JP4271604B2 - Electromagnetic shock absorber - Google Patents

Description

  The present invention has a mechanism for converting a linear motion of a screw shaft into a rotational motion of a motor via the screw nut by screwing a screw shaft to the screw nut so as to reduce the damping force by the electromagnetic force of the motor. The present invention relates to an electromagnetic shock absorber.

In general, a suspension in which a hydraulic shock absorber is interposed in parallel with a suspension spring between a vehicle body and an axle of the vehicle is known. This suspension suspends the vehicle body and attenuates input such as vibration from the road surface. In recent years, a new electromagnetic shock absorber that does not require oil, air, power supply, etc. has been researched and proposed, which improves the ride comfort and maneuverability or keeps the vehicle height constant by suppressing the displacement of the vehicle body (See Patent Document 1 and Non-Patent Document 1).

The basic structure of this electromagnetic shock absorber is composed of a screw shaft that is rotatably engaged with a ball screw nut, and a motor that is connected to one end of the screw shaft and short-circuits the electrode, and the ball screw nut is a shaft with respect to the screw shaft. The shaft of the motor and the shaft of the motor rotate, and the induced electromotive force generated by the rotation of the shaft attenuates the torque opposite to the direction of rotation of the shaft and the screw shaft to suppress the linear motion of the ball screw nut. It is used as power.
JP 2003-227543 A (paragraph number 0023, FIG. 1) Suematsu, Suda, "Study on Electromagnetic Suspension in Automobile", Japan Society for Automotive Engineers, Preprint of Academic Lecture, 2000, No4-00

  However, the conventional electromagnetic shock absorber described above is very useful in that it does not require a power source or the like, but has the following problems.

  In other words, the electromagnetic shock absorber uses a motor as a damping force generation source, but particularly when an AC motor or a three-phase brushless motor is used, when the motor rotation speed increases, the magnitude of the current flowing through the coil in the motor increases. Since the change in length and direction is severe, the torque generated by the motor due to the influence of the self-inductance and the mutual inductance of the coil itself decreases without being proportional to the rotational speed of the shaft.

  Therefore, there is a fear that it may be pointed out that if the relative movement speed in the axial direction between the screw shaft and the ball screw nut is increased, that is, the expansion / contraction speed of the electromagnetic shock absorber is increased, a damping force may be insufficient.

  Therefore, the present invention was created in consideration of the above-mentioned problems, and the object of the present invention is to provide an electromagnetic shock absorber capable of generating a sufficient damping force even when the expansion / contraction speed is high. is there.

In order to achieve the above object, one means of the present invention includes a first cylinder, a second cylinder slidably inserted into the first cylinder, and a screw provided in the second cylinder. A first shaft that includes a nut, a screw shaft that is rotatably engaged in the screw nut and rotatably connected to the first tube, and a motor provided in the first tube; When in the second relative movement suppressing electromagnetic shock absorber of the cylinder, the motor is constituted by one of a coil or magnet for interlocking with the screw shaft, and the other coil or magnet is opposed to one of the coils or magnets the outward of the first cylinder provided with a cylinder which is connected to the second cylinder, the first cylinder inner circumference in sliding contact with the inside the cylinder an annular piston mounted on an outer periphery of the cylinder of the hydraulic oil is partitioned into an upper chamber and a lower chamber that is filled, further reservoir supraventricular or lower chamber above Connect, also the passage communicating with the upper chamber and a lower chamber in the piston provided with the damping valve provided in the passage, even the damping damping force generated by the motor when the stretching speed is fast is reduced An electromagnetic shock absorber that compensates for a decrease in damping force with a valve .

Similarly, the other means includes a first cylinder, a second cylinder slidably inserted into the first cylinder, a screw nut provided in the second cylinder, and rotatable within the screw nut. A screw shaft fixedly connected to the first cylinder, and a motor provided in the second cylinder, and the relative movement of the first cylinder and the second cylinder by the electromagnetic force of the motor. In the electromagnetic shock suppressor, the motor is constituted by one of a coil or a magnet connected to the screw nut and the other of the coil or the magnet fixed in the second cylinder, and the first cylinder A cylinder connected to the second cylinder is provided outside the cylinder, and an annular piston provided on the outer periphery of the first cylinder is slidably contacted with the inner periphery of the cylinder to fill the cylinder with hydraulic oil. It is divided into an upper chamber and a lower chamber, further connects the upper chamber or the lower chamber to the reservoir above, also on the said piston The passage connecting the upper chamber and the lower chamber is provided, the damping valve provided in the passage, the damping force generated by the motor when the stretching speed is fast is to supplement the damping force decrease amount in the damping valve is also reduced It is characterized by.

