JP4696983B2 - Vehicle whose active stabilizer is controlled according to vehicle vibration - Google Patents

Description

  The present invention relates to control of an active stabilizer in a vehicle such as an automobile.

The stabilizer preferably has a high torsional rigidity from the viewpoint of restraining the roll of the vehicle body. However, from the viewpoint of the ride comfort of the vehicle, the stabilizer has a low rigidity, so that the rigidity of the stabilizer is low. When switching between the above, it is described in the following Patent Document 1 that a configuration for realizing the configuration is configured with low-cost and versatile parts. It also actively controls the stabilizer in response to input from the road surface, ensuring ride comfort against changes caused by road surface irregularities during straight traveling of the vehicle, and ensuring the vehicle body roll angle when turning the vehicle In the stabilizer control device that controls the torsional rigidity of the stabilizer disposed between the left and right wheels of the vehicle to actively control the roll motion of the vehicle body according to the turning state, the relative displacement of the vehicle body and the left and right wheels The external applied force for controlling the torsional rigidity of the stabilizer is set by at least one of the stabilizer free control and the roll damping control based on at least one of the wheel stroke left / right difference and the wheel stroke speed left / right difference. This is described in Patent Document 2 below.
JP-A-8-268027 JP2005-238971

  The stabilizer-free control in the above-mentioned patent document 2 detects a vibration input of 1 to 3 Hz due to road surface unevenness by a low frequency filter from the deviation between the strokes of a pair of left and right wheels, and increases in proportion to the amplitude. The torsion spring force of the stabilizer is reduced at the roll stiffness reduction target value. Since the active stabilizer is generally responsive to a control input up to about 5 Hz, it seems that such roll stiffness reduction target control is possible, but active control of the active stabilizer at a frequency exceeding 5 Hz is the current control. However, it is impossible. On the other hand, the vibration transmitted to the vehicle body from the road surface through the wheels and the wheel suspension device when the vehicle travels on a rough road includes many components having a frequency exceeding 5 Hz, and the ride comfort of the vehicle is impaired by these vibration components. Not a few.

  In view of the above circumstances, the present invention is based on the fact that an active stabilizer is provided in a vehicle in which the ride comfort of the vehicle is impaired due to vibrations transmitted from the wheels to the vehicle body through the wheel suspension device due to the unevenness of the road surface. It is the first problem to reduce it by controlling this. Further, the present invention provides a vehicle operating state in which the vehicle performance is more important than improving the ride comfort of the vehicle even when the first problem is achieved by controlling the active stabilizer. However, the second problem is to control an active stabilizer that is more suitable for such a demand. Furthermore, in the present invention, in achieving the above first and second problems, another object is to achieve an optimum adjustment between that and achieving other objects by controlling the active stabilizer. .

  In order to achieve the first object, the present invention is such that the vehicle body is supported by the left and right wheels via suspension springs, and the relative difference in displacement of the left and right wheels relative to the vehicle body is determined between the left and right wheels. The active stabilizer control comprising: an active stabilizer that exerts a variable elastic force in a direction in which the difference is canceled according to the vehicle; and an active stabilizer control means that variably controls the elastic force according to the relative difference of the active stabilizer. The means releases the active stabilizer based on the vertical acceleration of the vehicle body when the strength of the fluctuation of the vehicle vertical acceleration in a predetermined medium frequency region is equal to or greater than a predetermined first limit value. This is to propose a vehicle having the characteristics.

  The first limit value may be lowered as the lateral acceleration acting on the vehicle increases.

  The active stabilizer control means locks the active stabilizer based on the vertical acceleration of the vehicle body when the strength of the fluctuation of the vehicle vertical acceleration in a predetermined high frequency region is equal to or greater than a predetermined second limit value. It may be.

  The second limit value may be increased as the lateral acceleration acting on the vehicle body increases.

  In order to achieve the above-mentioned other problems, the present invention is designed to suppress the fluctuation of the vertical acceleration of the vehicle body in the middle frequency range by releasing the active stabilizer when the vehicle goes straight. The present invention proposes a vehicle characterized in that it is performed in preference to locking the active stabilizer and suppressing roll resonance of the vehicle body by control of the active stabilizer. In this case, when the vehicle travels straight, the active stabilizer may be locked against the wheel resonance in preference to suppressing the roll resonance of the vehicle body by the control of the active stabilizer.

