JP2005255012A - Stabilizer control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress increase of vehicle body roll motion by performing a suitable stabilizer control as the whole of the vehicle even when one stabilizer control means is failed. <P>SOLUTION: Stabilizer actuators FT and RT are arranged between a pair of stabilizer bars on the front wheel side and between a pair of stabilizer bars on the rear wheel side respectively. When any one of the actuators is failed, comparison with a control target value when both are normally operated is performed and the control target value of the stabilizer actuator at the normal side is set to a high degree. Stabilizer control is suitably performed as the whole of the vehicle based on first roll suppressing control at the normal time (M14) and based on second roll suppressing control at the failure (M15). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a stabilizer control device for a vehicle, and more particularly to a stabilizer control device that variably controls the torsional rigidity of a stabilizer disposed between left and right wheels before and after the vehicle by means of stabilizer control means before and after the vehicle.

  In general, a stabilizer control device for a vehicle is configured to reduce or suppress a roll motion of a vehicle body by applying an appropriate roll moment from the outside by the action of a stabilizer bar while the vehicle is turning. In order to realize this function, for example, Patent Document 1 discloses a stabilizer device including a stabilizer control unit that controls the elastic forces of the stabilizer bars on the front wheel side and the rear wheel side. And, as described in the summary of Patent Document 1, when one of the front wheel side and rear wheel side stabilizer control units is abnormal, the other stabilizer control unit is changed according to the rule changed according to the content of the abnormality. The following stabilizer devices have been proposed for the purpose of enabling control.

  That is, according to the stabilizer device disclosed in Patent Document 1, when a damping force generation state fixing abnormality occurs in the front wheel side stabilizer control unit, the rear wheel side stabilizer control unit is set in the damping force generation state, and the front wheel side It is described that the normal control is performed in the stabilizer control unit on the rear wheel side when the abnormality in the elastic force generation state occurs in the stabilizer control unit on the side, and FIG. 4 shows the operation of each stabilizer control unit. The state is disclosed.

  Further, Patent Document 2 proposes a vehicle roll stabilization device in which a stabilizer bar is divided into two parts and an electromechanical turning actuator is provided between the half of the stabilizer bar, and is described as follows. That is, in the device described in Patent Document 2, the opposite turning displacement of the stabilizer half is locked so as to provide the possibility of further reducing rolls compared to passive vehicles even outside the adjustment range. Therefore, an electromagnetic open brake or an electromagnetic close brake is used. The action taken at the time of failure of the device differs depending on the system, and it is described that in the electromagnetic closed brake, the roll characteristics and the suspension roll effect are determined only by the normal spring element and damping element.

JP 2003-226127 A Special table 2002-518245 gazette

  However, in the apparatus described in the above-mentioned Patent Document 1, it is described that the normal control is performed in the stabilizer control unit on the rear wheel side when the abnormality in fixing the elastic force generation state occurs in the stabilizer control unit on the front wheel side. As described above, when one stabilizer control unit fails, control including normal control is performed by the other stabilizer control unit. In other words, when one stabilizer control unit fails, it does not return to the stabilizer control as the entire vehicle and controls the other stabilizer control unit, including complementing the control state on the failure side. Further, in the device described in the above-mentioned Patent Document 2, the response on the other side from the viewpoint of stabilizer control as the entire vehicle when one of the devices before and after the vehicle breaks down is not considered.

  Therefore, the present invention provides a stabilizer control device having front wheel side and rear wheel side stabilizer control means between left and right wheels before and after the vehicle, and when one stabilizer control means fails, the other stabilizer control means causes the entire vehicle to It is an object of the present invention to provide a stabilizer control device that performs appropriate stabilizer control, suppresses an increase in vehicle body roll motion, and maintains suitable vehicle steering characteristics.

  In order to solve the above-described problems, the present invention is set according to the front wheel side stabilizer and the rear wheel side stabilizer disposed between the left and right wheels before and after the vehicle, and the turning state of the vehicle as described in claim 1. Front wheel side stabilizer control means for controlling the torsional rigidity of the front wheel side stabilizer based on the control target value to be controlled, and the torsional rigidity of the rear wheel side stabilizer based on the control target value set according to the turning state of the vehicle. In a stabilizer control device comprising a rear wheel side stabilizer control means for controlling according to a turning state, a monitoring means for monitoring a driving state of the front wheel side stabilizer control means and the rear wheel side stabilizer control means and determining a failure, When the monitoring means determines that one of the front wheel side stabilizer control means and the rear wheel side stabilizer control means is out of order. The control target value of the normal stabilizer control means is set higher than the control target value when both the front wheel side stabilizer control means and the rear wheel side stabilizer control means are operating normally. Is.

  According to a second aspect of the present invention, the control target value of the normal side stabilizer control means may be set according to the vehicle steering characteristic.

  In the stabilizer control device, as described in claim 3, the front wheel side stabilizer and the rear wheel side stabilizer are respectively provided on a pair of stabilizer bars and a rear wheel side provided on the front wheel side of the vehicle. The front wheel side stabilizer control means and the rear wheel side stabilizer control means are respectively a front wheel side stabilizer actuator and a rear wheel side pair disposed between the pair of front wheel side stabilizer bars. A stabilizer actuator on the rear wheel side disposed between the stabilizer bars of the front wheel, and a normal control target value and a control target value at the time of failure are set for the front wheel stabilizer actuator and the rear wheel stabilizer actuator. Depending on the monitoring result of the monitoring means, either one of the control target value at the normal time or at the time of failure is set. It may be configured to.

