JPS6221165Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to an improvement in a damping force adjustment mechanism for a hydraulic shock absorber that adjusts the pull-side damping force of the shock absorber.

In general, a hydraulic shock absorber generates a damping force due to the flow resistance generated when the hydraulic oil sealed inside passes through orifices, valves, etc. as it expands and contracts, effectively absorbing external shocks and vibrations. It absorbs and relaxes.

By the way, in such a hydraulic shock absorber, if the opening area of the orifice, valve, etc. is constant,
The damping force with respect to the operating speed (operating stroke) always takes a constant value.

However, for this type of hydraulic shock absorber,
It is desirable to adjust the generated damping force as necessary to obtain the optimum damping force for the conditions at that time. Therefore, as a mechanism for adjusting this damping force, for example, an adjusting plate with a plurality of orifices of different diameters is provided at the tip of a hollow rod, and the plate is rotated by rotating the rod fitted in the hollow rod. , one that changes the area of the oil passage inside the hollow rod has been proposed. That is, this type of adjustment mechanism adjusts the damping force by changing the flow path area of the hydraulic oil, and the damping force characteristics obtained by this type of mechanism are illustrated as shown in FIG. 5. In Fig. 5, the horizontal axis is the piston operating speed, the vertical axis is the damping force, and the flow path area (throttle ratio) is shown as a parameter. The area is getting smaller.

As is clear from FIG. 5, the damping force increases over the entire operating speed range as the flow path area is reduced.

However, particularly in the case of hydraulic shock absorbers for vehicles, there is a desire to adjust the damping force in the high operating speed range without significantly changing the magnitude of the damping force in the low piston operating speed range. In addition, hydraulic shock absorbers are often used in harsh environments where dust, foreign objects, muddy water, etc. are present, such as for vehicles, and the mechanism that performs their adjustment must be one that guarantees long-term adjustment function under such environments. It is desired that

The present inventor created the present invention in response to such a request, and its purpose is to apply the set load of the adjuster spring stretched between the pull side check valve and the push rod to the end of the push rod. Changes are made by rotating a cam shaft with a cam in contact with it and moving the push rod up and down,
The tensile damping force of the shock absorber remains unchanged in the low operating speed range and can be adjusted arbitrarily in the high operating speed range, and the camshaft is placed in a closed space to protect it from dust, foreign matter, etc. An object of the present invention is to provide an adjustment mechanism for a hydraulic shock absorber that can guarantee its adjustment function for a long period of time in an environment where muddy water or the like exists.

A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional side view of a hydraulic shock absorber equipped with an adjustment mechanism according to the present invention, FIG. 2 is a plan view of a check valve, and FIG. 3 is a sectional view taken along the line 3-3 in FIG.

In FIG. 1, numeral 1 is a cylinder, inside which a hollow rod 2 faces from below, and a piston 3 is connected to the upper part of the rod 2 as shown. The piston 3 is slidably fitted into the inner peripheral portion of the cylinder 1, and divides the inside of the cylinder 1 into an upper working chamber _S1 and a lower working chamber _S2 . and cylinder 1
The lower part of the rod 2 is closed by a guide member 4, and an oil seal 5 fitted into the guide member 4 allows the rod 2 to slide in an oil-tight and air-tight manner. Note that the upper and lower working chambers S ₁ and S ₂ are filled with hydraulic oil, and the upper working chamber S ₁ communicates with a sub-tank (not shown) via a conduit 6.

In addition, the piston 3 has push-side oil passages 7 vertically extending through the piston 3 at multiple locations around the circumference to allow hydraulic oil to flow only when the shock absorber operates on the push side, and a plurality of push-side oil passages 7 are provided on the lower surface of the piston 3 to block these push-side oil passages 7. A push-side check valve 8 is provided which is constructed by overlapping elastic metal plates. On the other hand, the piston 3 has a pull-side oil passage 9 that allows hydraulic oil to flow only when the shock absorber operates on the pull-side.
..., 10... are formed, one oil passage 9... is provided so as to communicate the upper and lower working chambers _S1 , _S2 , and these oil passages 9... are formed on the upper surface of the piston 3.
A pull-side check valve 11 made of a plurality of elastic metal plates is provided to close the rod 2, and the other oil passage 10...
It communicates with the hollow part 2a of the rod 2 via.