  In order to achieve the above-mentioned other problems, the present invention provides an active stabilizer that locks the active stabilizer against the resonance of the wheel and suppresses the roll resonance of the vehicle body by the control of the active stabilizer when the vehicle turns. The present invention proposes a vehicle characterized in that it is performed in preference to the suppression of fluctuations in the vertical acceleration of the vehicle body by releasing the vehicle. In this case, further, when the vehicle turns, suppression of fluctuations in the vertical acceleration of the vehicle body by releasing the active stabilizer may be performed in preference to locking the active stabilizer against the resonance of the wheel.

  As described above, the vehicle body is supported by the left and right wheels via the suspension spring, and a variable elastic force is applied between the left and right wheels in a direction that cancels the difference according to the relative difference in displacement of the left and right wheels with respect to the vehicle body. In a vehicle having an active stabilizer and active stabilizer control means for variably controlling an elastic force according to the relative difference between the active stabilizers, the active stabilizer control means is configured to detect the vertical acceleration of the vehicle body based on the vertical acceleration of the vehicle body. If the active stabilizer is released when the strength of the fluctuation in the predetermined medium frequency region is equal to or greater than the predetermined first limit value, the predetermined medium frequency region is set to about 5 Hz as an example. Set a frequency range within a predetermined range that exceeds the upper limit of the frequency for which active stabilizer tracking control is possible. Thus, when the vehicle is traveling on a rough road, etc., when vibration in a frequency region where active stabilizer tracking control is impossible is transmitted to the vehicle body from the wheel, by releasing the active stabilizer, Such vibration can be prevented from being transmitted from the wheel to the vehicle body via the active stabilizer, and the ride comfort of the vehicle can be improved accordingly. Here, releasing the active stabilizer may include not only making the active stabilizer completely free but also substantially reducing its torsional rigidity.

  When the lateral acceleration acting on the vehicle increases, the active stabilizer becomes correspondingly twisted, and vibration is more easily transmitted to the vehicle body through the active stabilizer than the wheel. Therefore, if the first limit value is lowered in accordance with the increase in lateral acceleration acting on the vehicle, when the lateral acceleration acting on the vehicle increases, the ride comfort of the vehicle is reduced by transmission of vibrations from the wheels to the vehicle body. It is possible to prevent damage early.

  In addition, when the active stabilizer control means has a predetermined medium frequency range of the fluctuation of the vertical acceleration of the vehicle based on the vertical acceleration of the vehicle in the above-described manner, it is equal to or more than a predetermined first limit value. Even when releasing the active stabilizer, if the strength in the predetermined high frequency region of the fluctuation of the vertical acceleration of the vehicle body is equal to or more than the predetermined second limit value, the active stabilizer is locked. In the predetermined high frequency region, the fluctuation frequency of the vertical acceleration of the vehicle body is not less than the upper limit of the medium frequency region, for example, about 8 Hz or more. Avoid a decrease in the ground load, and ensure that the predetermined frequency range is such that it is more important to secure the wheel's ground load and maintain the running performance of the vehicle. Therefore, when it is more important to secure the wheel ground load and maintain the vehicle's driving performance than to improve the vehicle's riding comfort, the vehicle's driving will be given priority over the improvement of the vehicle's riding comfort. By maintaining the performance, the safety performance of the vehicle can be enhanced. Note that locking the active stabilizer not only completely fixes the movement of the actuator of the active stabilizer, but also suppresses the movement of the actuator so that the movement of the actuator is substantially fixed. It may contain the state.

  In this case, when the lateral acceleration acting on the vehicle is increased, the ground contact load of the wheel is increased by the lateral acceleration in the wheel on the side where the ground load is increased by the lateral acceleration. The degree is suppressed. Therefore, the second limit value is increased as the lateral acceleration acting on the vehicle body increases, and the locking of the active stabilizer is delayed accordingly, and the ground contact load of the wheel is improved while improving the ride comfort as much as possible. Can be maintained and the running stability of the wheels can be maintained.

