JP2006232023A - Vehicle wheel ground load estimating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately estimate a ground load of each wheel by making use of the advantage of a ground load estimating method based on the spring force of a suspension spring, etc. , and of a ground load estimating method based on a load shift quantity. <P>SOLUTION: According to a wheel ground load estimating apparatus, a first ground load Fzi1 of each wheel is calculated as the sum of a vertical force Fsi applied to each wheel as a result of the spring force of the suspension spring, a vertical force Fdi applied to each wheel as a result of the damping force of each shock absorber, a vertical inertial force Fwmi acting on each wheel, and vertical forces Fstf and Fstr which are applied to left/right front wheels and to left/right rear wheels as a result of the spring force of an active stabilizer (S20). A second ground load Fzi2 of each wheel resulting from a load shift on the vehicle is calculated on the basis of a longitudinal acceleration Gx and a latitudinal acceleration Gy acting on the vehicle (S20). The first ground load Fzi1 is processed by a high-pass filter into a first ground load Fzi1f, and the second ground load Fzi2 is processed by a low-pass filter into a second ground load Fzi2f, and a ground load Fzi of each wheel is calculated as the sum of the first ground load Fzi1f and the second ground load Fzi2f (S70 to 90). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle wheel ground load estimating device, and more particularly to a wheel ground load estimating device that estimates the ground load of each wheel without detecting the load acting between the sprung and unsprung portions. .

As one of the wheel ground load detection devices for vehicles such as automobiles, for example, as described in the following Patent Document 1 relating to the application of the present applicant, each wheel is detected by a load sensor provided corresponding to each wheel. 2. Description of the Related Art A wheel ground load detection device that detects a ground load is conventionally known. In addition, in the case of a vehicle equipped with a hydropneumatic suspension, it is already known to estimate the ground contact load of each wheel based on the pressure in the hydropneumatic cylinder, and the detection values of the longitudinal acceleration sensor and the lateral acceleration sensor are known. It is also already known that the amount of load movement in the front-rear direction and the side direction of the vehicle is estimated based on the above, and the ground load of each wheel is estimated based on the ground load and the amount of load movement when the vehicle is stationary.
JP 11-151923 A

  However, in the conventional wheel ground load detection device as described above in which a load sensor is used, the load sensor is expensive. Therefore, there is a wheel ground load detection device in which a load sensor must be provided for each wheel. There is a problem that it must be expensive. Further, when the ground load of each wheel is estimated based on the pressure in the hydropneumatic cylinder, there is a problem that the suspension is limited to the hydropneumatic suspension.

  In addition, when estimating the contact load of each wheel based on the contact load and load movement amount of each wheel when the vehicle is stationary, when the vehicle travels on a flat road, the contact load of each wheel is relatively accurately determined. Although it can be estimated and is relatively difficult to be adversely affected by noise, the contact load of each wheel cannot be estimated relatively accurately in a situation where the road surface disturbance acts on the wheel and the contact load of the wheel fluctuates.

  It is also conceivable to estimate the spring force of the suspension spring, the damping force of the shock absorber, and the stabilizer generating force, and to estimate the ground load of each wheel based on these forces. According to this method, it is possible to estimate the ground contact load of each wheel by effectively using an existing sensor used for various controls in a vehicle such as an automobile such as a wheel stroke sensor, thereby avoiding an increase in cost. At the same time, it is possible to accurately estimate the ground contact load of each wheel even in the situation where road surface disturbance acts on the wheel without being restricted by the suspension type, but the ground load and load movement amount of each wheel when the vehicle is stationary There is a problem that it is more susceptible to the adverse effects of noise than when the ground contact load of each wheel is estimated based on the above.

  The present invention has been made in view of the above-described problems in conventional wheel ground load detection devices and wheel ground load estimation devices that detect or estimate the ground load of each wheel by a load sensor or the like provided for each wheel. The main object of the present invention is to estimate the ground contact load of each wheel based on the spring force of the suspension spring, the damping force of the shock absorber, and the stabilizer generating force, and the ground contact of each wheel when the vehicle is stationary. By paying attention to the pros and cons of the method of estimating the contact load of each wheel based on the load and the load moving amount, the contact load of each wheel is accurately estimated by taking advantage of the two methods.

  According to the present invention, the main problem described above is to estimate the first ground contact load of each wheel based on the configuration of claim 1, that is, at least the spring force of the suspension spring, the damping force of the shock absorber, and the stabilizer generating force. A vehicle is characterized by estimating a second ground load of each wheel based on longitudinal acceleration and lateral acceleration of the vehicle, and calculating a ground load of each wheel based on the first and second ground loads. This is achieved by the wheel ground load estimation device.

