JPH01240391A - Front fork - Google Patents

Abstract

PURPOSE:To always obtain a suitable cushioning effect, by opening and closing a communicating passage between an inner oil chamber of a damper and an oil reservoir, and setting variable the spring force of a relief spring of a damping valve according to variation of a stroke, in a front fork with the built-in damper. CONSTITUTION:In a front fork, an inner tube 2 is fitted within an outer tube 1 and a damper 3 is provided within said tube 2. The damper 3 comprises a cylinder 4 standingly provided on the bottom of the outer tube 1 and a piston 5 integrated with a piston rod 6 insertedly fitted in said cylinder 4. In this case, a ring-like passage 13 is formed between the piston rod 6 and a bearing 12 fixedly secured in the upper part of the cylinder 4, and said passage 13 is opened or closed with a damping valve 18. And a spring seat 15 supporting one end of a relief spring 16 which encourages the damping valve to the closing direction, is brought to be pinchedly supported between a suspension spring 14 and a detecting spring 17.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement of a 70-ton 7 oak with a built-in damper.

(Prior Art and its Problems) An example of a two-wheeled military front 7 oak with a built-in damper is Utility Model Application No. 145698/1984. The front 7 oak with a built-in damper supports the load between a telescopic outer tube and an inner tube, and the damping force is generated by the built-in damper.

However, in the case of this type of front 7 oak, the damping force is proportional to the operating speed of the front 7 oak, but is independent of its stroke position.

Therefore, if the opening pressure of the damping valve is set low, a soft ride can be obtained, but near the maximum stroke, there is a risk that the damping force will be insufficient and the inner tube will bottom out. Since a relatively high damping force is applied from the first half of the stroke, there is a problem in that the ride becomes stiff.

The present invention was made by focusing on these problems.
The purpose of the present invention is to provide a structure in which a damping force corresponding to the stroke position can be obtained in a front 7 oak with a built-in damper.

(Means for Solving the Problems) The present invention includes an inner tube housed in an outer tube, a piston slidably housed in a cylinder erected from the outer tube, and this piston suspended from the inner tube. The upper part of the cylinder is connected to the front 7 oak to form a damper, and the outer tube, the inner tube, and the cylinder define an oil reservoir chamber that compensates for the inflow and outflow of hydraulic oil corresponding to the piston rod intrusion volume. An annular passage communicating with the damper internal oil chamber is formed between the bearing fixed to the piston rod and the piston rod, and this annular passage is opened and closed via a damping valve slidably fitted to the piston rod. A suspension spring that supports the load and a detection spring are stretched in series between the cylinder and the inner tube, and a spring seat of a relief spring that biases the damping valve in the closing direction is sandwiched between the suspension spring and the detection spring. .

(Function) When the front 7 oak is activated, the detection spring is bent in accordance with the stroke via the suspension spring, and the spring seat moves while compressing the relief spring, increasing the urging force that presses the damping valve against the bearing. . As a result, the damping force applied by the damping valve to the hydraulic oil flowing from the upper oil chamber to the oil reservoir chamber through the annular passage becomes variable in accordance with the stroke of the front 7 oak.
It is possible to obtain a buffering effect that corresponds to both driving conditions and operating speeds.

In addition, by fitting the damping valve into the piston rod so that it can slide freely, the damping valve's 7 riction is prevented from increasing due to the eccentricity of the piston rod that occurs during the operation of the front 7 oak, and smooth operation is achieved. is obtained.

(Embodiment) As shown in FIG. 1, an inner tube 2 is slidably inserted into an outer tube 1, and a damper 3 is housed inside these tubes.

In the damper 3, a piston 5 is connected to a piston rod 6 suspended from the inner tube 2, and a cylinder 4 that accommodates the piston 5 in a freely slidable manner is erected at the bottom of the outer tube 1.

The upper end of the piston rod 6 is fastened to the upper end of the inner tube 2 via a cap 22.

A base valve case 39 is fixed to the lower end of the cylinder 4, and a pin 39A of the valve case 39 passes through the bottom of the outer tube 1 and is connected to the bolt 39A by a nut 29 through the lock piece 24. The cylinder 4 is tightened and fixed.