  When the vehicle goes straight, the active stabilizer is released to release the fluctuation of the vertical acceleration of the vehicle body in the middle frequency range, which locks the active stabilizer against the wheel resonance, and the vehicle body roll resonance is the skyhook control theory. Therefore, when the vehicle is traveling straight ahead, the resonance of the wheels and the roll resonance of the vehicle body are relatively unlikely to occur, but on the other hand, In response to the fact that the vibration of the vehicle body based on the rules is more conspicuous and impairs the ride comfort of the vehicle, the above active stabilizer release control is executed in preference to the suppression of the wheel resonance and the roll resonance of the vehicle body, thus By prioritizing multiple controls, the active stabilizers can interact with each other. Without causing interference between different control not, it is possible to effectively operate the active stabilizer maximally.

  In this case, when the vehicle goes straight ahead, if the active stabilizer is locked against the wheel resonance, the vehicle body roll resonance is controlled by controlling the active stabilizer. When the vehicle is traveling straight ahead, it is possible to give more appropriate prioritization between these two controls in view of the fact that the former is more likely to occur than the latter in the resonance of the wheels and the roll resonance of the vehicle body.

  While turning the vehicle, suppressing roll resonance of the vehicle body is more important than suppressing the ride comfort due to vibrations transmitted from irregular road surfaces. Some of the wheels on the outside of the turn are pressed against the road surface by the increased load, and the load on the wheels on the inside of the turn is reduced. Therefore, the resonance of the wheel is less likely to become a problem to the left. Therefore, while the vehicle is turning, suppressing the roll resonance of the vehicle body by controlling the active stabilizer suppresses vibration transmission from the road surface to the vehicle body due to the release of the active stabilizer and locks the active stabilizer against the resonance of the wheel. It may be done with priority. In particular, when the active stabilizer is electric, the electric actuator consumes electric power even in a steady roll state. Therefore, it is necessary to control the roll resonance of the vehicle body by controlling the active stabilizer when the vehicle is turning. It does not result in a significant increase in consumption. Furthermore, when the vehicle turns, it is unlikely that resonance will occur in the wheels. Therefore, suppression of fluctuations in the vertical acceleration of the vehicle body by releasing the active stabilizer has priority over locking the active stabilizer against the resonance of the wheels. It may be done.

  If the active stabilizer is released by stopping energization of the electric active stabilizer or stopping the hydraulic pressure supply to the hydraulic active stabilizer, the active stabilizer is controlled to be released by consuming energy. This is more advantageous in terms of energy consumption than

  In FIG. 1, a vehicle body is supported by a left and right wheel via a suspension spring, and a variable elastic force is applied between the left and right wheels in a direction that cancels the difference according to the relative difference in displacement of the left and right wheels with respect to the vehicle body. The main part of the structure which concerns on this invention of the vehicle which has an active stabilizer and the active stabilizer control means which variably controls the elastic force according to the said relative difference of an active stabilizer is shown in figure in the functional structure FIG.

  As illustrated, the vehicle has a structure in which a vehicle body 14 is supported by suspension wheels 12L and 12R by left and right wheels 10L and 10R, respectively. Between the left and right wheels, an active stabilizer 16 is provided that exerts a variable elastic force in a direction that cancels out the difference according to the relative difference in displacement of the left and right wheels with respect to the vehicle body. Although the active stabilizer 16 is shown in schematic form only, electrical or hydraulic active stabilizers are known in a variety of configurations. However, in the active stabilizer used in the present invention, the actuator that variably adjusts the relative twist angle between the torsion bar halves at the center and extending to the left and right is provided between the torsion bar halves. It is necessary to be able to take a release mode that allows dynamic displacement freely.

  The active stabilizer 16 includes a microcomputer and includes an electronic control unit (ECU) 18 including various functional units described below and an actuator control unit 20 that controls an actuator of the active stabilizer. The elastic force corresponding to is variably controlled. In the illustrated example, left and right shock absorbers 22L and 22R are provided in parallel with the suspension springs 12L and 12R between each of the left and right wheels 10L and 10R and the vehicle body 14 as in a general vehicle. It has been. In FIG. 1, 24L and 24R are displayed by replacing the elasticity exhibited by the tires of the wheels 10L and 10R with equivalent springs. In relation to functionally displaying the wheel, the vehicle body and the wheel suspension as a single vibration system as shown in FIG. 1, the wheel is referred to as “unsprung” and the vehicle body is referred to as “sprung”. Yes. In FIG. 1, the left and right wheels 10L and 10R, the left and right suspension springs 12L and 12R, and the left and right shock absorbers 22L and 22R may be either a pair of front wheels or a pair of rear wheels. .