In each of the above means, an outer cylinder is provided outside the cylinder, a reservoir is provided between the cylinder and the outer cylinder, and a damping valve is provided in the middle of a passage communicating the lower chamber and the reservoir. Is preferred.

Similarly, a reservoir may be formed by providing a free piston above the upper chamber or below the lower chamber.

  According to the invention of each claim, not only the damping force can be generated by the induced electromotive force generated in the motor, but also the damping force can be generated by the resistance of the damping valve or the hydraulic oil.

  Therefore, even if the damping force generated by the motor is reduced when the expansion / contraction speed of the electromagnetic shock absorber is high, it is possible to compensate for the reduction in the damping force by the resistance of the damping valve or hydraulic oil. That is, a sufficient damping force can be generated even if the extension speed is high.

  As described above, particularly when this electromagnetic shock absorber is applied to a vehicle, a sufficient damping force can be generated even if the expansion / contraction speed is high, and there is no adverse effect of insufficient damping force. Riding comfort can be improved.

  Even if the motor is damaged and the motor is unable to generate torque due to electromagnetic force, it will function as a normal hydraulic shock absorber in that case, so that it will not be possible to generate damping force. Is avoided. Therefore, fail safe can be performed.

  Further, by actively controlling the life and death of the short circuit of the motor, the damping characteristic generated by the motor can be added to the damping characteristic of the normal hydraulic shock absorber, so that the damping characteristic can be adjusted. .

 According to the first and second aspects of the present invention, since the first cylinder and the second cylinder are in sliding contact with each other, the shaft of the screw shaft with respect to the second cylinder and the screw nut is prevented, and thereby, It is possible to prevent a load from being concentrated on a part of the screw nut and to avoid a situation in which the screw nut or the screw groove of the screw shaft is damaged. Further, since the screw nut or the screw groove of the screw shaft can be prevented from being damaged, the smoothness of each operation of the rotation of the screw shaft and the screw nut or the movement of the electromagnetic shock absorber in the expansion / contraction direction can be maintained. Since the smoothness can be maintained, the function as an electromagnetic shock absorber is not impaired, and the failure of the electromagnetic shock absorber can be prevented. In addition, when bearings are separately received between the outer cylinder and the inner cylinder, the inner periphery of the lower end of the outer cylinder bites the outer peripheral surface of the inner cylinder, and the sealing performance between the outer cylinder and the inner cylinder deteriorates. This can prevent the risk of being lost.

  According to the invention of claim 2, since it is not necessary to provide a motor perpendicularly to the upper part of the screw shaft as in the conventional electromagnetic shock absorber, a stroke required for the shock absorber can be secured and the basic length can be shortened. . That is, space saving can be achieved. Therefore, it can be applied to parts where the installation space is limited, and the necessary stroke can be secured. Especially when an electromagnetic shock absorber is applied to a vehicle, the basic length can be shortened, which is necessary for the vehicle. Since the stroke of the shock absorber can be secured, the mountability to the vehicle is improved.

  In addition, since the motor is formed in the second cylinder, the magnet and the coil can be formed over substantially the entire length of the second cylinder, which was a dead space in the past, so the electromagnetic shock absorber is enlarged. Without doing so, only the motor can be enlarged. That is, since the motor output can be increased without increasing the size of the electromagnetic shock absorber, it is possible to generate a high damping force in the electromagnetic shock absorber.

  The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view conceptually showing the electromagnetic shock absorber according to the first embodiment of the present invention. FIG. 2 is a longitudinal sectional view conceptually showing the electromagnetic shock absorber according to the second embodiment of the present invention. FIG. 3 is a longitudinal sectional view conceptually showing the electromagnetic shock absorber according to the third embodiment of the present invention.