  Thus, according to the stabilizer control device of claim 1, when it is determined that any one of the stabilizer control means is out of order, both the front wheel side and rear wheel side stabilizer control means are operating normally. Since the control target value of the normal side stabilizer control means is set to be higher than the control target value of the normal control means, even when one of the stabilizer control means fails, the normal side stabilizer control means Stabilizer control appropriate for the vehicle as a whole can be performed, and an increase in vehicle body roll motion can be reliably suppressed.

  Further, according to the second aspect, even when one of the stabilizer control means fails, the control target value of the normal side stabilizer control means is set according to the vehicle steering characteristic. As a result, an appropriate stabilizer control can be performed to suppress an increase in the vehicle body roll motion and to maintain a suitable vehicle steering characteristic.

  In the stabilizer control device according to claim 1 or 2, specifically, as described in claim 3, with respect to the stabilizer actuators on the front wheel side and the rear wheel side, the control target value at normal time and By setting the control target value and setting either one of the control target value at the normal time or at the time of failure according to the monitoring result of the monitoring means, the stabilizer control appropriate for the entire vehicle can be performed with a simple configuration. It can be carried out.

  Hereinafter, preferred embodiments of the present invention will be described. FIG. 1 shows an overall configuration of a vehicle including a stabilizer control device according to an embodiment of the present invention. In the present embodiment, a front wheel side stabilizer SBf and a rear wheel side stabilizer SBr that act as torsion springs when a movement in the roll direction is input to a vehicle body (not shown) are provided. The front wheel side stabilizer SBf and the rear wheel side stabilizer SBr have a torsional rigidity of the front wheel side stabilizer actuator FT and the rear wheel side stabilizer actuator RT in order to suppress the vehicle body roll angle caused by the roll motion of the vehicle body. It is configured to be variably controlled by. These stabilizer actuators FT and RT constitute front wheel side stabilizer control means and rear wheel side stabilizer control means of the present invention, respectively, and are controlled by a stabilizer control unit ECU1 in the electronic control unit ECU.

  As shown in FIG. 1, each wheel WHxx is provided with a wheel speed sensor WSxx (subscript xx means each wheel, fr is a right front wheel, fl left front wheel, rr is a right rear wheel, and rl is a left rear wheel. These are connected to the electronic control unit ECU, and the rotation speed of each wheel, that is, a pulse signal having a pulse number proportional to the wheel speed is input to the electronic control unit ECU. Further, a steering angle sensor SA for detecting the steering angle (handle angle) δf of the steering wheel SW, a longitudinal acceleration sensor XG for detecting the longitudinal acceleration Gx of the vehicle, a lateral acceleration sensor YG for detecting the lateral acceleration Gy of the vehicle, and a yaw rate of the vehicle. A yaw rate sensor YR and the like for detecting Yr are connected to the electronic control unit ECU.

  In addition to the stabilizer control unit ECU1 described above, the electronic control unit ECU includes a brake control unit ECU2, a steering control unit ECU3, and the like. These control units ECU1 to ECU3 each have a communication CPU, It is connected to a communication bus via a communication unit (not shown) provided with a ROM and a RAM. Thus, information necessary for each control system can be transmitted from another control system.

  The stabilizer control unit ECU1 of the present embodiment is configured as shown in FIG. 2, for example, and controls the electric motors MF and MR constituting the stabilizer actuators FT and RT. In the stabilizer control unit ECU1, a roll suppression control unit CT that sets command values for the electric motors MF and MR and motor drive circuits MCf and MCr that drive the electric motors MF and MR based on the command values are integrated. Alternatively, it is configured as a separate body. Then, the alternator and the battery are used as a power source PW, and a voltage is supplied to the roll suppression control unit CT via a constant voltage regulator. Further, information on other control units and sensors is exchanged with each other via a communication bus.

  As will be described later, the roll suppression control unit CT generates motor drive command values for the stabilizer actuators FT and RT, and controls the motor drive circuits MCf and MCr based on the motor drive command values. These motor drive circuits MCf and MCr each incorporate a switching element and are supplied with a current from a power source PW. Further, current detection units ISf and ISr are connected to the motor drive circuits MCf and MCr, respectively, and are used for current control of the electric motors MF and MR. The electric motors MF and MR of this embodiment are constituted by three-phase brushless DC motors, and are provided with rotation angle sensors RSf and RSr as rotation angle detection means, and drive control of the electric motors MF and MR is performed based on the detection information. Done.

  Furthermore, the stabilizer control unit ECU1 is configured with a failure determination means FD, which monitors whether the motor operation is normal by monitoring the drive currents of the electric motors MF and MR and the detection information of the rotation angle sensors RSf and RSr. (This determination will be described later). Thus, in the unlikely event that the stabilizer actuators FT and RT fail, as will be described later, the roll suppression control unit CT is controlled based on the result determined by the failure determination means FD, so that the vehicle steering characteristics are appropriate. Thus, an increase in the vehicle body roll angle is suppressed. 2 indicates an interface.