  The vertical acceleration on the left side corresponding to the wheel 10L of the vehicle body and the vertical acceleration on the right side corresponding to the wheel 10R are detected by the sprung vertical acceleration sensors 26L and 26R, respectively. The vertical accelerations of the wheels 10L and 10R are detected by unsprung vertical acceleration sensors 28L and 28R, respectively. Further, the lateral acceleration acting on the vehicle is detected by a lateral acceleration sensor 30 attached to a part of the vehicle body in the illustrated example.

  A signal indicating the vertical accelerations of the left and right sides of the vehicle body detected by the left and right vehicle body vertical acceleration sensors 26L and 26R is configured as a part of the function in the electronic control unit 18 (the same applies hereinafter). (A band-pass filter, BP for short) is supplied to a subtracter 34 and a signal indicating a difference in vertical acceleration between the left side and the right side of the vehicle body. It is supplied to the band filtering unit 36 and the target actuator torque calculation unit 38. Signals indicating the vertical accelerations of the left and right wheels detected by the left and right wheel vertical acceleration sensors 28L and 28R are supplied to the band filtering unit 40. The band filtering unit 32 is also supplied with a signal indicating the lateral acceleration acting on the vehicle detected by the vehicle lateral acceleration sensor 30.

  In the band filtering unit 32, as an example, a signal in a frequency band of 5 Hz or more is transmitted through the signals indicating the vertical accelerations of the left and right sides of the vehicle body detected by the left and right vehicle body vertical acceleration sensors 26L and 26R. The signal is supplied to the rough road determination unit 42 and further supplied to the band filtering unit 44. As an example, the band filtering unit 44 transmits a signal having a frequency of 8 Hz or more. The signal transmitted by the band filtering unit 44 is also supplied to the rough road determination unit 42.

The rough road determination unit 42 determines that the vehicle is traveling on a rough road when the level of the signal supplied from the band filtering unit 32 is equal to or higher than a predetermined first limit value, and the actuator control device 20. The electronic control unit 18 is actuated to generate a control signal for releasing the active stabilizer. In this case, the bad road judging section 42, vehicle lateral basis of the signal indicating the lateral acceleration acting on the supplied vehicle from the acceleration sensor 30, the first brought to the magnitude of the lateral acceleration acting on the vehicle is you increase The signal level at which the active stabilizer is released is determined by lowering the limit value. This corresponds to the fact that as the lateral acceleration acting on the vehicle increases as described above, the active stabilizer becomes correspondingly twisted, and vibration is more easily transmitted to the vehicle body through the active stabilizer than the wheel. If the limit level of vibration that releases the active stabilizer is lowered in accordance with the increase in lateral acceleration acting on the vehicle in this way, even when the lateral acceleration acting on the vehicle increases, It is possible to prevent the ride comfort of the vehicle from being impaired by the transmission of vibrations at an early stage.

Further, when the level of the signal supplied from the band filtering unit 44 is equal to or greater than a predetermined second limit value, the rough road determination unit 42 cancels the release of the active stabilizer and outputs a control signal for locking the active stabilizer. The controller 18 operates so as to transmit the signal to the actuator controller 20. In this case, bad road determination unit 42, based on the signal indicating the lateral acceleration acting on the vehicle supplied from the vehicle lateral acceleration sensor 30, as the magnitude of the lateral acceleration acting on the vehicle is you increase the The signal level at which the active stabilizer is locked is determined by increasing the second limit value. This is because when the lateral acceleration acting on the vehicle increases as described above, the ground contact load of the wheel increases due to the lateral acceleration in the wheel on the side where the ground load increases due to the lateral acceleration. In consideration of the fact that the degree of decrease of the vibration is reduced, the release of the active stabilizer is canceled as the lateral acceleration acting on the vehicle increases, and the limit level of the vibration that locks the active stabilizer is increased. As a result, the vibration level for locking the active stabilizer can be increased at the expense of suppression of vehicle body vibration to ensure running stability.

