JP2005262939A - Active suspension - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active suspension capable of improving riding comfort of a vehicle and exhibiting enhanced vibration restraining effect of a vehicle body side member. <P>SOLUTION: This active suspension intervening between the respective vehicle body side members B1, B2, B3 and B4 and respective axle side members S1, S2, S3 and S4 and capable of adjusting generated control force F is provided with a movement conversion mechanism for converting relative movement (v) of the vehicle body side members B1, B2, B3 and B4 and the axle side members S1, S2, S3 and S4 to rotation movement; a motor 1 to which the rotation movement is transmitted; and a suspension device using electromagnetic force generated in the motor 1 as the control force F for restraining the relative movement of the vehicle body side members B1, B2, B3 and B4 and the axle side members S1, S2, S3 and S4. The control force F is adjusted based on at least sprung mass (m) of respective wheels of the vehicle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an improvement of an active suspension.

In general, in a vehicle, a suspension is interposed between the vehicle body side member and the axle side member in order to suppress the vibration of the vehicle body side member, and various control methods are used to efficiently suppress the vibration. Proposed. Since long ago, semi-active suspensions utilizing the Skyhook control law and the like have been developed, and their control methods are diverse. However, since the semi-active suspension only allows passive control with respect to vibration input, vibration may not be sufficiently suppressed. Accordingly, there is a demand for practical use of an active suspension capable of suppressing vibration more efficiently. This active suspension is forcibly applied to a vehicle body side member by an actuator against vibration input from a road surface while the vehicle is running. By applying an external force, the vibration of the vehicle body side member can be suppressed, that is, the vibration can be actively suppressed (for example, see Patent Documents 1 and 2).
JP 2000-264033 A (Embodiment of the Invention, FIG. 1) JP 2000-264034 A (Embodiment of the Invention, FIG. 1) JP 2001-10324 A (Embodiment of the Invention, FIG. 1)

  However, the above-described prior art has the following problems when suppressing the vibration of the vehicle body side member of the vehicle.

  That is, for example, when applied to a four-wheeled vehicle, the vehicle is interposed at four locations between the vehicle body side member and the axle side member of the vehicle. As the weight changes, the sprung mass carried by each active suspension also changes, so the sprung resonance point changes. It may be pointed out that there are cases where it cannot be suppressed.

  Therefore, the present invention is to improve the above-mentioned problems, and an object of the present invention is to provide an active suspension having a high vibration suppressing effect on the vehicle body side member and to improve the riding comfort of the vehicle.

  In order to achieve the above-described object, the suspension device according to the first problem solving means is an active suspension that is interposed between each vehicle body side member and each axle side member of the vehicle and can adjust the generated control force. A motion conversion mechanism that converts relative motion of the vehicle body side member and the axle side member into rotational motion, and a motor to which the rotational motion is transmitted, and the electromagnetic force generated in the motor is relative to the vehicle body side member and the axle side member. A suspension device used as a control force for suppressing movement is provided, and the control force is adjusted based on at least the sprung mass of each vehicle wheel.

  The second problem solving means is characterized in that, in the first problem solving means, the control force is adjusted so as not to change the sprung resonance frequency and the damping rate based on each sprung mass.

  The third problem-solving means is the first or second problem-solving means, wherein the control gain is set with reference to the control gain calculation map based on the sprung mass, and the relative relationship between the vehicle body side member and the axle side member The control force is adjusted based on the displacement, the relative speed, and the control gain.

  According to the invention of each claim, the suspension device of the present invention can not only generate a damping force but also function as an actuator, and an actuator is mounted in addition to a shock absorber like a conventional active suspension. In addition to eliminating the need to mount a hydraulic power source that drives the actuator, it is possible to improve the mountability of the suspension device on the vehicle and to reduce the weight compared to the conventional active suspension. Can do.

  In addition, in the conventional hydraulic and suspension devices, it is indispensable to mount the actuator and the hydraulic power source as described above, and it may be impossible to attach to an existing vehicle, so-called retrofitting due to the mounting space. Since the suspension device according to the embodiment is slim and space-saving compared to the conventional suspension device, it can be retrofitted to an existing vehicle.

  Furthermore, it becomes possible to effectively suppress the vibration of the vehicle body side member for each vehicle wheel corresponding to the change in the sprung mass in each vehicle wheel, and the riding comfort in the vehicle can be improved.

  Also, since the damping force generated by the suspension device is generated by the electromagnetic force of the motor, unlike a hydraulic shock absorber, which is determined by the valve opening, the damping coefficient is changed finely. In addition, it is possible to monitor the generated electromagnetic force by continuously supplying current with the ECU, thereby monitoring the damping force as an output, and to perform targeted control.

  Since the actuator function of the suspension device is also controlled by current supply, the control delay is less than that of the hydraulic actuator, and control aimed at this point can be realized.

  According to the second aspect of the present invention, in the suspension device that changes the control gain based on the change in the sprung mass of each wheel of the vehicle simply by the semi-active suspension, the sprung resonance frequency and the damping rate are changed. As the upper mass increases, the sprung resonance frequency decreases, so that it takes a long time to sufficiently dampen the vibration, so there is a concern that riding comfort may deteriorate, but in this embodiment, as described above, The sprung resonance frequency and the damping rate can be controlled so as not to change, and the above-described adverse effects can be prevented.

  The vibration transfer function can be controlled so as not to change regardless of the sprung mass change in each vehicle wheel, and the riding comfort of the vehicle is stabilized regardless of the sprung mass change in each vehicle wheel. In addition, the vehicle driver can always drive under the same conditions regardless of the sprung mass change in each vehicle wheel.

  Furthermore, it is possible to measure each spring constant of an accurate spring element and control based on the exact spring constant, so that vibration can be efficiently suppressed as compared with a conventional active suspension, and the vehicle In addition, it is possible to improve the ride comfort in the vehicle, and since the accurate measurement of the spring constant of the spring element is also performed by energizing the motor, there is no need to use a hydraulic power source that consumes a large amount of the power source of the vehicle. It is.