  FIG. 3 shows a front wheel side stabilizer SBf including a specific configuration example of the stabilizer actuator FT (RT is the same configuration). The front wheel side stabilizer SBf is divided into a pair of left and right stabilizer bars SBfr and SBfl, one end of which is connected to the left and right wheels, and one end of the other end is connected to the rotor RO of the electric motor MF via the speed reducer RD. The other side is connected to the stator SR of the electric motor MF. The stabilizer bars SBfr and SBfl are held on the vehicle body by holding means HLfr and HLfl. Thus, when the electric motor MF is energized, a torsional force is generated for each of the two divided stabilizer bars SBfr and SBfl, and the apparent torsion spring characteristics of the front wheel side stabilizer SBf are changed. Will be controlled. In addition, a rotation angle sensor RSf is disposed in the stabilizer actuator FT as a rotation angle detection means for detecting the rotation angle of the electric motor MF. Since the rear wheel side stabilizer SBr has the same configuration as described above, the description thereof is omitted.

  The electric motors MF and MR of this embodiment are three-phase brushless motors, but are not limited to this, and can be applied to motors having other numbers of phases. It is also possible to do. Further, as a power source of the stabilizer actuator, a pump (not shown) driven by a motor or an engine may be used instead of the electric motors MF and MR, and hydraulic control may be performed by this pump.

  The motor drive circuits MCf and MCr and the electric motors MF and MR shown in FIG. 2 are configured as shown in FIG. 4. Hereinafter, the motor drive circuit MCf and the electric motor MF will be described as representatives. In FIG. 4, relays RLY1, RLY2, and RLY3 that can short-circuit each terminal are connected in parallel to the coils L1, L2, and L3 of the electric motor MF between the terminals of the three-phase electric motor MF. . In FIG. 4, the relay is configured to short-circuit each of the U-phase, V-phase, and W-phase in the electric motor MF at the time of failure, but if any of the three phases is short-circuited between any two phases, Since all the phases are short-circuited, one of the three relays can be omitted. Moreover, if a short circuit state can be formed between any one of the three phases, a braking torque can be obtained. Therefore, if there is at least one relay, the function can be exhibited. However, if redundancy as a system is required, a configuration in which relays are arranged between all phases is desirable.

  If the device (for example, the stabilizer actuator FT) is determined to be in failure based on the determination result of the failure determining means FD, the relays RLY1, RLY2, and RLY3 are driven by the relay drive circuit RA, and a circuit including these is provided. Each is short-circuited. Since these relays RLY1, RLY2, and RLY3 are normally closed relays that are in a short-circuited state when not energized, they are instantaneously short-circuited to the coils L1, L2, and L3 of the electric motor MF when the relay drive current is turned off. Since the circuit is formed, the current caused by the counter electromotive force generated by the rotation of the electric motor MF so far flows through the short-circuited relay circuit.

  That is, the voltage across each of the coils L1, L2, and L3 of the electric motor MF has no potential difference, and the electric motor MF moves so as to stop. At this time, the short circuit is generated by the rotation of the electric motor MF. Current caused by back electromotive force flows. The current due to the counter electromotive force flows through the coils L1, L2, and L3, and is consumed by the internal resistance existing in these circuits, and the current value gradually decreases. This function acts as a braking torque of the electric motor MF and acts as if a braking force is applied, and rotation by an external force (vehicle body inertia force) on the electric motor MF is prevented. That is, a short circuit is formed by the motor relay RLY (generically referring to the relays RLY1, RLY2, and RLY3), the braking torque is applied to the electric motor MF by the back electromotive force generated as a result, and it becomes a binding force between the pair of stabilizer bars, The change in the vehicle body roll angle is suppressed.

  FIG. 5 shows a basic control block according to the present invention. Regarding the driver's steering wheel (steering) operation, information including the steering wheel angle (steering angle) δf is detected by the driver operation detecting means M11, and the vehicle The vehicle movement state quantity including the vehicle speed, the lateral acceleration and the yaw rate is detected by the running state detection means M12. Further, the vehicle behavior determination calculation unit M13 determines the steering characteristic (so-called understeer tendency, oversteer tendency) of the vehicle based on the steering operation of the driver and the vehicle motion state amount. Based on these information, the front and rear wheel active roll moment target value calculation unit M16 responds to the first roll suppression control unit M14 or the second roll suppression control unit M15, and the target value of the active roll moment of the front wheels and rear wheels. Is calculated, and the torsional forces generated by the stabilizer actuators FT and RT are controlled by the front-wheel and rear-wheel actuator servo controllers M17 and M18.

  On the other hand, failure determination is performed by the failure determination unit M19 based on information from the actuator servo control units M17 and M18 on the front wheel side and the rear wheel side, and the rotation angle sensors RSf and RSr. As a result, when it is not determined that there is a failure, the control is executed based on the first roll suppression control that is the active roll suppression control at the normal time (M14). On the other hand, when it is determined that a failure has occurred in the failure determination unit M19, control is performed based on the second roll suppression control that is the active roll suppression control at the time of failure (M15).

  In the second roll suppression control unit M15, the control amount of the normal side stabilizer actuator is based on the first roll suppression control unit M14 so as to compensate for the torsional force that should be generated by the malfunctioning and stopped stabilizer actuator. The value is set to a higher value as compared with the case of being controlled. For example, assuming that the front wheel side and rear wheel side stabilizer actuators FT and RT generate the same torsion force, if the rear wheel side stabilizer actuator RT fails, the stabilizer torsion force applied to the entire vehicle body. Decreases to 1/2. Therefore, the torsional force of the stabilizer actuator FT on the front wheel side that is operating normally is doubled to maintain the stabilizer torsional force that acts on the entire vehicle body, and the system body roll suppression performance is not degraded. Yes.

