JP2020125781A - Electromagnetic shock absorber - Google Patents

Abstract

To provide an electromagnetic shock absorber capable of avoiding enlargement while obtaining large thrust, and reducing weights and costs.SOLUTION: An electromagnetic shock absorber D includes a non-magnetic cylinder 1, a piston rod 2, an expansion side piston 3 partitioning an expansion side chamber R1 in the cylinder 1, a pressure side piston 4 partitioning a pressure side chamber R2 in the cylinder 1, a linear motor LM that has an armature E and a field F installed between the expansion side piston 3 and the pressure side piston 4 of the piston rod 2, gas filled in the expansion side chamber R1 and the pressure side chamber R2, a cooling passage CP facing the armature E, an expansion side restricting portion ER giving resistance to a flow of the gas from the expansion side chamber R1 toward the cooling passage CP, an expansion side straightening portion EC accepting only the flow of the gas from the cooling passage CP toward the expansion side chamber R1, a pressure side restricting portion CR giving resistance to the flow of the gas from the pressure side chamber R2 toward the cooling passage CP, and a pressure side straightening portion CC accepting only the flow of the gas from the cooling passage CP toward the pressure side chamber R2.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electromagnetic shock absorber.

The electromagnetic shock absorber includes, for example, a linear motor including an armature and a field, and the thrust generated by the linear motor is used as a damping force for suppressing the vibration of the vehicle body of the automobile or a control for controlling the attitude of the vehicle body. Use as power.

In such an electromagnetic shock absorber, the thrust of the linear motor is used as a damping force or a control force. However, in order to generate the thrust in the linear motor, it is necessary to energize the windings provided in the armature, and To generate the damping force, the amount of current supplied to the winding also becomes large.

When the amount of current applied to the winding becomes large, the winding heats up and becomes hot, and when the temperature inside the electromagnetic buffer becomes high, the permanent magnet on the field side weakens the magnetic field due to thermal demagnetization, and the electromagnetic buffer There is a risk that the damping force that can occur will decrease.

Therefore, in the conventional electromagnetic shock absorber, a field magnet mounted on the outer circumference of the cylindrical fixed yoke, and a cylindrical armature provided on the inner circumference of the cylindrical movable yoke provided on the outer circumference of the field magnet, A cylindrical case that is connected to the fixed yoke and is in sliding contact with the outer circumference of the movable yoke is provided, and when the movable yoke moves relative to the fixed yoke, a passage is provided between the inner circumference and the outer circumference of the armature winding. Is formed and the gas is passed through the passage to radiate heat from the armature (for example, see Patent Document 1).

JP, 2003-324934, A

In the conventional electromagnetic shock absorber, when the gas in the space closed by the movable yoke and the case flows during relative movement of the movable yoke with respect to the fixed yoke, the gas passes through the inner and outer passages of the armature winding. Although an attempt is made to obtain a cooling effect by doing so, since the passage itself causes pressure loss, heat is generated in the passage, so that the cooling effect is diminished. If a sufficient cooling effect cannot be obtained, the amount of current in the winding must be reduced, and in order to obtain a large thrust even with a small current, the electromagnetic shock absorber must be increased in size.

Therefore, an object of the present invention is to provide an electromagnetic shock absorber capable of avoiding an increase in size and reducing weight and cost while obtaining a large thrust.