  According to the invention of claim 3, based on each sprung mass, the control gain is set with reference to the corresponding control gain calculation map, the relative displacement and the relative speed of the vehicle body side member and the axle side member, and the control gain. Therefore, even if each sprung mass changes, an optimal vibration suppression effect can be obtained.

  The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view of a suspension device according to an embodiment of the present invention. FIG. 2 is a diagram showing a state in which the active suspension is applied to a vehicle. FIG. 3 is a flowchart showing a procedure for creating a control gain calculation map. FIG. 4 is a flowchart showing a processing procedure for changing the control gain. FIG. 5 is a longitudinal sectional view of a suspension device according to another embodiment.

 As shown in FIG. 1, the suspension device according to the present embodiment basically has a motion conversion composed of a ball screw nut 4 and a screw shaft 3 that is rotatably screwed into the ball screw nut 4. The mechanism and the motor 1 are configured, and the upper end of the screw shaft 3 is connected to the shaft 1a of the motor 1, and the torque generated by the motor 1 is adjusted by supplying current to the motor 1, and the torque is transmitted to the screw shaft 3. The vertical movement of the ball screw nut 4 in FIG. 1 when the suspension device expands and contracts can be controlled.

 The detailed structure will be described below. The motor 1 is installed in a bottomed cylindrical outer cylinder 2, and the shaft 1 a of the motor 1 is rotatably inserted into the outer cylinder 2 via ball bearings 9, 10, and 11. The shaft 1 a is connected to the screw shaft 3. In the figure, the screw shaft 3 and the shaft 1a are connected as separate members. However, the screw shaft 3 and the shaft 1a may be integrally formed. A bracket 20 for attaching the suspension device to the vehicle is provided at the upper end of the outer cylinder 2 in FIG.

The motor 1 is attached so as to face the magnets 7, 7 on the inner periphery of the outer cylinder 2, the shaft 1 a connected to the screw shaft 3, the magnets 7, 7 attached to the outer periphery of the shaft 1 a. In this case, the outer cylinder 2 serves as a frame for the motor 1. Each electrode (not shown) of the motor 1 is connected to the ECU 30 as shown in FIG. 2 to supply current from the ECU 30 to the motor 1 so that the motor 1 can generate torque caused by electromagnetic force. Yes, it is set to obtain a desired control force. In addition, this brushless motor is equipped with a Hall element H as a rotor position detecting means, and this Hall element H is connected to a rotation logic of a drive circuit, which will be described later. (Rotational angle, angular velocity, etc.) can be grasped. In place of the Hall element H, a magnetic sensor, an optical sensor, or the like may be mounted. When using a motor that does not have position detection means, such as a DC brush motor, it may be preferable to provide position detection means for controlling the suspension device. This will be described later. Further, if a Hall element as a position detecting means is taken as an example, it is necessary to energize the element from an external power source. However, the bracket 20 side is attached to the vehicle body side of the vehicle. If an electric wire (not shown) for energization is connected to the element via the bracket 20 and current is supplied, the electric wire extending from the upper end side of the bracket 20 in FIG. When connecting to the control device and the control circuit, it becomes easy and the electric wire is accommodated in the vehicle body, so that the chance of damaging the electric wire can be reduced. Further, since electric power is generated by the rotation of the ball screw nut 4 without using an external power source, the current generated by the induced electromotive force is supplied to the Hall element or stored in an external battery. A current may be supplied from the battery. Incidentally, the position detecting means is always energized and is connected to an ECU 30 or the like which will be described later, so that an accurate vehicle height can be detected. In this embodiment, the coil 6 is attached to the outer cylinder 2 side and the magnets 7 and 7 are attached to the shaft 1a side. However, the coil 6 is attached to the shaft 1a side and the magnets 7 and 7 are attached.
May be attached to the outer cylinder 2 side. In the present embodiment, the motor 1 is a brushless motor, but various motors such as a DC motor, an AC motor, an induction motor, and the like can be used as long as they can be used as an electromagnetic force generation source.

  The screw shaft 3 connected to the shaft 1a is provided with a screw groove 3a on the outer periphery thereof, and is inserted into a bottomed cylindrical inner cylinder 5 slidably inserted into the outer cylinder 2, The ball screw nut 4 fitted in the inner cylinder 5 is rotatably screwed. That is, in this embodiment, the screw shaft 3 and the ball screw nut 4 constitute a motion conversion mechanism, and the relative linear motion in the axial direction of the ball screw nut 4 and the screw shaft 3 is the same as that of the screw shaft 3. Converted to rotational motion. 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 compared to a mechanism such as a rack and pinion. However, the motion conversion mechanism is configured by a rack and pinion, and the pinion Of motor 1 It may be linked to Yafuto 1a.

  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. When the ball screw nut 4 moves downward in FIG. 1 and the suspension device is fully extended, the cushion member 15 provided at the lower end of the screw shaft 3 in FIG. The screw shaft 3 is prevented from coming out of the ball screw nut 4 by coming into contact with the lower end, and the shock at the time of full extension is alleviated. At the time of maximum compression, the screw shaft 3 is the bottom of the inner cylinder 5 described later. To reduce the impact.

 A dust seal (not shown) is provided between the outer cylinder 2 and the inner cylinder 5, thereby preventing dust, dust, rainwater, etc. from entering the space formed by the outer cylinder 2 and the inner cylinder 5. Has been. Incidentally, although the inner cylinder 5 is slidably inserted into the outer cylinder 2, an annular bearing may be provided between the outer cylinder 2 and the inner cylinder 5. In this case, it is possible to prevent the risk that the inner periphery of the lower end portion of the outer cylinder 2 bites the outer peripheral surface of the inner cylinder 5 and the sealing performance between the outer cylinder 2 and the inner cylinder 5 deteriorates.