  However, when the torsional force of the stabilizer actuator on the normal operating side is increased, the front-rear ratio of the roll rigidity becomes inappropriate, and the steer characteristic (understeer or oversteer characteristic) may be affected. Since the influence of the roll rigidity front / rear ratio is caused by the load movement in the lateral direction of the vehicle, this problem occurs mainly when the degree of turning is increased. Therefore, the vehicle behavior determination calculation unit M13 monitors the vehicle steering characteristic based on the driver's steering operation, vehicle speed, lateral acceleration, yaw rate, etc., and if the steering characteristic deviates from the desired steering characteristic, the second roll The control parameter of the suppression control unit M15 is adjusted so that the steering characteristic is appropriate.

  In addition, in the aspect of FIG. 5, 1st roll suppression control (at the time of normal) and 2nd roll suppression control (at the time of failure) are performed separately as the 1st roll suppression control part M14 and the 2nd roll suppression control part M15, respectively. Although it is set as the structure switched by a control switch, it is not necessary to set it as a separate control calculating part, and what is necessary is just a structure which can form a control target value different from the time of normal operation when a failure occurs. Therefore, it is possible to adjust the control gain when calculating the target value of the active roll moment, which will be described later.

  FIG. 6 shows a control flow corresponding to FIG. 5. First, initialization is executed in step 101, and a control signal including a sensor signal, a communication signal, and a motor control target value is read in step 102. Then, the process proceeds to step 103, where the steering characteristic ST of the vehicle is calculated. The vehicle steer characteristic ST represents an understeer or oversteer state of the vehicle, and can be set based on, for example, a deviation between a target yaw rate and an actual yaw rate calculated based on the relationship between the steering wheel angle and the vehicle speed. Next, the process proceeds to Steps 104 to 106, and the failure determination of the front wheel side stabilizer actuator FT and the rear wheel side stabilizer actuator RT is executed (this will be described later).

  When it is determined that neither the front wheel side stabilizer actuators FT nor RT have failed, the routine proceeds to step 107, where the first roll suppression control, which is the roll suppression control when the system is normal, is executed. . On the other hand, if both the front wheel side and rear wheel side stabilizer actuators FT and RT are determined to be faulty, it is determined that the system is faulty and the process proceeds to step 108, for example, between the terminals of the electric motor MF shown in FIG. The relay is short-circuited, the stabilizer bars SBfr and SBfl are restrained, and the minimum torsional rigidity of the stabilizer SBf is ensured. If it is determined that either one of the front wheel side and rear wheel side stabilizer actuators FT and RT has failed, the process proceeds from step 105 or 106 to the subroutine shown in FIG. 7 or FIG. The second roll suppression control that is control is executed. Hereinafter, the second roll suppression control will be described separately when the rear wheel side stabilizer actuator RT fails (FIG. 7) and when the front wheel side stabilizer actuator FT fails (FIG. 8).

  FIG. 7 shows a control flow of the second roll suppression control when the rear wheel side stabilizer actuator RT fails. First, at step 111, the failed rear wheel side control target value (Rmr) is set to zero. In step 112, the control target value of the front wheel side stabilizer actuator FT is set high (to a large value) so as to compensate the output of the rear wheel side stabilizer actuator RT. For example, a value obtained by multiplying the active roll moment target value Rmfx at the time of normal system by (1 + a) to the active roll moment target value Rmfx (how to obtain the active roll moment target value) is set as the front wheel side control target value (Rmf). Here, a is a control constant.

  Then, it is determined whether or not the vehicle steer characteristic ST calculated in step 113 is within a predetermined range. This is because when the torsional rigidity of the stabilizer on only one side is increased, the setting of the roll rigidity distribution ratio is not appropriate, and the steering characteristic of the vehicle is affected. Here, since the rear wheel side is out of order, the vehicle steering characteristics tend to be understeer as the torsional rigidity of the front wheel side stabilizer SBf increases. When the vehicle steering characteristic is within the predetermined range, the routine proceeds to step 114 where (1 + a) · Rmfx calculated at step 112 is set as the active roll moment target value for the front wheels. On the other hand, when the vehicle steering characteristic is outside the predetermined range, the routine proceeds to step 115 where the target value is reduced according to the steering characteristic and [(1 + a) · Rmfx−b · ST] is the active roll moment on the front wheel side. It is set as a target value (b is a control constant).

  On the other hand, FIG. 8 is a control flow of the second roll suppression control when the front wheel side stabilizer actuator FT fails. As in FIG. 7, first, the control target value on the front wheel side that failed in step 121 is set to zero. Then, at step 122, the control target value on the rear wheel side is set high so as to compensate the output of the stabilizer actuator FT on the front wheel side, and is set to (1 + c) · Rmrx. Here, c is a control constant, and Rmrx is a control target value on the rear wheel side when the system is normal. If the front wheel side stabilizer actuator FT fails, the vehicle steering characteristic tends to oversteer as the torsional rigidity of the rear wheel side stabilizer SBr increases, contrary to the processing shown in FIG. Therefore, if it is determined in step 123 that the vehicle steer characteristic ST is within the predetermined range, the process proceeds to step 124 where (1 + c) · Rmrx calculated in step 122 is the active roll moment target on the rear wheel side. When the vehicle steering characteristic ST is outside the predetermined range, the process proceeds from step 123 to step 125, and [(1 + c) · Rmrx−d · ST] is set as the active roll moment target value on the rear wheel side. (D is a control constant).

