JPH043143Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to a steering damper, and more specifically, the invention relates to a steering damper that generates a large damping force for small amplitude vibrations and substantially reduces the damping force for large amplitude movements. Regarding the steering damper that does not occur.

(Prior Art) In order to suppress minute vibrations of the steering wheel in the circumferential direction while the vehicle is running, a steering damper is sometimes installed in parallel to the steering device. This steering damper must satisfy the contradictory requirements of damping minute vibrations while not making the steering heavier.

As a steering damper used for the above purpose, for example, the diameter of the part of the cylinder corresponding to the micro-vibration range of the piston is reduced to make it a narrow part so that the piston can slide, and the part of the cylinder outside of this narrow part is expanded. There is something formed.

(Problem to be solved by the invention) In order to prevent liquid leakage between the piston and cylinder of a steering damper, a resin ring, rubber O-ring, or other piston ring is generally attached to the piston. The piston ring elastically expands when the piston moves out of the constriction when the steering wheel is rotated to turn the vehicle. As a result, after the end of a turn, a force is required to contract the piston ring radially inward, which prevents the steering wheel from automatically returning and makes the return process worse.

An object of the present invention is to provide a steering damper that does not use a piston ring and does not substantially cause liquid leakage when generating damping force.

(Means for Solving the Problem) The steering damper according to the present invention includes a cylindrical piston connected to a piston rod and through which liquid flows freely, and a damping force generating port through which liquid flows when the piston rod expands and contracts. an auxiliary piston made of metal and disposed inside the piston; a cylindrical cylinder movably housing the piston; attached to the inner periphery of the cylinder; A cylindrical insert disposed radially outward of the piston, the insert having an inner circumferential surface having a first straight surface at an intermediate portion and a pair of tapered surfaces extending in a divergent shape from the straight surface toward both ends. including. The outer peripheral surface of the piston is
When the piston is in the neutral position, a second straight surface in the intermediate portion facing the first straight surface with an annular gap from the first straight surface, and a second straight surface at both ends from the second straight surface. a pair of guide surfaces extending in a tapered manner toward the piston, and the size of the gap and the axial length of the piston are formed such that liquid leakage through the gap does not substantially occur; At least one of the inserts is made of a resin with a low coefficient of friction.

(Example) The steering damper 10 is shown in FIGS.
As shown in the figure, there is a cylindrical piston 12, a cylindrical cylinder 14, and a cylindrical insert 16, each of which has an inner circumferential surface 17 that extends from a straight surface at the intermediate portion and from the straight surface toward both ends. The insert 16 has a pair of tapered surfaces extending in a shape.

The piston 12 partitions the inside of the cylinder 14 into two liquid chambers A and B, and is made of a resin with a low coefficient of friction or by coating the outer peripheral surface 18 with a resin with a low coefficient of friction. Ru. piston 12
The outer circumferential surface 18 of the insert 16 extends from the straight surface of the insert 16 into an annular shape when the piston 12 is in the neutral position, that is, when the steering damper 10 is installed in a steering device of an automobile and the steering wheel is not rotated at all. An intermediate straight surface 19 facing the straight surface with a gap C therebetween, and a straight surface 1
It has a pair of guide surfaces 21 that extend in a tapered manner from 9 toward the end surface 20.

In the illustrated embodiment, the guide surface 21 is formed as a curved surface that is convexly curved from the straight surface 19 toward the end surface 20 . The guide surface 21 ensures smoothness when the piston 12 moves in and out of the insert 16, and eliminates catching on the tapered surface of the insert 16, and is most preferably a curved surface like this. .

The size h of the gap C and the axial length L of the piston are such that liquid leakage through the gap C does not substantially occur. Here, "substantially no liquid leakage" means that even if there is liquid leakage, the amount of liquid flowing through the port of the auxiliary piston, which will be described later, is
This means that the amount of liquid leakage is small, and is so small that it does not affect the damping force generated by the liquid flowing through the port.

Gap C between piston 12 and insert 16
The leakage flow rate Q of the liquid from the piston 12 is given by Q=πDh ³ /12μL×P, where D is the outer diameter of the piston 12, μ is the viscosity coefficient of the liquid, and P is the differential pressure between the liquid chambers above and below the piston 12. . Therefore, by making the size h of the gap C as small as possible and increasing the length L of the piston 12 as much as possible, the sealing performance is improved and liquid leakage through the gap is substantially prevented. It can be eliminated. This makes it possible to omit conventional piston rings.

The piston 12 integrally has a partition part 22 in the center. The end portion 2 of the piston rod 24 is attached to the partition portion 22.
The piston 12 and the piston rod 24 are connected by passing a washer 26 through the end 25 and screwing a nut 28.

The piston 12 has a port 30 in the partition 22. The port 30 is connected to an auxiliary piston 60 which will be described later.
The diameter of the piston rod 24 is sufficiently large compared to that of the piston rod 24 to allow liquid to flow freely when the piston rod 24 expands and contracts.

The insert 16 is separate from the cylinder 14.
It is formed of an elastically deformable material such as a resin with a low coefficient of friction, and is attached to the cylinder 14 . In the illustrated embodiment, the insert 16 has a convex portion 40 on its outer circumferential surface that extends all around the circumference. The length of the straight surface of the inner circumferential surface 17 of the insert 16 in the axial direction is approximately equal to the length L of the piston 12.