  According to the present invention, in order to effectively achieve the above main problem, in the configuration of claim 1, the first grounding load is used for a frequency region above the first reference value. For the frequency region less than the second reference value, the ground load of each wheel is calculated using the second ground load (configuration of claim 2).

  According to the present invention, in order to effectively achieve the above-mentioned main problem, in the configuration of claim 2, the first and second reference values are configured to be the same value ( Configuration of claim 3).

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 1, the ground load of each wheel is calculated as the weight sum of the first and second ground loads. However, the weight is configured to be variably set according to the situation of the vehicle (structure of claim 4).

  According to the present invention, in order to effectively achieve the above main problem, in the configuration of claim 4, when the estimation accuracy of the first ground load is low, the first ground load is reduced. The weight of the first ground load is made smaller and the weight of the second ground load is made larger than when the estimation accuracy is high (configuration of claim 5).

  According to the present invention, in order to effectively achieve the above main problem, in the configuration of claim 4, when the estimation accuracy of the second ground load is low, the second ground load is reduced. The weight of the first contact load is increased and the weight of the second contact load is decreased as compared with the case where the estimation accuracy is high (configuration of claim 6).

  According to the present invention, in order to effectively achieve the main problem described above, in the configuration of claim 4, the deviation of the first and second contact loads is calculated, and the magnitude of the deviation is calculated. When the deviation is large, the weight of the first ground load is increased and the weight of the second ground load is decreased as compared with the case where the deviation is small. ).

  According to the configuration of the first aspect, the first ground load of each wheel is estimated based on at least the spring force of the suspension spring, the damping force of the shock absorber, and the stabilizer generating force, and based on the longitudinal acceleration and lateral acceleration of the vehicle. The second ground contact load of each wheel is estimated, and the ground contact load of each wheel is calculated based on the first and second ground loads. Therefore, even in a situation where road surface disturbance acts on the wheels, It is possible to accurately estimate the ground load of each wheel by taking advantage of the first ground load that can accurately estimate the ground load and the second ground load that is relatively less susceptible to noise. it can.

  Further, according to the configuration of claim 1, since the first grounding load of each wheel is estimated based on at least the spring force of the suspension spring, the damping force of the shock absorber, and the stabilizer generating force, There is no need to provide a load sensor corresponding to each wheel, and the suspension is not limited to a hydropneumatic suspension. Further, the vertical force applied to the wheel by a suspension spring, and the wheel by a shock absorber for each wheel. The vertical force applied to the wheel and the vertical force applied to the wheel by the stabilizer for each wheel can be calculated based on the wheel stroke and its rate of change, and means for detecting the wheel stroke used for other vehicle control, etc. It can be used effectively to estimate the ground contact load of each wheel. The ground contact load of each wheel even in a situation where the acts road surface disturbance to the wheel without being restricted by the suspension form while avoiding the cost can be estimated accurately.

  In general, the first ground contact load is estimated based on at least the spring force of the suspension spring, the damping force of the shock absorber, and the stabilizer generation force. Therefore, road surface disturbances act on the wheels and the ground load of each wheel fluctuates at a high frequency. In this situation, the first contact load can be accurately estimated as compared to the second contact load. Conversely, the second contact load is estimated based on the longitudinal acceleration and the lateral acceleration of the vehicle, and noise. Therefore, the second contact load can be estimated relatively accurately in a region where the frequency of the change in the contact load of each wheel is low, such as when the vehicle travels on a flat road.

  According to the configuration of the second aspect, the first ground load is used for the frequency region above the first reference value, and the second ground load is used for the frequency region less than the second reference value. Since the contact load of each wheel is calculated, the advantage of the first contact load is utilized for the region where the frequency of the contact load variation is high, and the advantage of the second contact load is utilized for the region where the frequency of the contact load variation is low. Thus, the ground load of each wheel can be estimated.

  Further, according to the configuration of the third aspect, since the first and second reference values are the same value, the advantages of the first and second ground loads are utilized over the entire frequency range of the ground load variation. The ground contact load of the wheel can be estimated, and special processing necessary when the first and second reference values are different from each other is not necessary.

  According to the configuration of claim 4, the ground load of each wheel is calculated as the sum of the weights of the first and second ground loads, and the weight is variably set according to the situation of the vehicle. Regardless of being constant, the ground load of each wheel can be calculated as the sum of the ratios of the first and second ground loads appropriately set according to the vehicle conditions.

  According to the fifth aspect of the present invention, when the estimated accuracy of the first ground load is low, the weight of the first ground load is made smaller than when the estimated accuracy of the first ground load is high. Since the weight of the second contact load is increased, the influence of the low estimation accuracy of the first contact load can be reduced and the contact load of each wheel can be accurately calculated.

