JP2005249099A - Shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shock absorber capable of preventing damage to a ball screw nut. <P>SOLUTION: This shock absorber is provided with a support member 2 for rotatably supporting a screw shaft 3, a holding member 5 for holding the ball screw nut 4, to which the screw shaft 3 is rotatably screwed, and a motor 1 connected to the screw shaft 3, and relative movement of the support member 2 and the holding member 5 to each other is restricted by electromagnetic force of the motor 1. Each of the holding member 5 and the support member 2 is provided with stoppers 10 and 11 for abutting on each other when both the members are extended at the maximum. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention has a mechanism for converting linear motion of a screw shaft into rotational motion of a motor via a ball screw nut by screwing a screw shaft to a ball screw nut so as to be attenuated by electromagnetic force of the motor. The present invention relates to an improvement of a shock absorber that generates force.

As this kind of shock absorber, for example, as shown in FIG. 3, a bottomed cylindrical outer cylinder 30, a bottomed cylindrical inner cylinder 31 inserted into the outer cylinder 30, and an inner cylinder 31 are provided. A ball screw nut 32, a screw shaft 33 screwed into the ball screw nut 32, and a motor 34 provided in the outer cylinder 30 and connected to the screw shaft 33. At the time of extension, the ball screw nut 32 is brought into contact with a stopper 35 provided at the tip of the screw shaft 33, thereby mitigating the impact at the time of extension.
JP 2004-011750 A (from page 22, line 22 to line 28, FIG. 1)

  However, in the above-described conventional shock absorber, when the maximum extension is performed, the stopper on the screw shaft side and the ball screw nut are brought into contact with each other, so that the ball screw nut also functions as a stopper. However, if the extension speed of the shock absorber increases, it may be pointed out that the ball screw nut may be damaged. .

  In particular, large trucks that carry heavy loads are usually equipped with air springs as the spring elements of the suspension. Is pushed upward, and the shock absorber is fully extended. This is because in such a truck, the air pressure in the air spring is set to be very high compared to a passenger car because of the need to load heavy objects, and the shock absorber at the time of maximum extension A large load acts on the stopper.

  Then, a large load acts on the ball screw nut, and there is a concern that the ball screw nut may be damaged in this respect.

  Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a shock absorber capable of preventing damage to a ball screw nut.

  In order to achieve the above-described object, the present invention is connected to a screw shaft, a support member that rotatably supports the screw shaft, a holding member that holds a ball screw nut to which the screw shaft is rotatably screwed, and the screw shaft. In a shock absorber that includes a motor and suppresses relative movement between the support member and the holding member by the electromagnetic force of the motor, each of the holding member and the support member is provided with a stopper that abuts each other when fully extended.

  And a support member for rotatably supporting the screw shaft, a holding member for holding a ball screw nut to which the screw shaft is rotatably engaged, and a motor connected to the screw shaft. In the shock absorber that suppresses the relative movement of the support member and the holding member, a stopper that abuts each other at the time of maximum extension is provided on each of the outer periphery of the ball screw nut and the support member.

  According to the present invention, the ball screw nut is prevented from being damaged by the impact load at the time of the maximum extension, and the ball screw nut is prevented from being damaged. The ride comfort is guaranteed.

  Furthermore, even when the shock absorber is applied to a large truck, the ball screw nut is not damaged, so that the shock absorber of the present embodiment can be applied to a large truck.

  The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view of a shock absorber according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of a shock absorber according to another embodiment of the present invention.

  As shown in FIG. 1, the shock absorber in one embodiment includes a bottomed cylindrical outer cylinder 2 as a support member and an inner cylinder as a bottomed cylindrical holding member that is movably inserted into the outer cylinder 2. 5, a ball screw nut 4 provided in the inner cylinder 5, a screw shaft 3 that is rotatably screwed into the ball screw nut 4, and a motor 1 provided in the outer cylinder 2 and connected to the screw shaft 3. And a stopper 10 provided on the inner peripheral side of the lower end in FIG. 1 of the outer cylinder 2 and a flange 11 serving as a stopper provided on the outer periphery of the upper end in FIG. 1 of the inner cylinder 5. The linear motion of the screw nut 4 is converted into the rotational motion of the screw shaft 3, and the rotational motion is transmitted to the shaft 1a of the motor 1 to generate an electromagnetic force in the motor 1. The electromagnetic force of the shaft 1a is caused by the electromagnetic force. A ball screw nut by suppressing the rotational movement of the screw shaft 3 with a torque that resists rotation. 4 of the linear motion used as damping force for restricting, in which it is possible to suppress the relative axial movement between the ball screw nut 4 and the screw shaft 3.

