JPS609117Y2 - hydraulic shock absorber valve device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a relief valve for a hydraulic shock absorber having a function of preventing sinking during braking.

In motorcycles, as a countermeasure against sinking of the front fork caused by inertia during sudden braking, an IJ IJ valve is installed in the passage for excess hydraulic oil escaping to the pressure side operation, and the brake oil pressure during braking is sensed to prevent the front fork from sinking due to inertia. - The applicant has proposed a device that prevents sinking by increasing the valve setting force and suppressing the amount of hydraulic oil escaping.

To explain this now, FIG. 1 shows an example in which it is applied to a telescopic front fork, but the upper part of the device, which is exactly the same as a normal one, is not shown.

In the figure, 1 is an outer tube connected to the axle side, and 2 is a hollow pipe installed vertically at the bottom of the outer tube.

An inner tube (not shown) connected to the vehicle body side is slidably inserted into the outer tube 1, and an annular piston fixed to the tip of the inner tube is oil-tight between the inner circumferential surface of the outer tube 1 and the outer circumferential surface of the hollow pipe 2. It slides into contact with the piston, forming an oil chamber on the top and bottom surfaces of the piston.

A in the figure shows the oil chamber on the pressure side.

The hollow pipe 2 is fixed to the outer tube 1 by screwing it to a tightening rod 3 having a threaded portion 3a inserted through the bottom wall 1a of the outer tube 1.

A valve body 4 is attached close to the bottom wall 1a of the outer tube 1, and a relief valve 5 housed in the valve body 4 is connected to a passage 6 communicating with the oil chamber A and an internal oil reservoir chamber B of the hollow pipe 2. It is interposed so as to open and close the connection with the passage 7 which communicates with the passage 7.

The relief valve 5 has an annular valve body 10 that closes communication holes 9 at a plurality of circumferential locations formed in a valve case 8 that closes the passages 6 and 7 from the passage 7 side, and a coil-shaped valve body 10 on the back side. One end of the set spring 11 is brought into contact with the set spring 11.

The other end of this set spring 11 is pressed against a washer 13 provided integrally with the plunger 12, and due to the balance between the pressing force of this set spring 12 and the hydraulic pressure at the time of compression of the oil chamber A, which acts oppositely. The valve body 10 is moved.

14 is a conduit through which a part of the pressure oil from the master cylinder of the brake device is guided, and between the passage 7 and the cylinder 15
The plunger 12 is inserted in a slidable manner.

A modulator spring 16, which is interposed between the set spring 11 and the valve case 8, is pressed against the plunger 12 and biases the plunger 12 to the left in the figure.

Note that the plunger 12 is provided with a pair of seal members (O-rings) 17 and 18 at positions spaced apart in the axial direction to seal the hydraulic oil on the passage 7 side and the hydraulic oil on the pipe line 14 side from each other.

In the above, when the shock absorber receives an impact load from the road surface and operates to the pressure side, the hydraulic oil in the oil chamber A, which is compressed by the entry of the inner tube (not shown), pushes open the relief valve 5 through the communication hole 9, and the passage 6 Escapes to oil sump room B via .7.

In this case, a buffer spring (not shown) is compressed as the inner tube enters and absorbs the impact, and the compression side damping force characteristic is set according to the opening degree of the relief valve 5.

For example, if the opening degree of the relief valve 5 is small, the amount of hydraulic oil escaping from the oil chamber A will be small, so the oil pressure in the oil chamber A will increase.
The damping force increases and the speed of entry of the inner tube is reduced, and conversely, when the opening degree of the relief valve 5 increases, the hydraulic fluid escapes smoothly and the damping force decreases.

The opening degree of the relief valve 5 is determined to balance the pressure of the oil chamber A acting on the valve body 10 and the pressing force of the spring 11.

Therefore, by increasing the load on the spring 11 to strengthen the valve closing force, the pressure in the oil chamber A during the compression stroke can be increased accordingly.

When a shock is received from the road surface during normal driving, the shock absorber operates as described above to absorb and alleviate the shock, but when the brakes are applied, the front fork contracts as the center of gravity of the vehicle moves forward, making it difficult to control the vehicle. Impairs stability.

Since this sinking of the front fork occurs in response to the braking force, this sinking can be effectively suppressed by increasing the set load of the relief valve 5 in response to the brake pressure proportional to the braking force. be able to.