  Further, according to the configuration of the sixth aspect, when the estimation accuracy of the second ground load is low, the weight of the first ground load is increased compared to when the estimation accuracy of the second ground load is high. Since the weight of the second grounding load is reduced, the influence of the low estimation accuracy of the second grounding load can be reduced and the grounding load of each wheel can be accurately calculated.

  In general, when the road surface disturbance is applied to the wheel, the first ground contact load is changed accordingly, whereas the second contact load is not easily changed even if the road surface disturbance is applied to the wheel. The ground contact load deviation indicates the degree of road disturbance acting on the wheel. When the first and second ground load deviations are large, the first ground load is smaller than when the deviation is small. High reliability.

  According to the configuration of the seventh aspect, the deviation between the first and second ground loads is calculated. When the magnitude of the deviation is large, the first ground load is smaller than when the deviation is small. Since the weight is increased and the weight of the second ground load is decreased, the first and second ground contacts are made according to the degree of road disturbance acting on the wheels, in other words, depending on the reliability of the first ground load. The weight of the load is set optimally, so that the ground contact load of each wheel can be accurately calculated regardless of the degree of road surface disturbance acting on the wheel.

[Preferred embodiment of problem solving means]
According to one preferable aspect of the present invention, in the configuration of the above-described first to seventh aspects, the vertical force applied to the wheel by the spring force of the suspension spring is calculated based on the wheel stroke of each wheel, and each wheel is calculated. The vertical stroke force applied to the wheel by the stabilizer is calculated by calculating the vertical force applied to the wheel by the damping force of the shock absorber based on at least the wheel stroke or the vertical acceleration on the wheel. The estimating means estimates the wheel stroke for each wheel, calculates the vertical force applied to the wheel by the spring force of the stabilizer based on at least the wheel stroke of the left and right wheels, and calculates the first based on the three vertical forces It is comprised so that a grounding load may be calculated (Preferred aspect 1).

  According to another preferred aspect of the present invention, in the preferred aspect 1, the wheel ground load estimating device is configured to calculate the ground load of each wheel as the sum of three vertical forces (preferably). Aspect 2).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 1, the wheel ground load estimation device calculates the ground load of each wheel as the sum of the three vertical forces and the vertical inertia force of the wheels. (Preferred aspect 3).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 3 described above, the wheel ground load estimating device detects the vertical acceleration of the wheel for each wheel, and the vertical movement of the wheel based on the vertical acceleration of the wheel. It is comprised so that an inertial force may be calculated (Preferable aspect 4).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspects 1 to 4, the suspension spring is calculated as a product of the spring force of the suspension spring calculated based on the wheel stroke and the arm ratio of the suspension. It is comprised so that the up-and-down force provided to a wheel with a spring force may be calculated (Preferred aspect 5).

  According to another preferable aspect of the present invention, in the configuration of the preferable aspects 1 to 5, the shock absorber is calculated based on the wheel stroke or the sprung vertical acceleration and the damping force control position of the shock absorber. The vertical force applied to the wheel by the damping force of the shock absorber is calculated as the product of the damping force and the suspension arm ratio (preferred aspect 6).

  According to another preferred aspect of the present invention, in the configurations of the preferred aspects 1 to 6, the wheel stroke is detected for each wheel and is calculated based on the wheel stroke and the spring force control position of the stabilizer. The vertical force applied to the wheel by the spring force of the stabilizer is calculated as the product of the spring force of the stabilizer and the arm ratio of the suspension (preferred aspect 7).

  According to another preferred embodiment of the present invention, in the configuration of the above-mentioned claim 2 or the preferred embodiments 1 to 7, the first ground load is subjected to high-pass filtering at the first cutoff frequency, and the first The second ground load is low-pass filtered at the second cutoff frequency, and the ground load of each wheel is calculated as the sum of the first ground load after the high-pass filter processing and the second ground load after the low-pass filter processing. (Preferred aspect 8).

  According to another preferred embodiment of the present invention, in the preferred embodiment 8, the first cutoff frequency and the second cutoff frequency are configured to have the same value (preferred embodiment 9). ).

  According to another preferred aspect of the present invention, in the configuration of claim 4, when the degree of road surface disturbance acting on the wheel is high, compared to when the degree of road surface disturbance acting on the wheel is low. The weight of the first ground load is increased and the weight of the second ground load is decreased (preferred aspect 10).

  According to another preferred aspect of the present invention, in the configuration of claim 5, when the detection accuracy of the means for detecting information necessary for estimating the first ground load is low, the first ground load is reduced. It is configured to be determined that the estimation accuracy is low (preferred aspect 11).

  According to another preferred aspect of the present invention, in the configuration of claim 6, when the detection accuracy of the means for detecting information necessary for estimating the second ground load is low, the second ground load is reduced. The estimation accuracy is determined to be low (preferred aspect 12).