In order to achieve the above object, the electromagnetic shock absorber of the present invention includes a non-magnetic cylinder, a piston rod movably inserted into the inner circumference of the cylinder, and a piston rod slidably inserted into the cylinder. The expansion side piston that is provided on the rod and defines the expansion side chamber in the cylinder, and the expansion side piston that is slidably inserted into the cylinder and that is axially spaced from the expansion side piston A compression-side piston that defines a compression-side chamber, a cylindrical armature that is mounted between the expansion-side piston and the compression-side piston of the piston rod, and a cylindrical field that is provided on the outer periphery of the cylinder and faces the armature. A linear motor having, a gas filled in the expansion side chamber and the compression side chamber, a cooling passage facing the armature, and a resistance to the flow of gas from the expansion side chamber to the cooling passage while communicating the expansion side chamber with the cooling passage. An expansion-side restricting section that gives the expansion-side rectifying section that communicates the expansion-side chamber with the cooling passage and allows only a gas flow from the cooling passage to the expansion-side chamber, and a compression-side chamber that communicates with the cooling passage and a cooling passage from the compression-side chamber. And a pressure side rectifying unit that communicates the pressure side chamber with the cooling passage and allows only the gas flow from the cooling passage toward the pressure side chamber.

In the electromagnetic shock absorber thus configured, when the gas moves back and forth between the expansion side chamber and the compression side chamber through the cooling passage during the expansion and contraction operation, the pressure in the cooling passage must be the low pressure side of the expansion side chamber and the compression side chamber. The gas becomes equal to the pressure, and the gas that has entered the cooling passage from the high-pressure side chamber of the expansion side chamber and the pressure side chamber expands and the temperature decreases, so that the armature facing the cooling passage can be effectively cooled.

Further, the electromagnetic shock absorber has a tubular core having a tubular armature and a plurality of annular slots on the outer periphery, and a winding mounted in the slot, and the cooling passage is provided on the outer periphery of the piston rod. It may be formed by an annular void between the inner circumference of the core. According to the electromagnetic shock absorber configured as described above, the entire inner circumference of the core can be exposed to the gas having a lowered temperature, so that the armature can be evenly cooled in the circumferential direction and the structure of the core can be simplified to provide a cooling passage. The processing for providing is unnecessary.

Further, in the electromagnetic shock absorber, the core may have a cylindrical heat radiating plate on the inner circumference. With this structure, the heat radiating plate can be exposed to the gas passing through the cooling passage, and the winding can be efficiently performed. And the core can be cooled.

Further, the electromagnetic shock absorber may be provided with a vent hole that opens from the outer periphery to the cooling passage and communicates with the cooling passage. With such a structure, the armature can be cooled more effectively, and thus a large thrust force can be obtained. It becomes easier and the size of the electromagnetic shock absorber can be further reduced.

Further, the electromagnetic shock absorber is an annular check valve having a notch provided in the expansion side piston at the expansion side limiting portion and the expansion side rectifying portion, and the notch provided in the compression side piston by the compression side limiting portion and the compression side rectifying portion. It may be an annular check valve provided. According to the electromagnetic shock absorber configured in this manner, the expansion side limiting portion and the expansion side rectifying portion, the pressure side limiting portion and the pressure side rectifying portion are each configured by an annular check valve having a short axial length dimension. It is easy to secure the stroke length of the electromagnetic shock absorber.

According to the electromagnetic shock absorber of the present invention, it is possible to avoid an increase in size and reduce weight and cost while obtaining a large thrust.

It is a longitudinal section of an electromagnetic shock absorber of one embodiment.

The present invention will be described below based on the embodiments shown in the drawings. As shown in FIG. 1, an electromagnetic shock absorber D according to an embodiment includes a non-magnetic cylinder 1, a piston rod 2 movably inserted into the inner circumference of the cylinder 1, and a slidable inside the cylinder 1. The expansion side piston 3 that is inserted into the cylinder 1 and defines the expansion side chamber R1 in the cylinder 1, and is slidably inserted into the cylinder 1 and axially with respect to the expansion side piston 3. A pressure side piston 4 which is provided on the piston rod 2 at a distance to define a pressure side chamber R2 in the cylinder 1, and a tubular armature which is mounted between the extension side piston 3 of the piston rod 2 and the pressure side piston 4. E and a linear motor LM provided on the outer circumference of the cylinder 1 and having a cylindrical field F facing the armature E, the gas filled in the expansion side chamber R1 and the compression side chamber R2, and the surface of the armature E. The cooling passage CP, the expansion side restriction part ER, the expansion side rectification part EC, the compression side restriction part CR, and the compression side rectification part CC are provided.