Inside the damper 3, a lower oil chamber 7 that contracts during the compression side operation and an upper oil chamber 8 that contracts during the extension side operation are defined via the piston 5. The piston 5 is provided with a main valve (check valve) 5A that opens only during pressure side operation to allow hydraulic oil to flow from the lower oil chamber 7 to the upper oil chamber 8.

The piston rod 6 has a 17th pipe 1 that bypasses the main pulp 5A and communicates the lower oil chamber 7 and the upper oil chamber 8.
1 is formed.

An oil reservoir chamber 9 is formed above the damper 3 and located inside the inner tube 2, and this oil reservoir chamber 9 is connected to a base valve 19 disposed at the bottom of the cylinder 4 from an annular passage 10 outside the cylinder 4. It communicates with the lower oil chamber 7 via the lower oil chamber 7. The base valve 19 includes a compression side damping valve 20 that provides resistance to the hydraulic oil flowing from the lower oil chamber 7 to the annular passage 10 during overwhelming operation and generates a flow reduction force, and a compression side damping valve 20 that generates a flow reducing force when the hydraulic oil flows out from the lower oil chamber 7 to the annular passage 10 during overwhelming operation. It is equipped with a check valve 21 that allows the passage of water.

A bearing 12 is caulked and fixed to the upper part of the cylinder 4, and an annular passage 13 is defined between the bearing 12 and the piston rod 6.

An annular damping valve 18 is provided which is seated on the upper end surface of the bearing 12, and this damping valve 18 is slidably fitted onto the piston rod 6.

A spring seat 15 is slidably inserted into the upper end of the cylinder 4, and the spring seat 15 and the damping valve 18
An I-no-7 spring 16 is interposed between them.

A spring 123 is attached to the outside of the cylinder 4, and a suspension spring 14 and a detection spring 17 are stretched in series between the spring seat 23 and the cap 22.

The upper end of the spring seat 15 is held between the suspension spring 14 and the detection spring 17.

A stopper 30 for regulating the amount of movement of the spring seat 15 is fixed to the upper end of the cylinder 4 by caulking.

With this structure, the hydraulic circuit of the 70-ton fork is shown in FIG.

When the front 7t moves to the pressure side, a part of the hydraulic oil in the lower oil chamber 7 contracts, pushing open the pressure side damping valve 20 of the base valve 19 and flowing from the annular passage 10 to the oil reservoir chamber 9. The remaining oil flows from the main valve 5A into the expanding upper oil chamber 8 without resistance. Therefore, as shown in FIG. 3, the compression side damping force Tc increases primarily in proportion to the operating speed (2) due to the resistance applied to the compression side damping valve 20.

On the other hand, when the front 7 oak operates on the expansion side,
Since the main valve 5A is closed, the contracting hydraulic oil in the upper oil chamber 8 flows into the lower oil chamber 7 through the orifice 11 having an opening area al, and also pushes the damping valve 18 and flows into the oil reservoir chamber 9. The damping valve 18 is a relief spring 16
A damping force that is linearly proportional to the operating speed V is applied by the elastic restoring force of . Note that hydraulic oil is sucked into the expanding lower oil chamber 7 from the annular passage 10 via the check valve 21 of the base pulp 19 without resistance.

In this extension stroke, as the inner tube 2 rises, the amount of deflection of the suspension spring 14 and the detection spring 17 decreases, and the spring seat 15 rises relative to the damping valve 18. As a result, the relief-7 spring 16 expands, its initial load is reduced, and the elastic restoring force applied to the damping valve 18 is reduced, so that the resistance to oil passage is reduced.

Therefore, as shown in FIG. 3, the extension side fluid reduction force F' t
Even when the rising speed of the inner tube 2 is constant, it changes depending on its stroke position, and is maximum at the stroke position where the front 7 oak is most compressed.

Moreover, due to the elastic restoring force of the relief spring 16,
Since the speed-proportional characteristic of the rebound-side damping force Ft, in which the damping force increases in proportion to the rising speed of the inner tube 2, is maintained, a wide range of damping effects can be obtained in response to the speed of passage over uneven portions of the road surface.