  According to another preferred aspect of the present invention, in the configuration of claim 7, the average value of the deviations of the first and second contact loads of each wheel is calculated, and the magnitude of the average value of the deviations is calculated. When is large, the weight of the first ground load is increased and the weight of the second ground load is decreased as compared with the case where the average value of the deviation is small (preferred aspect 13).

  According to another preferred embodiment of the present invention, in the configuration of claim 7, the first and second ground load deviations are calculated for each wheel, and the maximum deviation magnitude for each wheel is calculated. When the value is large, the weight of the first ground load is made larger and the weight of the second ground load is made smaller than when the maximum value of the deviation is small (preferred aspect 14). .

  According to another preferred aspect of the present invention, in the configuration of claim 7, the first and second ground load deviations are calculated for each wheel, and the deviation magnitude is calculated for each wheel. When the deviation is large, the weight of the first contact load is made larger and the weight of the second contact load is made smaller than when the deviation is small (preferred aspect 15).

  In the two-wheel model 100 of the vehicle shown in FIG. 10, the spring constants of the left wheel suspension spring 102L and the right wheel suspension spring 102R are Ksl and Ksr, respectively, and the left wheel spring top 104L and right wheel spring top 104R. The vertical displacements of the left wheel unsprung 106L and the right wheel unsprung 106R are respectively Xwl and Xwr.

Also, the suspension arm ratio with respect to the suspension spring, that is, the lateral distance between the vehicle body side pivot point of the suspension arm and the suspension spring action point, and between the vehicle body side pivot point of the suspension arm and the ground contact point of the wheel. When the ratio to the vehicle lateral distance is Kas, the vertical forces Fsl and Fsr applied to the left wheel and the right wheel by the spring force of the suspension spring are expressed by the following equations 1 and 2, respectively.
Fsl = KasKsl (Xwl−Xbl) (1)
Fsr = KasKsr (Xwr-Xbr) (2)

Further, the damping coefficients of the left wheel shock absorber 108L and the right wheel shock absorber 108R are Csl and Csr, respectively, the vertical speeds of the left wheel sprung 104L and the right wheel sprung 104R are Xwld and Xwrd, respectively, and the left wheel unsprung 106L. When the vertical speed of the unsprung 106R of the right wheel and Xbrd are Xbld and Xbrd, respectively, and the suspension arm ratio of the shock absorber is Kad, the vertical forces Fdl and Fdr applied to the left and right wheels by the damping force of the shock absorber are These are represented by the following formulas 3 and 4, respectively.
Fdl = KadCsl (Xwld-Xbld) (3)
Fdr = KadCsr (Xwrd−Xbrd) (4)

When the stabilizer constant of the stabilizer 110 provided between the left and right wheels is Kst and the arm ratio of the stabilizer is Kat, the vertical force Fst applied to the left wheel and the right wheel by the spring force of the stabilizer 110 is expressed by the following equation (5). It is represented by
Fst = KatKst (Xwl-Xwr) (5)

Also, assuming that the vertical displacement of the road surface 112 of the left and right wheels is Xsl and Xsr, and the longitudinal spring constants of the left tire 114L and the right wheel 114R are Ktl and Ktr, respectively, the left and right wheels are given to the left and right wheels by the tire vertical force. The vertical forces Ftl and Ftr to be expressed are expressed by the following equations 6 and 7, respectively.
Ftl = Ktl (Xsl−Xwl) (6)
Ftr = Ktr (Xsr-Xwr) (7)

If the left and right wheel sprung masses are Mbl and Mbr, the left and right wheel unsprung masses are Mwl and Mwr, respectively, and the gravitational acceleration is g, the left and right wheel ground loads Fzl and Fzr are respectively It is represented by the following formulas 8 and 9.
Fzl = Ftl + (Mbl + Mwl) g (8)
Fzr = Ftr + (Mbr + Mwr) g (9)

Also, assuming that the vertical acceleration of the left-wheel sprung 104L is Xbldd, the vertical force as an external force accompanying turning of the vehicle is Ftnl, and the vertical acceleration of the unsprung 106L is Xwldd, the following equation of motion of the sprung 104L is as follows: Expression 10 is established, and the following expression 11 is established as an equation of motion of the unsprung 106L in the vertical direction.
MblXbldd = Fsl + Fdl + Ftnl (10)
MwlXwldd = −Fsl−Fdl−Fst + Ftl (11)

Similarly, if the vertical acceleration of the right wheel sprung 104R is Xbrdd, the vertical force as an external force accompanying turning of the vehicle is Ftnr, and the vertical acceleration of the unsprung 106R is Xwrdd, the equation of motion of the sprung 104R in the vertical direction The following equation 12 is established, and the following equation 13 is established as an equation of motion of the unsprung 106R in the vertical direction.
MbrXbrdd = Fsr + Fdr + Ftnr (12)
MwrXwrdd = −Fsr−Fdr−Fst + Ftr (13)