Hereinafter, each part of the electromagnetic shock absorber D will be described in detail. The cylinder 1 has a tubular shape and is made of a non-magnetic material, and a cylindrical back yoke 9 made of a soft magnetic material that forms an annular gap with the cylinder 1 is provided on the outer periphery of the cylinder 1. Has been. An annular rod guide 5 fitted to the upper end of the cylinder 1 in FIG. 1 is attached to the upper end of the back yoke 9 in FIG. 1, and the lower end of the back yoke 9 in FIG. A cap 6 that fits in is attached. The cap 6 is provided with a bracket 6a that allows the cap 6 to be mounted on a vehicle.

The piston rod 2 is inserted through the inner circumference of the rod guide 5 and is movably inserted into the cylinder 1. The extension side piston 3, the armature E, and the pressure side piston 4 are mounted on the outer circumference. Although not shown, a bracket that can be mounted on a vehicle is provided at the upper end in FIG. 1, which is the base end of the piston rod 2. A seal member 5a is provided on the inner circumference of the rod guide 5 to hermetically seal the inside of the cylinder 1.

The expansion side piston 3 and the compression side piston 4 are attached to the outer circumference of the piston rod 2 with a gap in the axial direction, and the armature E is the outer circumference of the piston rod 2 and includes the expansion side piston 3 and the compression side piston 4. It is attached so as to be in contact with both of them.

The expansion side piston 3 is annular, is attached to the piston rod 2 and is slidably inserted into the cylinder 1 as described above, and defines the expansion side chamber R1 in the cylinder 1 at the upper side in FIG. ing. Further, in the present embodiment, the pressure side piston 4 has an annular shape and is attached to the piston rod 2 and slidably inserted into the cylinder 1 as described above. The pressure side chamber R2 is partitioned into. The expansion side chamber R1 and the compression side chamber R2 are filled with gas. As the gas, a gas used as a refrigerant such as hydrochlorofluorocarbon, hydrofluorocarbon, or perfluorocarbon may be used, but other gas may be used.

The expansion side piston 3 has a piston ring 3a which is slidably in contact with the cylinder 1 on the outer periphery, an annular convex portion 3b provided at an end on the armature side, and an annular convex portion 3b which opens from the expansion side chamber side end which is the upper end in FIG. 1, a plurality of through holes 3c communicating with the armature side end, which is the lower end in FIG. 1, and an annular valve seat 3d provided at the extension side chamber side end and surrounding the outlet end of the through hole 3c. A check valve 7 is provided at the end of the expansion side piston 3 on the expansion side chamber side. The check valve 7 is an annular plate that is seated on the annular valve seat 3d to open and close the outlet end of the through hole 3c. The check valve 7 is provided with a notch 7a that functions as an orifice on the outer circumference, the inner circumference side is a fixed end, and the outer circumference side is allowed to bend. When the check valve 7 is seated on the annular valve seat 3d, the through hole 3c is closed. The extension side chamber R1 and the through hole 3c are communicated with each other only by the notch 7a, and when they are bent and separated from the annular valve seat 3d, the outlet end of the through hole 3c is opened. Therefore, the check valve 7 enables the notch 7a to resist the flow of gas from the extension side chamber R1 toward the through hole 3c side, and provides resistance to the flow of gas, so that the gas flowing from the through hole 3c toward the extension side chamber R1 is protected. Allows this with little resistance to flow. Therefore, in the present embodiment, the extension side restriction portion ER is configured by the cutout 7a of the check valve 7, and the extension side rectification portion EC is configured by the check valve 7. The configurations of the extension side limiting portion ER and the extension side rectifying portion EC are not limited to the above-mentioned ones, but the extension side limiting portion ER and the extension side limiting portion ER are provided in the check valve 7 made of one annular plate and having a short axial dimension. If the rectification unit EC is integrated, there is an advantage that it is easy to secure the stroke length of the electromagnetic shock absorber D.