In addition, since the damping valve 18 that opens and closes the annular passage 13 provided in the bearing 12 is freely slidably inserted into the piston rod 6, the damping valve 18 can be prevented from eccentricity of the piston rod 6 that occurs during the operation of the front fork. Smooth operability can be obtained without restricting movement and increasing sliding 7 luxidine.

Next, another embodiment shown in FIG. 4 will be described. Note that parts corresponding to those in FIG. 1 are designated by the same reference numerals as in the same figure, and their explanations will be omitted.

The base pulp 19 is provided with a check valve 21 that allows the hydraulic oil flowing into the lower oil chamber 7 from the annular passage 10 to pass therethrough without resistance during the expansion side operation.

A main valve (check valve) 5A is provided inside the piston rod 6, which opens only when the piston is overpowered and allows hydraulic oil to flow from the lower oil chamber 7 to the upper oil chamber 8. An orifice 27 is formed in the main valve 5A to constantly communicate the lower oil chamber 7 and the upper oil chamber 8.

With this structure, the hydraulic circuit for the front 7 oaks is shown in FIG.

When the front 7 oak operates overwhelmingly, the contracting hydraulic oil in the lower oil chamber 7 flows without resistance into the expanding upper oil chamber 8 via the main valve 5A because the check valve 25 is closed. , the hydraulic oil corresponding to the intrusion volume of the piston rod 6 flows into the oil reservoir chamber 9 via the damping valve 18. Therefore, as shown in FIG. 6, the compression side damping force 'rc is proportional to the operating speed (2) and changes depending on the stroke due to the resistance applied to the damping valve 18.

When the front 7 oak operates in the expansion direction, the contracting hydraulic oil in the upper oil chamber 8 flows through the orifice 27 to the lower oil chamber 7 because the main valve 5A is closed, and pushes the damping valve 18 open. and flows into the oil sump chamber 9. In addition,
Hydraulic oil flows into the expanding lower oil chamber 7 from the annular passage 10 via the check valve 25 of the base valve 19 without resistance.

Therefore, as shown in FIG. 6, the rebound-side damping force Ft is also proportional to the operating speed (■) due to the resistance applied to the damping valve 18, and changes (□) depending on the stroke, so that a wide range of damping effects can be obtained. As a result, the strong damping force prevents the inner tube 2 from bottoming out against large unevenness of the road surface, and the shaking of the vehicle body can be quickly stopped.

Next, another embodiment shown in FIG. 7 will be described. Note that parts corresponding to those in FIG. 1 are designated by the same reference numerals as in the same figure, and their explanations will be omitted.

A solenoid 31 is attached to the upper end of the inner tube 2, and a valve case 33 is attached coaxially with this solenoid 31.
A damping valve 32 housed in the damping valve 32 is disposed, and the piston rod 6 passes through the center thereof.

A passage 35 is formed through the interior of the piston rod 6, and this passage 35 is connected to the variable orifice 3 with respect to the lower oil chamber 7.
6 and opens to the upper oil chamber 8 via a boat 39. Further, the passage 35 communicates with a valve chamber 37 defined in the lower part of the valve/id 31 via a boat 38 . The valve chamber 27 is connected to the damping valve 32.
It communicates with the oil reservoir chamber 9 via.

An adjusting rod 41 of the variable orifice 36 is provided penetrating through the center of the passage 35 of the piston rod 6, and the base end of the adjusting rod 41 is screwed into the piston rod 6 and moves back and forth relative to the piston rod 6. Therefore, by inserting a screwdriver into the upper opening of the piston rod 6 and rotating the adjustment rod 41, the opening area of the variable orifice 36 can be adjusted. It is connected to a control circuit (not shown). The control circuit is used to adjust the damping force according to driving conditions, and increases the generated damping force by supplying an exciting current to the solenoid 31 during braking, high-speed driving, cornering, etc.

With this structure, the hydraulic circuit for the front 7 oaks is shown in FIG.