Next, the first roll suppression control unit M14 and the vehicle behavior determination unit M13 when the system is operating normally in FIG. 5 will be described with reference to FIG. First, the lateral acceleration Gy obtained from the signal of the lateral acceleration sensor YG in the vehicle active roll moment target value calculation unit M21, the actual lateral acceleration change amount dGy obtained by time-differentiating this, the steering wheel angle (steering angle) δf, and the vehicle speed (vehicle speed). Based on the calculated lateral acceleration Gye calculated from Vx and the calculated lateral acceleration change amount dGye that differentiates this over time, a vehicle active roll moment target value Rmv necessary for suppressing the roll motion in the entire vehicle is calculated. The calculated lateral acceleration Gye is obtained by the following equation (1).
Gye = (Vx ² · δf) / {L · N · (1 + Kh · Vx ² )} (1)
Here, L is a wheel base, N is a steering gear ratio, and Kh is a stability factor.

Thus, the vehicle active roll moment target value Rmv to be applied to the entire vehicle in order to achieve a suitable roll characteristic is obtained by the following equation (2) (K1, K2, K3, and K4 are control gains).
Rmv = K1 · Gye + K2 · dGye + K3 · Gy + K4 · dGy (2)
As described above, the calculated lateral acceleration Gye obtained from the steering wheel angle δf and the vehicle speed Vx and its change amount dGye are taken into account in order to compensate for the delay in the control calculation and the response of the actuator.

  In the front and rear wheel roll rigidity ratio target value calculation unit M22, the front and rear ratio target value of roll rigidity is determined as follows. First, initial values Rsrfo and Rsrro of the roll stiffness ratio on the front wheel side and the rear wheel side are set based on the vehicle speed (vehicle speed) Vx. As shown in FIG. 10, the initial value Rsrfo of the front wheel roll stiffness ratio is set so as to be low when the vehicle speed Vx is low, and high when the vehicle speed Vx is high, and so as to increase the understeer tendency during high-speed driving. The initial value Rsrro of the rear wheel roll stiffness distribution ratio is determined by (1−Rsrfo). Next, in the vehicle behavior determination calculation unit M13, in order to determine the vehicle steer characteristic, the target yaw rate Yre is calculated from the steering wheel angle δf and the vehicle speed Vx, and compared with the actual yaw rate Yr, the yaw rate deviation ΔYr is calculated. Based on the yaw rate deviation ΔYr, a roll stiffness ratio correction value Rsra is calculated.

  As a result, when the vehicle has an understeer tendency, correction is performed to lower the front-wheel-side roll rigidity ratio and increase it on the rear-wheel side. On the other hand, when the vehicle is in an oversteer tendency, correction is performed to increase the front-wheel-side roll rigidity ratio and decrease it on the rear-wheel side. Further, in the front wheel and rear wheel active roll moment target value calculation unit M16, based on the vehicle active roll moment target value Rmv and the front and rear wheel roll stiffness ratio target values Rsrf and Rsrr, the front wheel and rear wheel active roll moment target values Rmf and Rmr Are set as Rmf = Rmv · Rsrf and Rmr = Rmv · Rsrr, respectively.

  Then, the normal-side stabilizer actuator that is switched when one of the stabilizer actuators fails is subjected to the second roll suppression control shown in FIG. Basically, similarly to the first roll suppression control shown in FIG. 9, from the actual lateral acceleration Gy, the actual lateral acceleration change amount dGy that differentiates this over time, the steering wheel angle (steering angle) δf, and the vehicle speed (vehicle speed) Vx. Based on the calculated lateral acceleration Gye calculated and the calculated lateral acceleration change amount dGye obtained by time differentiation, the vehicle active roll moment target value Rmv necessary for suppressing the roll motion in the entire vehicle is calculated (M31, FIG. 9). Corresponding to M21). Then, based on failure determination result information including which wheel side stabilizer actuator has failed, vehicle behavior determination result (vehicle steer characteristic), the active roll moment target value Rmf on the front wheel side or the rear wheel side which is the normal side or Rmr is calculated (M16).

  Hereinafter, setting of the motor control target value when one of the stabilizer actuators fails will be described in time series with reference to FIGS. 12 and 13. First, in FIG. 12, when the driver starts a steering (handle) operation at t10, the turning state of the vehicle increases. In accordance with this turning state, the control target value (Rmf or Rmr, hereinafter) of the stabilizer actuator as the characteristics (SJ10-SJ13 ′ and KJ10-KJ13 ′) shown by broken lines in FIG. 12 (b) and (c). The same) should be output. However, when it is determined that a failure has occurred, the target value of the failure side stabilizer actuator is set to zero, and the motor relays RLY1 to RLY3 shown in FIG. 4 are short-circuited, and the rotational motion of the electric motor MF (or MR) is reduced. It is restrained. Since the failure side stabilizer actuator does not generate an active output, in this embodiment, the target value of the normal side stabilizer actuator is set to be larger than the target value at the normal time so as to compensate for the output. Set (SJ10-SJ11 characteristics).

  For example, the normal control target value of the failure side stabilizer actuator is set to be added to the control target value of the normal side stabilizer actuator. Or it is good also as setting to add a certain ratio of the target value at the time of the normal of the failure side stabilizer actuator. And since the steering characteristic of the vehicle is constantly monitored, when the steering characteristic deviates from the predetermined range (at t11), that is, when it becomes oversteer or understeer, the control target value of the normal side stabilizer actuator is immediately Is reduced (SJ11-SJ13 characteristics).