On the other hand, as shown in the figure, a valve case 13 is screwed onto the upper end of the hollow rod 2 that protrudes upward from the upper end surface of the piston 3. A valve seat 14 is fixedly installed, and a pull-side check valve 15 made of a single metal plate is seated on the upper surface of the valve seat 14 under the elastic force of a valve spring 16. This check valve 1
5 has semicircular notches 15a at multiple locations (four locations in this embodiment) on the outer periphery, as shown in FIG.
Further, the lower surface side of the check valve 15 receives the elastic force of an adjuster spring 18 stretched between the valve 15 and the upper end step of a push rod 17 which is fitted into the hollow portion 2a of the rod 2 so as to be able to slide vertically. ing. The elastic force of the adjuster spring 18 is smaller than that of the valve spring 16, so that under normal conditions, that is, when the shock absorber is not in operation, the valve 15
is seated on the seat 14 with the upper surface receiving the difference in elasticity between the two 16 and 18. The outer periphery of the lower end 17a of the push rod 17 is tightly fitted into the hollow portion 2a of the rod 2 via a seal ring 19, and the other portion is loosely fitted with a gap provided between the push rod 17 and the hollow portion 2a.

By the way, a stopper 20 and a mounting member 21 are screwed to the lower end of the hollow rod 2, and a stopper lever 22 is provided on the upper surface of the stopper 20. A space S is formed inside the mounting member 21, and a hole 23 with one side open to the outside is formed from the lateral direction of this 21 so as to be orthogonal to the space S, and a camshaft 24 and an adjuster 25 are arranged.

The camshaft 24 has a truncated conical cam 24a approximately in the center thereof, and its large diameter base 24b has a threaded portion on its outer periphery to be screwed into the mounting member 21, and the small diameter rod portion 24c has an adjuster. 25, and both 24 and 25 are integrally pin-engaged by a spring pin 26. on the other hand,
The large diameter part 25a of the adjuster 25 is fitted into the hole 23, and the small diameter end 25b is tightly fitted to the inner circumference of the bush 27 fitted in the hole 23 via a seal ring.
In addition, they are rotatably fitted, and the space S is closed off from the outside due to this structure. Further, as shown in FIG. 3, a plurality of semicircular grooves 28 (eight in the illustrated example) are formed in the outer periphery of the large diameter portion 25a in the axial direction. A ball 31 that is constantly pressed downward by a spring 30 housed in the vertical hole 29 is engaged with the ball 31 . The lower spherical portion of the push rod 17 is abutted and engaged with the cam 24a of the camshaft 24.

Further, spring seats 32 and 33 are fixed to the outer periphery of the cylinder 1 and the stopper 20, and a cushion spring 34 is stretched between these spring seats 32 and 33 as shown.

When the shock absorber constructed in this way is used for a vehicle, for example, the upper end of the cylinder 1 is connected to the vehicle body side, the lower end of the rod 2 is connected to the wheel side via the mounting member 21, and the cylinder 1 and the rod 2 are connected to each other. is constructed so as to move relative to each other.

Next, the function of this shock absorber will be explained.

First, when the shock absorber is operated on the pull side, when the cylinder 1 moves upward with respect to the rod 2, the volume of the lower working chamber _S2 of the cylinder 1 decreases, and the hydraulic oil in the chamber _S2 decreases. Pressure increases. Therefore, an amount of hydraulic oil corresponding to this volume reduction flows from the lower working chamber _S2 into the upper working chamber _S1 , but in the region where the piston operating speed with respect to the cylinder 1 is low, most of this hydraulic oil is The oil flows into the upper working chamber _S1 through one of the oil passages 9 and the valve 11, and therefore, in this low speed range, the pull-side damping force changes according to a single curve E as shown in FIG.

Next, when the piston operating speed increases, the pressure of the hydraulic oil in the lower working chamber _S2 increases, and eventually a portion of this hydraulic oil acts on the upper surface of the check valve 15 and the valve spring 16 and adjuster spring 1.
The check valve 15 is pushed up against the set load difference of 8, and the water flows from there into the upper working chamber _S1 . If the start point of the check valve 15 is _K1 in FIG. 4, for example, the pull-side damping force generated by the entire shock absorber is the sum of the damping forces generated by the valves 11 and 15, which is the above-mentioned K Changes according to curve A, which bends from _one point.

