JP4708237B2 - Vehicle height adjustment device - Google Patents

Description

  The present invention relates to a vehicle height adjusting device attached to a vehicle suspension, and relates to a technique for realizing a smooth operation against an input of a radial load from a spring.

As a vehicle height adjusting device provided in the suspension of an automobile, a hydraulic type or a hydropneumatic type is generally used, but the control accuracy is high and the system configuration is simplified (a hydraulic unit, an accumulator, etc. are not required). Therefore, an electric type equipped with a worm reduction mechanism, a ball screw type feeding mechanism, and the like has been developed (see Patent Document 1). The vehicle height adjusting device of Patent Document 1 is installed at the upper portion of a damper tube, and a ball screw type feed mechanism is interposed between an upper spring seat that supports a buffer spring and a vehicle body side member. The distance (that is, the vehicle height) between the upper spring seat and the vehicle body side member is adjusted by driving a rotor (male screw member) constituting the feed mechanism by an electric motor.
JP-A-11-108100

  In the suspension of an automobile, when the spring expands and contracts when traveling on a rough road, a load corresponding to the amount of expansion and contraction of the spring acts on the upper spring seat. This load consists of a component along the axis of the spring (thrust load) and a component perpendicular to the axis of the spring (radial load), but the radial load is relatively large depending on the winding shape of the spring. There is a risk that the smooth operation of the feed mechanism may be hindered.

  In the vehicle height adjusting device of Patent Document 1 described above, since the vehicle height adjusting device is configured with the damper rod as a shaft, the spring is deformed only in the axial direction, and a ball screw type feed mechanism is also employed. Together, the above-described problems caused by the radial load are unlikely to occur. However, many rear suspensions have dampers and springs arranged independently. In this case, the relative displacement between the upper spring seat and the lower spring seat becomes complicated, and the spring undergoes bending deformation called knee action. Sometimes. As a result, if a large radial load is applied to the upper spring seat and a relatively low-cost feed screw mechanism is used as the feed mechanism, wear of the threaded portion due to increased frictional resistance (torcross), biting (locking), etc. There was a risk of occurrence.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a vehicle height adjusting device that realizes a smooth operation against an input of a radial load from a spring.

The vehicle height adjusting device according to the invention of claim 1 is attached to a vehicle suspension comprising a buffer spring (7) interposed between a vehicle body side member (6) and a wheel side member (4) . a vehicle height adjustment device for adjusting the vehicle height by approaching or separating the spring retaining means (27) for holding one end of the spring against the vehicle body member by a feed screw mechanism (39) (9) The feed screw mechanism is rotationally driven by an electric motor (36) and has a drive shaft (31) in which a first drive gear (43) and a second drive gear (44) are arranged in parallel in the axial direction, and the first A first rotor (24) formed with a first driven gear (41) meshing with one drive gear and a second rotor (2) formed with a second driven gear (42) meshing with the second drive gear ), And a reduction ratio between the first drive gear and the first driven gear is made different from a reduction ratio between the second drive gear and the second driven gear. A housing (21) driven by the means and connected to the vehicle body side member , and a holding cylinder part ( formed in the housing, extending toward the inside of the spring holding means and containing the feed screw mechanism ) 21c) and an oil-impregnated resin material slidable contact portion which is provided in the spring retaining means and is in slidable contact with the retaining cylindrical portion, and the spring retaining means is moved in the radial direction by contacting the outer periphery of the retaining cylindrical portion. a first cylindrical bearing cylindrical regulating the (51), is secured to the lower end of the holding tubular portion, the second second cylindrical bearing sliding contact with the outer peripheral surface of the rotor (52 With the door, the first cylindrical bearing, and contact to the holding tubular portion in the axial direction at a substantially overlapping position with the end of the spring of the holding tubular portion, said second cylindrical bearings, the vehicle body-side When the spring holding means is farthest away from the member, the spring holding means substantially overlaps the end of the spring in the axial direction of the holding cylinder portion .

  According to the vehicle height adjusting device of the present invention, even if a radial load is input from the spring to the spring holding means, the spring holding means is supported by the shaft-like portion of the housing via the bearing, and is connected to the screwing portion of the feed mechanism. Wear and biting are less likely to occur.

  Hereinafter, an embodiment in which the present invention is applied to a rear suspension of a four-wheel vehicle and a partial modification thereof will be described in detail with reference to the drawings.