That is, the set load of the spring 11 of the relief valve 5 increases in proportion to the force pressing the plunger 12, that is, the brake pressure transmitted to the pipe line 14.

Therefore, when the front fork is about to sink during braking, the set load of the relief valve 5 increases due to the brake pressure, and the oil pressure in the oil chamber A that balances this increases in response to the braking force.

Therefore, prevention of sinking is always performed in accordance with the braking force, and functions effectively even during sudden braking.

On the other hand, if the internal pressure of oil chamber A increases due to factors other than braking,
The balance between the load of the spring 11 and the relief valve 5 is lost, and the relief valve 5 opens in response to this increase in internal pressure.

In other words, when the vehicle receives an impact from the road surface during braking, the opening degree of the relief valve 5 immediately increases to alleviate the impact.

Because the relief set load corresponds to the brake pressure, this action is always instantaneous when an external force other than the braking factor acts on the front fork, regardless of the magnitude of the braking force. Stability is significantly improved.

However, in this device, the stroke of the plunger 12 is displaced based on the balance between the pressure of the brake oil and the force acting on the relief spring, and the maximum stroke position is when the plunger 12 mechanically collides with the relief valve 5. Regarding the position, the maximum relief spring load that is substantially necessary to prevent the front fork from sinking can be obtained before the plunger 12 is displaced much.

On the other hand, if you pull the brake lever hard and force the brake oil from the master cylinder, in the normal case,
With the brake pad in contact with the brake disc,
Since any further oil entering the system is forcibly stopped, the brake lever cannot be moved any further even if the force applied to the brake lever is increased.

However, as described above, when the plunger 12 moves due to this brake pressure, oil enters by the amount of displacement of the plunger 12 even though the brake side has reached its limit, so the brake lever must be pressed. It becomes even more operable.

This causes the driver to feel anxious that the brakes may not work, unlike when braking while driving, because the brake lever moves freely, especially when the brake lever is gripped when the vehicle is stopped. There is a fear.

In order to solve this problem, the present invention provides a hydraulic shock absorber that is equipped with a stopper that limits the movement of the plunger that changes the set load of the relief valve at a certain position, thereby preventing excessive operation of the brake lever. do.

Hereinafter, the present invention will be explained based on FIG. 2. Since there is basically no difference in the anti-sinking function during braking, the same parts as in FIG. 1 will be given the same reference numerals.

In the embodiment shown in FIG. 2, a ring plate 40A is provided as a stopper 40 on the valve body 4, which can be engaged with the spring receiver 35 of the relief valve 5', to prevent the plunger 12 from stroking beyond a predetermined amount. .

This limit position is set so that the set load of the relief valve 5' becomes a value that can prevent sinking during maximum braking.

Similarly, in the embodiment shown in FIG. 3, a long groove 37 extending in the axial direction is formed on the circumferential surface of the plunger in the sliding hole 36 of the plunger 12, and a pin 40B is protruded from the valve body 4 side to be inserted into the long groove 37. This is realized by the pin 40B being locked at the end of the groove after a predetermined stroke.Furthermore, in the embodiment shown in FIG. 40c,
It is configured to function as a stopper 40 by bringing it into contact with the useful surface 38 after a predetermined stroke.

As a result, the plunger 12 moved to the right in the diagram in response to the pressure of the brake oil, increasing the set load on the relief valve 5' to prevent sinking during braking, but excessive pressure was applied. In this case, the plunger 12 is forcibly prevented from moving by the stopper 40, so that when the plunger 12 stops moving, the entry of brake oil is blocked, making the brake lever (not shown) no longer operable.

Therefore, according to the present invention, when the driver is clenching the brake lever when the vehicle is stopped, the brake lever does not move as much as possible, and a certain feeling and sense of moderation are established.

In addition, to explain the relief valve 5' shown in FIG. Stepped hole 23 formed in the center
The end face of the rod portion 20 is exposed to the upstream side of the relief valve 5', that is, the oil chamber A by freely sliding through the rod portion 20.

The poppet valve portion 21 has annular collar portions 24 and 25 at both ends thereof.
One of the flange portions 24 is in contact with and separated from a valve seat 26 whose end surface is in contact with the valve case 8, and the other flange portion 25 has an outer peripheral surface in sliding contact with the large diameter portion of the stepped hole 23.

