JP4329670B2 - Vehicle suspension system - Google Patents

Description

  The present invention generally relates to a vehicle suspension device, and more particularly to a vehicle suspension device including an electromagnetic suspension driven by a rotary motor.

  Active electromagnetic suspensions that can perform vehicle height adjustment, posture control, and ride comfort control are known. The electromagnetic suspension supports the weight of the sprung part of the vehicle and also adjusts the damping force on the spring and unsprung of the vehicle with a coil spring that prevents vibrations and shocks from the road surface from being transmitted to the vehicle body through the wheels. A shock absorber.

For example, in Patent Document 1, the motor of the electromagnetic suspension is held so as to be slidable up and down, and a damper that attenuates the vertical movement is configured to suppress the lock phenomenon of the motor against shock input, An active suspension device is disclosed that smoothes the behavior of sprung resonance and unsprung resonance. Patent Document 2 discloses a suspension control device in which a damper and an electromagnetic actuator are arranged in series between a wheel and a vehicle body to suppress vibration transmitted from the wheel to the vehicle body.
JP-A-8-197931 JP 2000-52738 A

  However, in Patent Document 1, since a spring element is arranged in series with the motor and the vertical direction of the motor is floatingly supported, a long space is required in the direction in which the motor slides up and down, and a suspension stroke is secured. It may be difficult to mount on the lower part of the vehicle.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle suspension apparatus including an electromagnetic suspension capable of installing an elastic means and a damping means in a space-saving manner.

  One embodiment of the present invention relates to a vehicle suspension apparatus. This device is composed of a linear motion member and a rotational member screwed to the linear motion member, and is coupled to an input conversion means for converting linear motion input from the unsprung state of the vehicle into rotational direction input, and to the rotational member of the input conversion means. A rotary motor having an output shaft, a telescopic member that couples the linear motion member of the input conversion means and the vehicle spring, and is expanded and contracted by the rotary motor to generate a damping force between the vehicle spring and the unsprung; And a resilient means provided in parallel with the damping means and elastically supporting the unsprung portion. The stator of the rotary motor is held so as to be rotatable around the output shaft.

  According to this aspect, when a shock load that cannot be followed at the motor operating speed is input, the motor stator is configured to rotate. Therefore, when there is a high-frequency input that the motor control cannot follow. In addition, the vehicle suspension device can be prevented from being locked.

  Note that the linearly moving member and the rotating member are, for example, a ball screw and a ball screw nut. In the embodiment, since the ball screw nut is fixed to the piston and linearly moves, the ball screw nut is a linear member, and the ball screw corresponds to the rotating member.

  The vehicle suspension device further includes second elastic means for generating an elastic force in a direction opposite to the rotation of the stator of the rotary motor, and second damping means for damping the vibration of the second elastic means. May be. Accordingly, since the elastic element and the damping element are provided in the rotation direction of the motor, it is possible to provide a vibration damping effect of high-frequency input while suppressing the overall height of the vehicle suspension device.

  The second damping means includes a housing provided so as to enclose the entire rotary motor, a fluid filled in the housing, and a fixed plate provided so as to protrude into the fluid from the side surface of the stator of the rotary motor. And an orifice formed in the fixing plate. By doing so, the motor is floated and supported in the housing, so that the stator of the motor can be easily rotated, and the damping element can be realized by the orifice.

  According to the vehicle suspension device of the present invention, the stator of the motor of the electromagnetic suspension is configured to be rotatable, so that the vehicle suspension device can be prevented from being locked while saving space.

  FIG. 1 is a schematic view of a four-wheel vehicle 10 including a vehicle suspension device according to the present embodiment. In FIG. 1, the vehicle suspension device is shown in a plan view for the sake of simplicity. However, in an actual vehicle, an appropriate space arrangement is used in order to exert the function of the vehicle suspension device, for example, a knuckle, It is configured by combining with other parts such as a tie rod, upper arm, and lower arm in a known manner.

  Between the vehicle body 12 and each wheel 14 of the vehicle 10, it is comprised with the coil suspension which is not shown in figure, and the electromagnetic suspension 90 comprised by arrange | positioning the expansion part 18 extended and retracted by the drive part 16 and a drive part in series. A vehicle suspension is installed. The coil spring prevents the impact of the wheel 14 from being directly transmitted to the vehicle body 12. The electromagnetic suspension 90 generates a damping force between the sprung and unsprung parts of the vehicle by controlling the force of the motor. In the present specification, the position of the member supported by the coil spring is referred to as “upper spring”, and the position of the member not supported by the coil spring is referred to as “unsprung”. That is, the sprung is on the vehicle body 12 side and the unsprung is on the wheel 14 side.