 The detailed structure will be described below. The outer cylinder 2 has a bottomed cylindrical shape, and a motor 1 is provided on the side of the outer cylinder 2 on the inner peripheral upper end side in FIG. 1 and a screw shaft 3 is rotatably mounted via a ball bearing 9. It has been.

 A flange 12 extending toward the inner peripheral side is provided at the lower end in FIG. 1 of the outer cylinder 2, and the flange 12 is provided at the inner peripheral side in the lower end in FIG. 1 of the outer cylinder 2. An annular stopper 10 that comes into contact with is fitted. The stopper 10 is made of an elastic material such as rubber or plastic.

 Similarly, a bottomed cylindrical inner cylinder 5 is movably inserted into the outer cylinder 2. 1 is provided with a flange 11 serving as a stopper extending from the opening. A bracket (not shown) is provided at each of the upper end in FIG. 1 of the outer cylinder 2 and the lower end in FIG. 1 of the inner cylinder 5, and for example, this shock absorber can be attached between the vehicle body and the axle. It can be done.

  Although the motor 1 is not shown in the figure, taking a brushless motor as an example, a shaft 1a rotatably inserted into the frame, a coil wound around a core attached to the frame, and a plurality of magnets attached to the shaft 1a The magnet is provided so as to face the coil and the core. That is, when the shaft 1a exhibits a rotational motion with respect to the frame, the permanent magnet also rotates, so that an induced electromotive force is generated when the coil crosses the magnetic field generated by the permanent magnet. Each of the electrodes 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 as to generate torque against the rotation of the shaft 1a caused by electromagnetic force. It is adjusted so that a desired damping force can be obtained. When this electromagnetic shock absorber is used as an active suspension, it is possible to drive the motor 1 by actively energizing the motor 1 so that it functions not only as a shock absorber but also as an actuator. Further, when the current is positively supplied to the motor 1, the torque resulting from the electromagnetic force of the motor 1 can be adjusted. The motor 1 is used as an electromagnetic force generation source, and various motors such as a DC motor, an AC motor, and an induction motor can be used.

  The fixing means for the motor 1 and the outer cylinder 2 is used in a conventional manner with sufficient durability so that the motor 1 itself does not rotate relative to the outer cylinder 2 due to the rotational torque generated by the electromagnetic force generated by the motor 1. Any fixing means may be used.

  The shaft 1a is fitted with a coupling 8, and although not shown, the shaft 1a is provided with a key (not shown), and this key is provided on the coupling 8 side. It is engaged with a key groove (not shown), and the coupling 8 is prevented from idling with respect to the shaft 1a. Further, the lower part of the coupling 8 in FIG. 1 is connected to the upper end of the screw shaft 3, and a key (not shown) is also provided on the screw shaft 3, and this key is provided on the coupling 8 side. The coupling 8 is engaged with a key groove (not shown), and the coupling 8 is prevented from idling with respect to the screw shaft 3.

  Subsequently, the screw shaft 3 is provided with a screw groove 3 a on the outer periphery thereof, and the upper portion of the screw shaft 3 in FIG. 1 is rotatably supported on the inner peripheral side of the outer cylinder 2 via a ball bearing 9. ing. The screw shaft 3 is inserted into the inner cylinder 5 and is rotatably screwed into a ball screw nut 4 fitted to the upper end of the inner cylinder 5 in FIG. 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, when the screw shaft 3 is rotatably engaged with the ball screw nut 4 along the screw groove 3a, and 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.

  Now, as described above, the shock absorber in the present embodiment is configured, and the operation thereof will be described below. When the shock absorber expands and contracts, that is, when the inner cylinder 5 moves in the vertical direction in FIG. 1 with respect to the outer cylinder 2, the linear motion in the vertical direction of the ball screw nut 4 connected to the inner cylinder 5 is the ball screw nut. It is converted into a rotational movement of the screw shaft 3 by a ball screw mechanism of 4 and the screw shaft 3.

  Then, the rotational movement of the screw shaft 3 is transmitted to the shaft 1 a of the motor 1 through the coupling 8.

  When the shaft 1a of the motor 1 exhibits a rotational motion, the coil 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 so as to generate a torque against the rotation of the shaft 1a caused by the electromagnetic force of 1, the torque against the rotation of the shaft 1a suppresses the rotational movement of the shaft 1a. It becomes.

  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. If the coil is actively energized at this time, it can also function as an actuator, and can control the linear motion. As a result, the shock absorber can be used as an active suspension as described above. Can also be used.

  Therefore, the torque resisting 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 acts as a damping force that suppresses the linear motion of the inner cylinder 5 relative to the outer cylinder 2. Absorbs and relaxes vibration energy.

  That is, in this shock absorber, a damping force can be generated by the electromagnetic force generated in the motor 1.