The pressure side piston 4 has a piston ring 4a slidingly contacting the cylinder 1 on the outer circumference, an annular convex portion 4b provided at an end on the armature side, and an annular convex portion 4b opening from the end on the pressure side chamber side which is the lower end in FIG. A plurality of through holes 4c communicating with the armature side end, which is the upper end in FIG. 1, and an annular valve seat 4d provided at the pressure side chamber side end and surrounding the outlet end of the through hole 4c are provided. A check valve 8 is provided at the end of the pressure side piston 4 on the pressure side chamber side. The check valve 8 is an annular plate that is seated on the annular valve seat 4d to open and close the outlet end of the through hole 4c. The check valve 8 is provided with a notch 8a that functions as an orifice on the outer circumference, has a fixed end on the inner circumference side, and is allowed to bend on the outer circumference side. When the check valve 8 is seated on the annular valve seat 4d, the through hole 4c is closed. The pressure side chamber R2 and the through hole 4c are communicated with each other only by the notch 8a, and when bent and separated from the annular valve seat 4d, the outlet end of the through hole 4c is opened. Therefore, the check valve 8 enables the notch 8a to resist the flow of gas from the pressure side chamber R2 to the side of the through hole 4c, and resists the flow of the gas, so that the gas flowing from the through hole 4c toward the pressure side chamber R2 is protected. Allows this with little resistance to flow. Therefore, in the present embodiment, the pressure side restriction portion CR is formed by the notch 8a of the check valve 8 and the pressure side rectification portion CC is formed by the check valve 8. The configurations of the pressure-side restricting portion CR and the pressure-side rectifying portion CC are not limited to those described above, but the pressure-side limiting portion CR and the pressure-side rectifying portion CC are provided in the check valve 8 that is made of one annular plate and has a short axial dimension. If they are put together, there is an advantage that it is easy to secure the stroke length of the electromagnetic shock absorber D.

The armature E is mounted in a cylindrical iron core 11 arranged on the outer circumference of the piston rod 2 and a slot 11a formed of an annular groove provided on the outer circumference of the core 11 side by side at a predetermined pitch in the axial direction. And a line 12. The winding 12 mounted in the slot 11a is a U-phase, V-phase, and W-phase three-phase winding. An annular gap is provided between the outer circumference of the core 11 and the inner circumference of the cylinder 1 to prevent the core 11 and the cylinder 1 from directly interfering with each other.

Further, the core 11 is provided with a cylindrical heat radiating plate 11b formed on the inner circumference thereof with a metal having a high thermal conductivity such as copper. The inner diameter of the heat dissipation plate 11b, which is the minimum inner diameter of the core 11, is larger than the outer diameter of the piston rod 2, and an annular gap is formed between the inner circumference of the core 11 and the outer circumference of the piston rod 2. The cooling passage CP is provided in this annular gap. The core 11 is fitted in the annular convex portion 3b of the expansion side piston 3 and the annular convex portion 4b of the compression side piston 4, and is positioned in the radial direction while being sandwiched between the expansion side piston 3 and the compression side piston 4, and the piston rod 2 Fixed to. Since the through holes 3c and 4c open at the armature-side ends of the annular protrusions 3b and 4b, they respectively communicate with the cooling passages CP, and the through holes 3c and 4c and the cooling passages CP form the expansion side chamber R1. It is connected to the pressure side chamber R2.

Further, the core 11 is provided with a plurality of ventilation holes 11c that open from the outer circumference to the inner circumference of the heat dissipation plate 11b, and the cooling passage CP and the gap between the cylinder 1 and the core 11 are communicated by the ventilation holes 11c. Has been done.

