JP2018192930A - Rear wheel steering device - Google Patents

Abstract

To provide a rear wheel steering device capable of achieving smooth motor driving and excellent quietness.SOLUTION: A rear wheel steering device S includes: a first connection part J1 and a second connection part J2 mounted over a member on wheel side and a member on vehicle body side and installed on both ends thereof, of a suspension mechanism supporting rear wheels of a vehicle; a cylindrical housing 1 extending from the first connection part J1; a rod 2 extending from the second connection part J2 and reciprocatable on the same axial center as an axial center X of the housing 1 inside the housing 1; a motor M installed inside the housing 1 to drive the rod 2; a deceleration part 5 which decelerates a rotational speed of an output shaft 41 of the motor M and simultaneously transforms the rotation into reciprocation of the rod 2; a cover 6 which is disposed inside the housing 1, partitions between the motor M and the deceleration part 5 and has bearings supporting the output shaft 41; and a vibration control member 8 for suppressing mutual vibration transmission between the cover 6 and the housing 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rear wheel steering device that is attached to a wheel side member and a vehicle body side member of a suspension mechanism that supports a rear wheel of a vehicle and steers the rear wheel by a motor.

  Conventionally, as such a rear wheel steering device, for example, there is one shown in Patent Document 1. In a vehicle equipped with such a rear wheel steering device, the rear wheels are steered together with the front wheels in accordance with the operation of the steering handle. At that time, a drive current is supplied to rotate the motor, and this rotational motion is converted into a linear motion of the shaft via a ball screw or the like. This shaft is connected to the support portion of the rear wheel, and the rear wheel is steered according to the moving distance of the shaft.

  According to the description of [0011] to [0015] of the known document and FIG. 2, the motor 30 is built in the casing 21, and the shaft 22 is converted into a reciprocating linear motion based on the rotational drive of the motor 30. The The motor 30 includes a permanent magnet 32 fixed to the casing 21 and a rotor 31 that is located on the center side of the permanent magnet and is supplied with current. The ball nut 41 rotates together with the rotor 31, and this rotation is transmitted to the ball screw 42 engaged with the ball nut 41. The ball screw 42 is integrally formed with a part of the shaft 22, but the shaft 22 does not rotate relative to the casing 21 by other components. Thereby, the reciprocating linear motion of the shaft 22 is enabled by driving the motor 30.

Japanese Patent Laid-Open No. 6-211143

  According to FIG. 2 of Patent Document 1, the rotor 31 driven by the motor 30 is supported by bearings 23 and 24. In particular, the bearing 24 is supported by the casing 21 via an annular support member. In Patent Document 1, the mounting structure of the support member is not clearly described. However, normally, such a support member is formed separately from the casing 21 and inserted into the casing 21 for positioning. It is fixed by the C-ring.

  However, such a support member needs to be moved along the inner surface of the casing 21 to a fixed position. Therefore, a slight gap exists between the support member and the inner surface of the casing 21. Due to this gap, when the motor 30 is driven and the rotor 31 rotates, the rotational vibration of the rotor 31 is transmitted to the wall surface of the casing 21 via the bearing 24, and abnormal noise is generated. Such abnormal noise is a factor that makes the driver feel uncomfortable particularly in the case of a vehicle with high quietness in the vehicle.

  Further, as a result of the vibration of the support member, the rotation operation of the rotor 31 and the ball nut 41 to which rotation is transmitted from the rotor 31 is not smooth, and there is a problem that the driving efficiency of the motor is reduced.

  In view of such problems, conventionally, in the technical field of rear wheel drive devices, there has been a demand for the development of an actuator that can smoothly drive a motor and has excellent quietness.

(Feature configuration)
The characteristic configuration of the rear wheel steering device according to the present invention is:
Of the suspension mechanism that supports the rear wheel of the vehicle, it is mounted across the wheel side member and the vehicle body side member,
A first connecting portion and a second connecting portion provided at both ends;
A cylindrical housing extending from the first connecting portion;
A rod extending from the second connecting portion and reciprocally movable on the same axis as the axis of the housing inside the housing;
A motor provided inside the housing for driving the rod;
A decelerating unit that converts the rotation into the reciprocating movement of the rod while decelerating the rotation speed of the output shaft of the motor;
A cover that is disposed inside the housing, partitions the motor and the speed reduction unit, and has a bearing that supports the output shaft,
An anti-vibration material that suppresses mutual vibration transmission is provided between the cover and the housing.