From the above formulas, the ground contact load Fzl of the left wheel is represented by the following formula 14 or 15, and the ground load Fzr of the right wheel is represented by the following formula 16 or 17.
Fzl = (Mbl + Mwl) g + MwlXwldd + Fsl + Fdl + Fst (14)
Fzl = (Mbl + Mwl) g + MwlXwldd + MblXbldd + Fst + Ftnl (15)
Fzr = (Mbr + Mwr) g + MwrXwrdd + Fsr + Fdr-Fst (16)
Fzr = (Mbr + Mwr) g + MwrXwrdd + MbrXbrdd-Fst + Ftnr (17)

  Therefore, according to another preferred aspect of the present invention, in the configuration of claims 1 to 7 or preferred aspects 1 to 15, the ground contact load Fzl of the left wheel is calculated according to the above formula 14 or 15, and the right wheel The ground contact load Fzr is calculated according to the above formula 16 or 17 (preferred aspect 16).

In general, since the unsprung mass is much smaller than the unsprung mass, the vertical force MwlXwldd and MwrXwrdd applied to the wheel by the vertical inertia force of the unsprung direction, that is, the vertical force due to the unsprung vertical acceleration is omitted. May be. Therefore, according to another preferred aspect of the present invention, in the configuration of claims 1 to 7 or preferred aspects 1 to 15, the ground load Fzl of the left wheel is calculated according to the following equation 18 or 19, The wheel ground load Fzr is configured to be calculated according to the following equation 20 or 21 (preferred aspect 17).
Fzl = (Mbl + Mwl) g + Fsl + Fdl + Fst (18)
Fzl = (Mbl + Mwl) g + MblXbldd + Fst + Ftnl (19)
Fzr = (Mbr + Mwr) g + Fsr + Fdr-Fst (20)
Fzr = (Mbr + Mwr) g + MbrXbrdd-Fst + Ftnr (21)

  The present invention will now be described in detail with reference to a few preferred embodiments with reference to the accompanying drawings.

  FIG. 1 shows vehicle wheel ground load estimation according to the present invention applied to a vehicle in which a vehicle height control device and a damping force variable shock absorber are provided on each wheel, and an active stabilizer device is provided on the front wheel side and the rear wheel side. It is a schematic block diagram which shows Example 1 of an apparatus.

  In FIG. 1, 10 FL and 10 FR respectively indicate left and right front wheels that are driven wheels of the vehicle 12, and 10 RL and 10 RR respectively indicate left and right rear wheels that are drive wheels of the vehicle 12. The left and right front wheels 10FL and 10FR, which are also steered wheels, are steered via tie rods by a power steering device (not shown) that is driven in response to steering of the steering wheel 14 by the driver.

  An active stabilizer device 16 is provided between the left and right front wheels 10FL and 10FR, and an active stabilizer device 18 is provided between the left and right rear wheels 10RL and 10RR. The active stabilizer device 16 is integrally connected to a pair of torsion bar portions 16TL and 16TR extending coaxially with each other along an axis extending in the lateral direction of the vehicle, and to the outer ends of the torsion bar portions 16TL and 16TR, respectively. And a pair of arm portions 16AL and 16AR. The torsion bar portions 16TL and 16TR are supported by a vehicle body not shown in the drawing via brackets not shown in the drawing so as to be rotatable around their own axes. The arm portions 16AL and 16AR extend in the longitudinal direction of the vehicle so as to intersect the torsion bar portions 16TL and 16TR, respectively, and the outer ends of the arm portions 16AL and 16AR are respectively left and right through rubber bush devices not shown in the drawing. The front wheels 10FL and 10FR are connected to wheel support members or suspension arms.

  The active stabilizer device 16 has an actuator 20F between the torsion bar portions 16TL and 16TR. The actuator 20F rotates the pair of torsion bar portions 16TL and 16TR in opposite directions as necessary, so that when the left and right front wheels 10FL and 10FR bounce and rebound in opposite phases, the wheel bounces due to torsional stress. Then, the force to suppress rebound is changed, thereby increasing or decreasing the anti-roll moment applied to the vehicle at the position of the left and right front wheels, and variably controlling the roll rigidity of the vehicle on the front wheel side.