 As shown in FIG. 1, the electromagnetic shock absorber according to the first embodiment includes a bottomed cylindrical first cylinder 2 and a second cylinder 5 that is slidably inserted into the first cylinder 2. A ball screw nut 4 which is a screw nut provided in the second cylinder 5, a screw shaft 3 which is rotatably screwed into the ball screw nut 4 and is rotatably connected to the first cylinder 2; The motor 1, a cylinder 20 provided outside the first cylinder 2 and connected to the second cylinder 5, an annular piston 21 provided on the outer periphery of the first cylinder 2, and a piston 21 in the cylinder 20 The upper chamber R1 and the lower chamber R2, which are partitioned by each other, the passage 30 that communicates the upper chamber R1 and the lower chamber R2, and a damping valve 31 provided in the middle of the passage 30, and this electromagnetic shock absorber expands and contracts. The linear motion of the ball screw nut 4 during the rotation is converted into the rotational motion of the screw shaft 3, and the rotational motion is shuffled by the motor 1 A linear motion of the ball screw nut 4 by transmitting to 1a and generating an electromagnetic force in the motor 1 and suppressing a rotational motion of the screw shaft 3 with a torque that resists the rotation of the shaft 1a due to the electromagnetic force. Is used as a damping force to suppress the axial movement of the ball screw nut 4 and the screw shaft 3, and at the same time, a damping force is also generated by a pressure loss caused when the hydraulic oil O passes through the damping valve 31. It can be done.

 The detailed structure will be described below. The first cylinder 2 is a bottomed cylinder, and a motor 1 is provided on the inner peripheral side thereof, and a screw shaft 3 integrally formed with the shaft 1 a of the motor 1 is interposed via ball bearings 9 and 10. It is rotatably mounted. In the figure, the screw shaft 3 and the shaft 1a are integrally formed. However, the screw shaft 3 and the shaft 1a may be connected as separate members.

  The motor 1 includes a shaft 1 a formed integrally with the screw shaft 3, magnets 7 and 7 attached to the outer periphery of the shaft 1 a, and an inner periphery of the first cylinder 2, and faces the magnets 7 and 7. In this case, the first cylinder 2 serves as a frame of the motor 1. The brushless motor includes the core 8 attached in this manner and the coil 6 fitted to the core 8. Each electrode (not shown) of the motor 1 is connected to a control circuit or the like (not shown), or is short-circuited to be a closed circuit, so that a torque that resists rotation of the shaft 1a caused by electromagnetic force is applied. By making it generate | occur | produce, it adjusts so that a desired damping force may be obtained. In the case of a brushless motor, a Hall element, a magnetic sensor, an optical sensor, or the like is mounted as a rotor position detecting means. However, as long as a torque due to electromagnetic force is simply generated, the position detecting means is used. There is no need to provide it. However, by providing the position detection means, it is possible to grasp the state of rotation of the rotor (rotation angle, angular velocity, etc.), which is convenient for motor control. For example, taking a Hall element as an example, it is necessary to energize the element from an external power source, but it is sufficient to supply a current by connecting an electric wire for energization to the element. Since power is generated by the rotation of the ball screw nut 4 without using a power source, the current generated by the induced electromotive force is supplied to the Hall element or is stored in an external battery and the current is supplied from the battery. May be supplied. In this embodiment, the coil 6 is attached to the first cylinder 2 side and the magnets 7 and 7 are attached to the shaft 1a side. However, the coil 6 is attached to the shaft 1a side and the magnets 7 and 7 are attached to the first cylinder 1 side. You may attach to the cylinder 2 side. In the present embodiment, the motor 1 is a brushless motor, but various motors such as a DC motor, an AC motor, an induction motor, and the like can be used as long as they can be used as an electromagnetic force generation source.

  The screw shaft 3 formed integrally with the shaft 1a is provided with a screw groove 3a on the outer periphery thereof, and has a bottomed cylindrical second cylinder 5 which is slidably inserted into the first cylinder 2. The ball screw nut 4 is inserted into the second tube 5 and is rotatably screwed into the ball screw nut 4 fitted in the second tube 5. Here, although the structure of the ball screw nut 4 is not particularly illustrated, for example, a spiral ball holding portion is provided on the inner periphery of the ball screw nut 4 so as to coincide with the spiral screw groove 3 a of the screw shaft 3. A large number of balls are arranged in the holding portion, and a passage is provided in the ball screw nut 4 to communicate both ends of the helical holding portion so that the balls can circulate. When the screw shaft 3 is screwed into the ball screw nut 4, the ball of the ball screw nut 4 is fitted into the spiral screw groove 3 a of the screw shaft 3, and the screw shaft 3 is rotated. Accordingly, the ball itself is rotated by the frictional force with the screw groove 3a of the screw shaft 3, so that a smooth operation is possible as compared with a mechanism such as a rack and pinion.