(effect)
As in this configuration, by providing a vibration isolating material that suppresses mutual vibration transmission between the cover and the housing, vibration based on the rotation of the motor is hardly transmitted from the cover to the housing. Therefore, it is possible to obtain a rear wheel steering device in which vibrations and noise transmitted to the vehicle are greatly reduced.

(Feature configuration)
In the rear wheel steering apparatus according to the present invention, the housing is made of a metal material, the cover is made of a resin material, and the cover includes an outer peripheral surface facing the entire circumference of the inner surface of the housing, It can be set as the structure by which the said vibration isolator was provided over the perimeter between the outer peripheral surface and the said inner surface.

(effect)
The cover that partitions between the motor and the speed reduction unit is configured using, for example, a resin material. Thereby, the bearing of the output shaft of a motor can be comprised efficiently. However, in this case, a gap fitting or the like is often used so that excessive stress is not concentrated on the cover when the housing is attached. Due to the remaining gap, the vibration of the output shaft may be transmitted to the housing through the cover when the motor is driven.

  Therefore, as in the present configuration, by providing a vibration isolating material over the entire circumference between the inner surface of the housing and the outer peripheral surface of the cover, vibration transmitted from the cover to the housing can be effectively reduced. Thereby, it is possible to obtain a rear wheel steering device that further suppresses the generation of vibration and sound.

(Feature configuration)
In the rear wheel steering device according to the present invention, the vibration isolator can be formed of a rubber ring member.

(effect)
As in this configuration, the vibration isolating material is a rubber ring member, and the vibration isolating effect can be further enhanced by appropriately selecting, for example, the type and elasticity of the rubber material.

  Further, the elasticity of the rubber material can be used to appropriately set the position of the cover with respect to the housing, and the effect of aligning the axis of the output shaft of the motor to an appropriate position over a long period can also be maintained. .

  Furthermore, a rubber ring member has a simple structure and is easy to manufacture, and an increase in cost of the rear wheel steering device can be suppressed.

(Feature configuration)
In the rear wheel steering apparatus according to the present invention, it is advantageous that an annular groove portion in which the ring member is disposed is provided on at least one of the outer peripheral surface and the inner surface.

(effect)
When the ring member is disposed between the inner surface of the housing and the outer peripheral surface of the cover, the ring member can be easily mounted if the ring member is fitted in the groove, and the ring member is difficult to drop off from the position. However, the groove for mounting may be provided on the inner surface of the housing or may be provided on the outer peripheral surface of the cover.

  For example, by providing a groove on the outer peripheral surface of the cover, it is possible to prevent scratches due to the edge of the cover. However, when providing a groove part in the outer peripheral surface of a cover, a cover will be inserted in the inside of a housing in the state which installed the ring member in the said groove part. If the distance from the insertion opening of the housing to the mounting position of the ring member is long, the distance that the ring member rubs against the inner surface of the housing becomes long. Therefore, in this case, it is preferable to configure the inner surface of the housing as smooth as possible without any unevenness.

  When the groove is provided on the inner surface of the housing, the ring member is often mounted in the groove prior to the insertion of the cover into the housing. In this case, when the cover is inserted, the outer peripheral surface of the cover comes into contact with the ring member and slides a predetermined distance along the axial direction. However, the length along the axial direction of the outer peripheral surface of the cover is not so long and the sliding distance is limited, so that the ring member is hardly damaged, and the ring member can be reliably installed.

  A groove may be provided on both the outer peripheral surface of the cover and the inner surface of the housing in accordance with the dimension of the cross-sectional diameter of the ring member.