  Further, when the vehicle steer characteristic deviates from the predetermined range, the control target value is held as shown by the one-dot chain line in FIG. 12B or is shown by the two-dot chain line according to the vehicle steer characteristic. Alternatively, the control target value may be decreased until the steering characteristic becomes the desired characteristic (SJ11-SJ12 characteristic). Thus, when a failure occurs in the stabilizer actuator that is one stabilizer control means, it is possible to alleviate a decrease in roll suppression performance due to the failure by increasing the control target value of the other stabilizer actuator. Become. Moreover, since the control target value of the stabilizer actuator on the normal side can be increased while monitoring the steering characteristic of the vehicle, the desired steering characteristic can be maintained.

  This failure determination may be performed during vehicle turning as shown in FIG. 13 (at t22 in FIG. 13). In this case as well, as in the case described with reference to FIG. 12, the control target value of the failure side stabilizer actuator is set to zero, and the control target value of the normal side stabilizer actuator is set high. If the vehicle steer characteristic deviates from the predetermined range, the control target value increment is decreased (SJ23-SJ25 in FIG. 13B) or the control target value is maintained (one point in FIG. 13B). The desired steer characteristic can be maintained by reducing the value (a chain line) or decreasing (the two-dot chain line in FIG. 13B).

  FIG. 14 shows an example of the above-described failure determination calculation process. After initialization in step 201, the target value Yt and the actual value Ya are read in steps 202 and 203, and these are compared in step 204. The If it is determined that the absolute value of the deviation between the target value Yt and the actual value Ya is greater than or equal to the predetermined value H2, the process proceeds to step 205 and a failure state occurs. The control of the electric motor shown in FIGS. 9 and 11 is basically performed based on the deviation between the target value and the actual value. That is, in the normal case, the target value Yt and the actual value Ya are not greatly different from each other, but the absolute value of the deviation is large, which means that the state quantity that generates the target value Yt or the actual value Ya is This is because there is an abnormality in the sensor to be detected, the calculation result, and the like. When the absolute value of this deviation is equal to or greater than the predetermined value H2, the process proceeds to step 205 and is determined to be a failure state. Here, the target value Yt and the actual value Ya mean the target value and the sensor value or the calculated value shown in FIGS.

  In the mode shown in FIG. 15, after being initialized in step 301, the process proceeds to step 302, and the actual value Za detected by the electric motor MF (or MR) current or the rotation angle sensor RSf (or RSr) is read. In step 303, the actual value Za is compared with a predetermined value H3. As a result, if it is determined that Za ≧ H3, the routine proceeds to step 304 where a failure state occurs. For example, in FIG. 2, the motor drive current of the motor drive circuit MCf (MCr) is detected, and the failure determination is performed when the overcurrent exceeds a predetermined value. The actual value has not only the upper limit value but also a preferred value. For example, when the rotation angle from the rotation angle sensor RSf (or RSr) in FIG. 2 is equal to or greater than a predetermined value or equal to or less than a predetermined value H4 even though the vehicle is in a predetermined turning state, As the motor MF (or MR) is overcurrent or unable to rotate, the routine proceeds to step 304 where it is determined to be a failure state.

  FIG. 16 shows one mode of control of the electric motor MF (or MR). The target value of the motor output is calculated from the active roll moment target values Rmf and Rmr (M31), and the result is compared with the actual motor output. Then, the motor output deviation is obtained (M32). Further, the PWM output to the electric motor M is determined according to this deviation (M33), and the switching element in the motor drive circuit MCf (MCr) is controlled. As described above, when it is determined that a failure occurs in any of the stabilizer actuators before and after the vehicle, the short-circuit relays RLY1 to RLY3 between the motor terminals of the electric motor of the failure-side stabilizer actuator are switched to the short-circuit state, and the rotation is performed. Is restrained. And since the electric motor of the stabilizer actuator on the normal side is controlled as described above, it is possible to minimize performance degradation due to failure.

  Next, the case where the output of the electric motor does not include the entire area of active (active) roll suppression control will be described. Since the electric motor MR is the same, the MF will be described below as a representative. FIG. 17 shows the relationship between the lateral acceleration Gy (inertial force acting on the vehicle body) and the vehicle body roll angle φ in order to consider the characteristics of the output of the electric motor MF and the vehicle body roll angle in consideration of the efficiency of the speed reducer RD. Show. In a steady roll motion, the vehicle body is supported by spring elements (coil springs, leaf springs, air springs, etc.) and stabilizers arranged on each wheel. In the region OX (O indicates the origin), the torsion spring constant (also referred to as torsional rigidity) of the stabilizer increases because it is within the output range of the electric motor of the stabilizer actuator, and the change in the vehicle body roll angle φ with respect to the lateral acceleration Gy. The rate (roll rate) is reduced. In the region XY, the torsional rigidity inherent to the stabilizer bar (for example, the torsional rigidity when the two divided stabilizer bars (for example, SBfr and SBfl described above) are fixed) is provided based on the reason described later. Locked. Further, in the region YZ, the electric motor MF is rotated so that the torsion of the stabilizer bar is returned by the inertial force acting on the vehicle body, contrary to the region OX. Therefore, the torsional rigidity of the stabilizer is reduced, and the vehicle body roll angle is increased.