  As described above, the screw shaft 3 is rotatably engaged with the ball screw nut 4 along the screw groove 3a. When the ball screw nut 4 moves linearly in the vertical direction in FIG. Since the rotational movement of the screw nut 4 is restricted by, for example, the inner cylinder 5 fixed to the vehicle body or the axle side, the screw shaft 3 is forcibly driven to rotate. That is, the linear motion of the ball screw nut 4 is converted into the rotational motion of the screw shaft 3 by the above mechanism. Further, when the ball screw nut 4 moves downward in FIG. 1 and the electromagnetic shock absorber is fully extended, the cushion member 15 provided at the lower end in FIG. The screw shaft 3 is prevented from coming off from the ball screw nut 4 in contact with the middle and lower ends, and the impact at the time of full extension is alleviated. Further, the screw shaft 3 and a sealing member 25 described later are Prevents interference and alleviates impact during maximum compression.

 In addition, a seal member (not shown) is provided between the first cylinder 2 and the second cylinder 5, whereby an operation described later in a space formed by the first cylinder 2 and the second cylinder 5 is provided. Oil O is prevented from entering. Incidentally, although the second cylinder 5 is slidably inserted into the first cylinder 2, an annular bearing may be provided between the first cylinder 2 and the second cylinder 5. In this case, there is a risk that the inner periphery of the lower end portion of the first cylinder 2 bites the outer peripheral surface of the second cylinder 5 and the sealing performance between the first cylinder 2 and the second cylinder 5 is deteriorated. Can be prevented.

 In addition, since the second cylinder 5 is slidably inserted into the first cylinder 2, the screw shaft 3 is prevented from shaking with respect to the second cylinder 5 and the ball screw nut 4. Accordingly, it is possible to prevent a load from being concentrated on a part of the balls (not shown) of the ball screw nut 4 and to prevent the ball or the screw groove 3a of the screw shaft 3 from being damaged. In addition, since the ball or the screw groove 3a of the screw shaft 3 can be prevented from being damaged, the smoothness of each operation of the rotation of the screw shaft 3 and the ball screw nut 4 or the movement of the electromagnetic shock absorber in the expansion / contraction direction can be maintained. Since the smoothness of each of the above operations can be maintained, the function as an electromagnetic shock absorber is not impaired, and consequently failure of the electromagnetic shock absorber can be prevented.

 On the other hand, a cylindrical cylinder 20 is provided outside the first cylinder 2, and the lower end in FIG. 1 of this cylinder 20 is connected to the lower end in FIG. 1 of the second cylinder 5 via a sealing member 25. It is connected. Further, an annular piston 21 is provided on the outer periphery of the lower end in FIG. 1 of the first cylinder 2, and this piston 21 is in sliding contact with the inner periphery of the cylinder 20. And a lower chamber R2. Further, an outer cylinder 23 covering the cylinder 20 is provided, and the lower end in FIG. 1 of the outer cylinder 23 is also connected to the sealing member 25. Further, a disk-shaped sealing member 26 is provided at the upper ends in FIG. 1 of the cylinder 20 and the outer cylinder 23, and the inner periphery of the sealing member 26 is in sliding contact with the outer periphery of the first cylinder 2. Although not shown, a sealing member (not shown) is provided between the first cylinder 2 and the sealing member 26, and the cylinder 20 and the outer cylinder 23 are sealed.

 The gap between the cylinder 20 and the outer cylinder 23 is defined as a reservoir R. The reservoir R is filled with hydraulic oil O and gas G, and the hydraulic oil is also contained in the upper chamber R1 and the lower chamber R2. O is enclosed. The piston 21 is provided with a passage 30 that communicates the upper chamber R1 and the lower chamber R2, and the passage 30 is provided with a damping valve 31. The sealing member 25 has a lower chamber R2 and a reservoir. A passage 32 communicating with R is provided, and a damping valve 33 is provided. As the damping valves 31 and 33, known damping valves that can generate a damping force when the hydraulic oil O passes may be used.