Explanatory drawing which shows the whole structure of the rear-wheel steering apparatus which concerns on this invention The disassembled perspective view which shows the principal part structure of the rear-wheel steering apparatus which concerns on 1st Embodiment. Sectional drawing which shows the principal part which shows the attachment structure of the vibration isolator which concerns on 1st Embodiment Sectional drawing which shows the principal part which shows the attachment structure of the vibration isolator which concerns on 2nd Embodiment Sectional drawing which shows the principal part which shows the attachment structure of the vibration isolator which concerns on 3rd Embodiment Sectional drawing which shows the principal part which shows the attachment structure of the vibration isolator which concerns on 4th Embodiment

[First Embodiment]
An embodiment of a rear wheel steering apparatus according to the present invention will be described with reference to the drawings.

(Overview)
1 to 3 show a structure of a rear wheel steering device S according to the first embodiment of the present invention. The rear wheel steering device S constitutes a part of a four-wheel steering system (4WS), for example. The rear wheel steering device S is mounted across the wheel side member and the vehicle body side member of the suspension mechanism that supports the rear wheels RL and RR of the vehicle.

  Specifically, as shown in FIG. 1, left and right wheel supports 96 are swingably connected to a cross member 95 on the vehicle body side, and these left and right wheel supports 96 swing to the cross member 95. The steering links 97 are freely connected via left and right tie rods 98, respectively. In this rear wheel steering device S, the first connecting portion J1 and the second connecting portion J2 provided at both ends are connected to a part of the cross member 95 and one end of the steering link 97, respectively. The rear wheel is steered by swinging the steering link 97 by expansion and contraction.

  As shown in FIG. 1, a cylindrical housing 1 extends from the first connecting portion J1, and from the second connecting portion J2 toward the inside of the housing 1 on the coaxial core X with the axis X of the housing 1. A reciprocating rod 2 extends. A motor M that drives the rod 2 is provided inside the housing 1. The motor M is controlled by a controller 92 provided inside the housing 1.

(Decelerator)
The output shaft 41 of the rotor 4 that constitutes the motor M is provided with a speed reduction portion 5 that reduces the rotational speed of the output shaft 41 and converts this rotation into the reciprocating movement of the rod 2. As the speed reduction unit 5, for example, a planetary gear mechanism is used. The output shaft 41 of the motor M has a hollow structure and is supported by two bearings B1 and B2. One bearing B2 is attached to the housing 1 on the second connecting portion J2 side. The other bearing B <b> 1 is attached to a hole 61 provided in an annular cover 6 inserted in the housing 1. The cover 6 partitions the motor M and the speed reduction unit 5 inside the housing 1.

  A sun gear 51 constituting a planetary gear mechanism is fixed to, for example, an end portion of the output shaft 41 close to the first connecting portion J1. A planetary gear 52 and a ring gear 53 are engaged with the sun gear 51. For example, three planetary gears 52 are pivotally supported by an annular carrier 54, and the carrier 54 is fixed to the housing 1 via a bearing B3. Incidentally, the said bearing B3 and the ring gear 53 are being fixed to the cylindrical support body 7 inserted in the housing 1, for example.

  The housing 1, the rotor 4 or the carrier 54 is made of a metal such as steel or aluminum. The cover 6, the sun gear 51, the planetary gear 52, and the ring gear 53 are made of, for example, a resin material.

  As shown in FIGS. 1 and 3, a female screw portion 42 coaxial with the rotor 4 is provided at the center of the carrier 54. The female screw portion 42 is screwed into the male screw portion 21 formed at the end portion of the rod 2. The rotation of the rotor 4 is transmitted to the carrier 54 via the speed reduction part 5, the rotation of the carrier 54 is transmitted to the rod 2 via the female screw part 42 and the male screw part 21, and the rod 2 moves along the axis X. Move back and forth.

  The rod 2 is supported by the position detector 91 and the like so that it cannot rotate with respect to the housing 1, that is, can only perform thrust movement. The position of the rod 2 is specified by, for example, a position detection unit 91 that measures the position of a magnet provided integrally with the rod 2.

〔cover〕
In the rear wheel steering device S of the present embodiment, the fixing portion of the cover 6 is configured as follows in order to prevent the generation of vibration and noise due to the driving of the motor M. As shown in FIG. 3, the cover 6 is inserted and fixed between the motor M and the speed reduction portion 5 with the outer peripheral surface 65 facing the inner surface 11 of the housing 1.