  The coil spring and the electromagnetic suspension 90 are preferably configured integrally from the viewpoint of space saving, but may be provided separately. The detailed configuration of the electromagnetic suspension 90 will be described later with reference to FIG.

  A vehicle height sensor 104 that detects the vehicle height at the wheel position is disposed in the vicinity of each wheel 14. The vehicle height sensor 104 is of a type that detects the relative distance between the vehicle body 12 and the wheels 14 by measuring the displacement of a link connecting the axle and the vehicle body, for example. A detection signal of the vehicle height sensor 104 is sent to an electronic control device 100 (hereinafter referred to as “ECU 100”) provided in the vehicle body 12.

  For each wheel, a stroke sensor 106 for obtaining a stroke speed, which is a relative vertical displacement speed between the sprung and unsprung parts, and a rotation angle sensor 108 for detecting the rotation amount of the motor are provided. Detection signals from the stroke sensor 106 and the rotation angle sensor 108 are transmitted to the ECU 100.

  The vehicle body 12 is provided with a sensor 102 for detecting the motion state of the vehicle and the operation states of various devices. The sensors 102 are collectively represented. Specifically, an acceleration sensor for detecting acceleration such as vertical acceleration, longitudinal acceleration, and lateral acceleration of the vehicle, a voltage sensor for knowing the remaining battery level, and the vehicle 10 A vehicle speed sensor that detects the vehicle speed and a steering angle sensor that detects the steering angle of the vehicle 10 are included.

  The ECU 100 executes control of the electromagnetic suspension 90 of each wheel. The ECU 100 is communicably connected to an amplifier (not shown) that supplies power to the motor of the electromagnetic suspension 90. The ECU 100 determines the state of the vehicle 10 based on detection signals from various sensors including a stroke sensor. The electromagnetic suspension 90 is controlled so as to exhibit an appropriate damping force to stabilize the motor.

  FIG. 2 is a diagram showing the structure of the drive unit 16 and the telescopic unit 18 of the electromagnetic suspension 90 in more detail. In the present embodiment, the electromagnetic suspension 90 and the coil spring 54 are integrally formed.

  An output shaft 36 of the motor 22 that is a drive source of the electromagnetic suspension 90 is configured integrally with the ball screw 44. The output shaft 36 and the ball screw 44 may be coaxially coupled via a coupling. The output shaft 36 is rotatably supported by a bearing 40 inside the rod 42.

  The ball screw 44, the rod 42, the outer shell 50, and the piston 78 are arranged coaxially. The ball screw 44 forms a ball screw mechanism by sandwiching a ball screw nut 46 having a ball passage formed therein and a plurality of balls 48 circulating in the ball passage. When the ball 48 is in rolling contact between the ball screw 44 and the ball screw nut 46, the linear motion and the rotational motion are converted with high efficiency.

  The ball screw nut 46 is connected and fixed to the upper part of the piston 78, and the piston 78 is connected coaxially to the outer shell 50. The outer shell 50 is slidably supported with respect to the outer periphery of the rod 42 by bearings 56 and 58.

  When the motor 22 rotates the output shaft 36 with electric power supplied from a battery (not shown), the ball screw 44 rotates relative to the ball screw nut 46. Then, the outer shell 50 connected to the ball screw nut 46 via the piston 78 is pushed downward with respect to the rod 42 or pulled upward. As a result, the outer shell 50 can be expanded and contracted with respect to the rod 42 and functions as an expandable member controlled by the motor 22.

  In this embodiment, an example in which the ball screw 44 is provided on the spring of the vehicle and the ball screw nut 46 is provided below the spring of the vehicle will be described. Conversely, the ball screw 44 is provided below the vehicle and the ball screw nut 46 is provided on the vehicle. It may be provided on the spring. The drive unit 16 of the electromagnetic suspension 90 is installed inside the vehicle body, and the telescopic unit 18 is installed so as to protrude to the lower part of the vehicle body. However, the drive unit 16 may also be installed so as to protrude below the vehicle body.

  The outer shell 50 has a dust seal 76 disposed between the outer shell 50 and the rod 42. The dust seal 76 seals between the outer shell 50 and the rod 42 to prevent foreign matters such as dust from entering the outer shell 50.

  A second attachment portion 60 is provided at the lower portion of the outer shell 50. The second attachment portion 60 is a portion attached to a lower arm (not shown) extending from the wheel 14 and plays a role of connecting the vehicle suspension device and the wheel 14.