 Further, brackets (not shown) are provided at the upper end in FIG. 1 of the first cylinder 2 and the lower end in FIG. 1 of the sealing member 25, respectively, so that an electromagnetic shock absorber can be provided between the vehicle body and the axle, for example. Can be mounted on.

 The electromagnetic shock absorber according to the first embodiment is configured as described above. Next, the operation thereof will be described. First, the electromagnetic shock absorber extends, that is, when the first cylinder 2 moves upward in FIG. 1 with respect to the second cylinder 5, a ball screw with respect to the screw shaft 3 connected to the first cylinder 2. The nut 4 is linearly moved downward in FIG. 1, but since the rotation of the ball screw nut 4 is restricted, the ball screw mechanism of the ball screw nut 4 and the screw shaft 3 rotates the screw shaft 3. The shaft 1a of the motor 1 integrated with the screw shaft 3 is also rotated.

  When the shaft 1a of the motor 1 exhibits a rotational motion, the coil 6 in the motor 1 crosses the magnetic field of the magnet, an induced electromotive force is generated, and each electrode of the motor 1 is short-circuited as described above. Since the current flows through the coil 6 so as to generate torque against the rotation of the shaft 1a caused by the electromagnetic force of the motor 1, the torque against the rotation of the shaft 1a suppresses the rotational movement of the shaft 1a. Will be.

  The action of suppressing the rotational movement of the shaft 1a suppresses the rotational movement of the screw shaft 3, and the rotational movement of the screw shaft 3 is suppressed, so that the linear movement of the ball screw nut 4 is suppressed. .

  Therefore, the torque against the shaft 1 a caused by the electromagnetic force of the motor 1 suppresses the linear motion of the ball screw nut 4, and thus suppresses the linear motion of the first cylinder 2 relative to the second cylinder 5. Acts as a damping force to absorb and relax vibration energy.

  At the same time, when the first cylinder 2 moves upward in FIG. 1 relative to the second cylinder 5, the piston 21 provided on the outer periphery of the first cylinder 2 moves upward in FIG. Since the chamber R1 contracts and the pressure in the upper chamber R1 increases, the hydraulic oil O in the upper chamber R1 flows into the lower chamber R2 through the passage 30. Furthermore, since the hydraulic oil O corresponding to the volume of the first cylinder 2 leaving the cylinder 20 is insufficient in the lower chamber R <b> 2, the insufficient hydraulic oil O is compensated from the reservoir R via the passage 32. Then, since the hydraulic oil O passes through the damping valves 31 and 33, a damping force corresponding to the pressure loss generated at this time is generated.

  On the contrary, when the electromagnetic shock is contracted, the screw shaft 3 is rotated by the ball screw nut 4, so that the motor 1 generates a torque that suppresses the rotation, so that a damping force is generated by the motor 1.

  Further, since the first cylinder 2 moves downward in FIG. 1 with respect to the second cylinder 5, the piston 21 provided on the outer periphery of the first cylinder 2 moves downward in FIG. Since R1 contracts and the pressure in the lower chamber R2 increases, the hydraulic oil O in the lower chamber R2 flows into the upper chamber R1 through the passage 30. Further, since the hydraulic oil O corresponding to the volume of the first cylinder 2 entering the cylinder 20 becomes surplus in the lower chamber R2, the surplus hydraulic oil O flows out to the reservoir R through the passage 32. . Then, since the hydraulic oil O passes through the damping valves 31 and 33, a damping force corresponding to the pressure loss generated at this time is generated.

  That is, in this electromagnetic shock absorber, not only the damping force is generated by the induced electromotive force generated in the motor 1, but also the damping force can be generated by the damping valves 31 and 33.

  Therefore, even if the damping force generated by the motor 1 decreases when the electromagnetic buffer expands and contracts at high speed, the damping valve 31 and 33 can compensate for the damping force decrease. That is, a sufficient damping force can be generated even if the extension speed is high.

  As described above, particularly when this electromagnetic shock absorber is applied to a vehicle, a sufficient damping force can be generated even if the expansion / contraction speed is high, and there is no adverse effect of insufficient damping force. Riding comfort can be improved.

  Even if the motor 1 is damaged and the motor 1 cannot generate torque due to electromagnetic force, in that case, the motor 1 acts as a normal hydraulic shock absorber, so that the damping force cannot be generated. Will be avoided. Therefore, fail safe can be performed.