  As shown in FIG. 3, a fixing ring 13 is used when the cover 6 is installed at a predetermined position of the housing 1. The fixing ring 13 is a C-shaped member, for example, and is engaged with an annular housing groove 12 formed on the inner surface 11 of the housing 1. A step 64 into which the fixing ring 13 is fitted is formed at the edge of the cover 6. By providing the stepped portion 64 and bringing the fixing ring 13 closer to the cover 6 side, the speed reducing portion 5 adjacent to the cover 6 is closer, and the length of the housing 1 is shortened. In this way, the cover 6 is sandwiched between the fixing ring 13 and the motor M and is fixed in position inside the housing 1.

  The hole 61 provided on the center side of the cover 6 serves as a holding portion for the bearing B1. When the motor M is driven, the rotor 4 rotates, and this rotation is transmitted to the planetary gear mechanism of the speed reduction unit 5, but at this time, some vibration is generated in the rotor 4. This vibration is transmitted to the cover 6 through the bearing B1, and further transmitted to the housing 1 so that the entire housing 1 is vibrated. In addition, the collision sound between the cover 6 and the housing 1 becomes noise, and the entire housing 1 may vibrate, and the noise spreading to the surroundings may increase.

  Therefore, as shown in FIG. 3, a vibration isolator 8 is provided between the outer peripheral surface 65 of the cover 6 and the inner surface 11 of the housing 1. As the vibration isolator 8, for example, a silicon material can be used, and the shape is arbitrary. For example, as shown in FIGS. 2 and 3, the cover 6 can be formed in a thin plate shape that covers the entire circumference of the outer peripheral surface 65. In addition, the vibration isolator 8 may be affixed intermittently along the circumferential direction.

  As described above, by providing the vibration isolator 8 between the cover 6 and the housing 1, it is possible to suppress the vibration based on the rotation of the motor M from being transmitted from the cover 6 to the housing 1. Therefore, vibration and sound transmitted to the inside of the vehicle are greatly reduced.

  Such a vibration isolator 8 has a predetermined elasticity. Therefore, the backlash of the cover 6 with respect to the inner surface 11 of the housing 1 is eliminated, and the alignment effect of the cover 6 and the rotor 4 with respect to the housing 1 is exhibited. Therefore, the motor M can be driven more smoothly.

  In the case where the cover 6 is made of a resin material and the housing 1 is made of various metal materials, and the anti-vibration material 8 is provided over the entire circumference of the outer peripheral surface 65 of the cover 6, the anti-vibration material 8 is used. Will be more effective. That is, when the cover 6 is formed of a resin material, the bearing of the output shaft 41 of the motor M can be obtained simply and efficiently, and the cost of the device can be reduced.

  As the resin material, for example, polyphenylene sulfide resin (PPS) having excellent heat resistance, oil resistance, dimensional stability and high mechanical strength is suitable. In that case, the connection between the two is configured such as a clearance fit so that excessive stress is not concentrated on the cover 6 when the housing 1 is attached. In that case, since a slight gap is generated between the cover 6 and the housing 1, vibration generated when the motor M is driven is easily transmitted to the housing 1 through the cover 6.

  When the cover 6 is formed of a resin material in this way, the vibration isolator 8 is provided over the entire circumference between the inner surface 11 of the housing 1 and the outer peripheral surface 65 of the cover 6, so The vibration transmitted to 1 can be effectively reduced.

[Second Embodiment]
As shown in FIG. 4, the vibration isolator 8 is composed of, for example, a rubber ring member 82.

  When a rubber material is used, the vibration isolation effect can be set optimally by appropriately selecting the type of rubber material and the elastic characteristics. Moreover, the core effect of the cover 6 with respect to the housing 1 becomes appropriate by appropriately setting the elasticity of the rubber material. By appropriately selecting the type of rubber material, it is possible to maintain such a vibration-proofing effect and a sculpting effect over a long period. Further, the rubber ring member 82 can be configured more simply, and the cost of the rear wheel steering device S can be reduced. As the rubber material to be used, for example, nitrile rubber (NBR) excellent in wear resistance and oil resistance is preferable.