  The electromagnetic suspension 90 operates as follows. When a drive current is applied to the motor 22, the outer shell 50 actively expands and contracts to generate a damping force. When the wheel moves up and down due to external input such as road surface unevenness, the coil spring 54 expands and contracts due to the relative movement between the rod 42 and the outer shell 50. As a result, when the ball screw 44 rotates relative to the ball screw nut 46, the output shaft 36 rotates and the motor 22 acts as a generator. At this time, the damping force can also be generated by the resistance force generated in the motor 22. Further, the ECU 100 sets a current to be applied to the motor 22 according to the vertical acceleration of the vehicle body, and adjusts the damping force. In this way, the electromagnetic suspension 90 generates a desired damping force and attenuates the vertical vibration of the coil spring 54.

  Even when there is no external input, by rotating the ball screw 44 and changing the position of the outer shell 50 relative to the rod 42, the vehicle body can be displaced in the vertical direction, so the electromagnetic suspension 90 can be used for vehicle height adjustment. Can also be used.

  The first attachment portion 28 is a portion attached to the vehicle body 12 and plays a role of connecting the suspension device and the vehicle body 12. An annular stopper 82 having a buffering function is provided at a connection portion between the first attachment portion 28 and the rod 42 to prevent direct contact between the upper end portion of the outer shell 50 and the first attachment portion 28. The movable range of the outer shell 50 is defined by the stopper 82 and the dust seal 76.

  A spring seat 52 provided so as to surround the outer periphery is provided on the outer peripheral portion of the outer shell 50. A coil spring 54 is contracted between the spring seat 52 and the vehicle body surface in the vicinity of the first attachment portion 28, and given a predetermined load in advance.

  The coil spring 54 supports the weight of the sprung portion of the vehicle 10 and prevents vibrations and shocks from the road surface from being transmitted to the vehicle body 12 through the wheels 14 due to its elastic force. The vertical vibration of the vehicle body 12 due to the elastic force of the coil spring 54 is attenuated by the damping force generated by the electromagnetic suspension 90.

  The motor 22 of the drive unit 16 is accommodated in the housing 20. The motor 22 is, for example, a DC motor, and includes a stator that receives power supply from the outside, and a rotor (not shown) that has a permanent magnet attached to the outer periphery and is coupled to the output shaft 36. The outer periphery of the stator of the motor 22 is rotatably supported with respect to the housing 20 by bearings 24 and 26. The housing 20 is filled with lubricating oil. The rotary seal 38 seals the output shaft 36 so that the lubricating oil in the housing 20 does not enter the rod 42 and the output shaft 36 can rotate. With this configuration, the entire motor 22, that is, both the rotor and the stator can be rotated around the output shaft 36 inside the housing 20.

  From the outer periphery of the stator of the motor 22, a damping plate 30 having an orifice 34 is provided so as to protrude from the lubricating oil. One end of a small coil spring 32 is fixed to the damping plate 30.

  FIG. 3 is a cross-sectional view taken along the line AA of FIG. As shown in the figure, a plurality of (four in FIG. 3) damping plates 30 are provided at equal intervals around the stator, and each has an orifice. The housing 20 is also provided with a plurality of stop plates 62 at equal intervals, and the stop plate 62 and the damping plate 30 are connected by small coil springs 32, respectively. The stop plate 62 defines an angular range in which the stator of the motor 22 can rotate.

  When the motor 22 rotates, an elastic force acts in the opposite direction to the rotation of the motor 22 by the small coil spring 32 connected to the damping plate 30. Further, when the damping plate 30 with the orifice 34 formed therein moves in the lubricating oil, a damping force acts in the opposite direction to the rotation of the motor 22.

  FIG. 4 is a principle diagram showing the correlation between the vehicle body 12 which is a spring and the wheel 14 which is an unspring. In FIG. 4, the damping element 80 collectively represents the damping force generated by the interaction of the damping plate 30, the orifice 34, and the lubricating oil in the housing 20 described in FIG. 3. As shown in the figure, the small coil spring 32 and the damping element 80 are provided in parallel, and these sets are provided in series with the electromagnetic suspension 90. Further, a coil spring 54 is provided in parallel with the electromagnetic suspension 90.

  In this embodiment, the ECU 100 controls the motor 22 so as to generate a damping force in the electromagnetic suspension 90 that mainly cancels the low-frequency component among the inputs transmitted to the vehicle suspension device. The input of the high frequency component is attenuated mainly by the attenuation element 80.