[Embodiment]
FIG. 1 is a perspective view showing a rear suspension according to the embodiment, FIG. 2 is an enlarged vertical sectional view of a portion II in FIG. 1, and FIG. 3 is an engagement of the drive shaft and the first and second rotors according to the embodiment. FIG. 4 is a perspective view showing a combined state of each gear and a radial support mechanism according to the embodiment.

<< Configuration of Embodiment >>
<Suspension configuration>
As shown in FIG. 1, a rear suspension (vehicle suspension: hereinafter simply referred to as a suspension) 1 of the embodiment is a so-called multilink suspension, and a wheel W can freely rotate via a hub bearing (not shown). A knuckle 2 supported on the upper side, an upper arm 3 for connecting the upper end of the knuckle 2 to the vehicle body side, a lower arm (wheel side member) 4 for connecting the lower end of the knuckle 2 to the vehicle body side, and a front end of the knuckle 2 to the vehicle body side. A trailing arm 5, a shock-absorbing spring 7 interposed between the lower arm 4 and the suspension member (vehicle body side member) 6, and a portion between the lower arm 4 and the vehicle body at a portion outside the vehicle body from the spring 7. Vehicle height adjustment device (linear actuator) installed between the mounted damper 8 and the spring 7 and the suspension member 6 It is the major components of the door. 1 is an ECU (Electronic Control Unit) that drives and controls the vehicle height adjusting device 9, and is mounted in a vehicle compartment or a trunk room.

<Vehicle height adjustment device>
As shown in FIG. 2, the vehicle height adjusting device 9 includes a housing 21 having an upper half 21 a and a lower half 21 b, which is divided into upper and lower parts, and a cylindrical holding cylinder portion 21 c projecting downward from the center. A first rotor 24 rotatably supported by an upper half 21a via an angular bearing 22, a cylindrical second rotor 25 coupled to the first rotor 24 so as to be relatively rotatable, and a holding cylinder portion 21c of the housing 21 are surrounded. A sheet holder (spring holding means) 27 having a cylindrical portion 27 a and connected to the lower end of the second rotor 25 via an angular bearing 26, and fixed to the lower surface of the upper end portion of the sheet holder 27 to support the upper end of the spring 7. Encloses the upper spring seat 28 and the first and second rotors 24 and 25 and A drive shaft 31 rotatably supported via a pair of needle bearings 29, an idler gear 33 rotatably supported on a housing 21 via a needle bearing 32, and a housing 21 rotatable via a pair of upper and lower ball bearings 34 The drive pinion 35 supported by the housing 21, the electric motor 36 that is fastened to the housing 21 to drive the drive shaft 31, the rotary encoder 37 that detects the rotation amount of the drive shaft 31 and outputs it to the ECU 10, and is held by the housing 21. A radial support mechanism 38 that supports the two rotors 25 in the radial direction is a main component.

  In the case of the present embodiment, the cylindrical portion 27a of the seat holder 27 is connected to the holding cylindrical portion 21c of the housing 21 via a cylindrical bearing (bearing) 51 fixed to the upper portion (that is, near the upper end of the spring 7). It is in sliding contact with the outer peripheral surface. The holding cylinder portion 21 c of the housing 21 is in sliding contact with the outer peripheral surface of the second rotor 25 through a cylindrical bearing 52 fixed to the lower end thereof. The cylindrical bearings 51 and 52 are made of oil-containing resin such as polyacetal, and both have a cylindrical shape.

A disk-shaped gear portion 53 is formed on the outer periphery of the upper portion of the drive shaft 31. As shown in FIG. 3, this gear portion 53 is connected to a drive pinion 35 via an idler gear 33, thereby providing a primary reduction mechanism. It is composed. In the case of this embodiment, since the gear portion 53 has 72 teeth and the drive pinion 35 has 11 teeth, the reduction ratio RP of the primary reduction mechanism is
RP = 72/11 = 6.545
It becomes.