  FIG. 4 shows a ring member 82 having a circular cross-sectional shape, for example. FIG. 4 shows a state in which the ring member 82 is appropriately compressed between the housing 1 and the cover 6 and is deformed into an elliptical shape. However, the cross-sectional shape of the ring member 82 may be appropriately changed according to various conditions such as an area in contact with the housing 1 and the cover 6 and an elastic characteristic of the rubber material, such as an elliptical shape or a rectangular shape.

  FIG. 4 shows an example in which the ring member 82 is attached to the annular groove 63 provided on the outer peripheral surface 65 of the cover 6.

  If the ring member 82 is fitted in the groove 63 as described above, the ring member 82 can be easily attached and thereafter it is difficult to drop off the groove 63. In particular, when the groove portion 63 is provided on the outer peripheral surface 65 of the cover 6, the cover 6 can be inserted into the housing 1 with the ring member 82 attached to the groove portion 63. It will be something.

  When the cover 6 is inserted into the housing 1, the ring member 82 undergoes a slight compression deformation. However, after the ring member 82 is positioned between the groove portion 63 of the cover 6 and the inner surface 11 of the housing 1, the ring member 82 moves into the housing 1 together with the groove portion 63 according to the insertion operation of the cover 6. . Therefore, when the cover 6 is mounted at a predetermined position, the ring member 82 can also be reliably installed at the intended position.

  A tapered portion 62 whose outer side is narrowed along the direction of the axis X is formed at one edge portion along the direction of the axis X of the outer peripheral surface 65 of the cover 6. By forming such a tapered portion 62, the ring member 82 can be easily attached to the outer peripheral surface 65 of the cover 6. Moreover, the operation | work which inserts the cover 6 equipped with the ring member 82 in the inside of the housing 1 becomes easy.

  An annular housing groove 12 for fixing the fixing ring 13 is formed on the inner surface 11 of the housing 1. Since the housing groove 12 may damage the rubber member when the cover 6 is inserted, care must be taken. For example, when the width of the housing groove 12 is particularly larger than the cross-sectional dimension of the ring member 82, the ring member 82 may be fitted into the housing groove 12 when the cover 6 is inserted. In this case, the ring member 82 is engaged with the corner portion of the housing groove 12 and the corner portion of the groove portion 63 of the cover 6, and the ring member 82 may be damaged. Therefore, it is preferable that the width of the housing groove 12 be as narrow as possible, or that the length along the axial direction of the ring member 82 be large.

  Thus, when providing the groove part 63 in the cover 6, it is not necessary to change the design of the housing 1 in particular, and the low-vibration and low-noise rear wheel steering device S can be reasonably realized.

[Third Embodiment]
As shown in FIG. 5, the rubber ring member 82 may be attached to the annular groove portion 14 provided on the inner surface 11 of the housing 1.

  When the groove portion 14 is provided on the inner surface 11 of the housing 1, the ring member 82 is attached to the groove portion 14 before the cover 6 is inserted into the housing 1. Although the housing groove 12 for attaching the fixing ring 13 is provided on the inner surface 11 of the housing 1, the ring member 82 is attached to the groove portion 14 by itself, so that the ring member 82 is not damaged by the housing groove 12.

  However, the ring member 82 cannot be visually observed when the cover 6 is subsequently inserted. Therefore, if the insertion posture of the cover 6 is inclined, the edge of the outer peripheral surface 65 of the cover 6 may interfere with the ring member 82 and the ring member 82 may be pushed out of the groove 14 or the surface of the ring member 82 may be damaged. There is. However, as shown in FIG. 5, since the tapered portion 62 is provided at the end portion of the cover 6, the tip of the tapered portion 62 rarely comes into contact with the ring member 82 when the cover 6 is inserted. Even if the surface of the tapered portion 62 abuts against the ring member 82, the surface of the tapered portion 62 has a predetermined angle, so that the ring member 82 is merely pressed against the bottom surface of the groove portion 14 by the surface. Therefore, the ring member 82 is reliably prevented from coming off.