When the front 7 oak operates on the expansion side, the hydraulic oil in the upper oil chamber 8 that contracts in the damper 3 flows through the variable orifice 36 to the lower oil chamber 7 because the main valve 5A closes, and a part of it also flows into the lower oil chamber 7. Push open the damping valve 18 to open the oil sump chamber 9.
The rest flows from the passage 35 of the piston rod 6 to the oil sump chamber 9 via the damping valve 32. Note that hydraulic oil is sucked into the expanding lower oil chamber 7 from the annular passage 10 via the check valve 25 of the base valve 19 without resistance. In this case, when the solenoid 31 is energized, the excitation force increases the resistance that the damping valve 32 applies to the hydraulic oil, and a large damping force is generated.

When the 70 ton is operated to the pressure side, the hydraulic oil in the lower oil chamber 7, which contracts, flows from the main valve 5A into the upper oil chamber 8, which expands, because the check valve 25 is closed. A part of the hydraulic oil corresponding to the intrusion volume of the piston rod 6 flows into the oil reservoir chamber 9 from the damping valve 18, and the rest flows into the oil reservoir chamber 9 from the passage 35 of the piston rod 6 via the damping valve 32. do.

Therefore, as shown in FIG. 9, the rebound damping force F' t
and compression side damping force Tc are both proportional to the operating speed of the front 7 oak due to the resistance applied to the damping valve 18 and change depending on the stroke. The damping force increases as the excitation force increases. Further, by adjusting the opening area fil of the variable orifice 36, the extension side damping force Ft in the low speed operating range can be changed. This provides a wide range of cushioning effects depending on the road surface conditions.

(Effects of the Invention) As described above, according to the present invention, in a dual-tube front 7 oak housing a built-in damper, the damper internal oil chamber and the oil sump chamber are provided between the damper's piston rod and the bearing through which it is inserted. A damping valve that opens and closes this annular passage is slidably fitted to the piston rod, while a suspension spring and a detection spring that support the load are connected in series between the outer tube and the inner tube. The spring seat of the relief spring that biases the damping valve in the closing direction is sandwiched between the suspension spring and the detection spring, so the damping force can be varied according to the stroke of the 70-ton fork without impairing the damper function. This makes it possible to control the damping effect according to both driving conditions and operating speed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a diagram showing a hydraulic circuit, and FIG. 3 is an operating characteristic diagram showing the relationship between the piston speed and the damping force generated on the expansion side and compression. FIG. 4 is a sectional view showing another embodiment, FIG. 5 is a diagram showing a hydraulic circuit,
FIG. 6 is an operational characteristic diagram showing the relationship between the damping force generated on the expansion side and the compression side with respect to the piston speed. FIG. 7 is a sectional view showing still another embodiment, FIG. 8 is a diagram showing a hydraulic circuit, and FIG. 9 is an operating characteristic diagram showing the relationship between the damping force generated on the expansion side and the compression side with respect to the piston speed. 1... Outer tube, 2... Inner tube, 3... Damper, 4... Cylinder, 6... Piston rod, 7.8... Oil chamber, 9... Oil reservoir chamber, 11・
... Solenoid, 12... Bearing, 13... Annular passage, 14... Suspension spring, 15... Spring seat, 16... Relief spring, 17...
・Detection spring, 18... damping valve.

Claims (1)

[Claims] The inner tube is housed in the outer tube, and a piston is slidably housed in a cylinder that stands up from the outer tube, and this piston is connected to a piston rod suspended from the inner tube to form a damper. In a front fork in which a tube, an inner tube, and a cylinder define an oil reservoir chamber that compensates for the inflow and outflow of hydraulic oil corresponding to the volume that the piston rod enters, a damper is provided between the bearing fixed to the upper part of the cylinder and the piston rod. a suspension spring that forms an annular passage communicating with an internal oil chamber, opens and closes the annular passage via a damping valve slidably fitted to the piston rod, and supports a load between the cylinder and the inner tube; A front fork characterized in that a detection spring is stretched in series, and a spring seat of a relief spring that biases the damping valve in a closing direction is sandwiched between the suspension spring and the detection spring.