JPS6218776B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a hydraulic shock absorber that generates damping force by applying resistance to the flow velocity of a piston as the piston expands and contracts. This invention relates to a hydraulic shock absorber equipped with a damping force adjustment device that can be arbitrarily adjusted from the above.

Conventionally, in this type of hydraulic shock absorber, in order to arbitrarily adjust the magnitude of the damping force, a damping valve is installed and the adjustment is made from the outside, but this method requires the use of a complicated mechanism and a large number of parts. It didn't happen.

The present invention fundamentally changes these conventional problems and seeks to provide a device that is simple and works reliably. An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the damping force adjusting device of the present invention. In the figure, a piston 3 fitted to the tip of a hollow piston rod 2 is slidably fitted into a damper case 4 filled with a magnetic fluid that is a mixture of oil and magnetic material, and the piston rod 2 is inserted into the damper case 4. This is a hydraulic shock absorber with a coil spring 6 stretched between the installation base 5 and the damper case, and the piston 3
Damping force is obtained in the compression stroke or extension stroke by oil holes 7, 8 provided in the cylinder and valve mechanisms 9, 10. On the other hand, the rod pipe 11 protruding from the center of the upper part of the damper case 4 is inserted into the hollow part 2a of the piston rod 2, and a diameter-reducing step 3a is provided in a part of the piston 3 to create a gap between the rod pipe 11 and the diameter-reducing step 3a. A suitable gap 12 is provided between the damper case 4, the piston 3, and the rod pipe 11 to form a magnetic circuit. An electromagnetic coil 13 is provided in a part of the magnetic circuit, for example, at the root of the rod pipe 11. Additionally, there is an oil passage that communicates from the lower oil chamber A to the upper oil chamber B of the damper case 4 via the oil hole 14 provided in the piston rod 2 and the gap 12, and the damper case as shown in the enlarged view of FIG. The upper oil chamber B is communicated with the upper end of the rod pipe 11 by an oil passage 15 provided in the oil passage 1.
For example, a ball 16a and a spring 16 are provided in the oil chamber 5 to allow flow from the oil chamber B to the rod pipe 11 and prevent reverse flow.
Install the check valve 16 consisting of b. In addition, 17 is a separate tank, and a diaphragm 17a
The oil chamber C is divided into an oil chamber C and a gas chamber D through the
is communicated with the upper oil chamber B of the damper case 4 via a flexible pipe 18, and the expansion and contraction of the piston rod 2 absorbs and discharges oil corresponding to the change in volume within the damper case 4.

Next, its operation will be explained.

During the compression stroke of the shock absorber, the inside of the oil chamber B is compressed and becomes high pressure, but a portion of the pressure is absorbed into the oil chamber C of the tank 15. However, since the rod pipe 11 enters the hollow portion 2a of the piston rod 2, the pressure inside the hollow portion 2a becomes higher. Therefore, the check valve 16 from the rod pipe 11 to the oil passage 15 is pushed up by the magnetic fluid, and the oil passage 15 to the oil chamber B is closed. Therefore, the magnetic fluid in the hollow part 2a flows into the oil chamber B through the gap 12, and at the same time the magnetic fluid flows into the valve mechanism 1.
0 is seated due to the internal pressure of oil chamber B, so oil chamber B
The magnetic fluid pushes open the valve mechanism 9 from the oil hole 7 and flows into the lower oil chamber A, and a buffering effect is performed between the two.

In this case, if the electromagnetic coil 13 is energized from the outside, the strength of the magnetic field in the gap 12 will increase depending on the magnitude of the energization, and therefore the viscosity of the magnetic fluid flowing in the gap 12 will also increase, and the damping force will also increase. .
That is, the damping force can be adjusted.

On the other hand, during the extension stroke, the pressure inside the oil chamber B becomes negative, and some of the oil is replenished from the oil chamber C of the tank 17, but since the rod pipe 11 is pulled out from the inside of the hollow section 2a, the inside of the hollow section 2a is The pressure becomes more negative.
Therefore, as shown in FIG. 2, the check valve 16 opens and the magnetic fluid in the oil chamber B flows into the hollow part 2a from the rod pipe 11 through the oil passage 15, and the buffering effect in the gap 11 is not performed. Not possible. However, the valve mechanism 9 in the piston 3 is seated due to the internal pressure of the oil chamber A, and therefore the magnetic fluid in the oil chamber B pushes open the valve mechanism 10 through the oil hole 8 and flows into the lower oil chamber B. That is, the damping force is not adjusted during the extension stroke.

FIG. 3 shows another embodiment of the invention in which, contrary to the previous embodiment, the damping force is made variable only during the extension stroke. That is, the check valve 16' is installed in the opposite direction from that of the first embodiment. Since its operation is completely opposite to that of the first embodiment, its explanation will be omitted.

As described above in detail, the present invention has an extremely simple configuration and has the effect of reliably adjusting the damping force in only one direction from the outside.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the damping force adjusting device of the present invention, FIG. 2 is an enlarged view of the main part thereof, and FIG. 3 is an enlarged sectional view of the main part showing another embodiment of the present invention. 1...Hydraulic shock absorber, 2...Piston rod, 2
a...Hollow part, 3...Piston, 3a...Reduced diameter step part, 4...Damper case, 6...Coil spring,
7, 8... Oil hole, 9, 10... Valve mechanism, 11...
Rod pipe, 12... Gap, 13... Electromagnetic coil, 14... Oil hole, 15... Oil path, 16, 16'
...Check valve, 17...Tank, A, B,
C...Oil chamber, D...Gas chamber.

Claims (1)

[Claims] 1. A piston equipped with a valve mechanism at the tip of a hollow piston rod that generates a damping force during expansion and compression is slidably fitted into a damper case filled with magnetic fluid, while the piston is made to protrude from inside the damper case. inserting a rod pipe into the hollow part of the piston rod, and forming a magnetic circuit between the damper case, the piston, and the rod by creating a gap between the rod pipe and the diameter-reducing step by a diameter-reducing step provided in a part of the piston; A part of the damper case is equipped with an electromagnetic coil, and has an oil passage that communicates from the lower oil chamber of the damper case to the upper oil chamber through the oil hole provided in the piston rod and the gap, and a check valve from the upper oil chamber to the damper case. An oil passage leading to the upper end of the rod pipe is provided through a passage inside the rod, and the strength of the magnetic field in the gap between the piston part and the rod is changed by the current flowing through the electromagnetic coil, thereby controlling the viscosity of the magnetic fluid flowing through the gap. A damping force adjustment device for a hydraulic shock absorber characterized by changing the damping force in one direction only.