  The groove portions 63 and 14 for attaching the ring member 82 may be provided on both the outer peripheral surface 65 of the cover 6 and the inner surface 11 of the housing 1. In this case, since the sum of the depths of both the grooves 63 and 14 becomes long, the ring member 82 having a large cross-sectional area can be attached. Therefore, the vibration-proof performance, sound-proof performance, or centering function exhibited by the ring member 82 can be further enhanced.

[Fourth Embodiment]
In FIG. 6, other embodiment of the vibration isolator 8 is shown. Here, the vibration isolator 8 is constituted by, for example, a linear member 83 having elasticity or spring property. The linear member 83 may be a resin material or a rubber material in addition to a metal spring material or the like, and any material can be used as long as it generates a repulsive force between the housing 1 and the cover 6. There may be.

  FIG. 6 shows an example in which a linear member 83 configured in, for example, a wavy shape is used. With this configuration, the linear member 83 can be bent when the linear member 83 is sandwiched between the outer peripheral surface 65 of the cover 6 and the inner surface 11 of the housing 1. Therefore, the amount of change in the difference between the maximum inner diameter and the maximum diameter of the vibration isolator 8 can be secured larger than when the rubber ring member 82 is formed in a simple annular shape. Therefore, it is easy to align the center of the cover 6 and the housing 1 while ensuring a wide gap and reliably preventing contact between the two.

  Further, if the bending deformation of the linear member 83 is used, the vibration isolator 8 having an arbitrary elastic characteristic can be obtained by appropriately selecting the material and cross-sectional dimensions of the linear member 83. In addition, the said linear member 83 may be C-shaped other than what is continued cyclically | annularly.

  When the linear member 83 is made of a metal material, for example, grooves 63 and 14 are formed on both the outer peripheral surface 65 of the cover 6 and the inner surface 11 of the housing 1, and the linear member 83 is engaged. Good. If the linear member 83 is made of metal, its own rigidity is high, and a function of preventing the cover 6 from being displaced relative to the housing 1 can be expected. Therefore, the separate fixing ring 13 and the housing groove 12 can be omitted, and the configuration of the rear wheel steering device S can be further simplified.

  The rear wheel steering device is attached to, for example, a wheel side member and a vehicle body side member of a suspension mechanism that supports the rear wheel of the vehicle, and is used for a rear wheel steering device that steers the rear wheel by a motor. Can be widely applied.

DESCRIPTION OF SYMBOLS 1 Housing 2 Rod 41 Output shaft 5 Deceleration part 6 Cover 65 The outer peripheral surface 8 of a cover Anti-vibration material 82 Ring member J1 1st connection part J2 2nd connection part M Motor S Rear-wheel steering apparatus X Axle core

Claims (4)

Of the suspension mechanism that supports the rear wheel of the vehicle, it is mounted across the wheel side member and the vehicle body side member,
A first connecting portion and a second connecting portion provided at both ends;
A cylindrical housing extending from the first connecting portion;
A rod extending from the second connecting portion and reciprocally movable on the same axis as the axis of the housing inside the housing;
A motor provided inside the housing for driving the rod;
A decelerating unit that converts the rotation into the reciprocating movement of the rod while decelerating the rotation speed of the output shaft of the motor;
A cover that is disposed inside the housing, partitions the motor and the speed reduction unit, and has a bearing that supports the output shaft,
A rear wheel steering apparatus in which a vibration isolating material that suppresses mutual vibration transmission is provided between the cover and the housing. The housing is made of a metal material, and the cover is made of a resin material,
The rear according to claim 1, wherein the cover includes an outer peripheral surface facing an entire circumference of the inner surface of the housing, and the vibration-proof material is provided over the entire circumference between the outer peripheral surface and the inner surface. Wheel steering device.   The rear wheel steering apparatus according to claim 2, wherein the vibration isolator is a rubber ring member.   The rear wheel steering apparatus according to claim 3, wherein an annular groove portion in which the ring member is disposed is provided on at least one of the outer peripheral surface and the inner surface.

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