  As shown in FIG. 2, the first rotor 24 includes a cylindrical shaft portion 24a and a gear portion 24b having a larger diameter than the shaft portion 24a formed at the upper end of the shaft portion 24a. The second rotor 25 includes a cylindrical portion 25a that is fitted on the shaft portion 24a of the first rotor 24, and a gear portion 25b that is formed on the upper portion of the cylindrical portion 25a. A male screw portion 24 c is formed on the outer periphery of the shaft portion 24 a of the first rotor 24, while a female screw portion 25 c that engages with the male screw portion 24 c of the first rotor 24 is formed on the inner periphery of the cylindrical portion 25 a of the second rotor 25. The feed screw mechanism (feed mechanism) 39 is formed by the male screw portion 24c and the female screw portion 25c. 2 is a stopper fastened to the lower end in the cylindrical portion 25a of the second rotor 25, and a metal touch with the second rotor 25 when the shaft portion 24a of the first rotor 24 is lowered. To prevent.

  A first driven gear 41 having the number of teeth Za (35 in this embodiment) is formed on the outer periphery of the gear portion 24b of the first rotor 24, and the number of teeth Zb (present) is formed on the outer periphery of the gear portion 25b of the second rotor 25. In the case of the embodiment, the second driven gear 42 of 36) is formed. On the other hand, on the inner periphery of the drive shaft 31, the first drive gear 43 having the number of teeth Zc meshed with the first driven gear 41 (40 in this embodiment) and the number of teeth Zd meshed with the second driven gear 42 (this embodiment). In this case, two internal gears with the second drive gear 44 of 40) are formed. The first drive gear 43 and the first driven gear 41 have substantially the same axial length, but the second drive gear 44 has a length so that the meshing is maintained even if the second driven gear 42 moves up and down. The axial length is set sufficiently larger than the axial length of the second driven gear 42. Hereinafter, the first drive gear 43 and the first driven gear 41 will be described as a first gear set, and the second drive gear 44 and the second driven gear 42 will be described as a second gear set.

  The rotary encoder 37 is composed of an encoder disk 37 a fixed to the upper portion of the drive shaft 31 and a sensor 37 b attached to the upper half 21 a of the housing 21. During driving of the vehicle, a detection signal is constantly output from the sensor 37b of the rotary encoder 37 to the ECU 10, and the ECU 10 feedback-controls the vehicle height adjusting device 9 based on this detection signal.

  As shown in FIG. 4, the radial support mechanism 38 is fixed to the guide plate 61 whose upper and lower ends are held by the housing 21, the slider 62 that is guided by the inner surface of the guide plate 61 and slides up and down, and the slider 62. A pair of upper and lower washers 63 and a pair of upper and lower adjustment blocks 64 and 65 interposed between the guide plate 61 and the housing 21 are configured. The radial support mechanism 38 has an angular phase of about 180 ° with respect to the meshing portion of the second driven gear 42 and the second drive gear 44 so as to bias the second rotor 25 toward the axial center (left side in FIG. 2). The slider 62 is installed at a different position, and the slider 62 moves up and down as the second rotor 25 moves up and down.

<< Operation of Embodiment >>
When the vehicle starts driving and there is an operation of the vehicle height adjustment switch by the driver or a change in the vehicle driving condition (change from normal driving to rough road driving or high speed driving, etc.), the ECU 10 After setting the ground clearance, a drive current is output to the electric motor 36 of each vehicle height adjusting device 9.

When the electric motor 36 is activated, the drive pinion 55 fixed to the output shaft 36 a rotates in either the forward or reverse direction, and the drive shaft 31 is rotationally driven via the idler gear 33. Then, the first driven gear 41 (namely, the first rotor 24) meshed with the first drive gear 43 of the drive shaft 31 and the second driven gear 42 (namely, the second rotor 25) meshed with the second drive gear 44 are obtained. It is rotationally driven in the same direction. At this time, the reduction ratio R1 of the first gear set and the reduction ratio R2 of the second gear set are respectively
R1 = Za / Zb = 36/40 = 0.900
R2 = Zc / Zd = 35/40 = 0.875
It becomes.

In the case of the present embodiment, the reduction ratio R1 of the first gear set and the reduction ratio R2 of the second gear set are very slightly different. Therefore, when the drive shaft 31 rotates, the first rotor 24 and the second rotor 25 are slightly different. The second rotor 25 moves up and down relative to the first rotor 24 by differential rotation and the action of the feed screw mechanism 39. As a result, the upper spring seat 28 pressed against the lower surface of the second rotor 25 via the angular bearing 26 and the seat holder 27 also moves up and down, and the suspension member 6 that is the vehicle body side member and the lower arm 4 that is the wheel side member The distance between them (ie, the vehicle height) changes. At this time, if the ratio of the rotational speed of the drive shaft 31 and the rotational speed of the feed screw mechanism 39 is the total reduction ratio RT, the total reduction ratio RT has the reduction ratio RP of the primary reduction mechanism described above.
RD = RP.R1.R2 / (R1-R2)
= 6.545.0.900.0.875 / (0.900-0.875) = 206.2
As a result, the electric motor 36 can be downsized and power consumption can be reduced.