 Further, since the inner cylinder 5 is slidably inserted into the outer cylinder 2, the axial movement of the screw shaft 3 with respect to the inner cylinder 5 and the ball screw nut 4 is prevented, whereby the ball screw nut 4. It is possible to prevent a load from being concentrated on a part of the balls (not shown), and to avoid a situation in which the ball or the screw groove 3a of the screw shaft 3 is damaged. Further, since the ball or the screw groove 3a of the screw shaft 3 can be prevented from being damaged, the smoothness of each operation of the rotation of the screw shaft 3 and the ball screw nut 4 or the movement of the suspension device in the expansion / contraction direction can be maintained. Since the smoothness of each operation can be maintained, the function as a suspension device is not impaired, and the failure of the suspension device can be prevented.

 Further, an eye bracket 21 is provided at the lower end of the inner cylinder 5 in FIG. 1, and the eye bracket 21 and the bracket 20 provided at the upper end of the outer cylinder 2 in FIG. A suspension device can be interposed between the vehicle body and the axle.

  The suspension device configured as described above 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 ball screw nut 4 connected to the inner cylinder 5 also has a shaft. A linear motion in the direction, that is, a linear motion in the vertical direction in FIG. This linear motion of the ball screw nut 4 is converted into a rotational motion of the screw shaft 3 by the ball screw mechanism of the ball screw nut 4 and the screw shaft 3.

  When the screw shaft 3 exhibits a rotational motion, the shaft 1a also rotates. Then, the coil 6 in the motor 1 crosses the magnetic fields of the magnets 7 and 7, and an induced electromotive force is generated in the coil 6, and the motor 1 resists the rotation of the shaft 1a caused by the induced electromotive force. Generate torque. The torque against the rotation of the shaft 1a suppresses the rotation of the screw shaft 3 and the linear motion of the ball screw nut 4 because the shaft 1a is connected to the screw shaft 3. The sum of the current flowing in the coil 6 caused by the induced electromotive force generated by the rotation of the shaft 1a with the rotation of the screw shaft 3 and the current supplied from the ECU 30 (described later) to which the motor 1 is connected. An electromagnetic force is generated, and the suspension device generates a damping force commensurate with the electromagnetic force. The generated damping force of the suspension device can be adjusted by supplying current from the ECU 30 and is supplied to the motor 1. It can also be used as an actuator by adjusting the amount of current.

  Therefore, the action of suppressing the rotational movement of the shaft 1a of the motor 1 works to suppress the linear movement of the ball screw nut 4, and thus acts as a damping force that suppresses the linear movement of the ball screw nut 4. Absorbs and relaxes energy. Here, if the amount of current supplied to the motor 1 is adjusted, the torque generated by the motor 1 not only acts as a damping force but also as a force in the direction of increasing the expansion / contraction with respect to the expansion / contraction of the suspension device. In contrast, the suspension device can be actively expanded and contracted, and the expansion and contraction of the suspension device can be freely controlled.

  As described above, through a series of operations, the suspension device can not only generate a damping force but also function as an actuator. Therefore, unlike the conventional active suspension, it is not necessary to mount an actuator in addition to the shock absorber, and it is not necessary to mount a hydraulic power source or the like for driving the actuator. As well as improving the performance, the weight can be reduced compared to the conventional active suspension.

  In addition, in the conventional hydraulic suspension device, it is indispensable to mount the actuator and the hydraulic power source as described above, and it may be impossible to attach to the existing vehicle, so-called retrofitting due to the mounting space. Since the suspension device of this form is slim and space-saving compared to the conventional suspension device, it can be retrofitted to an existing vehicle.

 Next, a state in which this suspension device is applied to an actual vehicle will be described. Each suspension device D1, D2, D3, D4 configured as described above is, for example, a four-wheeled vehicle, as shown in FIG. , B4 and the axle side members S1, S2, S3, S4, and suspension springs K1, K2, K3, K4 such as metal springs and air springs in parallel with the suspension devices D1, D2, D3, D4 Intervened. In this case, the outer cylinder 2 of the suspension devices D1, D2, D3, and D4 is attached to the vehicle body side, and the inner cylinder 5 is attached to the axle side.

Each motor 1 and each hall element H of each suspension device D1, D2, D3, D4 is connected to an ECU 30 that is a controller for the suspension device. This ECU 30 is used for controlling the suspension device. The ECU 30 calculates the sprung mass m of each vehicle wheel from the rotational position of the shaft 1a of the motor 1 consisting of the Hall voltage detected by the Hall element H. Based on the control gain calculation map, the two control gains Gc and Gk are determined, and the vehicle body side members B1, B2, and B3 are determined from the rotational positions of the shafts 1a of the motors 1 detected by the Hall elements H, respectively. , B4 and the axle side members S1, S2, S3, S4 and the vehicle body side members B1, B2 at each wheel of the vehicle from the angular velocity obtained by differentiating the rotational position of the shaft 1a of each motor 1. , B3, B4 and the axle side members S1, S2, S3, S4 are calculated, and based on the control gains Gc, Gk, the relative displacement x and the relative speed v, The control force F generated in the suspension devices D1, D2, D3, D4 is calculated, and the current necessary to generate the control force F is supplied to the motor 1 of each suspension device D1, D2, D3, D4. Can be done. Although not specifically shown as hardware, the ECU 30 calculates a control force F based on the Hall voltage detected by the Hall element H, and outputs a necessary current corresponding to the control force to each motor 1. Specifically, for example, an amplifier for amplifying a signal at the rotational position of the shaft 1a composed of a Hall voltage detected by each Hall element H, and a converter for converting an analog signal into a digital signal And a band-pass filter that cuts low and high frequency components, a CPU, a storage device such as a ROM, a RAM, a crystal oscillator, and a bus system that connects these, and a drive circuit that drives the motor 1. The control gain calculation map used for calculating the control force, the control force calculation processing procedure, and the control signal output procedure It may be a known system to keep is previously stored in the ROM or other storage device as a ram. In the case of the motor 1 as a brushless motor, the drive circuit includes, for example, a PWM circuit connected to a voltage source, a base drive circuit connected to the PWM circuit, a transistor inverter connected to the base drive circuit, and a hall A well-known device composed of a rotation logic to which the element H is connected can be used, and other devices that can adjust the amount of current according to the type of the motor can be used.

