JPS6342012Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shock absorber for a suspension, and more particularly to a shock absorber whose damping force can be adjusted by adjusting the position of a piston rod.

The damping force of the shock absorber is determined by the speed of the piston and has nothing to do with the position of the piston, that is, the degree of expansion and contraction of the piston rod. Therefore, for example, in the case of a shock absorber installed in the suspension of a vehicle such as a truck,
The damping force when the load is small and the piston rod is extending upward, and the damping force when the load is large and the piston rod is contracting downward are:
They are the same as long as the piston speeds are the same. the result,
When the load capacity increases and the vehicle height decreases, problems such as bottoming and poor riding comfort occur.

In order to deal with the above problem, it is necessary to increase or decrease the damping force depending on the vehicle height, and there have already been many proposals based on this point of view. However, all of these methods change the effective area of an orifice or the like that allows the liquid to flow, requiring precise processing accuracy, resulting in high costs, and other problems.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a shock absorber for a suspension that can increase damping force when the vehicle height is lowered and can be manufactured at low cost.

The shock absorber of the present invention includes a cylinder filled with magnetic liquid and a piston formed of a magnetic material that is slidably disposed within the cylinder, and is designed to cause the magnetic liquid to flow in opposite directions. a piston having a lower end connected to the piston and an upper end connected to the cylinder, the piston having two sets of ports arranged in the cylinder and a coil disposed at a location capable of exerting a magnetic field on at least one set of the ports; A piston rod protruding outward from the piston rod, a switch built into the piston rod, a member built into the cylinder to activate the switch, and a coil and the switch connected to an external power source. including an electrical circuit. The switching means is actuated by retraction of the piston rod and remains activated until the piston rod extends a predetermined length.

When the piston rod is lowered, that is, the vehicle height is lowered and reaches a predetermined height, a switch means built into the piston rod is activated by a member provided in the cylinder and turned ON. As a result, a magnetic field is applied to the port, which provides resistance to the flow of the magnetic liquid and increases the damping force.

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a piston 12 is slidably disposed inside a cylinder 10, a lower end of a piston rod 14 is connected to the piston 12, and an upper end of the piston rod 14 is connected to the outside of the cylinder 10. It is a shock absorber that protrudes from the front.

In the illustrated example, the cylinder 10 is of a so-called monotube type. Therefore, inside this cylinder 10, a free piston 16 is slidably disposed below the piston 12 at a distance. Inside this cylinder 10, above the free piston 16, a magnetic liquid is filled.

The piston 12 is made of a magnetic material. Here, the term "magnetic material" means that it is not diamagnetic. Therefore, it includes paramagnetic materials and ferromagnetic materials. As shown in FIG. 2, this piston 12 has two sets of ports that allow the magnetic liquid to flow in opposite directions, namely, a port 18 that allows the magnetic liquid to flow when the piston rod 14 is extended, and a port 18 that allows the magnetic liquid to flow in opposite directions.
It has a port 20 that allows the magnetic liquid to flow when it contracts. A plurality of ports are provided in the circumferential direction of the piston 12. The piston 12 also has a port 18
and a coil 22 that applies a magnetic field to the port 20. This coil 22 magnetizes the magnetic liquid flowing through the ports 18 and 20, and determines its installation location and winding direction so that a force acts on the magnetic liquid in a direction opposite to the flowing direction of the magnetic liquid.

A leaf spring valve body 24 for opening and closing the port 18 is disposed below the piston 12, and constitutes a valve that generates a damping force when the piston rod is extended. Further, a leaf spring valve body 26 for opening and closing the port 20 is arranged above the piston 12, and constitutes a valve that generates a damping force when the piston rod is compressed.

A switching means 28 is incorporated into the piston rod 14. On the other hand, a member 30 for activating the switch means 28, that is, turning it ON, is incorporated into the cylinder 10. In the illustrated example, the switch means 2
8 is a reed switch, and member 30 is a bar magnet. This member 30 is arranged within the cylinder 10. The positions of the switch means 28 and the member 30 are such that when the piston rod 14 reaches a predetermined depth, the switch means 28 is turned ON, and when the piston rod 14 is fully extended, the piston 1
2 will not interfere with other members.