  Further, by actively controlling the life and death of the short circuit of the motor 1, the damping characteristic generated by the motor 1 can be added to the damping characteristic of the normal hydraulic shock absorber, so that the damping characteristic can be adjusted. It is.

  In the present embodiment, the hydraulic shock absorber portion is formed in a so-called double cylinder shape in which the reservoir R is disposed outside the cylinder 20, but for example, above the upper chamber R1 or in the lower chamber R2. A reservoir may be formed by providing a free piston below, and a single cylinder type may be formed.

  Incidentally, although the motor 1 is provided in the first cylinder 2, the structure is complicated, but the motor 1 is inserted into the second cylinder 5 so as to allow only vertical movement, and the motor 1 If the shaft 1 a and the screw shaft 3 are connected, the motor 1 may be provided in the second cylinder 5.

  Next, a second embodiment will be described. As shown in FIG. 2, the electromagnetic shock absorber according to the second embodiment includes a screw shaft 3 rotatably connected to the first cylinder 2 in the first embodiment. And a motor is provided in the second cylinder 5. Since other members are the same as those in the first embodiment, the same members are only given the same reference numerals, and detailed descriptions thereof are omitted.

  A motor 41 different from that of the first embodiment is fitted to a ball screw nut 4 that is rotatably fitted in a second cylinder 5 via ball bearings 48 and 49, and an inner periphery of the second cylinder 5. 2, a coil 46 wound around the core 45, and a plurality of magnets 47, 47 suspended from the lower end in FIG. 2 of the ball screw nut 4. It is provided so as to face the core 45. That is, when the ball screw nut 4 exhibits a rotational movement with respect to the second cylinder 5, the magnets 47, 47 suspended from the lower end of the ball screw nut 4 in FIG. An induced electromotive force is generated by crossing the magnetic field generated by 47. Therefore, the motor 41 is a brushless motor composed of the above-described ball screw nut 4, the second cylinder 5, the core 45, the coil 46, and the magnets 47, 47. In this case, the ball screw nut 4 serves as a shaft. The second cylinder 5 serves as a frame. The lower ends of the magnets 47 and 47 are fitted in a ball bearing 50 that is fitted to the inner periphery of the second cylinder 5, and the shafts of the magnets 47 and 47 are prevented from being shaken. Is prevented from interfering with the screw shaft 3 and the second cylinder 5.

  As in the first embodiment, the screw shaft 3 is screwed into the ball screw nut 4, but in the second embodiment, the first cylinder 2 is relative to the second cylinder 5. When the screw shaft 3 moves, the rotation of the screw shaft 3 is restricted by the first tube 2, so that the ball screw nut 4 is forcibly rotated. Since the magnets 47 and 47 are also rotated by the rotation of the ball screw nut 4, the coil 46 crosses the magnetic field generated by the magnets 47 and 47 to generate an induced electromotive force, and the motor 41 has the ball screw nut 4. Therefore, the linear motion of the screw shaft 3 is suppressed. Therefore, also in the second embodiment, a damping force is generated by the motor 41. However, since the other members are the same as those in the first embodiment, when the electromagnetic shock absorber expands and contracts, the damping valve 31 and 33 also generate a damping force. That is, as in the first embodiment, even if the damping force generated by the motor 1 decreases when the electromagnetic buffer expands and contracts at a high speed, the damping valve 31 and 33 compensate for the decrease in the damping force. Is possible. That is, a sufficient damping force can be generated even if the extension speed is high.

  As described above, particularly when the electromagnetic shock absorber according to the second embodiment is applied to a vehicle, a sufficient damping force can be generated even if the expansion / contraction speed is high, resulting in a problem of insufficient damping force. Therefore, the ride comfort in the vehicle can be improved.

  Further, in the second embodiment, unlike the conventional electromagnetic shock absorber, it is not necessary to provide a motor vertically above the screw shaft, so that the stroke required for the shock absorber can be secured and the basic length is shortened. Can do. That is, space saving can be achieved. Therefore, it can be applied to parts where the installation space is limited, and the necessary stroke can be secured. Especially when an electromagnetic shock absorber is applied to a vehicle, the basic length can be shortened, which is necessary for the vehicle. Since the stroke of the shock absorber can be secured, the mountability to the vehicle is improved.