  Here, the control gain calculation map stored in advance in the storage device of the ECU 30 is created, for example, according to the procedure shown in FIG.

  First, in step P1, the damping coefficient C and the control force F of the suspension devices D1, D2, D3, D4 serving as a reference are determined. In the suspension devices D1, D2, D3, and D4, the electromagnetic force of the motor 1 mounted on each suspension is used as the damping force and the control force F. Therefore, the damping force and the control force depend on the amount of current supplied to each motor 1. Since F can be changed, the optimum damping coefficient C and control force F for the vehicle are first determined. Specifically, currents are respectively supplied to the motors 1 of the suspension devices D1, D2, D3, and D4, the suspension devices D1, D2, D3, and D4 are expanded and contracted, and each motor 1 is determined from the current value output on the ECU 30 side. The torque of the suspension devices D1, D2, D3, and D4 is calculated from the torque, and how much the suspension springs K1, K2, K3, and K4 contract with respect to the force. From the rotational position of the shaft 1a detected by each Hall element H, how much the vehicle body side member B1, B2, B3, B4 is suspended by the suspension springs K1, K2, K3, K4. It is calculated whether the members B1, B2, B3, B4 and the axle side members S1, S2, S3, S4 have undergone relative displacement x. And the exact spring constant k of each suspension spring K1, K2, K3, K4 is calculated from this relative displacement and the said force, and it memorize | stores in the memory | storage device in ECU30. Since the actual vehicle suspension includes spring elements such as bump stoppers, the accurate and total vehicle body side member B1 includes not only the suspension springs K1, K2, K3 and K4 but also spring elements such as bump stoppers. , B2, B3, B4 and the relative displacement x of the axle side members S1, S2, S3, S4, it is possible to obtain a non-linear spring constant k.

  Subsequently, after obtaining an accurate spring constant k for each vehicle wheel, the ECU 30 obtains the relative displacement x of each vehicle body side member B1, B2, B3, B4 and the axle side member S1, S2, S3, S4. The sprung mass m of each vehicle wheel is calculated from the spring constant k, and the sprung mass m is stored as a reference sprung mass in the storage device. When calculating the sprung mass m of each vehicle wheel, the sprung mass of each vehicle wheel at the time of shipment of the vehicle is measured and stored in the ECU 30, and the spring constant k is calculated as the value. And the amount of sprung mass change calculated from the relative displacement x. In calculating the sprung mass m, a current is supplied to each motor 1 to cause the vehicle to vibrate, causing the vehicle body side members B1, B2, B3, and B4 to freely vibrate, and the vibration frequency and spring constant at that time. The sprung mass m may be calculated from k.

  Then, from this spring constant k and the obtained sprung mass m, vibration analysis is performed to obtain the vibration characteristics of the vehicle body side members B1, B2, B3, and B4 at each wheel, which may be input during vehicle travel The optimum suspension devices D1, D2, D3, and D4 for suppressing vibrations in a certain frequency region are the reference damping factors C for the suspension devices D1, D2, D3, and D4 and the reference suspension devices D1. , D2, D3, and D4, the theoretical value of the control force F is determined. This damping coefficient C depends on the expansion / contraction speed of the suspension devices D1, D2, D3, D4, that is, the relative speed v of the vehicle body side members B1, B2, B3, B4 and the axle side members S1, S2, S3, S4. Since it varies, the relationship between the damping coefficient C and the relative speed v is separately determined for each suspension device D1, D2, D3, D4 for determining the damping coefficient with the vertical axis representing the damping coefficient C and the horizontal axis representing the relative speed v. It is mapped and stored in the storage device of the ECU 30 so that the ECU 30 can refer to the map for determining the attenuation coefficient by the control during traveling of the vehicle described later. Further, the control force F is obtained by adding the damping coefficient C and the relative speed v to the spring constant k and the relative displacement x of the vehicle body side members B1, B2, B3, B4 and the axle side members S1, S2, S3, S4. This is obtained by adding the integrated values and is calculated by F = C · v + k · x (Equation 1). Here, the relative speed v of the vehicle body side members B1, B2, B3, B4 and the axle side members S1, S2, S3, S4 takes a positive value in the compression direction of the respective suspension devices D1, D2, D3, D4. In addition, a negative value is assumed on the extending side, and the relative displacement x also takes a positive value in the compression direction of each suspension device D1, D2, D3, D4, and a negative value on the extending side. It is supposed to take.

  Here, the suspension devices D1, D2, D3, and D4 of the present embodiment have a function as a shock absorber and a function as an actuator, and the damping coefficient C referred to here is a shock absorber. Attenuation coefficient for the functioning part. In practice, the suspension device of the present embodiment generates a damping force obtained by integrating the damping coefficient C and the relative speed v and a control force F as an actuator. 1 is generated by the electromagnetic force of 1, the ECU 30 calculates the force to be generated for each suspension device D1, D2, D3, D4 by the sum of the damping force and the control force F. The current required to generate the force is calculated from the torque constant, the lead of the screw shaft 3 and the resistance of the control circuit, and the current is output to each motor 1 of each suspension device D1, D2, D3, D4. It becomes.

  Then, after obtaining the above-described reference damping coefficient C and control force F, in step P2, it is assumed that a heavy object is loaded on the vehicle or a passenger is on the vehicle. The mass m is changed.