Electric circuit 32 includes coil 22 and switch means 28
and are connected to an external power source 34. This electrical circuit 32 incorporates a self-holding circuit for the switch means 28, as shown in FIG. That is, a switch 36 is provided which is turned on by the piston rod 14 when the piston rod 14 moves upward a predetermined distance from the position where the switch means 28 is turned on, thereby energizing and demagnetizing the relay _R1 . Switching means 2 switches the a contact of this relay _R1 .
8 to excite and demagnetize the relay R ₂ , self-hold by the a contact of the relay R ₂ , and connect the coil 22 and the power source 34 .

When the vehicle installed with the shock absorber has a large load, the piston rod 14 is contracted and the vehicle height is lowered, and when the switch means 28 reaches the position of the member 30, the switch means 28 is turned on. At this time, since the switch 36 is separated from the piston rod 14, the relay _R1 is energized, and the switch means 28 is turned ON, so that the relay _R2 is energized, and the switch means 28 is self-held. Therefore, as long as the installation position of the switch 36 is determined so that even if the vehicle bounces or rebounds in this position, the switch 36 will not turn on, the relay will not turn on.
R ₂ remains energized and conducts current from power supply 34 to coil 22 .

When current from power source 34 flows through coil 22,
A magnetic field is generated in the ports 18, 20, which exerts an opposing force on the magnetic liquid flowing through the ports 18, 20, increasing the damping force.

Next, the load capacity of the vehicle decreases, the piston rod 14 moves upward, and the switch 36 is turned ON.
, relay R ₁ demagnetizes and at the same time relay R ₂
Also demagnetizes. Therefore, no current is supplied to the coil 22, and only the original damping force due to the magnetic liquid flowing through the ports 18, 20 is generated.

In the above example, since the cylinder 10 is a monotube type, the piston 12 is equipped with valves that generate damping force when the piston rod is extended and retracted, and the ports 18 and 20 are magnetized by the coil 22. ing. Instead, when the cylinder 10 is of a so-called twin-inch tube type configured with an inner cylinder and an outer cylinder arranged radially outward of the inner cylinder, the inner cylinder is A valve is installed at the bottom of the cylinder to generate a damping force when compressed. Therefore, in this case, only the port 18 of the piston is magnetized by the coil 22, and the port of the valve at the bottom of the inner cylinder is magnetized by a similar configuration.

According to the present invention, the damping force can be automatically increased depending on the degree of reduction of the piston rod, that is, the degree of reduction of the vehicle height, so bottoming does not occur. Furthermore, when the vehicle height is high, the damping force can be set low, improving ride comfort. Furthermore, since the present invention utilizes a combination of magnetic liquid and a coil, it is inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing a shock absorber according to the present invention, FIG. 2 is an explanatory view systematically showing the main parts, and FIG. 3 is a circuit diagram of self-holding of the switch means. 10: cylinder, 12: piston, 14: piston rod, 18, 20: port, 22: coil, 28: switch means, 30: member, 32: circuit, 34: power source.

Claims (1)

[Scope of utility model registration request] A cylinder filled with a magnetic liquid, a piston formed of a magnetic material slidably disposed within the cylinder, and two sets of ports provided to flow the magnetic liquid in opposite directions. a piston having a coil located at a location capable of exerting a magnetic field on at least one set of said ports; and a piston rod connected to said piston at one end and having another end projecting outwardly from said cylinder. , a switch means built into the piston rod, a member built into the cylinder for activating the switch means, and an electric circuit connecting the coil and the switch means to an external power source; A shock absorber for a suspension, wherein the switch means is activated by the contraction of the piston rod and is maintained in the activated state until the piston rod is extended by a predetermined length.