DE-112024002566-T5 - Suspension device and control method of a suspension device

DE112024002566T5DE 112024002566 T5DE112024002566 T5DE 112024002566T5DE-112024002566-T5

Abstract

A design is achieved in which vehicle height adjustment can be carried out uniformly. A control unit 51 has a function for controlling an electric motor 3 such that when adjusting a vehicle height, if the direction of a rotational torque applied oppositely to a clutch output element 11 and the direction in which a clutch input element 10 is rotated are the same, and the rotational speed of the clutch input element 10 is within a speed range equal to or lower than a predetermined threshold at which a jerking phenomenon is likely to occur, the electric motor 3 can quickly pass through the speed range.

Inventors

Hideyuki Saito
Shin Yamamoto

Assignees

NSK LTD.

Dates

Publication Date: 20260513
Application Date: 20240628
Priority Date: 20230720

Claims (15)

Suspension device, including: a spring provided to be tensioned between a vehicle body and a wheel-supporting element, a vehicle height adjustment mechanism, including: an electric motor with a motor output shaft; a reverse input locking clutch with a clutch input element, which is rotationally driven based on the rotation of the motor output shaft, and a clutch output element, and which transmits a rotational torque applied to the clutch input element to the clutch output element when the rotational torque is applied to the clutch input element, whereas it does not transmit a rotational torque applied in the opposite direction to the clutch output element to the clutch input element when the rotational torque is applied in the opposite direction to the clutch output element; and a spring adjustment mechanism which causes the spring to move in an up-down direction or to rotate in accordance with the rotation of the clutch output element; wherein the vehicle height adjustment mechanism adjusts a vehicle height of the vehicle body from a ground contact surface of the wheel by causing the spring to move in the up-down direction or to rotate by the spring adjustment mechanism based on the rotational drive of the motor output shaft, and a controller that controls the electric motor, the controller comprising a function of at least one of: a first function of activating the motor output shaft at a first rotational acceleration upon initiation of a control for adjusting the vehicle height in a direction in which the clutch input element is rotated in the same direction as a direction of a rotational torque, applied opposite to the clutch output element, from a state in which the opposite input locking clutch is locked by the rotational torque applied opposite to the clutch output element, and switching the rotational acceleration of the motor output shaft to a second rotational acceleration less than the first rotational acceleration, in a stage in which a Rotational speed of the clutch input element becomes greater than a predetermined first threshold, or a second function for setting a target value of the rotational speed of the clutch input element to 0 when the rotational speed of the clutch input element is equal to or lower than a predetermined second threshold in a termination stage of the control for adjusting the vehicle height and in a case where a direction of torque applied opposite to the clutch output element is the same as a direction of rotation of the clutch input element.
Suspension device according to Claim 1 , wherein the controller has the first function and is configured to control the motor output shaft by speed control or position control.
Suspension device according to Claim 1 , wherein the control has the first function and is configured to control the motor output shaft by torque control in a range where the speed of the clutch input element is equal to or less than the predetermined first threshold from activation of the motor output shaft, and after the speed of the clutch input element becomes greater than the predetermined first threshold, to control the motor output shaft by speed control or position control.
Suspension device according to one of the Claims 1 until 3 , wherein the counter-directional input locking coupling includes: a pressed element with a pressed surface on an inner circumferential surface thereof, the coupling input element with an input-side engagement section arranged on an inside in a radial direction of the pressed surface and arranged coaxially to the pressed surface, the coupling output element with an output-side engagement section arranged on the inside in the radial direction of the input-side engagement section and arranged coaxially to the pressed surface, and an engagement element with a pressure surface facing the pressed surface, an input-side engagement section which engages with the input-side engagement section, and an output-side engagement section which engages with the output-side engagement section, wherein the engagement element is movably arranged in the radial direction, wherein the engagement element moves in the radial direction towards the inside based on the engagement the input-side engagement section moves with the input-side engagement section when a rotational torque is applied to the coupling. input element, and the rotational torque applied to the coupling input element is transmitted to the coupling output element by the engagement of the output-side engagement section with the output-side engagement section, whereas, if a rotational torque is applied in the opposite direction to the coupling output element, based on the engagement of the output-side engagement section with the output-side engagement section, the engagement element presses the pressure surface against the pressed surface, thereby bringing the pressure surface into frictional engagement with the pressed surface.
Suspension device according to Claim 4 , wherein the pressure surface is composed of two pressure surfaces, and the counter-rotating input locking clutch is configured such that, in a state where the two pressure surfaces are pressed against the pressed surface due to a rotation of the clutch output element in a predetermined direction, and the input-side engagement section and the input-side engagement section are engaged due to a rotation of the clutch input element in a direction opposite to the predetermined direction, a distance in a second direction perpendicular to both a first direction, which is a radial direction of the engagement element, and to a center of rotation of the clutch input element, between a contact section of the input-side engagement section and the input-side engagement section and the center of rotation of the clutch input element is greater than a distance in the second direction between a contact section of the output-side engagement section and the output-side engagement section and a center of rotation of the clutch output element, and in a state where rotational torque is counter-rotating is applied to the coupling output element and the two pressure surfaces are in contact with the pressed surface, the contact section between the output-side engagement section and the output-side engagement section is located closer to the center of rotation of the coupling output element on one side with respect to the first direction than an imaginary line connecting a contact section between a pressure surface of the two pressure surfaces and the pressed surface and the center of rotation of the coupling output element.