  Similarly, the active stabilizer device 18 has a pair of torsion bar portions 18TL and 18TR extending coaxially with each other along an axis extending in the lateral direction of the vehicle, and the outer ends of the torsion bar portions 18TL and 18TR, respectively. It has a pair of arm portions 18AL and 18AR connected together. The torsion bar portions 18TL and 18TR are respectively supported by a vehicle body not shown in the drawing via brackets not shown in the drawing so as to be rotatable around their own axes. The arm portions 18AL and 18AR extend in the longitudinal direction of the vehicle so as to intersect the torsion bar portions 18TL and 18TR, respectively, and the outer ends of the arm portions 18AL and 18AR are respectively left and right through rubber bushing devices not shown in the drawing. The rear wheels 10RL and 10RR are connected to wheel support members or suspension arms.

  The active stabilizer device 18 has an actuator 20R between the torsion bar portions 18TL and 18TR. The actuator 20R rotates the pair of torsion bar portions 18TL and 18TR in directions opposite to each other as necessary, so that when the left and right rear wheels 10RL and 10RR bounce and rebound in opposite phases, the torsional stress causes the wheel The force that suppresses bounce and rebound is changed, thereby increasing / decreasing the anti-roll moment applied to the vehicle at the positions of the left and right rear wheels, and variably controlling the roll rigidity of the vehicle on the rear wheel side.

  The active stabilizer devices 16 and 18 themselves do not form the gist of the present invention, and may have any configuration known in the art as long as the roll rigidity of the vehicle can be variably controlled. However, for example, the active stabilizer device described in Japanese Patent Application No. 2003-324212 (reference number AT-5552) specification and drawings relating to the application of the applicant of the present application, that is, fixed to the inner end of one torsion bar portion, and a drive gear is attached. An electric motor having a rotating shaft and a driven gear fixed to the inner end of the other torsion bar portion and meshed with the driving gear. The driving gear and the driven gear transmit the rotation of the driving gear to the driven gear. The active stabilizer device is preferably a gear that does not transmit the rotation of the gear to the drive gear.

  In the illustrated embodiment 1, the left and right front wheels 10FL, 10FR and the left and right rear wheels 10RL, 10RR are each provided with a variable damping force shock absorber 22FL, 22FR having an arbitrary configuration known in the art. , 22RL and 22RR are provided. The damping coefficients of the shock absorbers 22FL to 22RR are changed over n (positive integer) stages from the lowest stage Smin to the highest stage Smax by an actuator not shown in FIG.

  Further, in the illustrated embodiment 1, air spring devices 24FL, 24FR, 24RL, 24RR as suspension springs are provided between the shock absorbers 22FL, 22FR, 22RL, 22RR and the vehicle body not shown in FIG. Is provided. The air spring devices 24FL to 24RR are arranged so that compressed air is supplied to and discharged from the air chamber as required by a pneumatic circuit not shown in FIG. rl, rr) is increased or decreased in m (positive integer) steps from the minimum target vehicle height Htmini to the maximum target vehicle height Htmaxi (i = fl, fr, rl, rr).

  As shown in FIGS. 1 and 2, the actuators 20F and 20R of the active stabilizer devices 16 and 18 are controlled by an electronic control device 52 for controlling the active stabilizer device of the electronic control device 50, and the electronic control device 52 is controlled by the active stabilizer device. The target rotation angles φFt and φRt of the actuators 20F and 20R of 16 and 18 are calculated, and control is performed so that the rotation angles φF and φR of the actuators 20F and 20R become the corresponding target rotation angles φFt and φRt, respectively.

  The actuators of the shock absorbers 22FL to 22RR are controlled by the damping force control electronic control unit 54 of the electronic control unit 50, and the electronic control unit 54 sets the target control stage Sti (i = fl, fr) of the damping coefficient of the shock absorbers 22FL to 22RR. , Rl, rr) and control so that the damping coefficient control stages Si of the respective shock absorbers 22FL to 22RR become the corresponding target control stages Sti.

  The pneumatic circuits of the air spring devices 24FL to 24RR are controlled by a vehicle height control electronic control device 56 of the electronic control device 50. The electronic control device 56 uses the target vehicle height Hti (i = fl, fr, rl, rr) is calculated, and control is performed so that the vehicle height Hi at each wheel position becomes the corresponding target vehicle height Hti.

  Although not shown in detail in FIGS. 1 and 2, each of the electronic control devices 52, 54, and 56 and the electronic control device 66 described later has a CPU, a ROM, a RAM, and an input / output port device, respectively. It may be composed of a microcomputer and a drive circuit connected to each other by a bidirectional common bus. Various control methods for the active stabilizer devices 16 and 18 by the electronic control device 52, the control of the damping force of the shock absorbers 22FL to 22RR by the electronic control device 54, and the vehicle height control by the electronic control device 56 are known in the art. In addition, since it does not form the gist of the present invention, description thereof will be omitted.