  For the sake of simplicity, FIG. 18 shows the relationship between the lateral acceleration Gy and the vehicle body roll angle φ when the above-described spring component is excluded from FIG. 17 and is supported only by the stabilizer. It is classified into one area. First, in [Area 1 of lateral acceleration 0 to Ga], an operation state of [an area in which the vehicle body roll motion can be actively controlled within the output range of the electric motor (operation area for active roll suppression control)] is set. The rate relationship is [RK1 <RK0]. In [region 2 of lateral acceleration Ga to Gb], [the region in which the electric motor holds the output, the relative displacement of the stabilizer bar divided into two is locked, and the torsional rigidity of the stabilizer becomes a passive characteristic ( The region where the torsional rigidity is obtained when the stabilizer bar divided into two is fixed)], and the relationship of the roll ratio is [RK2 = RK0]. In [Area 3 greater than the lateral acceleration Gb], the operation state is [A region where the electric motor is returned by an external force (inertial force acting on the vehicle body, and the torsional rigidity of the stabilizer is reduced)]. [RK3> RK0]. Here, the roll rate is the rate of change of the vehicle body roll angle φ with respect to the lateral acceleration Gy as described above, and RK0 is the torsion spring characteristic when the bistable stabilizer bar (for example, SBfr and SBfl) is fixed. Indicates the roll rate.

Next, the characteristic OABC in consideration of the efficiency of the speed reducer RD will be described. Here, the efficiency (positive efficiency) when the electric motor MF transmits power to the stabilizer bars SBfr and SBfl via the speed reducer RD is ηP, and the electric motor is input via the speed reducer RD by the input from the stabilizer bar side. The efficiency (reverse efficiency) when MF is returned is ηN. The balance between the torque output Tma (roll moment conversion) of the electric motor MF at the intersection A between the region 1 and the region 2 and the roll moment Tra caused by the inertial force (lateral acceleration) acting on the vehicle body is as follows. Within output range. Therefore, since the electric motor MF is a region for transmitting power to the stabilizer bars SBfr and SBfl, the following equation (3) is obtained.
Tra = Tma · ηP (3)
Conversely, the balance between the torque output Tmb (roll moment conversion) of the electric motor and the roll moment Trb caused by the inertial force (lateral acceleration) at the intersection B of the regions 2 and 3 is as follows. Since the region 3 is twisted back by the inertial force, the following equation (4) is obtained.
Tmb = Trb · ηN (4)

The active roll suppression control that actively suppresses the vehicle body roll angle increases the torque output of the electric motor MF as the turning state increases, and maintains the torque output of the electric motor at the point A (the output limit point of the electric motor). When such control is performed, the torque output of the electric motor becomes Tma = Tmb, and therefore, from the above equations (3) and (4), the following equation (5) is obtained.
Trb = Tra / (ηP · ηN) (5)
Here, since the roll moment resulting from the vehicle body inertia force is approximately proportional to the lateral acceleration, when the lateral acceleration at points A and B is Ga and Gb, respectively, from the equation (5), the following equation (6): The relationship is guided.
Gb = Ga · {1 / (ηP · ηN)} (6)

  In the range in which the electric motor MF can output torque (active (active) roll suppression control region), active roll suppression control is executed, and the turning state (lateral acceleration) increases, and the limit point of motor torque output ( In the turning state after reaching the lateral acceleration Ga corresponding to the point A) in FIG. 18, the motor control is performed so as to maintain the motor torque output. The lateral acceleration Gb (the point B in FIG. 18, hereinafter referred to as a stabilizer lock limit point) at which the electric motor MF starts to be twisted back by the vehicle body inertia force is set to the lateral acceleration corresponding to the output limit of the motor torque. It is a value obtained by multiplying the inverse of the product of the normal efficiency and the reverse efficiency. Therefore, by maintaining the motor output, based on the relationship between the normal efficiency when twisting the stabilizer bars SBfr and SBfl by the electric motor MF and the reverse efficiency when the electric motor MF is returned by the body inertia force, In the area AB of FIG. 18, the relative positions of the stabilizer bars SBfr and SBfl are locked.

  In the active roll suppression control device, when the output of the electric motor MF does not include all of the control region, the efficiency (normal efficiency, reverse efficiency) of the speed reducer RD is designed and selected within an appropriate range. The maximum turning state is set to Gb or less. Then, adjustment is made so that the BC state in FIG. 18 does not actually occur (for example, Gb is set to be sufficiently larger than the tire friction limit) to prevent the body roll from rapidly increasing. .

  As described above, when the output of the electric motor MF does not include the entire range of the active roll suppression control, an upper limit value exists for the output of the electric motor MF. A value will be provided. 19 and 20 show changes in time-series control target values corresponding to FIGS. 12 and 13 described above, and when failure determination is made before the start of turning and when failure determination is made during turning. Respectively. In FIG. 19, failure determination is performed before the start of turning, and the control target value of the normal stabilizer actuator is increased to the SJ50-SJ51 characteristic with respect to the SJ50-SJ54 characteristic at the time of normal operation of the system. When the steering characteristic deviates from the predetermined value, the control target value increment is decreased (SJ51-SJ53). To maintain the predetermined steering characteristic, the control target value is maintained (indicated by a one-dot chain line) or decreased. There may also be a case (SJ51-SJ52 indicated by a two-dot chain line). In addition, since the output limit of the electric motor exists, the increment of the control target value is saturated at the upper limit value.