  In addition, since the motor is formed in the second cylinder 5, magnets and coils can be formed over substantially the entire length of the second cylinder 5, which was a dead space in the past. Only the motor can be enlarged without increasing the size. That is, since the motor output can be increased without increasing the size of the electromagnetic shock absorber, it is possible to generate a high damping force in the electromagnetic shock absorber.

  Further, a third embodiment will be described. As shown in FIG. 3, the electromagnetic shock absorber according to the third embodiment includes a motor 50, a screw shaft 3 connected to a shaft (not shown) of the motor 50, and a ball screw into which the screw shaft 3 is screwed. The nut 4, a cylinder 60 to which the ball screw nut 4 is fitted, a resistor 70 provided at the tip of the screw shaft 3, and a cylinder 80 surrounding the resistor 70 are configured.

  More specifically, although not shown, the motor 50 includes a coil, a magnet, and a shaft, as in the first and second embodiments. The screw shaft 3 is connected to or integrally formed with the shaft. Further, the screw shaft 3 is also rotatably engaged with the ball screw nut 4. On the other hand, the ball screw nut 4 is fitted into the cylinder 60, and a key 61 is provided on the inner periphery of the cylinder 60 along the axial direction thereof. Further, a resistor 70 is provided at the tip of the screw shaft 3, and the resistor 70 is composed of a rotating shaft 71 connected to the screw shaft and a plurality of blades 72 provided on the outer periphery of the rotating shaft 71. ing.

  The resistor 70 is housed in a cylindrical body 80 provided at the tip of the screw shaft 3. The cylindrical body 80 is provided with a ball bearing 81 into which the tip of the rotary shaft 71 is fitted, and a seal member 82 that is slidably in contact with the screw shaft 3 is provided at the upper end opening in FIG. The inside is sealed, and the cylinder 80 is filled with hydraulic oil O. Furthermore, a key groove 83 that engages with a key 61 provided on the inner periphery of the cylinder 60 is provided on the outer periphery of the cylinder 80, and the cylinder 80 is restricted only in rotation with respect to the cylinder 60, That is, only movement in the vertical direction in FIG. 3 is allowed. In order to prevent the cylinder 80 from falling off the screw shaft 3, for example, a stopper that engages with the outer peripheral side of the rotating shaft 71 of the resistor 70 and the inner peripheral side of the cylindrical body 80 may be provided.

  That is, the cylindrical body 80 is connected to the screw shaft 3 and can move in the vertical direction in FIG. 3, but the screw shaft 3 does not follow the rotation. Therefore, the resistor 70 can exhibit a rotational movement with respect to the cylindrical body 80.

  When the electromagnetic shock absorber according to the third embodiment expands and contracts, the ball screw nut 4 moves in the vertical direction in FIG. Then, the screw shaft 3 is forcibly rotated by the ball screw nut 4. At this time, the motor 41 generates a torque that resists the rotation of the screw shaft 3. As a result, the ball screw nut 4 is moved in the vertical direction. Linear motion is suppressed, thereby generating a damping force.

  At the same time, the resistor 70 provided at the tip of the screw shaft 3 also rotates. However, since the wing 72 provided on the outer periphery of the rotating shaft 71 rotates in the hydraulic oil O, the hydraulic oil O It becomes resistance to the rotation, and as a result, the rotation of the screw shaft 3 is suppressed. That is, a damping force is generated by the resistance of the hydraulic oil O.

  Therefore, also in the third embodiment, when the electromagnetic shock absorber expands and contracts, a damping force is also generated by the resistance of the hydraulic oil O other than the motor 41. That is, as in the first embodiment, even if the damping force generated by the motor 41 is reduced when the electromagnetic buffer has a high expansion / contraction speed, the reduction of the damping force is compensated by the resistance of the hydraulic oil O. Is possible. That is, a sufficient damping force can be generated even if the extension speed is high.

  As described above, particularly when the electromagnetic shock absorber according to the third embodiment is applied to a vehicle, a sufficient damping force can be generated even if the expansion / contraction speed is high, resulting in a problem of insufficient damping force. Therefore, the ride comfort in the vehicle can be improved.