Suspension device according to Claim 4 or 5 , wherein the opposing input locking clutch includes a preloading element which elastically preloads the engagement element in a direction in which the contact surface approaches the pressed surface.
Suspension device according to one of the Claims 1 until 6 , wherein the control unit has the first function, and at least one is provided by a speed sensor for measuring the rotational speed of the clutch input element; a lift sensor for measuring the vehicle height; or an angle sensor for measuring a rotational angle of the clutch input element.
Suspension device according to one of the Claims 1 until 7 , including a damper with a cylinder supported by the wheel and a piston supported by the vehicle body and inserted in the cylinder, wherein the damper is arranged parallel to the spring between the vehicle body and the wheel.
Suspension device according to Claim 8 , including a spring seat which is supported in relation to the cylinder in such a way that it is capable of relative movement in the up-down direction and is not capable of relative rotation, wherein the spring is composed of a coil spring which is held elastically between the vehicle body and the spring seat, and the spring adjusting mechanism is configured to convert a rotational movement of the clutch output element into an up-down movement of the spring seat in relation to the cylinder.
Suspension device according to Claim 9 , wherein the spring adjusting mechanism includes a nut with an outer diameter-side ball screw groove on an inner circumferential surface, which is rotaryally driven based on the rotation of the coupling output element, and a plurality of balls arranged rolling between an inner diameter-side ball screw groove provided on an outer circumferential surface of the cylinder or on an outer circumferential surface of an element supported by and attached to the cylinder, and the outer diameter-side ball screw groove, and the nut is supported such that it can move in the up-down direction and rotate relative to the cylinder and can move integrally with the spring seat in the up-down direction.
Suspension device according to one of the Claims 1 until 8 , wherein the spring is composed of a torsion bar, and the spring adjustment mechanism is configured to rotate the torsion bar when the coupling output element rotates.
A method for controlling a suspension device, wherein the suspension device includes: a spring provided to be tensioned between a vehicle body and a wheel, a vehicle height adjustment mechanism including an electric motor with a motor output shaft; a reverse-actuator locking clutch comprising a clutch input element driven rotationally based on the rotation of the motor output shaft, and a clutch output element, and transmitting a rotational torque applied to the clutch input element to the clutch output element when a rotational torque is applied to the clutch input element, whereas it does not transmit a rotational torque applied in the opposite direction to the clutch output element to the clutch input element when a rotational torque is applied in the opposite direction to the clutch output element; and a spring adjusting mechanism that causes the spring to move or rotate in an up-down direction as the clutch output element rotates, whereby the vehicle height adjustment mechanism adjusts a vehicle height of the vehicle body from a ground contact surface of the wheel by causing the spring to move in the up-down direction or rotate by the spring adjusting mechanism based on the rotational drive of the motor output shaft, the method comprising the following steps: upon initiating a vehicle height adjustment control from a state in which the reverse input locking clutch is locked due to a rotational torque applied in the opposite direction to the clutch output element, in a direction in which the clutch input element rotates in the same direction as the rotational torque applied in the opposite direction to the clutch output element, activating the motor output shaft with an initial rotational acceleration, and in a stage in which the rotational speed of the clutch input element is greater than a predetermined initial The threshold is reached when the rotational acceleration of the motor output shaft is switched to a second rotational acceleration that is smaller than the first rotational acceleration.
Method for controlling the suspension device according to Claim 12 , whereby the motor output shaft is controlled by speed control or position control.
Method for controlling the suspension device according to Claim 12 , wherein in a range where the speed of the clutch input element is equal to or less than the predetermined first threshold after activation of the motor output shaft, the motor output shaft is controlled by torque control, and after the speed of the clutch input element becomes greater than the predetermined first threshold, the motor output shaft is controlled by speed control or position control.
A method for controlling a suspension device, wherein the suspension device includes: a spring provided to be tensioned between a vehicle body and a wheel; a vehicle height adjustment mechanism including an electric motor with a motor output shaft; a reverse input locking clutch comprising a clutch input element which is rotationally driven based on the rotation of the motor output shaft, and a clutch output element, and which transmits a rotational torque applied to the clutch input element to the clutch output element when a rotational torque is applied to the clutch input element, whereas it does not transmit a reverse rotational torque applied to the clutch output element to the clutch input element when a reverse rotational torque is applied to the clutch output element; and a spring adjusting mechanism that causes the spring to move or rotate in an up-down direction as the clutch output element rotates, wherein the vehicle height adjustment mechanism sets a vehicle height of the vehicle body from a ground contact surface of the wheel by causing the spring to move in the up-down direction or rotate by the spring adjusting mechanism based on the rotational drive of the engine output shaft, and in a termination stage of the control for adjusting the vehicle height when the rotational speed of the clutch input element is equal to or less than a predetermined second threshold, and in a case where a direction of rotational torque applied opposite to the clutch output element is the same as a direction of rotation of the clutch input element, a target value of the rotational speed The digkeit of the coupling input element is set to 0.