  FIG. 20 shows the processing when it is determined that the vehicle is in a failure state while the vehicle is turning. As in the case described above, the increment of the control target value of the normal actuator is performed while considering the vehicle steering characteristic. Is called. As a result, the steer characteristic of the vehicle is within a desired range, and it is possible to suppress a decrease in system performance while maintaining a suitable steer characteristic even if a failure occurs.

  In addition, the influence with respect to the vehicle steering characteristic of the front-rear ratio of the roll rigidity is generated due to the load movement in the vehicle left-right direction. Therefore, when the turning state is relatively small, the influence of the roll rigidity front / rear ratio does not appear. When the control range of the active roll suppression control is limited, that is, when Ga in FIG. 18 is set in the normal turning state instead of the limit turning state, the vehicle by controlling only the actuator on one side The effect on steering characteristics is small. Accordingly, in this case, the determination based on the vehicle steering characteristic ST in FIGS. 7 and 8 can be omitted.

It is a lineblock diagram showing an outline of vehicles provided with a stabilizer control device concerning one embodiment of the present invention. It is a block diagram which shows an example of the stabilizer control unit in one Embodiment of this invention. It is a block diagram which shows the specific structural example of the front-wheel side stabilizer in one Embodiment of this invention. It is a circuit diagram of a motor drive circuit and an electric motor in one embodiment of the present invention. It is a control block diagram which shows the basic control in one Embodiment of this invention. It is a flowchart which shows an example of the active roll suppression control in one Embodiment of this invention. It is a flowchart which shows an example of the 2nd roll suppression control in FIG. It is a flowchart which shows the other example of the 2nd roll suppression control in FIG. It is a control block diagram which shows an example of the 1st roll suppression control in one Embodiment of this invention. 10 is a graph showing an example of an initial value setting map of a front wheel roll stiffness ratio in FIG. 9. It is a control block diagram which shows an example of the 2nd roll suppression control in one Embodiment of this invention. It is a graph which shows an example of the setting of a motor control target value when one stabilizer actuator fails in one Embodiment of this invention in time series. It is a graph which shows other examples of setting of a motor control target value when one stabilizer actuator fails in one embodiment of the present invention in time series. It is a flowchart which shows an example of the failure determination calculation in one Embodiment of this invention. It is a flowchart which shows the other example of the failure determination calculation in one Embodiment of this invention. It is a control block diagram which shows an example of the motor control in one Embodiment of this invention. 6 is a graph showing an example of the relationship between lateral acceleration and vehicle body roll angle when the output of an electric motor does not cover the entire range of active roll suppression control as another embodiment of the present invention. It is a graph which shows simply the relationship between the lateral acceleration and vehicle body roll angle shown in FIG. The graph which shows an example of control target value setting in time series about the case where a failure determination is made before the start of turning in the case where the output of the electric motor does not include the entire region of the active roll suppression control in one embodiment of the present invention It is. FIG. 4 shows another example of control target value setting in a time series when a failure determination is made during a turn in a case where the output of the electric motor does not cover the entire range of the active roll restraint control in one embodiment of the present invention. It is a graph.

Explanation of symbols

SBf Front wheel side stabilizer SBfr, SBfl Front wheel side stabilizer bar SBr Rear wheel side stabilizer FT, RT Stabilizer actuator SW Steering wheel SA Steering angle sensor WHfr, WHfl, WHrr, WHrl Wheel WSfr, WSfl, WSrr, WSY Ray sensor Y Longitudinal acceleration sensor YG Lateral acceleration sensor ECU Electronic control unit PW Power supply FD Failure determination means

Claims (3)

  Front wheel side stabilizer and rear wheel side stabilizer disposed between left and right wheels before and after the vehicle, and front wheel side stabilizer control means for controlling torsional rigidity of the front wheel side stabilizer based on a control target value set according to the turning state of the vehicle And a rear wheel side stabilizer control means for controlling torsional rigidity of the rear wheel side stabilizer according to the turning state of the vehicle based on a control target value set according to the turning state of the vehicle. Monitoring means for monitoring the operating state of the front wheel side stabilizer control means and the rear wheel side stabilizer control means to determine a failure, and the monitoring means is any one of the front wheel side stabilizer control means and the rear wheel side stabilizer control means. When one side is determined to be faulty, the front wheel side stabilizer control means and the rear wheel side stabilizer Compared with the control target value when the control means is operating normally together stabilizer control apparatus characterized by setting high the control target value of the normal side of the stabilizer control means.   The stabilizer control device according to claim 1, wherein a control target value of the normal-side stabilizer control means is set according to a vehicle steering characteristic. The front wheel side stabilizer and the rear wheel side stabilizer each include a pair of stabilizer bars disposed on the front wheel side of the vehicle and a pair of stabilizer bars disposed on the rear wheel side, the front wheel side stabilizer control means, The rear wheel side stabilizer control means includes a front wheel side stabilizer actuator disposed between the pair of front wheel side stabilizer bars and a rear wheel side stabilizer actuator disposed between the pair of rear wheel side stabilizer bars. A normal control target value and a failure control target value for the front wheel side stabilizer actuator and the rear wheel side stabilizer actuator, and the normal time and failure according to the monitoring result of the monitoring means. The stabilizer control according to claim 1 or 2, wherein any one of control target values at the time is set. Apparatus.

Images