spool 23 when receiving thrust and the AND valve 26
The relief pressure of A is variable depending on the braking force.

FIG. 5 shows an embodiment of the second invention, the basic configuration of which is the same as the embodiment of the first invention shown in FIG. 1, and the same reference numerals are used for the same parts.

In this case, the bearing sliding portion diameter D ₁ of the spool 23 is set larger than the valve seat diameter D ₂ .

That is, the balance of forces acting on the spool 23 is D ₁
> D ₂ Based on the pressure receiving area difference ΔA = A ₁ - _{A 2} , ΔA (PH - PL) acts in the closing direction of the spool 23, so the holding force Ft of the spool 23 is equal to the force of the spring 30. Since it is added to the spring force, Ft=Kv・Xv+ΔA(PH−PL)+A ₂・PL(PH:
The pressure on the oil chamber A side, PL: the pressure on the oil reservoir chamber side),
The set acceleration at which the spool 23 begins to move in the opening direction when it receives thrust during braking is α ₀ =Ft/mv.

According to this, the holding force of the AND valve 26 in the closed position is ΔA(PH
−PL). In other words, ΔA
The load on the solenoid 28 can be reduced by (PH-PL).

Incidentally, as other embodiments of the present invention, it is of course possible to apply the embodiments (FIGS. 2 to 4) described in the first invention.

(Effects of the Invention) In summary, according to the first invention, the upthrust acceleration is sensed by the acceleration-sensitive spool, which is separate from the armature, and the spool itself is relatively displaced. Even when the body is pushed up, it can be accommodated by the displacement of the spool, and the "rugged feeling" caused by a series of small thrusts can be effectively prevented from being transmitted, improving ride comfort. At the same time, during normal operation, AND according to the internal pressure of the front forks.
Since the opening degree of the valve is reduced and the compression side damping force is increased in accordance with the internal pressure, it is possible to increase the damping force when the load increases and prevent bottoming out, etc., without impairing ride comfort in normal conditions.

Furthermore, the acceleration-sensitive spool has a separate armature for the solenoid to prevent malfunctions due to warping, etc., so even though the solenoid is small, stable AND and G cancel effects can be obtained.

Further, according to the second invention, since the sliding bearing diameter of the acceleration sensitive spool is set larger than the valve seat diameter, the hydraulic pressure acts in the closing direction of the spool based on this pressure receiving area difference. This has the effect of reducing the burden on the solenoid.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an anti-nose dive mechanism showing an embodiment of the first invention, FIG. 2 is a diagram of its installation state,
FIG. 3 is an installation state diagram of another embodiment, FIG. 4 is a sectional view showing another embodiment of the anti-nose dive mechanism,
FIG. 5 is a cross-sectional view of an anti-nose dive mechanism showing an embodiment of the second invention, and FIG. 6 is a cross-sectional view of an anti-nose dive mechanism showing a conventional technique. 20... Valve housing, 21... Solenoid, 22... Armature, 23... Acceleration sensing spool, 24... Sliding bearing section, 25... Valve seat, 26... AND valve, 29... Return spring, 31 ...Seal member, Y...Anti-nose dive mechanism, Z...Front fork.

Claims (1)

[Scope of Claims] 1. In an anti-nose dive mechanism for a front fork in which an anti-nose dive valve that closes during braking is interposed in a passage through which hydraulic oil flows when the front fork is operated on the pressure side, a valve housing forming part of the passage is provided with an anti-nose dive valve that closes during braking. , an armature that is driven against a return spring by a solenoid that is energized during braking, and an acceleration-sensitive spool that is coaxially arranged with this armature are slidably installed inside, and a valve seat that this spool passes through is installed. a valve seated on the valve seat from below the front fork is provided on the spool, and the spool is provided on the valve housing so that its sliding bearing portion is upstream of the valve seat, and The upper portion of the spool protrudes into the solenoid provided outside the passage, while the lower end of the spool is disposed in the passage downstream of the valve seat, and the upper portion of the spool is attached to the sliding bearing portion. An anti-nose dive mechanism for a front fork, characterized by interposing a sealing means to prevent internal pressure from acting on the front fork. 2. In a front fork anti-nose dive mechanism in which an anti-nose dive valve that closes during braking is interposed in a passage through which hydraulic oil flows when the front fork is operated on the pressure side, the valve housing that forms part of the passage is energized during braking. An armature driven by a solenoid against a return spring and an acceleration sensitive spool arranged coaxially with the armature are slidably installed inside the armature, and a valve seat is provided through which this spool is inserted. A valve that is seated from below the front fork is provided on the spool, and the spool is provided in the valve housing with its sliding bearing portion upstream of the valve seat, and the portion above the sliding bearing portion is provided in the passageway. The spool protrudes into the solenoid provided on the outside of the spool, while its lower end is disposed in a passage downstream of the valve seat, and the sliding bearing portion is configured to prevent internal pressure from acting on the upper portion of the spool. 1. An anti-nose dive mechanism for a front fork, characterized in that a sealing means for preventing the dive is provided, and the sliding bearing diameter is set larger than the valve seat diameter.