Subsequently, in step P3, vibration analysis is performed on the vibration characteristics of the vehicle using the sprung mass m for each wheel of the vehicle, and control for optimal vibration suppression of the vehicle body side members B1, B2, B3, B4 of the vehicle is performed. The control gain Gc and the control gain Gk for each suspension device D1, D2, D3, D4 are set so as to realize the force F. Specifically, a simulation is performed that gives vibrations in a frequency range that may be input while the vehicle is running, and the control force that each suspension device should generate and the control force that serves as the reference so that vibration suppression is optimal. And the control gains Gc and Gk are set so that the control force F at that time can be derived by the equation F = Gc · C · v + Gk · k · x (Equation 2). If vibration suppression can be sufficiently achieved with the reference control force, the control gains Gc and Gk may be set to a if the sprung mass m is a times the reference. By doing so, since the vibration transfer function is exactly the same when the sprung mass m is the reference sprung mass m and the transfer function when the sprung mass m is a times, the sprung resonance frequency and damping The rate does not change, and the vibration does not change. That is, even if there is a change in the sprung mass m, the vibration is always the same as the reference sprung mass m. Vibration suppression of B1, B2, B3, and B4 can be brought into an optimum state. Here, the relative displacement x of the vehicle body side members B1, B2, B3, B4 and the axle side members S1, S2, S3, S4 in each vehicle wheel is suspended by the suspension springs K1, K2, K3, K4. In the balanced state, it is always set to zero, that is, when the sprung weight m changes, the relative displacement x is adjusted to be zero in the changed balanced state. Specifically, the ECU 30 stores the rotational position of the shaft 1a of the motor 1 in a state where only the vehicle is suspended and balanced by the suspension springs K1, K2, K3, and K4. When the sprung mass m changes in step P14 for detecting the sprung mass m shown in FIG. 4 to be described later, the rotational position of the shaft 1a for each suspension device D1, D2, D3, D4 is also stored in the storage device. When the relative displacements x of the vehicle body side members B1, B2, B3, B4 and the axle side members S1, S2, S3, S4 are calculated, the stored currents of the shafts 1a of the respective motors 1 are stored. By subtracting the rotational position of the shaft 1a of each motor 1 after the change of sprung mass m from the rotational position, the rotational angle of each shaft 1a is calculated, and the rotational angle and screw of each shaft 1a are calculated. The lead of the child shaft 3 is integrated and calculated. Therefore, in the present embodiment, the rotational position of the shaft 1a of each motor 1 of each suspension device D1, D2, D3, D4 which is a reference stored in the ECU 30 is used to calculate the sprung mass m. The

  When the vehicle is stopped on a slope or when a heavy object is loaded on the vehicle, the vehicle tends to be inclined. Therefore, the shaft of each motor 1 serving as a reference in which the ECU 30 stores the inclination state of the vehicle. The rotational position of 1a and the current rotational position of the shaft 1a of each motor 1 are compared, and the ECU 30 calculates the inclination of the vehicle, taking the inclination into account, and correcting and calculating the sprung mass m of each wheel of the vehicle By doing so, an accurate sprung mass m of each vehicle wheel may be calculated. Therefore, in the first step P1, it is desirable to stop the vehicle on a flat ground and measure the rotational position of the shaft 1a of each motor 1 serving as a reference.

  In step P4, after the driver has boarded the vehicle, the vehicle is run with the sprung mass m in step 3 maintained, or the vehicle is vibrated and each suspension device D1, D2, D3, D4 is driven. Every time, the passenger determines whether or not the vibration is sufficiently suppressed by the control force F calculated by the above formula 2, and if not enough, fine adjustment of the control gain Gc and the control gain Gk is performed, and the final adjustment is made. Control gains Gc and Gk for each suspension device D1, D2, D3 and D4 are set.

  Further, at step P5, the set control gains Gc and Gk for each of the suspension devices D1, D2, D3 and D4 are written in the control gain setting map and stored in the storage device of the ECU 30.

  Then, the operations from Step P2 to Step P5 are repeated by changing the sprung mass m, and finally, for each suspension device D1, D2, D3, D4 with respect to the sprung mass m for each vehicle wheel. A map showing the control gains Gc and Gk is created. That is, the control gain Gc integrated with the damping coefficient C is a coefficient that changes with respect to the sprung mass m, and the control gain Gc calculation map has the control gain Gc on the vertical axis and the sprung mass m on the horizontal axis. The control gain Gk integrated with the spring constant k is also a coefficient that changes with respect to the sprung mass m, and the vertical axis represents the control gain Gk and the horizontal axis represents the sprung mass m. It becomes.

  Note that the control gain calculation map stored in the storage device of the ECU 30 does not need to be created using the ECU 30, but is created using the computer system for creating maps in the suspension devices D1, D2, D3, and D4. Of course it is good. In the suspension device according to the present embodiment, the spring constant k of the spring element of the suspension such as a suspension spring can be accurately grasped, so that the ECU 30 is optimal from the vibration analysis program and the result of the vibration analysis. A program for calculating a control force is stored and executed, or the damping coefficient C and the control force F corresponding to a plurality of spring constants k are mapped in advance in view of changes in the spring constant k due to aging degradation or the like. If the damping coefficient C and the control force F are determined by referring to the ECU 30, the vibration can be suppressed in consideration of changes in the spring constant due to aging of the suspension spring or the like.

  Further, the damping coefficient C that is theoretically a reference and the control force F that is a reference are calculated in Step P2, but the driver is on the basis of the state in which the driver is on board between Step P2 and Step 3. A step of finely adjusting the reference attenuation coefficient C and the reference control force F may be added according to the sense of feeling the vibration.