Next, a plurality of annular permanent magnets 10a and 10b are laminated and mounted on the outer periphery of the cylinder 1, and these permanent magnets 10a and 10b are provided in an annular gap between the cylinder 1 and the back yoke 9. It is housed. In the present embodiment, the permanent magnets 10a and 10b and the back yoke 9 form a field F that alternately applies magnetic fields of S poles and N poles on the inner peripheral side of the cylinder 1. Since the cylinder 1 is made of a non-magnetic material, the magnetic field generated by the field F can pass through the cylinder 1 and act inside the cylinder 1.

Further, in the present embodiment, the permanent magnets 10a of the main magnetic poles and the permanent magnets 10b of the auxiliary magnetic poles are stacked in the Halbach array so that the S poles and the N poles alternately appear on the inner peripheral side of the cylinder 1 in the axial direction. ing. In FIG. 1, the triangular marks on the permanent magnet 10a of the main magnetic pole and the permanent magnet 10b of the auxiliary magnetic pole indicate the magnetizing direction, and the magnetizing direction of the permanent magnet 10a of the main magnetic pole is the radial direction. Therefore, the permanent magnet 10b of the auxiliary magnetic pole is magnetized in the axial direction. The axial length of the permanent magnet 10a of the main magnetic pole is longer than the axial length of the permanent magnet 10b of the auxiliary magnetic pole, and the magnetic force between the core 11 of the armature E and the permanent magnet 10a of the main magnetic pole is increased. Since the resistance can be reduced and the magnetic field applied to the core 11 can be increased, the thrust of the linear motor LM can be improved. The permanent magnets 10a and 10b need not be arranged in the Halbach array, because the magnetic fields may act on the inner peripheral side of the cylinder 1 so that the S poles and the N poles alternately appear in the axial direction. In that case, the permanent magnets 10a and 10b need only have the same axial length and have different magnetic poles on their inner circumferences, and may be laminated alternately.

Since the back yoke 9 can secure a magnetic path with low magnetic resistance even if the axial length of the permanent magnet 10b of the auxiliary magnetic pole is shortened, a linear motor for increasing the axial length of the permanent magnet 10a of the main magnetic pole is provided. The thrust of the LM can be effectively improved. More specifically, when the back yoke 9 is provided on the outer circumference of the permanent magnets 10a and 10b, a magnetic path having a low magnetic resistance can be ensured, so that the magnetic resistance increases due to the reduction in the axial length of the permanent magnet 10b of the auxiliary pole. Suppressed. Therefore, if the axial length of the permanent magnet 10a of the main magnetic pole is made longer than the axial length of the permanent magnet 10b of the auxiliary magnetic pole, and the cylindrical back yoke 9 is provided on the outer circumference of the permanent magnets 10a and 10b, the linear motor LM is driven. Thrust can be greatly improved. The thickness of the back yoke 9 may be set to a thickness suitable for suppressing an increase in external magnetic resistance of the permanent magnet 10a of the main pole. Since the back yoke 9 can secure a magnetic path having a low magnetic resistance even when the permanent magnets 10a and 10b are not arranged in the Halbach array, the thrust of the linear motor LM can be improved.

In the present embodiment, the back yoke 9 also functions as an outer shell of the electromagnetic shock absorber D, and also plays a role of protecting the permanent magnets 10a and 10b and as a strength member that receives axial force and lateral force. Although the increase in the magnetic resistance can be suppressed by providing the back yoke 9, the back yoke 9 can be omitted. When the back yoke 9 is omitted, the permanent magnets 10a and 10b do not function as a back yoke but are permanent magnets. It is preferable to provide a tube that protects 10a and 10b and functions as a strength member.

The electromagnetic shock absorber D is configured as described above, and its operation will be described below. When the electromagnetic shock absorber D is extended, the piston rod 2 moves upward in FIG. 1 with respect to the cylinder 1, the expansion side chamber 3 is reduced by the displacement of the expansion side piston 3, and the compression side is generated by the displacement of the compression side piston 4. Room R2 is enlarged. Then, the check valve 7 which is the expansion side rectifying section EC is closed, and the expansion side chamber R1 and the cooling passage CP are communicated with each other only through the notch 7a which is the expansion side restriction section ER. Therefore, the gas passes from the contracted expansion side chamber R1 through the notch 7a and the cooling passage CP, and the gas moves to the compression side chamber R2 by opening the check valve 8 that is the compression side rectification unit CC.