  In a conventional active suspension device, when the wheel is suddenly displaced in the vertical direction, such as when the wheel rides on a stone, that is, when there is a high-frequency input from the road surface, the vertical input is rotated by the ball screw mechanism. Even if converted to the input, the rotor cannot be rotated because the control of the motor cannot follow, and the suspension is locked, and an impact is transmitted to the occupant. In this embodiment, since the stator of the motor 22 is configured to rotate, when the control cannot follow, both the stator and the rotor of the motor 22 rotate. As a result, the suspension does not lock even when there is a high frequency input that the motor control cannot follow.

  In addition, when the spring and the damping element are arranged in series in order to reduce transmission in the high frequency region as in the prior art 1, the overall height of the vehicle suspension increases, but in this embodiment, the rotational direction of the motor Since the elastic element and the damping element are provided in the vehicle, the vibration damping effect of the high frequency input can be provided while suppressing the overall height of the vehicle suspension device. Accordingly, there is an advantage that the interior space can be expanded.

  The motor 22 may be cooled by circulating lubricating oil in the housing 20 using a pump (not shown).

Modification 1
FIG. 5 shows a first modification in which an elastic force is exerted on the motor that is rotated and held in the housing 20. In FIG. 5, the structure of the expansion / contraction part 18 is the same as that of the above-described embodiment, and is omitted. In this modification, instead of fixing the small coil spring to the damping plate 30, a cylindrical rubber 64 is attached to the inner peripheral surface of the housing 20. Then, the length of the damping plate 30 is set to such a length that it slightly presses the inner peripheral surface of the rubber 64. With this configuration, when the motor 22 rotates, an elastic force is generated by the rubber 64 so as to prevent the rotation.

  When the stop plate 62 and the damping plate 30 are connected by the small coil spring 32 as in the above-described embodiment, the angular range in which the stator of the motor 22 can rotate is limited. The stator can rotate 360 degrees.

Modification 2
FIG. 6 shows a second modification in which an elastic force is exerted on the motor that is rotated and held in the housing 20. In FIG. 6, since the structure of the expansion / contraction part 18 is the same as that of the above-mentioned embodiment, it is abbreviate | omitted and only the drive part 16 is shown. A torsion bar 72 is installed on the lower surface of the lid portion of the housing 20. A gear is formed on the outer periphery of the tip portion of the torsion bar 72 and meshes with a planetary gear 70 provided on the upper bottom portion of the stator of the motor 22. The planetary gear 70 reduces the rotation angle of the motor 22 and transmits it to the torsion bar 72. As a result, the torsion bar 72 can be twisted to exert an elastic force against the rotation of the motor 22.

  The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention.

It is a mimetic diagram of a four-wheeled vehicle provided with a vehicle suspension device concerning this embodiment. It is a figure which shows the structure of an electromagnetic suspension in detail. It is AA sectional drawing of FIG. It is a principle figure which shows the correlation of a spring top and a spring bottom. FIG. 11 is a cross-sectional view of a drive unit in Modification 1. FIG. 10 is a front view of a drive unit in Modification 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Vehicle, 12 Car body, 14 Wheel, 16 Drive part, 18 Telescopic part, 20 Housing, 22 Motor, 24, 26 Bearing, 30 Damping plate, 32 Small coil spring, 34 Orifice, 36 Output shaft, 42 Rod, 44 Ball screw, 46 ball screw nut, 48 ball, 50 outer shell, 52 spring seat, 54 coil spring, 90 electromagnetic suspension.

Claims (3)

An input conversion means that includes a linear motion member and a rotary member that is screwed to the linear motion member, and that converts an input in the linear motion direction from the unsprung portion of the vehicle into an input in the rotational direction; and an output shaft coupled to the rotary member of the input conversion means. A rotation motor having a linear motion member of the input conversion means and a spring on the vehicle, and an expansion / contraction member that is controlled by the rotation motor to generate a damping force between the spring on and under the spring. Having damping means;
Elastic means provided in parallel with the damping means and elastically supporting the unsprung portion,
A vehicle suspension device, wherein a stator of the rotary motor is held so as to be rotatable around the output shaft. Second elastic means for generating an elastic force in a direction opposite to the rotation of the stator of the rotary motor;
Second damping means for damping vibrations of the second elastic means;
The vehicle suspension device according to claim 1, further comprising: The second damping means comprises:
A housing provided so as to contain the entirety of the rotary motor;
A fluid filled in the housing;
A fixing plate provided so as to protrude into the fluid from a side surface of the stator of the rotary motor;
An orifice drilled in the fixed plate;
The vehicle suspension apparatus according to claim 2, comprising:

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