  In addition, as in the first and second embodiments, the configuration of a hydraulic shock absorber is not further provided on the outer periphery of the electromagnetic shock absorber, but the hydraulic oil O and the cylinder 80 that generate a damping force in the electromagnetic shock absorber. Since the resistor 70 is housed, the electromagnetic shock absorber can be slim and space-saving. Therefore, the mountability of the electromagnetic shock absorber is improved. Furthermore, since the inside of the cylinder body 80 can be sealed only by providing the seal member 82 only at one location between the cylinder body 80 and the rotating shaft 71, as in other embodiments in which a plurality of seal members are required. Compared to a structure in which a so-called hydraulic shock absorber is held in an electromagnetic shock absorber, it is economical.

  In addition to the above, the shape of the resistor may be any shape as long as the rotation of the screw shaft 3 can be suppressed. If a plurality of blades 72 are used as described above, the hydraulic oil O Therefore, the rotation of the screw shaft 3 can be effectively suppressed.

  In the above description, the case where the electromagnetic shock absorber is applied to a vehicle in particular has been described, but it goes without saying that the electromagnetic shock absorber can be used in a portion where the normal shock absorber is used.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

It is a longitudinal cross-sectional view which shows notionally the electromagnetic shock absorber in the 1st Embodiment of this invention. It is a longitudinal cross-sectional view which shows notionally the electromagnetic shock absorber in the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which shows notionally the electromagnetic shock absorber in the 3rd Embodiment of this invention.

Explanation of symbols

1, 41, 50 Motor 1a Shaft 2 First cylinder 3 Screw shaft 3a Screw groove 4 Ball screw nut as screw nut 5 Second cylinder 6, 46 Coil 7, 47 Magnet 20 Cylinder 21 Piston 23 Outer cylinder 30 Passage 31 Damping Valve 70 Resistor 71 Rotating shaft 72 Wings 80 Tubular body R Reservoir R1 Upper chamber R2 Lower chamber

Claims (4)

  A first cylinder, a second cylinder that is slidably inserted into the first cylinder, a screw nut provided in the second cylinder, and a first screw that is rotatably screwed into the screw nut. In an electromagnetic shock absorber comprising a screw shaft rotatably connected to a cylinder and a motor provided in the first cylinder, and suppressing relative movement between the first cylinder and the second cylinder by the electromagnetic force of the motor, The motor is composed of one of a coil or a magnet linked to the screw shaft and the other of the coil or the magnet opposed to one of the coil or the magnet, and the second cylinder is disposed outside the first cylinder. A cylinder to be connected is provided, an annular piston provided on the outer periphery of the first cylinder is slidably contacted with the inner periphery of the cylinder, and the inside of the cylinder is divided into an upper chamber and a lower chamber filled with hydraulic oil, Further, the upper chamber or the lower chamber is connected to a reservoir, and the upper chamber and the lower chamber are connected to the piston. An electromagnetic shock absorber characterized in that a passage is provided, a damping valve is provided in the passage, and the damping valve compensates for the reduction in the damping force even when the damping force generated by the motor decreases when the expansion / contraction speed is high . A first cylinder, a second cylinder slidably inserted into the first cylinder, a screw nut provided in the second cylinder, and a screw nut rotatably engaged in the screw nut; In an electromagnetic shock absorber comprising a screw shaft fixedly connected to a cylinder and a motor provided in the second cylinder and suppressing relative movement between the first cylinder and the second cylinder by the electromagnetic force of the motor The motor is composed of one of a coil or a magnet linked to the screw nut and the other of a coil or a magnet fixed in the second cylinder, and the second is disposed outward of the first cylinder. A cylinder connected to the cylinder is provided, and an annular piston provided on the outer periphery of the first cylinder is slidably brought into contact with the inner periphery of the cylinder. compartment and, further connects the upper chamber or the lower chamber above the reservoir, also communicates the said upper chamber and a lower chamber in the piston That the provided passages, the electromagnetic shock absorber for the damping valve provided in the passage, the damping force generated by the motor when the stretching speed is fast is characterized in that to compensate for damping force decrease amount in the damping valve is also reduced.   3. An outer cylinder is provided outside the cylinder, a reservoir is provided between the cylinder and the outer cylinder, and a damping valve is provided in the middle of a passage communicating the lower chamber and the reservoir. The electromagnetic shock absorber described.   The electromagnetic shock absorber according to claim 1 or 2, wherein a free piston is provided above the upper chamber or below the lower chamber to form a reservoir.

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