Here, during the expansion operation of the electromagnetic shock absorber D, the pressure in the expansion side chamber R1 rises due to the pressure loss generated when the gas passes through the notch 7a which is the expansion side restriction portion ER. However, the cooling passage CP is communicated with the pressure side chamber R2 through the pressure side rectifying portion CC, and the pressure in the cooling passage CP becomes almost the same pressure as the pressure in the pressure side chamber R2 that expands due to the expansion operation of the electromagnetic shock absorber D. .. Therefore, when the electromagnetic shock absorber D extends, the pressure of the gas until it passes through the notch 7a that is the extension side limiting portion ER is high, and passes through the notch 7a that is the extension side limiting portion ER. The pressure of the gas reaching the cooling passage CP becomes low. In this way, when the gas passes through the extension side restriction portion ER and reaches the cooling passage CP, the pressure of the gas suddenly drops and the volume of the gas expands, so that the gas temperature drops. Therefore, the temperature in the cooling passage CP decreases, and the armature E facing the cooling passage CP can be cooled due to the temperature decrease of the gas.

When the electromagnetic shock absorber contracts, the piston rod 2 moves downward in FIG. 1 with respect to the cylinder 1, and the displacement of the compression side piston 4 reduces the compression side chamber R2 and the displacement of the expansion side piston 3. The expansion chamber R1 is expanded. Then, the check valve 8 that is the pressure side rectifying unit CC is closed, and the pressure side chamber R2 and the cooling passage CP are communicated with each other only through the notch 8a that is the pressure side limiting unit CR. Therefore, the gas from the pressure side chamber R2 to be reduced passes through the notch 8a and the cooling passage CP, and the gas moves to the extension side chamber R1 by opening the check valve 7 that is the extension side rectifying unit EC. Here, during the contraction operation of the electromagnetic shock absorber D, the pressure in the pressure side chamber R2 rises due to the pressure loss generated when the gas passes through the notch 8a which is the pressure side limiting portion CR. However, the cooling passage CP is communicated with the expansion side chamber R1 through the expansion side rectifying section EC, and the pressure in the cooling passage CP is almost the same as the pressure in the expansion side chamber R1 which expands due to the contraction operation of the electromagnetic shock absorber D. Become. Therefore, when the electromagnetic shock absorber D contracts, the pressure of the gas until it passes through the notch 8a that is the pressure-side restriction portion CR is high, and passes through the notch 8a that is the pressure-side restriction portion CR to pass through the cooling passage. The pressure of the gas reaching CP becomes low. In this way, when the gas passes through the pressure side restriction portion CR and reaches the cooling passage CP, the pressure of the gas suddenly drops and the volume of the gas expands, so that the gas temperature drops. Therefore, the temperature in the cooling passage CP decreases, and the armature E facing the cooling passage CP can be cooled due to the temperature decrease of the gas.

Since the expansion/contraction operation of the electromagnetic shock absorber D causes a difference in pressure between the expansion side chamber R1 and the pressure side chamber R2, a damping force that hinders the expansion/contraction operation of the electromagnetic shock absorber D is generated. Further, since the electromagnetic shock absorber D includes the linear motor LM, the thrust generated by the linear motor LM can be used as a damping force that suppresses the expansion and contraction operation and can function as a damper, and the thrust of the linear motor LM can be used positively. It can also be expanded and contracted to function as a quotator.