Description

TECHNICAL AREA The present disclosure relates to a suspension device for supporting wheels on a vehicle body and a control method thereof. STATE OF THE ART For large vehicles like buses, it is preferable to lower the vehicle height when stationary to facilitate passenger entry and exit. For vehicles like sports cars, where the vehicle height is low and the distance between the underbody and the road surface is small, it is preferable to raise the vehicle height when crossing a curb step at extremely low speed. This prevents the underbody from touching the step and also facilitates passenger entry and exit. For this reason, the suspension systems of these vehicles may be equipped with a height adjustment device for raising and lowering the vehicle height. JP 2021-037868A Disclosing a vehicle height adjustment device installed in a vehicle suspension assembly. The vehicle height adjustment device, with a conventional structure, includes a sleeve mounted externally on a shock absorber housing and having an external threaded section, a housing rotatably supporting a coil element with an internal threaded section screwed onto the external threaded section, and a drive motor that rotates the coil element. In the conventional vehicle height adjustment device, the housing moves up and down relative to the sleeve by rotating the coil element using the drive motor, and the vehicle height adjustment is provided by raising and lowering a spring seat provided on an upper surface of the housing. This vehicle height adjustment device further includes a reverse input locking clutch, arranged between the drive motor and the coil element, which transmits forward and reverse rotation inputs from the drive motor to the coil element and prevents reverse rotation inputs from the coil element to the drive motor. Therefore, in this vehicle height adjustment device, even if the power supply to the drive motor is stopped after the vehicle height has been set, rotation of the coil element based on the weight of the vehicle body and occupants is prevented by the reverse input locking clutch, and the vehicle height is maintained. SOURCE REFERENCE PATENT LITERATURE Patent literature 1: JP 2021-037868 (A ) BRIEF SUMMARY OF THE INVENTION TECHNICAL PROBLEM In the case of the vehicle height adjustment device with conventional structure, which is in JP 2021-037868A As described, the behavior when adjusting the vehicle height can become unstable. This means that before the vehicle height is adjusted, a force is applied to rotate an output section of the opposing input locking clutch onto the output section from the wheel side, based on the weight of the vehicle body and occupants and the elasticity of a spring. If the direction of the force exerted on the output part of the clutch from the wheel side coincides with the direction in which the input part of the clutch is rotated by the drive motor to adjust the vehicle height to a desired level, and if the rotational speed of the output part of the clutch is greater than the rotational speed of the input part, the rotation of the housing will be locked, and the rotation of the coil element will also be locked. However, even in this state, as soon as a torque is applied to the input part, the clutch will be released from the locked position, and the coil element will rotate. This means that if the direction of the force applied to the output section of the clutch from the wheel side, based on the weight of the vehicle body and occupants and the elasticity of the spring, coincides with the direction in which the input section of the clutch is rotated by the drive motor to adjust the vehicle height to a desired level, a jerking phenomenon can occur in which the input and output sections rotate intermittently in a predetermined direction, while in a short time they alternately enter a disengaged state in which a torque is transmitted between the input and output sections. The torque can be transmitted, and a locked state, in which no torque can be transmitted between the input and output sections, is repeated. When this jerking phenomenon occurs, the behavior of the coil element becomes uneven, making smooth vehicle height adjustment impossible. One objective of the present disclosure is to provide a suspension device and a method for controlling the suspension device that can perform a uniform vehicle height adjustment. SOLUTION TO THE PROBLEM The inventors of the present disclosure have conducted extensive studies on the conditions under which a jerk phenomenon occurs in a reverse-direction input locking clutch of a suspension device and have consequently determined that the jerk phenomenon occurs when the rotational speed of a clutch input element rotating in a predetermined direction falls below a predetermined threshold while a torque in the predetermined direction is applied to a clutch output element in the opposite direction. The suspension device of one aspect of the present disclosure and