  Next, the operation of the above embodiment will be described based on FIG. 4 showing an example of the processing procedure of the CPU of the ECU 30. That is, the process of FIG. 4 is executed as a timer interrupt process at the wait time of step P11, for example, every 10 msec. First, at step P12, for example, the vehicle speed detected by the vehicle speed sensor is zero, or It is determined whether the engine is being started or the side brake is on, that is, whether the vehicle is stopped. If it is determined that the vehicle is running, the process proceeds to step 13. Then, the interruption process is terminated without changing the control gains Gc and Gk for each suspension device D1, D2, D3 and D4. In other words, in this case, the control gains Gc and Gk for the suspension devices D1, D2, D3, and D4 are not changed, and the ECU 30 sets the suspensions that have been set to the suspension devices D1, D2, D3, and D4. The control force F for each suspension device D1, D2, D3, D4 calculated by the above equation 2 by the control gain Gc, Gk for each device D1, D2, D3, D4, and each suspension device D1, D2, D3, In order to generate each damping coefficient C for each D4 and each damping force obtained by integrating the vehicle body side members B1, B2, B3, B4 and the relative speeds v of the axle side members S1, S2, S3, S4. The suspension devices D1, D2, D3, D4 are controlled. Conversely, when it is determined that the vehicle is stopped, the process proceeds to step P14, and the sprung mass m of each vehicle wheel is detected. At this time, the ECU 30 indicates that the shaft 1a of the motor 1 of each of the suspension devices D1, D2, D3, and D4 has the above-mentioned reference sprung mass m of the suspension springs K1, K2, and so on as the sprung mass m of each vehicle wheel changes. Since the vehicle is rotated by the change in the sprung mass m of each wheel from the rotation position of each shaft 1a in a state where K3 and K4 are loaded, i.e., when no passenger or luggage is loaded on the vehicle, The rotation angle of each shaft 1a is calculated from the difference between the current rotation position of each shaft 1a and the rotation position of each shaft 1a when no passenger or luggage is loaded on the vehicle. Each displacement amount corresponding to a change in the sprung mass m of the vehicle body side member B1, B2, B3, B4 in each vehicle wheel is calculated, and each sprung mass is calculated from each displacement amount and each spring constant k of the spring element. m is calculated.

  Then, the process proceeds to Step P15, where the ECU 30 determines the control gains Gc, Gk from the obtained sprung mass m of each vehicle wheel and the control gain calculation map for each of the suspension devices D1, D2, D3, D4. Then, the control gains Gc, Gk for the respective suspension devices D1, D2, D3, D4 are changed to the determined control gains Gc, Gk for the respective suspension devices D1, D2, D3, D4, and this is stored in the storage device. And interrupt processing is terminated.

  In this case, the ECU 30 applies the suspensions D1, D2, D3, D4 to the suspensions calculated by the above formula 2 using the control gains Gc, Gk for the suspension devices D1, D2, D3, D4 after the change. Suspension devices D1, D2, D2, D2, D2, D2, D2, D4, D4, D4, D4, D4, D4, D4, D4 D3 and D4 are controlled.

  The control gains Gc and Gk are determined as described above. Next, the control of the suspension device while the vehicle is traveling will be described. While the vehicle is running, the ECU 30 constantly grasps the rotational position of each shaft 1a detected by the hall elements H of the suspension devices D1, D2, D3, and D4, and at step 14 when the vehicle is stopped, the spring in each wheel of the vehicle. Relative displacements x of the vehicle body side members B1, B2, B3, B4 and the axle side members S1, S2, S3, S4 at each wheel of the vehicle with reference to the rotational position of each shaft 1a in a state where the upper mass m is detected. Is calculated. Further, the ECU 30 differentiates each obtained relative displacement x to calculate the relative speeds v of the vehicle body side members B1, B2, B3, B4 and the axle side members S1, S2, S3, S4 at each wheel of the vehicle. Further, since the damping coefficient C for each suspension device D1, D2, D3, D4 varies depending on each relative speed v as described above, the ECU 30 determines the suspension device D1, D2, D3, D4 for each suspension device D1, D2, D3, D4. Referring to the damping coefficient determination map, the damping coefficient C for each suspension device D1, D2, D3, D4 corresponding to each relative speed v is determined, and the damping for each suspension device D1, D2, D3, D4. The coefficient C and each corresponding relative speed v are integrated to calculate the damping force that the suspension devices D1, D2, D3, and D4 should generate, and the suspension devices described above. Using the control gains Gc, Gk for each of 1, D2, D3, and D4, the calculated relative displacements x and relative speeds v, the determined damping coefficients C, and the spring constants k measured in advance, the above equation 2 The control force F for each suspension device D1, D2, D3, D4 obtained by the following formula is calculated.

  Subsequently, the ECU 30 adds the calculated damping force and the control force F, and calculates the total force to be generated by each suspension device D1, D2, D3, D4 for each suspension device D1, D2, D3, D4. Based on the calculation result, the necessary current supplied to each motor 1 of each suspension device D1, D2, D3, D4 is calculated so that the total force is exerted on each suspension device D1, D2, D3, D4. calculate. Here, in the suspension devices D1, D2, D3, and D4 of the present embodiment, when vibration is input from the road surface to the suspension devices D1, D2, D3, and D4, the screw shaft 3 rotates, and the screw shaft The shaft 1a of the motor 1 connected to 3 also rotates. Then, the motor 1 generates an induced electromotive force in the coil 6 due to the rotation of the shaft 1a as the screw shaft 3 rotates, and an electric current flows through the coil 6 due to the induced electromotive force. In consideration of the current caused by the induced electromotive force, the current is supplied to each motor 1 of each suspension device D1, D2, D3, and D4 so that the necessary current flows through the coil 6 of the motor 1.

  And control during this vehicle travel is performed at any time, for example for every 10 msec, and suppresses vibration of vehicle body side members B1, B2, B3, and B4 of vehicles. In the above description, the ECU 30 is controlled by supplying a current to the motor 1, but it goes without saying that the control may be performed by applying a voltage.