  The band filtering unit 36 is set so as to transmit a signal in a roll resonance frequency band that is likely to be generated in the vehicle body according to the type of the vehicle, from a signal indicating a difference in vertical acceleration between the left side and the right side of the vehicle body supplied thereto. The transmitted signal is supplied to the sprung roll resonance determination unit 46. The sprung roll resonance determination unit 46 determines whether roll resonance has occurred in the vehicle body based on the level of the roll vibration signal of the vehicle body supplied through the band filtering unit 36, and roll resonance has occurred in the vehicle body. In order to operate the active stabilizer so as to suppress it, the control signal for controlling the active stabilizer is transmitted from the electronic control unit 18 to the actuator control unit 20. The suppression of the roll resonance of the vehicle body by the control of the active stabilizer may be performed based on the skyhook control theory or the like. At this time, the target actuator torque calculation unit 38 sets the active stabilizer to suppress the roll resonance of the vehicle body based on the signal indicating the difference in vertical acceleration between the left side portion and the right side portion of the vehicle body supplied from the subtractor 34. The target actuator torque when operating is calculated.

  However, the control of the active stabilizer for suppressing the vehicle body roll resonance by the sprung roll resonance determination unit 46 and the release or lock control of the active stabilizer by the rough road determination unit 42 are mutually exclusive. Control over which is prioritized is performed as described below.

  The band filtering unit 40 is a resonance frequency band that is likely to be generated in the wheel according to the characteristics of the wheel suspension device that differs depending on the type of vehicle from the signals indicating the vertical acceleration of the left wheel and the right wheel supplied by the left and right wheel vertical acceleration sensors 28L and 28R. The transmission signal is supplied to the unsprung resonance determination unit 48. The unsprung resonance determination unit 48 determines whether or not resonance has occurred in the wheel based on the level of the vibration signal of the wheel that has been transmitted through the band filtering unit 40, and when the resonance has occurred in the wheel, In order to lock the active stabilizer, the electronic control device 18 operates to transmit a control signal for locking the active stabilizer from the electronic control device 18 to the actuator control device 20.

  However, the active stabilizer lock for suppressing the wheel resonance by the unsprung resonance determination unit 48 is also the release or lock control of the active stabilizer by the rough road determination unit 42 and the above-mentioned by the sprung roll resonance determination unit 46. Since the vehicle body roll resonance suppression control is mutually exclusive, control as to which of these is prioritized is performed as follows.

  First, when the vehicle goes straight, the resonance of the wheels and the roll resonance of the vehicle body are relatively unlikely.On the other hand, the vibration of the vehicle body due to irregular road surface is more conspicuous and impairs the ride comfort of the vehicle. Since the vehicle speed also increases, it is more important to ensure that the wheels are in contact with the road surface. Therefore, when the vehicle goes straight, the active stabilizer release or lock control performed by the rough road determination unit 42 is performed by the sprung roll resonance suppression control or the unsprung resonance determination by the active stabilizer operation control performed by the sprung roll resonance determination unit 46. The active stabilizer lock performed by the unit 48 is prioritized.

  In this case, one of the active stabilizer lock for the wheel resonance performed by the unsprung resonance determination unit 48 and the sprung roll resonance suppression control by the active stabilizer operation control performed by the sprung roll resonance determination unit 46 is the other. However, when the vehicle is going straight ahead, the active stabilizer lock by the unsprung resonance determination unit 48 is considered in view of the fact that the wheel resonance is more likely to occur than the roll resonance of the vehicle body when the vehicle goes straight. This may be performed in preference to the active stabilizer operation control for suppressing the sprung roll resonance by the sprung roll resonance determining unit 46.

  During the turning of the vehicle, suppressing the roll resonance of the vehicle body is more important than the problem that the ride comfort of the vehicle is impaired by vibrations transmitted from the road surface to the vehicle body. On the other hand, during the turning of the vehicle, the load distribution between the pair of left and right wheels is greatly biased toward the wheels on the outside of the turn, the wheels on the outside of the turn are pressed against the road surface by the increased load, and the wheels on the inside of the turn Since the load is reduced, the resonance of the wheel is less likely to be a problem to the left. Therefore, during the turning of the vehicle, suppression of roll resonance of the vehicle body by controlling the active stabilizer by the sprung roll resonance determination unit 46 means that vibration transmission from the road surface to the vehicle body due to the release of the active stabilizer by the rough road determination unit 42. This may be performed in preference to the active stabilizer lock for the suppression of the wheel and the resonance of the wheel by the unsprung resonance determination unit 48. Moreover, when the active stabilizer is an electric type, the electric actuator consumes power even if it is in a steady roll state. Therefore, it is necessary to control the roll resonance of the vehicle body by controlling the active stabilizer when the vehicle turns. Will not result in a significant increase.