  As shown in FIG. 2, a signal indicating the vehicle height Hi at each wheel position detected by vehicle height sensors 58FL to 58RR provided corresponding to each wheel is input to the vehicle height control electronic control device 56. The vehicle height Hi is detected as a relative displacement between the sprung and unsprung parts. The electronic control unit 56 calculates the spring constants Ksi (i = fl, fr, rl, rr) of the air spring devices 24FL to 24RR based on the target vehicle height Hti at each wheel position.

Further, the electronic control unit 56 applies the left and right front wheels to the left and right front wheels by the spring force of the left and right front wheel air spring devices 24FL and 24FR according to the following formulas 22 and 23 corresponding to the above formulas 1 and 2 based on the vehicle heights Hfl and Hfr of the left and right front wheels. The springs of the left and right rear wheel air spring devices 24RL and 24RR are calculated according to the following formulas 24 and 25 corresponding to the above formulas 1 and 2 based on the applied vertical forces Fsfl and Fsfr and the left and right rear wheel heights Hrl and Hrr. The vertical forces Fsrl and Fsrr applied to the left rear wheel and the right rear wheel by the force are calculated.
Fsfl = KasfKsflHfl (22)
Fsfr = KasfKsfrHfr (23)
Fsrl = KasrKsrlHrl (24)
Fsrr = KasrKsrrHrr (25)

  The damping force control electronic control unit 54 has a signal indicating the vehicle height Hi at each wheel position from vehicle height sensors 58FL to 58RR, and shock absorbers 22FL to 22RR from position sensors 60FL to 60RR provided on the actuators of the shock absorbers 22FL to 22RR. A signal indicating the control stage Si (i = fl, fr, rl, rr) of the damping coefficient of the wheel, and the vertical acceleration Xwddi of the wheel as the unsprung mass detected by the vertical acceleration sensors 62FL to 62RR provided for each wheel. A signal indicating i = fl, fr, rl, rr) is input.

  The damping force control electronic control unit 54 calculates the damping coefficient Csi (i = fl, fr, rl, rr) of each shock absorber based on the control stage Si of the shock absorbers 22FL to 22RR, and time differential value of the vehicle height Hi. Is calculated as the stroke speed Hvi (i = fl, fr, rl, rr) of each wheel.

The electronic control unit 54 for controlling the damping force controls the left front wheel and the left front wheel by the damping force of the left and right front wheel shock absorbers 22FL and 22FR according to the following formulas 26 and 27 corresponding to the above formulas 3 and 4 based on the stroke speeds Hvfl and Hvfr of the left and right front wheels. The vertical force Fdfl, Fdfr applied to the right front wheel is calculated, and the left and right rear wheel shock absorbers 22RL, 22RR according to the following equations 28, 29 corresponding to the above equations 3 and 4 based on the left and right rear wheel stroke speeds Hvrl, Hvrr. The vertical forces Fdrl and Fdrr applied to the left rear wheel and the right rear wheel by the damping force are calculated.
Fdfl = KadfCsflHvfl (26)
Fdfr = KadfCsfrHvfr (27)
Fdrl = KadrCsrlHvrl (28)
Fdrr = KadrCsrrHvrr (29)

Further, the damping force control electronic control unit 54 is based on the mass Mwi (i = fl, fr, rl, rr) of each wheel and the vertical acceleration Xwddi of each wheel. Inertial force Fwmi (i = fl, fr, rl, rr) is calculated. The inertial force Fwmi of each wheel may be calculated by the vehicle height control electronic control device 56 or the active stabilizer device control electronic control device 52.
Fwmi = MwiXwddi (30)

Signals indicating the rotation angles φF and φR of the actuators 20F and 20R are input from the rotation angle sensors 64F and 64R provided in the actuators 20F and 20R of the active stabilizer devices 16 and 18 to the electronic control device 52 for controlling the active stabilizer device. . The electronic control unit 52 calculates the stabilizer constants Kstf and Kstr of the active stabilizer devices 16 and 18 based on the rotation angles φF and φR, and the following equations 31 and 32 corresponding to the above equation 5 based on the vehicle height Hi at each wheel position. Accordingly, the vertical forces Fstf and Fstr applied to the left and right front wheels and the left and right rear wheels by the spring force of the active stabilizer devices 16 and 18 are calculated.
Fstf = KatfKstf (Hfl−Hfr) (31)
Fstr = KatrKstr (Hrl−Hrr) (32)

  Further, the electronic control unit 50 shown in FIG. 1 includes an electronic control unit 66 for vehicle motion control, and the electronic control unit 66 is configured so that each wheel is driven by the spring force of the air spring devices 24FL to 24RR from the electronic control unit 56 for vehicle height control. A signal indicating the vertical force Fsi applied to the wheel is input, and a signal indicating the vertical force Fdi applied to each wheel by the damping force of the shock absorbers 22FL to 22RR and the inertial force of each wheel from the electronic control device 54 for damping force control. A signal indicating Fwmi is input, and signals indicating vertical forces Fstf and Fstr applied to the left and right front wheels and the left and right rear wheels by the spring force of the active stabilizer devices 16 and 18 are input from the active stabilizer device control electronic control device 52. .

