JPS63176794A - Front fork - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a dual-tube type front seven-wheel that allows variable control of the damping force on the rebound and compression sides.

(Prior Art) A dual-tube type front seven-hole is known as a front seven-hole for a motorcycle, which is equipped with a cylinder coaxially with an outer tube and has an inner tube slidably housed in the outer tube. ing.

(Problems to be Solved by the Invention) By the way, these double-tube type 70-ton forks, including those disclosed in Japanese Utility Model Application Publication No. 56-143986, have an inner tube slidably housed in the inner circumference of the outer tube. However, because the brake support member, axle mounting member, etc. are placed at the bottom of the outer tube, the outer tube is integrally molded using aluminum casting, etc., and the sliding surface with the inner tube is finished by machining.

However, if the shape of the lower part of the outer tube becomes complicated, the wall thickness will become uneven, making it easier for cavities to form inside the tube during aluminum casting, which will impair its durability when subjected to high pressure caused by oil lock.

In addition, because the inner tube is slidably arranged on the inner circumference of the outer tube, it is difficult to arrange the damping valves on the rebound and compression sides separately due to space constraints, making it difficult to place the damping valves on the rebound and compression sides to accurately obtain the required damping force. Difficult to demonstrate characteristics,
In particular, when the damping force is variably controlled by an external signal depending on the operating conditions, it is difficult to apply this method to a device that is subject to such restrictions on the installation of a damping valve.

Also, when the front 7-hole expands and contracts, hydraulic oil passes through the inside of the cylinder and enters and exits between the oil reservoir chamber above the inner tube. Therefore, a cylinder that is arranged so as to define a predetermined oil chamber between it and the inner circumference of the inner tube inevitably has a small inner diameter, so the flow velocity of hydraulic oil is high when passing through this cylinder. This blows up the oil level in the oil sump chamber and causes airage, which makes it easy for air bubbles to get mixed into the hydraulic oil, reducing generation.
There was a tendency for power to be difficult to stabilize.

It is an object of the present invention to solve these problems and provide a front fork that can meet more advanced requirements by variably controlling the damping force depending on the extension/retraction position of the front fork.

(Means for Solving the Problems) Therefore, the present invention provides a system in which a cylinder is coaxially arranged and fixed inside an outer tube, an inner tube is arranged on the inner periphery of the cylinder so as to be able to slide freely via a piston, and the inner tube A suspension spring is interposed between the cylinder and the outer tube, a rebound damping valve is arranged at the bottom of the cylinder, and a compression damping valve is arranged freely to slide around the inner circumference of the inner tube.
While interlocking with the suspension spring to increase the closing force of the compression side damping valve in accordance with the amount of compression of the suspension spring,
At least one of the damping valves is provided with a solenoid that variably controls the valve closing pressure according to an externally applied excitation current, and the oil chamber formed between the inner tube and the cylinder is connected to the gap between the cylinder and the outer tube and the expansion side damping. It was made to communicate with the oil chamber inside the inner tube via a valve.

(Function) During the 70-ton and 7-year rebound operation, the hydraulic oil in the oil chamber generates a predetermined damping force when passing through the rebound damping valve at the bottom of the cylinder through the gap between the cylinder and the outer tube.

During pressure operation, hydraulic oil corresponding to the volume entered by the inner tube is pushed out toward the oil reservoir chamber, and a predetermined damping force is generated when it passes from the inner circumference of the inner tube to the pressure side damping valve. The closing pressure of these expansion-side and compression-side damping valves changes depending on the excitation current of the solenoid, that is, the generated damping force is variably controlled. Furthermore, as the compression side stroke amount increases, the position detection spring increases the closing pressure of the compression side damping valve, generating a high damping force in the latter half of the stroke. Since the inner diameter of the inner tube is large and the flow velocity of hydraulic oil does not increase, airage is suppressed.

Since the inner tube slides on the inner circumference of the cylinder, even if an oil lock mechanism is formed between the two to prevent oxygen deficiency, the cylinder, unlike the outer tube, has a simple cylindrical shape and must be made of iron-based pipe material. Moreover, since high pressure does not act on the outer 7 outer tubes, sufficient durability can be ensured.

(Example) Embodiments of the present invention will be described below based on the drawings.

A cylinder 2 is coaxially arranged and fixed on the inner circumference of an outer tube 1 with a predetermined gap 5 therebetween.

An inner tube 3 is housed in the inner periphery of the cylinder 2 so as to be freely slidable.

An hour tube 1 made of aluminum casting or the like supports an axle with a plumket 4 integrally formed at its lower part. Although not shown, the inner tube 3 is connected to the vehicle body side by a blanket formed on the upper part.

The cylinder 2 arranged inside the outer tube 1 is formed by a thin iron fan pipe, and the annular gap 5 formed between the cylinder 2 and the outer tube 1 is set to the minimum necessary size to allow passage of hydraulic oil. However, a groove extending in the vertical direction may be formed on the inner periphery of the outer tube 1 in order to smooth the flow of working oil.