  On the other hand, when the wheel W moves up and down during traveling of the vehicle, the spring 7 is deformed as the lower arm 4 swings, and as shown by the arrow in FIG. 5, the upper spring seat 28 that supports the upper end of the spring 7 moves from the seat holder. A radial load is input to 27. However, the seat holder 27 is hardly displaced in the radial direction because the cylindrical portion 27 a is in sliding contact with the outer peripheral surface of the holding cylindrical portion 21 c of the housing 21 via the cylindrical bearing 51 in the vicinity of the upper end of the spring 7. As a result, the lateral load due to the radial load is not applied to the feed screw mechanism 39, and the feed screw mechanism 39 achieves a smooth feed operation and wear of the screwing surface due to long-term use or the feed screw mechanism. There is no longer any risk of biting.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, in the above embodiment, the present invention is applied to a vehicle height adjusting device provided in a rear suspension of a four-wheeled vehicle. However, a vehicle height adjustment provided in a suspension of a front suspension, a two-wheeled vehicle, or a six-wheeled vehicle or more. It can also be applied to devices. In the above embodiment, the feed screw mechanism is used as the feed mechanism. However, a ball screw type feed mechanism, a cylindrical cam mechanism, or the like may be adopted. Moreover, in the said embodiment, although the thing made from oil-containing resin which exhibits a cylindrical shape was used as a bearing, you may employ | adopt a needle bearing etc. In addition, the specific configuration and the like of the vehicle height adjusting device can be changed as appropriate without departing from the spirit of the present invention.

It is a perspective view which shows the rear suspension which concerns on embodiment. It is the II section enlarged vertical sectional view in FIG. It is a perspective view which shows the meshing state of the drive shaft which concerns on embodiment, and a 1st, 2nd rotor. It is a perspective view which shows the combined state of each gear and radial support mechanism which concern on embodiment. It is a longitudinal cross-sectional view which shows the effect | action of embodiment.

Explanation of symbols

1 Suspension 4 Lower arm (wheel side member)
6 Suspension member (vehicle body side member)
7 Spring 9 Vehicle height adjusting device 21 Housing 21c Holding cylinder part (shaft-like part)
27 Sheet holder (spring holding means)
28 Upper spring seat 51 Cylindrical bearing (bearing)

Claims (1)

Is attached to vehicle suspension obtained by interposing a spring for cushioning between the vehicle body-side member and the wheel-side member, a spring holding means for holding one end of the spring against the vehicle body member by a feed screw mechanism A vehicle height adjustment device that adjusts the vehicle height by approaching or moving away,
The feed screw mechanism includes a drive shaft that is rotationally driven by an electric motor and has a first drive gear and a second drive gear arranged in parallel in the axial direction, and a first driven gear that meshes with the first drive gear. 1 rotor and a second rotor formed with a second driven gear that meshes with the second drive gear, and a reduction ratio between the first drive gear and the first driven gear is set to the second drive gear and the second drive gear. Driven by a feed screw mechanism driving means that is different from the reduction ratio with the second driven gear,
A housing connected to the vehicle body member,
A holding cylinder portion formed in the housing and extending toward the inside of the spring holding means, and containing the feed screw mechanism;
A cylinder that is provided in the spring holding means, has a sliding contact portion of an oil-impregnated resin material that is in sliding contact with the holding cylinder portion, and regulates movement of the spring holding means in the radial direction by contacting the outer periphery of the holding cylinder portion. A first cylindrical bearing having a shape ;
A second cylindrical bearing fixed to the lower end of the holding cylinder portion and in sliding contact with the outer peripheral surface of the second rotor ;
Said first cylindrical bearing, and contact to the holding tubular portion in the axial direction at a substantially overlapping position with the end of the spring of the holding tubular portion,
The second cylindrical bearing substantially overlaps the end of the spring in the axial direction of the holding cylinder when the spring holding means is farthest from the vehicle body side member. Adjustment device.

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