Between the stepped portion 28 of the stepped hole 23 and the collar portion 25, hydraulic pressure (low pressure) on the downstream side of the relief valve is guided through a bottomed hole 29 and a narrow passage 30 formed in the poppet valve portion 21.
Balance (offset) the hydraulic pressure acting on the poppet valve part 21
I'm letting you do it.

Note that the inner diameter of the valve seat 26 that the flange 24 contacts is as follows:
It is set equal to the inner diameter (of the large diameter portion) of the stepped hole 23 with which the other flange portion 25 slides.

In the figure, 31 is a snap ring fitted to the rod part 20 to prevent removal, 32 is a relief spring in contact with the end face of the poppet valve part 21, and 33 is a modulator spring set to balance the brake pressure. be.

Further, the valve case 8 is fixed with a snap ring 34 such that the valve seat 26 is sandwiched between the stepped portion of the valve body 4.

With the above configuration, when the upstream pressure of the relief valve 5' is below the set value, the relief spring 32 presses against the valve seat 26 and closes, but the pressure balance regarding the valve body 22 is maintained by the poppet valve portion 21. Since the pressures are completely canceled out, it is determined only based on the relationship between the cross-sectional area of the rod portion 20 and the spring 32.

That is, in the poppet valve section 21, the pressure on the upstream side of the relief valve acts equally on the inside of both collar sections 24 and 25, and conversely, the pressure on the downstream side acts equally on the outside thereof, so the pressure on both sides is completely balanced and the pressure on the upstream side attempts to remain stationary regardless of the pressure difference downstream.

On the other hand, the rod portion 20 has one end surface exposed to the upstream side, and the pressure on the downstream side acts on the other end, so the differential pressure between the upstream and downstream causes the rod portion 20 to move toward the left downstream side in the figure. It works as if to press it.

Therefore, the valve body 22 is pushed to a position where this pressing force balances with the relief spring 32, and at that time, the minimum cross section of the space formed between the valve seat 26 and the collar 24 is the same as that of the relief valve 5'. Effective valve opening area.

The rod part 2 senses the pressure in the oil chamber 1 in this way.
As a result, the spring load of the relief spring 32 that balances this can be set to the above-mentioned valve effective area. Therefore, without increasing the load of the relief spring 32, the fork can be relieved up to the maximum value of the fork expansion and contraction speed at the time of relief. The maximum effective area of the valve can be made large enough to ensure that the flow rate is accurately proportional, that is, that the damping pressure has the desired nearly constant proportionality over the entire operating range.

As a result, the disadvantages that occur when the spring load of the relief spring 32 is increased, such as the impact received during braking propagating to the brake circuit, worsening the braking feeling, and excessively increasing the brake circuit pressure, can be avoided. can be avoided.

As described above, the present invention provides a stopper for the plunger,
At brake pressures within the normal braking range, the set load of the relief valve is increased to maintain the anti-sinking function, but at higher pressures, the movement of the plunger is restricted.
It is possible to block the inflow of brake oil and give a sense of moderation when operating the brake lever.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional device, FIG. 2 is a sectional view of a first embodiment of the present invention, and FIGS. FIG. 7 is a sectional view of a main part of a third embodiment. 5'...Relief valve, 8...Valve case, 9...Communication hole, 21...Rod part, 23...Stepped Hole, 24, 25...
...Brim part, 26... Valve seat, 28...
...Dan section, 30...Narrow path, 32...
・Relief spring, 35... Spring holder, 36
...Sliding hole, 38...Stepped surface, 40.
... Stopper, 40A ... Ring plate, 40B ... Pin, 40C ... Flange part.

Claims (1)

[Scope of utility model registration request] It has an inner tube and an outer tube that slide on each other in the axial direction, and allows excess hydraulic oil in the oil chamber that contracts during line side operation to escape to the oil reservoir chamber, and a relief valve is interposed in the escape passage of the bracket. In this hydraulic shock absorber, the spring set load of the relief valve is increased or decreased according to the brake oil pressure, and the relief spring of the relief valve is pressed via a plunger that responds to the brake oil pressure, and the displacement of this plunger is A hydraulic shock absorber characterized by being provided with a stopper that limits the amount by a predetermined amount.