An oil chamber 8 formed between a piston 7 fixed to the inner periphery of the tip of the inner tube 3 and the inner periphery of the cylinder 2 communicates with the gap 5 through an orifice 9 formed in the cylinder 2.

A rebound damping valve 10 is attached to the bottom of the cylinder 2, and a bottom chamber 1 outside the cylinder 2 communicates with the gap 5 during the rebound operation.
1 to the oil chamber 12 inside the inner tube 3.

The expansion side damping valve 10 is installed in a valve case 13 fixed to 11g of the cylinder 2, and the annular valve body 15 that closes the passage with its own elastic force has a check valve 17 placed on its outer periphery that opens when pressure is activated. It is also used as

Compression side damping valve 20 arranged on the inner periphery of the inner tube 3
generates a compression damping force by imparting resistance to the hydraulic oil flowing from the oil chamber 12 to the upper oil reservoir chamber 21 during compression side operation.

The compression side damping valve 20 has a solenoid 22 disposed inside a valve case 24 fixed to the inner periphery of the inner tube 3 via a washer 18, and an annular valve body 25 that is attracted by the excitation force of the slide/id 22. is seated on a check valve 23 which is arranged on its outer periphery and also serves as a seat part. The annular valve body 25 is supported at one end by the valve/id 22 or
The spring 29 urges the valve in the valve closing direction. Note that the check valve 23 opens during expansion side operation.

A suspension spring 19 is disposed on the inner periphery of the inner tube 3, and one end thereof is supported at the bottom of the cylinder 2.

The suspension spring 19 consists of two springs 19A and 19B.
The valve base 26, which is slidable within the valve case 24, is sandwiched between these parts. The other end of the upper stroke position detection spring 19B is supported by a washer 27 that is secured to the inner periphery of the valve case 24.

When a compression force acts on the suspension spring 19 and the upper spring 19B contracts by a predetermined amount, the spring receiver 28 supporting the lower spring 19A comes into close contact with the valve case 24, and only the lower spring 19A is compressed. ing. Therefore, when the spring 19B is compressed and the valve base 26 is moved, the IJ-7 spring 29 is also compressed at the same time, the initial load becomes higher, and the generation of the compression side damping valve 20 increases.

The upper end of the cylinder 2 is connected by a cylindrical guide 30.
It is held on the inner periphery of the upper end of the outer tube 1. guide 30
A bearing 31 for slidably supporting the inner tube 3 is disposed on the inner periphery of the tube.

In order to prevent separation of the front 7 motors, the stopper 32 of the inner tube 3 is brought into contact with the side 30 at the most extended position. At this time, the piston 7 attached to the tip of the inner tube 3 closes the orifice 9 of the cylinder 2, thereby placing the oil chamber 8 in an oil-locked state and mitigating the impact at the time of full extension.

In addition, during this oil lock (to prevent high pressure leaking from the oil chamber 8 from acting on the oil seal 33, which is placed above the bearing 31 and seals the gap between the inner tube 3 and the outer tube 1), A through hole 34 is formed in the inner tube 3.

In addition, the valve case 1 is attached to the ItE part of the cylinder 2.
A cylindrical oil lock piece 36 is formed integrally with 3, and when the piston 7 enters the lock chamber 37 between the oil lock piece 36 and the cylinder 2 at the time of maximum compression, the oil is locked. It is designed to cushion the impact.

The structure is as described above, and the operation will be explained next.

During pressure side operation when the inner tube 3 enters from the illustrated state, the oil chamber 12 inside the inner tube 3 moves from the oil chamber 12 inside the inner tube 3 to the check valve 17 and the bottom chamber 1.
1. Hydraulic oil flows in through the annular gap 5, the orifice 9, and partially from the oil chamber 12 through the through hole 34.

At the same time, the hydraulic oil in the oil chamber 12 corresponding to the intrusion volume of the inner tube 3 is transferred to the pressure side area y valve 20 on the inner circumference of the inner tube 3.
is pushed open and flows out into the oil reservoir chamber 21, and at this time a predetermined compression side damping force is generated.

By the way, the valve base 26 of the compression side damping valve 20 held between the springs 19A and 19B rises relative to the inner tube 3 because the spring 19B is bent in accordance with the compression stroke of the inner tube 3. The initial load of the relief spring 29 is increased accordingly. As a result, the compression damping force generated by the compression damping valve 20 becomes extremely large depending on the compression stroke amount.

This allows it to exert high damping force and improve driving stability when the vehicle is heavy or when driving on rough roads. Of course, when driving on a flat road with a small compression stroke, the damping force can be lowered to maintain good ride comfort.

Note that at the maximum compression point, the piston 7 enters the oil lock piece 26 and oil lock is performed.

In this way, the damping force can be increased proportionally according to the compression side stroke position, but in addition to this, by energizing the solenoid 22, the annular valve body 25 is attracted to the seat portion of the check valve 23, and this 6. For example, a solenoid 22 increases the damping force according to the adsorption force during braking.
By energizing it, a large damping force is generated, which prevents the sinking of a 70-ton 7-year-old, or by energizing it in the same way when driving at high speed, the damping force is increased and stability is improved. It is possible to do so.