As described above, the electromagnetic shock absorber D of the present invention includes the non-magnetic cylinder 1, the piston rod 2 that is movably inserted into the inner circumference of the cylinder 1, and the piston 1 that is slidably inserted into the cylinder 1. An expansion side piston 3 that is provided on the piston rod 2 and defines an expansion side chamber R1 in the cylinder 1, and a piston that is slidably inserted into the cylinder 1 and is axially spaced from the expansion side piston 3. The compression side piston 4 provided on the rod 2 and defining the compression side chamber R2 in the cylinder 1, the cylindrical armature E mounted between the expansion side piston 3 and the compression side piston 4 of the piston rod 2, and the cylinder 1 A linear motor LM provided on the outer periphery and having a cylindrical field F facing the armature E, gas filled in the expansion side chamber R1 and the compression side chamber R2, and a cooling passage CP facing the armature E. , The expansion side chamber R1 is connected to the cooling passage CP, and the expansion side restricting portion ER that gives resistance to the flow of gas from the expansion side chamber R1 to the cooling passage CP, and the expansion side chamber R1 is connected to the cooling passage CP and from the cooling passage CP. The expansion side rectification section EC that allows only the flow of gas toward the expansion side chamber R1 and the pressure side restriction section CR that connects the compression side chamber R2 to the cooling passage CP and provides resistance to the flow of gas from the compression side chamber R2 toward the cooling passage CP. And a pressure side rectifying section CC that communicates the pressure side chamber R2 with the cooling passage CP and allows only the flow of gas from the cooling passage CP toward the pressure side chamber R2.

In the electromagnetic shock absorber D configured in this manner, when the gas moves back and forth between the expansion side chamber R1 and the compression side chamber R2 via the cooling passage CP during the expansion and contraction operation, the pressure in the cooling passage CP is always the expansion side chamber R1 and the compression side. Since the pressure in the chamber R2 becomes equal to the pressure on the low pressure side and the gas that has entered the cooling passage CP from the high pressure side chamber of the expansion side chamber R1 and the pressure side chamber R2 expands and the temperature decreases, it faces the cooling passage CP. The armature E can be effectively cooled.

As described above, in the electromagnetic shock absorber D of the present invention, since the armature E can be sufficiently cooled during the expansion and contraction operation, it is not necessary to limit the amount of current supplied to the winding 12 to a small value, and a large thrust can be exerted even in a small size. .. Therefore, according to the electromagnetic shock absorber D of the present invention, it is possible to avoid an increase in size and reduce weight and cost while obtaining a large thrust.

In addition, in the electromagnetic shock absorber D of the present embodiment, the armature E includes a tubular core 11 having a tubular shape and a plurality of annular slots 11a on the outer periphery, and a winding wire 12 mounted in the slot 11a. The cooling passage CP is formed by an annular gap between the outer circumference of the piston rod 2 and the inner circumference of the core 11. In the electromagnetic shock absorber D configured as described above, since the cooling passage CP is formed by the annular gap in the inner circumference of the core 11, the entire inner circumference of the core 11 can be exposed to the gas whose temperature has decreased. The child E can be evenly cooled in the circumferential direction without unevenness. The cooling passage CP may be provided inside the core 11 instead of being formed by an annular gap between the piston rod 2 and the core 11, but the cooling passage CP may be formed between the piston rod 2 and the core 11. Forming with an annular gap between them also has the advantage that the armature E can be uniformly cooled, the structure of the core 11 is simplified, and the processing for providing the cooling passage CP is unnecessary.

Further, in the electromagnetic shock absorber D of the present embodiment, since the core 11 has the cylindrical heat radiating plate 11b on the inner circumference, the heat radiating plate 11b can be exposed to the gas passing through the cooling passage CP and can be wound efficiently. The wire 12 and the core 11 can be cooled.

Further, in the electromagnetic shock absorber D of the present embodiment, the core 11 is provided with the vent hole 11c which opens from the outer periphery and communicates with the cooling passage CP. Since the cooling passage CP and the annular gap between the armature E and the cylinder 1 are communicated with each other via the ventilation hole 11c, the winding whose temperature is lowered also circulates around the armature E to generate heat. 12 can be directly exposed to gas. Therefore, according to the electromagnetic shock absorber D of the present embodiment, the armature E can be cooled more effectively, so that a large thrust can be easily obtained, and the electromagnetic shock absorber D can be further downsized.