  When the shock absorber is fully extended, the stopper 10 and the flange 11 come into contact with each other, but the impact load at the time of contact acts on the outer cylinder 2 and the inner cylinder 5, but the ball screw nut No impact load acts on 4. Therefore, the ball screw nut 4 is prevented from being damaged by the impact load, and the ball screw nut 4 is prevented from being damaged, so that the operation of the smooth shock absorber is ensured, thereby ensuring the riding comfort in the vehicle. It is done.

  Further, even when the shock absorber is applied to a large truck, as described above, no load is applied to the ball screw nut 4, so that the ball screw nut 4 is not damaged. Can be applied to large trucks.

  In the case of the present embodiment, stoppers are provided on the inner peripheral side of the outer cylinder 2 and the outer peripheral side of the inner cylinder 5, and the contact area of the stopper itself is larger than that of the stopper of the conventional shock absorber. Therefore, since the pressure acting on the stopper itself at the time of contact can be reduced as compared with the conventional case, the durability of the stopper is also improved.

  Next, another embodiment will be described. In a shock absorber according to another embodiment, as shown in FIG. 2, a ball screw nut 21 is an opening in FIG. The flange portion 22 is provided on the outer periphery of the ball screw nut 21 as a stopper, and the other components are the same as those in the above-described embodiment. The detailed description is omitted only by attaching the same reference numerals.

  In the shock absorber in the other embodiment, a damping force is generated by the electromagnetic force of the motor 1 as in the shock absorber in the one embodiment. When the shock absorber is fully extended, the ball screw nut 21 is generated. The flange portion 22 provided on the outer periphery of the contact portion abuts on the stopper 10.

  In this case, a load is naturally applied to the ball screw nut 21 when it comes into contact with the stopper 10. However, since the load is received on the outer peripheral side of the ball screw nut 21, the ball screw nut 21 is arranged on the inner peripheral side of the ball screw nut 21. The ball and the screw groove 3a of the screw shaft 3 are not damaged.

  Therefore, even in the shock absorber according to the other embodiment, similarly to the shock absorber according to the one embodiment, the ball screw nut 21 is prevented from being damaged by the impact load at the time of the maximum extension. Since the screw nut 21 is prevented from being damaged, a smooth operation of the shock absorber is ensured, thereby ensuring the riding comfort in the vehicle.

  Further, even when the shock absorber is applied to a large truck, the ball screw nut 4 is not damaged as described above, and therefore, the shock absorber according to the present embodiment can be applied to a large truck. .

  Also in the case of this other embodiment, stoppers are provided on the inner peripheral side of the outer cylinder 2 and the outer peripheral side of the ball screw nut 21, and the contact area of the stopper itself is compared with that of a conventional shock absorber. Since the pressure acting on the stopper itself at the time of contact can be reduced as compared with the conventional case, the durability of the stopper is also improved.

  In each of the embodiments described above, the flange 11 or the flange portion 22 is brought into direct contact with the stopper 10 at the time of maximum extension, but in one embodiment, it is fitted to the outer periphery of the inner cylinder 5. In addition, an annular elastic member that abuts against the flange 11 is provided separately. In other embodiments, the annular elastic member is fitted to the outer periphery of the ball screw nut 21 or the inner cylinder 2 and abuts against the flange portion 22. As the annular elastic member, the stopper 10 and the elastic member may be brought into contact with each other at the maximum extension.

  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 of the shock absorber in one embodiment of the present invention. It is a longitudinal cross-sectional view of the buffer in other embodiment of this invention. It is a longitudinal cross-sectional view of the conventional shock absorber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 1a Shaft 2 Outer cylinder 3 Screw shaft 3a Screw groove 4,21 Ball screw nut 5,20 Inner cylinder 10 Stopper 11 Stopper flange 12 Flange 22 Stopper flange

Claims (3)

A support member that rotatably supports the screw shaft, a holding member that holds a ball screw nut to which the screw shaft is rotatably engaged, and a motor that is coupled to the screw shaft. A shock absorber for suppressing relative movement of the holding member, wherein the holding member and the support member are each provided with a stopper that abuts each other when fully extended. A support member that rotatably supports the screw shaft, a holding member that holds a ball screw nut to which the screw shaft is rotatably engaged, and a motor that is coupled to the screw shaft. A shock absorber for suppressing relative movement of the holding member, wherein a stopper that abuts each other at the time of maximum extension is provided on each of the outer periphery of the ball screw nut and the support member. The support member is a bottomed cylindrical outer cylinder, and the holding member is a bottomed cylindrical inner cylinder inserted into the outer cylinder, and the ball screw nut is located in the inner cylinder or at the end of the inner cylinder opening. The shock absorber according to claim 1 or 2, wherein one of the stoppers is provided on the inner peripheral side of the outer cylinder, and the other stopper is provided on the outer periphery of the ball screw nut or the outer periphery of the inner cylinder.

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