By the way, since the hydraulic oil flowing from the oil chamber 12 to the oil reservoir chamber 21 passes through the inner circumference of the large-diameter inner tube 3, it passes through the inner circumference of a cylinder with a narrow inner diameter arranged inside the inner tube as in the conventional case. Unlike passing through, the flow velocity is not so high, therefore, the blowing up of the oil level in the oil sump chamber 21 due to the compression of the front 7 oak is suppressed, and aeration, where internal air mixes into the hydraulic oil, is reduced. On the other hand, during the rebound-side operation, the hydraulic oil in the oil chamber 8, which contracts, pushes open the rebound-side damping valve 10 from the orifice 9, the annular gap 5, and the bottom chamber 11, and flows into the oil chamber 12. At this time, a rebound damping force is generated based on the resistance of the rebound damping valve 10.

The expansion damping valve 10 is located at the bottom of the cylinder 2, and since there is almost no air entrainment, the generated damping force can maintain stable characteristics.

With the withdrawal of the inner tube 3, hydraulic oil also flows from the oil reservoir chamber 21 into the oil chamber 12 via the check valve 23. Note that since the check valve 23 allows the hydraulic oil to pass through with almost no resistance, suction into the oil chamber 12 is not inhibited.

The extension stroke of the inner tube 3 increases,
Near the end of the extension where the orifice 9 is eventually blocked by the piston 7, there is no place for the hydraulic oil in the oil chamber 8 to escape.
It becomes an oil lock state and generates high damping force.

In this case, some of the high pressure oil leaking from the oil chamber 8 is
And sliding Tl between bearing 31 and inner tube 3! I
Since the oil is released from the through hole 34 into the oil reservoir chamber 21 through the J gap, high pressure is prevented from acting on the oil seal 33, thereby preventing damage.

By the way, as mentioned above, it is possible to lock the oil on both the compression side and the expansion side, but in this case, the oil lock is achieved by sealing the chamber formed between the inner tube 3 and the cylinder 2. Therefore, the high pressure during oil lock, which is significantly higher than that during steady state, does not act on the outer tube 1. Therefore, the 7-section tube 1 with a complicated external shape is formed of aluminum 1D material, etc.
Even if there are cavities inside, the mechanical strength will not be impaired, and the wall thickness of the outer tube 1 can be made thinner.

Note that since the cylinder 2 has a simple cylindrical shape, an iron pipe can be used as is, and in this case, since it has uniform strength, it can exhibit sufficient durability even under high pressure during oil lock.

In the above embodiment, the damping force of the compression side damping valve 20 is controlled by the solenoid 2.
2, it is possible to variably control the damping force, but it is also possible to variably control the damping force by providing a twist/id in the expansion side damping valve 10, or by providing it in both the damping valves 10 and 20.

(Effects of the Invention) As described above, according to the present invention, when the front seven-cylinder engine is operating on the rebound side, a predetermined damping force is generated when it passes through the rebound damping valve at the bottom of the cylinder, and when operating on the compression side, the inner tube The hydraulic oil corresponding to the intrusion volume is pushed out to the oil sump chamber side,
When it passes through the compression side damping valve on the inner circumference of the inner tube, it generates a damping force according to the stroke position, and at least one of the damping valves can increase or decrease the damping force according to the operating state using an external signal. These factors combine to provide optimal rupture force characteristics depending on the operating conditions.

Note that during pressure side operation, the hydraulic oil passes through the inner periphery of the large diameter inner tube, so the flow velocity does not increase, airage tongue is suppressed, and the control accuracy of the generated damping force is improved.

Since the inner tube slides on the inner circumference of the cylinder, there is an oil lock between the two! In this case, unlike the outer tube, the cylinder has a simple cylindrical shape and can be made of iron-based pipe material with high pressure resistance and uniform quality. Since high pressure is not applied to the tube, sufficient durability can be ensured.

[Brief explanation of the drawing]

The drawings are cross-sectional views showing embodiments of the present invention. 1...Outer tube, 2...Cylinder, 3...
・Inner tube, 5... Annular gap, 7... Piston, 8.12... Oil chamber, 10... Rebound side damping valve, 1
9.19A. 19B... Suspension spring, 20... Compression side damping valve,
21...Oil sump chamber, 22...Solenoid.

Claims (1)

[Claims] A cylinder is coaxially arranged and fixed inside the outer tube, an inner tube is arranged on the inner circumference of the cylinder so as to be able to slide freely via a piston, and a suspension spring is interposed between the inner tube and the outer tube. A compression damping valve is arranged at the bottom of the inner tube, and a compression damping valve is arranged freely to slide around the inner circumference of the inner tube. At least one of the damping valves is equipped with a solenoid that variably controls the valve closing pressure in response to external excitation current, and the oil chamber formed between the inner tube and the cylinder is connected to the gap between the cylinder and the outer tube. and a front fork, characterized in that the front fork communicates with an oil chamber inside the inner tube via the rebound damping valve.