Further, in the electromagnetic shock absorber D of the present embodiment, the expansion side restriction portion ER and the expansion side rectification portion EC are the annular check valve 7 provided with the notch 7a provided in the expansion side piston 3, and the compression side restriction portion CR. The pressure side rectifying portion CC is an annular check valve 8 having a notch 8a provided in the pressure side piston 4. According to the electromagnetic shock absorber D configured in this way, the expansion side restriction portion ER and the expansion side rectification portion EC, the compression side restriction portion CR and the compression side rectification portion CC are annular check valves 7 each having a short axial length dimension. , 8, the stroke length of the electromagnetic shock absorber D can be easily secured.

Although the preferred embodiments of the present invention have been described in detail above, modifications, variations, and changes can be made without departing from the scope of the claims.

1... Cylinder, 2... Piston rod, 3... Expansion side piston, 4... Compression side piston, 7... Check valve (expansion side rectification part), 8... Check valve (compression side rectification) Part), 7a... Notch (extension side restriction part), 8a... Notch (pressure side restriction part), 9... Back yoke, 10a, 10b... Permanent magnet, 11... Core, 11a. ..Slots, 11b... Heat sinks, 11c... Vents, 12... Windings, CC... Pressure side rectifying section, CP... Cooling passages, CR... Pressure side limiting section, D. ..Electromagnetic shock absorber, E... Armature, EC... Extension side rectification section, ER... Extension side restriction section, F... Field, LM... Linear motor, R1... Extension Side chamber, R2... Pressure side chamber

Claims (5)

A non-magnetic cylinder,
A piston rod movably inserted into the inner circumference of the cylinder;
An expansion side piston that is slidably inserted into the cylinder and is provided on the piston rod to partition an expansion side chamber in the cylinder,
A pressure side piston that is slidably inserted into the cylinder, is provided on the piston rod at a distance in the axial direction with respect to the extension side piston, and defines a pressure side chamber within the cylinder,
A linear motor having a cylindrical armature mounted between the expansion side piston and the compression side piston of the piston rod, and a cylindrical field magnet provided on the outer periphery of the cylinder and facing the armature. When,
Gas filled in the expansion side chamber and the compression side chamber,
A cooling passage facing the armature,
An expansion side limiting portion that communicates the expansion side chamber with the cooling passage and applies resistance to the flow of gas from the expansion side chamber toward the cooling passage,
An expansion side rectifying unit that allows only the flow of gas from the cooling passage to the expansion side chamber while communicating the expansion side chamber with the cooling passage,
A pressure side restricting portion which communicates the pressure side chamber with the cooling passage and gives resistance to the flow of gas from the pressure side chamber toward the cooling passage,
An electromagnetic shock absorber, comprising: a pressure side rectifying unit that communicates the pressure side chamber with the cooling passage and allows only a gas flow from the cooling passage toward the pressure side chamber. The armature has a tubular core having a tubular shape and a plurality of annular slots on the outer periphery, and a winding mounted in the slot,
The electromagnetic shock absorber according to claim 1, wherein the cooling passage is formed by an annular gap between an outer circumference of the piston rod and an inner circumference of the core. The electromagnetic shock absorber according to claim 2, wherein the core has a cylindrical heat dissipation plate on an inner circumference thereof. The electromagnetic shock absorber according to claim 2 or 3, wherein the core has a vent hole that opens from an outer periphery and communicates with the cooling passage. The extension side limiting portion and the extension side rectifying portion are annular check valves each having a notch provided in the extension side piston,
The electromagnetic shock absorber according to any one of claims 1 to 4, wherein the pressure-side restricting portion and the pressure-side rectifying portion are annular check valves each having a notch provided in the pressure-side piston.

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