  Therefore, this active suspension can effectively suppress the vibration of the vehicle body side member for each vehicle wheel corresponding to the change of the sprung mass in each vehicle wheel, and improve the riding comfort in the vehicle. Can do.

  Further, since the damping force generated by the suspension device is generated by the electromagnetic force of the motor, unlike the hydraulic shock absorber, which is determined by the valve opening, the damping coefficient is changed finely. In addition, it is possible to monitor the generated electromagnetic force continuously by supplying current with the ECU and to monitor the damping force as an output, and to perform targeted control.

  Since the actuator function of the suspension device is also controlled by current supply, the control delay is less than that of the hydraulic actuator, and control aimed at this point can be realized.

  Further, in a suspension device that simply changes the control gain based on a change in the sprung mass of each vehicle wheel by a semi-active suspension, the sprung resonance frequency changes, and particularly when the sprung mass increases, the sprung resonance frequency increases. Since it takes a long time to sufficiently dampen the vibration, there is a concern that the riding comfort may deteriorate, but in this embodiment, control is performed so as not to change the sprung resonance frequency as described above. It is possible to prevent the above-mentioned adverse effects.

  The vibration transfer function can be controlled so as not to change regardless of the sprung mass change in each vehicle wheel, and the riding comfort of the vehicle is stabilized regardless of the sprung mass change in each vehicle wheel. In addition, the vehicle driver can always drive under the same conditions regardless of the sprung mass change in each vehicle wheel.

  Furthermore, it is possible to measure each spring constant of an accurate spring element and control based on the exact spring constant, so that vibration can be efficiently suppressed as compared with a conventional active suspension, and the vehicle In addition, it is possible to improve the ride comfort in the vehicle, and since the accurate measurement of the spring constant of the spring element is also performed by energizing the motor, there is no need to use a hydraulic power source that consumes a large amount of the power source of the vehicle. It is.

  Further, based on each sprung mass, a control gain is set with reference to the corresponding control gain calculation map, and the control force based on the relative displacement and relative speed between the vehicle body side member and the axle side member and the control gain. Therefore, even if the mass on each spring changes, the optimum vibration suppressing effect can be obtained.

  In the above embodiment, the Hall element H can detect the rotational position of the shaft 1a to calculate the relative displacement x, the relative speed v, the spring constant k, and the sprung mass m. Instead, as described above, a magnetic sensor or an optical sensor may be used, and instead of detecting the rotational position of the shaft 1a of the motor 1, the sprung mass m of each wheel of the vehicle is detected. A load sensor and a stroke sensor for detecting the relative displacement x of the vehicle body side members B1, B2, B3, B4 and the axle side members S1, S2, S3, S4 may be provided in each of the suspension devices D1, D2, D3, D4. .

  Next, a modification of the above embodiment will be described. In the above description, it is assumed that the screw shaft 3 is rotationally moved. In this modified example, however, as shown in FIG. The rotational movement of the ball screw nut 4 is transmitted to the shaft 51a of the motor 51. In this case, a driving side gear 62 b is provided on the outer periphery of the ball screw nut 4, a driven side gear 62 a meshing with the driving side gear 62 b is provided, and the driven side gear 62 a is connected to the shaft 51 a of the motor 51. The rotational movement of the ball screw nut 4 can be transmitted to the shaft 51a of the motor 51 through a gear mechanism composed of the drive side gear 62b and the driven side gear 62a, and the linear motion of the screw shaft 3 is transferred to the ball screw. The rotational motion of the nut 4 is converted into the rotational motion of the nut 51 so that the rotational motion can be transmitted to the shaft 51a of the motor 51. The motor 51 generates an electromagnetic force, and the torque generated by the electromagnetic force is generated by the screw shaft 3. The relative movement in the axial direction between the ball screw nut 4 and the screw shaft 3 is suppressed using a damping force that suppresses linear motion. Even in this modification, it can function as an actuator by applying torque to the ball screw nut 4. As in the above embodiment, the motor 51 includes a hall element H (not shown) so that the rotational position of the shaft 51a can be detected. The motor 51 is connected to the ECU 30.

  The suspension device of this modification will be described in detail. The screw shaft 3 is provided with an eye-shaped bracket 50 at the lower end in FIG. 5 so that it can be attached to a location where the suspension device is applied. The screw shaft 3 is rotatably engaged with the ball screw nut 4 and is inserted into the outer cylinder 55.

  The outer cylinder 55 has a bottomed cylinder shape, and a bracket (not shown) is provided at the upper end in FIG. 5 so that the outer cylinder 55 can be attached to a place where the suspension device is applied. Therefore, particularly when this suspension device is applied to a vehicle, the suspension device can be interposed between the vehicle body and the axle through the eye bracket 50 and a bracket (not shown). .

  5 is connected to a hollow housing 59. The housing 59 is provided with holes 59a, 59b, 59c and a hole 59d. The outer cylinder 55 is provided with a hole 59a in the housing 59. , 59b and connected to the housing 59 so as to be concentric. Further, ball bearings 40 and 41 are fitted in the inner peripheries of the holes 59a and 59b of the housing 59, and the ball screw nut 4 is fitted in the ball bearings 40 and 41, respectively. Accordingly, the ball screw nut 4 can rotate with respect to the housing 59.

  Ball bearings 42 and 43 are also provided in the hole 59 c and the hole 59 d of the housing 59, and the rotating shaft 60 is fitted in the ball bearings 42 and 43. Further, a cylinder 65 is coupled to the housing 59 so as to be concentric with the hole 59 c, and a motor 51 having the same configuration as the motor 1 is fixed in the cylinder 65.