Then, by rotating the adjuster 25 by a predetermined amount and moving the camshaft 24, which rotates together with the adjuster 25, to the right (in the direction of the arrow) in FIG. The matching push rod 17 moves downward, and the set load on the adjusting spring 18 becomes lower. As a result, the force pressing the check valve 15 from above toward the seat 14 increases, and therefore, as shown in _FIG . The generated damping force increases and changes according to curve B.

Further, by rotating the adjuster 25 and moving the cam 24a to the right, the check valve 1 is opened in the same manner as described above.
The operation starting point of 5 shifts to the high speed side at K ₃ and K ₄ ,
The generated damping force also changes according to curves C and D.

In this way, the pull side damping force of the shock absorber remains unchanged in the low operating speed range and can be arbitrarily adjusted in the high operating speed range. Further, the bush 27 fitted in the hole 23 serves as a stopper against rightward movement of the camshaft 24 due to rotation of the adjuster 25, and prevents the adjuster 25 from protruding in the radial direction.
Furthermore, due to such rotation, the large diameter base 2 of the camshaft 24
Although the threaded portion provided on the outer periphery of 4b is exposed in the space S, the space S is closed from the outside by the adjuster 25, and the threaded portion is not directly exposed to external dust or the like.

Although the pull-side operation of the shock absorber has been described above, the push-side operation is performed in exactly the same manner as in the conventional case. That is, if the cylinder 1 moves downward relative to the rod 2, the upper working chamber
The hydraulic oil in _S1 flows into the lower working chamber _S2 through the oil passage 7 and the check valve 8, and the flow resistance when the hydraulic oil passes through the valve 8 generates the required damping force.

As is clear from the above explanation, according to the present invention, the set load of the adjusting spring stretched between the pull side check valve and the push rod is changed by the vertical movement of the push rod, so that Not only can the damping force be kept unchanged in the low operating speed range and can be adjusted arbitrarily in the high operating speed range, but the adjuster can also be used to fill the space where the threaded portion of the large diameter base of the camshaft is exposed when the camshaft rotates. Since the threaded portion is protected by closing, its adjustment function can be guaranteed for a long period of time in an environment where dust, foreign matter, muddy water, etc. are present.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a vertical sectional side view of a hydraulic shock absorber equipped with an adjustment mechanism according to the present invention, FIG. 2 is a plan view of a check valve, and FIG. 3-3 line sectional view, FIG. 4, and FIG. 5 are damping force characteristic diagrams. In the figure, 1 is a cylinder, 2 is a hollow rod, 3 is a piston, 7, 9, 10 are oil passages, 8, 11, 15 are check valves, 13 is a valve case, 14 is a valve seat, 16 is a valve spring, 17 is push rod, 18 is adjustable spring, 2
1 is a mounting member, 24 is a camshaft, 24a is a cam, 2
5 is an adjuster, S ₁ is an upper working chamber, and S ₂ is a lower working chamber.

Claims (1)

[Scope of utility model registration request] A piston is slidably fitted into the cylinder, and the other end of the hollow rod with the piston fixed to one end extends out of the cylinder, and a mounting member is tied to the end. An oil hole communicating with the oil passage inside the piston is bored in the peripheral wall to configure the inside of the rod as an oil passage, and a check valve pressed by a spring is disposed in the oil passage inside the rod, and a push rod is inserted into the hollow rod. In the hydraulic shock absorber, the mounting member is provided with a vertical recess in the extending direction of the hollow rod; Further, a lateral recess having an opening to the outside on one side is provided perpendicularly to the vertical recess, and a central cam and the mounting member are rotatably screwed into the lateral recess. A camshaft having a large-diameter base at one end and a small-diameter rod at the other end, an adjuster coupled to the small-diameter rod and closing the opening, and a cam of the camshaft that is connected to the push rod. A damping force adjustment mechanism for a hydraulic shock absorber, characterized in that the end portions are abutted and engaged.