  Further, when the vehicle turns, it is unlikely that the wheel will resonate. Therefore, the unsprung resonance determination unit 48 is more likely to suppress the vehicle body vibration caused by releasing the active stabilizer by the rough road determination unit 42. In contrast, it may be performed in preference to locking the active stabilizer.

  In the above, the present invention has been described in detail with respect to one embodiment comprehensively including several control aspects, but various modifications can be made within the scope of the present invention. Will be apparent to those skilled in the art.

An outline diagrammatically showing the main part of the configuration according to the present invention of a vehicle in which the vehicle body is supported by a left and right wheel via a suspension spring and an active stabilizer is incorporated between the left and right wheels in its functional configuration. Figure.

Explanation of symbols

10L, 10R ... wheels, 12L, 12R ... suspension springs, 14 ... vehicle body, 16 ... active stabilizer, 18 ... electronic control unit (ECU), 20 ... actuator control device, 22L, 22R ... shock absorber, 24L, 24R ... tire Equivalent springs showing elasticity, 26L, 26R ... sprung vertical acceleration sensor, 28L, 28R ... unsprung vertical acceleration sensor, 30 ... lateral acceleration sensor, 32 ... band filter, 34 ... subtractor, 36 ... band filter, 38 ... Target actuator torque calculation unit, 40 ... Band filter unit, 42 ... Bad road determination unit, 44 ... Band filter unit, 46 ... Spring roll resonance determination unit, 48 ... Unsprung resonance determination unit

Claims (10)

  An active stabilizer that supports a vehicle body via a suspension spring by each of the left and right wheels, and exerts a variable elastic force in a direction that cancels the difference between the left and right wheels in accordance with a relative difference in displacement of the left and right wheels with respect to the vehicle body. And active stabilizer control means for variably controlling the elastic force according to the relative difference of the active stabilizer, wherein the active stabilizer control means varies the vertical acceleration of the vehicle body based on the vertical acceleration of the vehicle body. The active stabilizer is released when the strength in a predetermined medium frequency region is equal to or greater than a predetermined first limit value.   The vehicle according to claim 1, wherein the first limit value is lowered in accordance with an increase in lateral acceleration acting on the vehicle.   The active stabilizer control means locks the active stabilizer based on the vertical acceleration of the vehicle body when the strength of the fluctuation of the vehicle vertical acceleration in a predetermined high frequency region is equal to or greater than a predetermined second limit value. The vehicle according to claim 1 or 2, wherein:   4. The vehicle according to claim 3, wherein the second limit value is increased in accordance with an increase in lateral acceleration acting on the vehicle body.   When the vehicle goes straight, the suppression of fluctuations in the vertical acceleration of the vehicle body in the middle frequency range by releasing the active stabilizer locks the active stabilizer against the resonance of the wheel and roll resonance of the vehicle body The vehicle according to claim 1, wherein the vehicle is preferentially controlled by the control of the active stabilizer.   When the vehicle goes straight, locking the active stabilizer against the resonance of the wheel is performed in preference to suppressing the roll resonance of the vehicle body by the control of the active stabilizer. The vehicle according to claim 5.   When turning the vehicle, suppression of roll resonance of the vehicle body by the control of the active stabilizer locks the active stabilizer against resonance of the wheel and releases fluctuations in vehicle vertical acceleration caused by releasing the active stabilizer. The vehicle according to claim 1, wherein the vehicle is performed with priority over suppression.   When turning the vehicle, suppression of fluctuations in vertical acceleration of the vehicle body by releasing the active stabilizer is performed in preference to locking the active stabilizer against resonance of the wheels. The vehicle according to claim 7.   The vehicle according to any one of claims 1 to 8, wherein the release of the active stabilizer is performed by stopping energization of the electric active stabilizer. The vehicle according to any one of claims 1 to 8, wherein the release of the active stabilizer is performed by stopping the supply of hydraulic pressure to the hydraulic active stabilizer.

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