  As described above, when the screw shaft 3 is rotatably engaged with the ball screw nut 4 along the screw groove 3a and the screw shaft 3 moves linearly in the vertical direction in FIG. Since the screw nut 4 is restricted from moving in the vertical direction in FIG. 5 by the housing 59 and is only allowed to rotate, the ball screw nut 4 is forcibly driven to rotate. That is, the linear motion of the screw shaft 3 is converted into the rotational motion of the ball screw nut 4 by the above mechanism.

  On the other hand, as shown in FIG. 5, the gear mechanism includes a driven gear 62a formed on the outer periphery of the rotary shaft 60 and a drive gear 62b formed on the outer periphery of the ball screw nut 4, and the teeth of the gears 62a and 62b. Are arranged horizontally so as to mesh with each other and are rotatably inserted into the housing 59, and the rotating shaft 60 is coupled to the shaft 51 a of the motor 51.

  In addition, what is necessary is just to use well-known gears, such as an involute gear, for example, and each gearwheel 62a, 62b uses two gearwheels in this Embodiment, However, You may use three or more gear trains. .

  As described above, since the shaft centers of the gears 62a and 62b are offset in the lateral direction, the shaft center of the motor 51 coupled to the gears 62a and 62b and the shaft center of the ball screw nut 4 are shifted in the lateral direction. As a result, the motor 51 is disposed in parallel to the side of the ball screw nut 4 outside the outer cylinder 65.

  Since the motor 51 is arranged on the side of the ball screw nut 4 by adopting the above configuration, it is not necessary to provide the motor 1 vertically above the screw shaft 3 unlike the conventional suspension device. In other words, by arranging the motor 51 in parallel with the outer cylinder 5, the stroke required for the shock absorber can be secured and the basic length can be shortened. That is, space saving can be achieved.

  In addition, although the motor 51 is arrange | positioned in the side vicinity of the ball screw nut 4, it is also possible to arrange | position the motor 51 in the position away from the ball screw nut 4 using the gear train as mentioned above. . Therefore, for example, it is possible to prevent the motor 51 from being damaged by rainwater, mud, stepping stones, etc. by arranging only the motor 51 in the vehicle body.

  Although not shown, the motor may be configured by attaching one of a magnet or a coil to the outer periphery of the ball screw nut 4 and attaching the other of the magnet or the coil to the housing 59. In this case, the gear mechanism can be eliminated.

  With the above configuration, the rotational movement of the ball screw nut 4 by the linear movement of the screw shaft 3 in the vertical direction in FIG. 5 is transmitted to the shaft 51a of the motor 51 because the drive gear 62b and the driven gear 62a are engaged with each other. As a result, the motor 51 rotates, and the torque that resists the rotation of the shaft 51a caused by the electromagnetic force acts as a damping force that suppresses the rotation of the ball screw nut 4 via the gear mechanism.

  In the above description, the driving gear and the driven gear are horizontally arranged to transmit the rotational motion of the ball screw nut 4 to the motor 51. However, each gear is used as a bevel gear and the motor 51 is attached to the ball screw nut 4. It is also possible to change the angle. In this case, since the attachment angle can be adjusted, the suspension device according to the present invention can be attached according to the structure of the vehicle to be applied. Therefore, it is possible to attach the suspension device without being influenced by the layout of a new or existing vehicle. Further, any type of bevel gear may be used, but a helical bevel gear or the like capable of smooth transmission is preferable.

  Further, in order to transmit the rotational motion of the ball screw nut 4 to the shaft 51a of the motor 51, a friction wheel mechanism or a belt mechanism may be used in addition to the gear mechanism.

  When the suspension device configured in this manner expands and contracts, the screw shaft 3 exhibits a linear motion up and down in FIG. 5, and this linear motion is converted into a rotational motion of the ball screw nut 4. The rotational movement of the screw nut 4 is transmitted to the shaft 51a through a gear mechanism. Therefore, the torque that resists the rotation of the shaft 51 a caused by the electromagnetic force generated by the motor 51 suppresses the rotation of the ball screw nut 4, and the action of suppressing the rotation of the ball screw nut 4 is the screw shaft 3. As a result, the suspension acts by acting as a damping force for suppressing the relative movement of the ball screw nut 4 and the screw shaft 3 in the axial direction, and by supplying current to the motor 51. The device can also be used as an actuator.

  Even in the modified example configured as described above, control based on the sprung mass of each wheel of the vehicle is possible, and the same operational effects as in the above embodiment can be obtained.

  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 suspension apparatus in one embodiment of this invention. It is a figure which shows the state which applied the active suspension to the vehicle. It is a flowchart which shows the procedure which produces the map for control gain calculation. It is a flowchart which shows the process sequence which changes a control gain. It is a longitudinal cross-sectional view of the suspension apparatus in other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,51 Motor 1a, 51a Shaft 3 Screw shaft 3a Screw groove 4 Ball screw nut 30 Controller ECU
B1, B2, B3, B4 Car body side member D1, D2, D3, D4 Suspension device H Hall element K1, K2, K3, K4 Suspension spring S1, S2, S3, S4 Axle side member

Claims (3)

Motion conversion that converts the relative motion between the vehicle body side member and the axle side member into a rotational motion in an active suspension that is interposed between each vehicle body side member and each axle side member of the vehicle and can adjust the generated control force. A suspension device that includes a mechanism and a motor to which the rotational motion is transmitted, and that uses an electromagnetic force generated in the motor as a control force for controlling the relative movement between the vehicle body side member and the axle side member. An active suspension characterized in that the control force is adjusted based on the sprung mass of each wheel. The active suspension according to claim 1, wherein the control force is adjusted based on each sprung mass so as not to change the sprung resonance frequency and the damping rate. Based on each sprung mass, the control gain is set by referring to the corresponding map for calculating the control gain, and the control force is adjusted based on the relative displacement and relative speed between the vehicle body side member and the axle side member and the control gain. The active suspension according to claim 1 or 2.

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