The cylinder 14 is provided with a groove 42 extending all around the circumference, and the protrusion 40 of the insert is fitted into the groove 42, so that the insert 16 is attached to the cylinder 14. The position of groove 42 in cylinder 14 is such that when piston 12 is in the neutral position, insert 16
center in the axial direction.

An auxiliary piston 60 is arranged inside the piston 12. The auxiliary piston 60 is made of iron or other metal, and is connected to the piston rod 24 together with the piston 12.
a port 62 through which liquid flows when 4 is extended;
A port 64 through which liquid flows during contraction is provided. A valve body 34, a spacer 36, and a stopper 38 are arranged in this order above the auxiliary piston 60, and an O-ring 66 is attached to the outer periphery of the auxiliary piston 60. Furthermore, a spacer 68 is arranged below the auxiliary piston 60, and the auxiliary piston 60 is connected to the piston 12.
It is fitted with.

When the piston 12 is molded from resin, there is a risk that the peripheral edge portion will be damaged by the force acting on the peripheral edge of the port 30 during use, and the possibility of such damage increases as the diameter of the port 30 becomes smaller. In the present invention, the diameters of the ports 62 and 64 provided in the metal auxiliary piston 60 are made small, and while these ports contribute to the generation of damping force, the diameter of the port 30 of the piston 12 can be made sufficiently large, which prevents damage. It is possible to prevent fluctuations in damping force caused by Further, as the auxiliary piston 60, a ready-made one for a steering damper can be used, and mass production is possible.

A base valve 44 having a valve mechanism similar to the valve mechanism of the piston 12 and a rubber tank 46 filled with air are arranged in the cylinder 14. The piston rod 24 is then projected to the outside through a rod guide 48 and an oil seal 50 arranged at the open end of the cylinder 16.

The steering damper 10 is connected to the piston rod 2
4, attach the dust cover 52 to the eyes 54, 5.
6 is used by attaching it to a steering device, for example, a rack bar and a vehicle body.

When a car is running at high speed, when minute vibrations are applied to the rack bar, the piston 12 and cylinder 14
At this time, there is substantially no liquid leakage from the gap C between the outer peripheral surface 18 of the piston 12 and the inner peripheral surface 17 of the insert 16, and the cylinder 14
The liquid filled inside flows through the ports 62 and 64 of the auxiliary piston 60 as shown by solid and dotted arrows, respectively, and generates a damping force.

During steering, the piston 12 is removed from the insert 16, so no damping force is generated and the steering becomes lighter.

(Effects of the invention) Since there is no piston ring and there is a gap between the piston and the insert, the sliding performance of the piston can be improved. In addition, when a piston band is attached to a piston, liquid leakage occurs due to the piston band vibrating during minute vibrations, but in this invention, there is no piston band, so there is no room for such liquid leakage to occur. .

Because there are no piston rings, there is nothing to expand radially when the piston is removed from the insert, so when the steering wheel returns,
Since no force is required to compress the steering wheel in the radial direction, the return of the steering wheel can be maintained well.

The presence of a tapered guide surface at the end of the outer circumferential surface of the piston, while the diverging tapered surface at the end of the inner circumferential surface of the insert allows the piston to enter the insert smoothly.

Since at least one of the piston and the insert is made of resin with a low coefficient of friction,
Even if the piston swings and hits the insert when it moves, smooth movement of the piston can be ensured. Thereby, the gap between the piston and the insert can be made sufficiently small.

Since the insert and cylinder are formed separately, processing time and processing costs can be reduced compared to creating a diameter-reduced portion in the cylinder, and mass production is possible. Furthermore, when grooves are formed on the cylinder by cutting, even if chips or burrs remain attached to the cylinder, the insert is attached to the cylinder, so there is no risk of the piston getting caught in the burrs during steering.

Since the metal auxiliary piston is equipped with a port that contributes to the generation of damping force, even if the piston is made of resin, the diameter of the port provided on the piston can be increased, preventing damage to the peripheral portion of the piston port. , it is possible to prevent the occurrence of a situation such as a fluctuation in damping force due to this damage.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing essential parts of a steering damper according to the present invention, and FIG. 2 is a sectional view of the steering damper. 10... Steering damper, 12... Piston, 14... Cylinder, 16... Insert, 1
7... Inner circumferential surface, 18... Outer circumferential surface, 20... Guide surface, 24... Piston rod, 60... Auxiliary piston.

Claims (1)

[Scope of utility model registration request] The auxiliary piston is made of metal and has a cylindrical piston that is connected to the piston rod and allows liquid to flow freely, and a port for generating damping force through which the liquid flows when the piston rod expands and contracts. An auxiliary piston disposed inside, a cylindrical cylinder movably housing the piston, and a cylindrical insert attached to the inner periphery of the cylinder and disposed radially outward of the piston. an insert having an inner circumferential surface having a first straight surface at an intermediate portion and a pair of tapered surfaces extending from the straight surface in a divergent shape toward both ends; At some point, a second straight surface in the intermediate portion faces the first straight surface with an annular gap from the first straight surface, and a second straight surface extends in a tapered shape from the second straight surface toward both ends. a pair of guide surfaces, the size of the gap and the axial length of the piston are formed such that liquid leakage through the gap does not substantially occur, and at least one of the piston and the insert A steering damper made of resin with a low coefficient of friction.