JPS59738Y2 - oil dart pot - Google Patents

Description

[Detailed description of the invention] As shown in Fig. 1, a conventional oil dashpot has oil sealed in a cylinder b made of a non-magnetic material whose upper opening is hermetically closed with a lid a made of a magnetic material. A plunger C made of a magnetic material is slidably housed in the cylinder b, a spring d is elastically loaded between the lid a and the plunger C, and one end is fixed to the outer circumferential side of the middle part of the cylinder b. The base end of a flat plate-shaped movable iron piece f is pivotally supported on the other end of the yoke e that is attached, the free end side surface of the movable iron piece f is opposed to the outer surface of the lid body a, and the free end side surface of the movable iron piece f is attached to the lid body a. It is equipped with a return spring g that acts in a direction to pull it away from the outer surface of the cylinder b, and a coil h is wound around the upper end of the outer circumferential shell of the cylinder b. Due to the magnetic flux generated by the plunger C, the plunger C moves very slowly toward the lid C side, and then the plunger C comes into contact with the lid body a, and the magnetic resistance to the magnetic flux created by the overcurrent flowing through the coil h decreases, and the above-mentioned As the magnetic flux increases, the free end of the movable iron piece f is attracted to the outer surface of the lid body a, and an overcurrent in the coil h can be detected by the movement of the movable iron piece f.

However, when the plunger C comes into contact with the lid a so that the side surface of the free end of the movable iron piece f is attracted to the outer surface of the lid a, the lid a protrudes from the upper end of the coil h.

Therefore, the lid body a has an outer surface as a movable iron piece f, and an end surface a'
are opposed to the yoke e and the surface support parts el and fl of the movable iron piece f, respectively, and the magnetic flux from the lid body a is transferred from the original outer surface to the movable iron piece f.
In addition to passing through the free end of the movable iron piece f, it also flows from the end a1 to the surface support ends el and fl as leakage magnetic flux as shown by the arrow, and the original attractive force is the movable iron piece f.
There was a drawback in that there was a loss in the force of suctioning the free end side surface of the lid body a to the outer surface of the lid body a.

The present invention is intended to eliminate the above-mentioned drawbacks of the conventional technology, and the embodiments of the present invention will be explained below with reference to the drawings. The cylinder 1 is made of a solid body, and silicone oil or other oil is sealed inside the cylinder 1.

A plunger 3 is made of a magnetic material and is housed in the cylinder 1 so as to be slidable therein.

4 is a spring that is elastically loaded between the lid body 2 and the plunger 3; 5 is a movable iron piece whose base end is pivoted to the other end of a yoke 6 whose one end is fixed to the outer peripheral side of the middle part of the cylinder 1; The tip end surface of the salient magnetic pole 5a provided protruding from the side surface is opposed to the outer surface of the lid body 2.

Reference numeral 7 denotes a return spring that is elastically loaded to act in a direction to pull the tip end surface of the salient magnetic pole 5a away from the outer surface of the lid body a, and 8 is a coil that is wound around the outer circumferential body of the upper end of the cylinder 1, the upper end of which is attached to the lid body a. The outer surface of the lid body a, which protrudes from the body a, is designed to fit within the inner peripheral body of the coil 8.

The present invention has the above-mentioned configuration, and when an overcurrent of a certain level or more flows through the coil 8, the plunger 3 moves against the viscous resistance of the coil and the spring force of the spring 4 due to the magnetic flux created by the overcurrent flowing through the coil 8. The plunger 3 moves slowly toward the lid 2, and finally comes into contact with the lid 2, and the magnetic resistance to the magnetic flux created by the overcurrent flowing through the coil 8 decreases, and the magnetic flux increases, causing the movable iron piece 5 to protrude. The tip end surface of the magnetic pole 5a is attracted to the outer surface of the lid 2, and the coil 8 is moved by the movement of the movable iron piece 5.
can detect overcurrent.

When the plunger 3 comes into contact with the lid 2 so that the tip surface of the salient magnetic pole 5a of the movable iron piece 5 is attracted to the outer surface of the lid 2, the upper end of the coil 8 protrudes from the outer surface of the lid 2. Since the outer surface of the lid 2 is located within the inner circumferential shell of the coil 8 and the tip surface of the salient magnetic pole 5a of the movable iron piece 5 faces the outer surface of the lid 2, overcurrent flowing through the coil 8 is prevented. The leakage invalid portion of the generated magnetic flux acts as an attractive force of the plunger 3 and is used as a salient magnetic pole 5a.
Therefore, the suction force that attracts the tip end surface of the salient magnetic pole 5a of the movable iron piece 5 to the outer surface of the lid body 2 increases accordingly.

Furthermore, the equivalent magnetic circuit of the oil dash pot is the movable iron piece 5 - lid body 2 when ignoring leakage magnetism due to small magnetic resistance.
It is known that if the magnetic resistance between the lid 2 and the plunger 3 is RA (armature resistance) and the magnetic resistance between the lid 2 and the plunger 3 is RP (plunger resistance), then RP'==5RA.

This is obtained from the relationship that the plunger 3 moves at 1.2 times the rated value, and the movable iron piece 5 moves immediately without waiting for the plunger 3 to move at 8 times the rated value.

Therefore, lowering the overall magnetic resistance and increasing the magnetic efficiency of the oil dashpot is achieved by reducing the RA.

The present invention reduces RA, resulting in the following effects.

(2) The overall magnetic resistance (approximately 6RA) is reduced.

■ RP===, 5 From the relationship of RA, as RA becomes smaller, RP becomes smaller, and since RP increases or decreases in proportion to the distance between the lid body 2 and the plunger 3, as RP becomes smaller, the lid body 2 becomes smaller. The distance between the and plunger 3 can be shortened.

■ Also, the ampere turns of the coil 8 can be reduced, resulting in resource saving and downsizing.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional oil dashpot, and FIG. 2 is a sectional view of an embodiment of the present invention. 1 is a cylinder, 2 is a lid, 3 is a plunger, 4 is a spring, 5 is a movable iron piece, 5a is a salient magnetic pole, 6 is a yoke, 7 is a return spring, and 8 is a coil.

Claims (1)

[Scope of utility model registration request] Oil is sealed in a cylinder 1 made of a non-magnetic material whose upper end opening is hermetically closed with a lid 2 made of a magnetic material, and a plunger 3 made of a magnetic material is slidably housed in the cylinder 1. A spring 4 is elastically loaded between the lid body 2 and the plunger 3, and the base end of the movable iron piece 5 is pivoted to the other end of the yoke 6, which has one end fixed to the outer peripheral side of the intermediate part of the cylinder 1. The tip of the salient magnetic pole 5a protruding from the side surface of the free end is opposed to the outer surface of the lid 2, and a return spring 7 is elastically mounted to act in a direction to separate the tip of the salient magnetic pole 5a from the outer surface of the lid 2. , a coil 8 is wound around the outer circumference of the upper end of the cylinder 1, and the upper end of the coil 8 is wrapped around the lid 2.
The oil dash pot is characterized in that the outer surface of the lid body 2 protrudes from the outer surface of the coil 8 and is located within the inner peripheral body of the coil 8.