  Further, the electronic control device 52 for controlling the active stabilizer device calculates the roll stiffness Krf of the front wheels based on the rotation angles φF and φR of the actuators 20F and 20R, and a signal indicating the roll stiffness Krf of the front wheels is also used. To the vehicle motion control electronic control unit 66.

  The vehicle motion control electronic control unit 66 includes a first ground load calculation block 68 for calculating a first ground load Fzi1 (i = fl, fr, rl, rr) based on the vertical force acting on each wheel, and load movement. And a second contact load calculation block 70 for calculating a second contact load Fzi2 (i = fl, fr, rl, rr) based on the above.

The first ground load calculation block 68 is based on the vertical forces Fsi, Fdi, Fstf, Fstr and the inertial force Fwmi, and the first ground loads Fzfl1, Fzfr1 of the left and right front wheels according to the following equations 33 and 34 corresponding to the above equations 14 and 16. And the first ground loads Fzrl1 and Fzrr1 of the left and right rear wheels are calculated according to the following formulas 35 and 36 corresponding to the above formulas 15 and 17.
Fzfl1 = (Mbfl + Mwfl) g + Fwfl + Fsfl + Fdfl + Fstf (33)
Fzfr1 = (Mbfr + Mwfr) g + Fwfr + Fsfr + Fdfr-Fstf (34)
Fzrl1 = (Mbrl + Mwrl) g + Fwrl + Fsrl + Fdrl + Fstr (35)
Fzrr1 = (Mbrr + Mwrr) g + Fwrr + Fsrr + Fdrr-Fstr (36)

Signals indicating the longitudinal acceleration Gx and the lateral acceleration Gy of the vehicle are input from the longitudinal acceleration sensor 72 and the lateral acceleration sensor 74 to the second ground load calculation block 70 of the vehicle motion control electronic control device 66, respectively. The second ground load calculation block 70 has the mass of the vehicle as M, the height of the center of gravity of the vehicle as Hg, the front and rear treads of the vehicle as Tf and Tr, respectively, and the center of gravity of the vehicle and the front and rear axles. The horizontal contact distances of the wheels are set to Lf and Lr, respectively, and the second ground load Fzi2 (i = fl, fr, rl, rr) of each wheel according to the following equations 38 to 41 based on the longitudinal acceleration Gx and the lateral acceleration Gy of the vehicle. Calculate.
Fzfl2 = MLr / (Lf + Lr)
+ M {-2GxHg / (Lf + Lr) -GyHgKrf / Tf} (38)
Fzfr2 = MLr / (Lf + Lr)
+ M {-2GxHg / (Lf + Lr) + GyHgKrf / Tf} (39)
Fzrl2 = MLf / (Lf + Lr)
+ M {2GxHg / (Lf + Lr) -GyHg (1-Krf) / Tr} (40)
Fzrr2 = MLf / (Lf + Lr)
+ M {2GxHg / (Lf + Lr) + GyHg (1-Krf) / Tr} (41)

  The vehicle motion control electronic control unit 66 further includes a high-pass filter processing block 76, a low-pass filter processing block 78, and a ground load calculation block 80. The high-pass filter processing block 76 calculates the first ground load Fzi1f (i = fl, fr, rl, rr) after the high-pass filter processing by performing high-pass filter processing on the first ground load Fzi1, and the low-pass filter processing block 78 Calculates the second ground load Fzi2f (i = fl, fr, rl, rr) after the low-pass filter processing by subjecting the second ground load Fzi2 to low-pass filter processing. The ground load calculation block 80 calculates the ground load Fzi (i = fl, fr, rl, rr) of each wheel as the sum of the first ground load Fzi1f after the high-pass filter processing and the second ground load Fzi2f after the low-pass filter processing. Is calculated.

  The vehicle motion control electronic control unit 66 controls the vehicle motion by controlling the braking / driving force of the wheel or the steering angle of the steering wheel, which is known in the art, and the ground loads Fzfl to Fzrr of each wheel are Although used for vehicle motion control, the ground load of each wheel may be used for arbitrary control of the vehicle.

  Next, with reference to the flowchart shown in FIG. 3, a routine for calculating the contact load of each wheel in the first embodiment will be described. Note that the arithmetic control according to the flowchart shown in FIG. 3 is started by closing an ignition switch (not shown), and is repeatedly executed every predetermined time.

  First, in step 10, a signal indicating the vertical force Fsi applied to each wheel is read by the spring force of the air spring devices 24FL to 24RR, and in step 20, each of the signals according to the above equations 33 to 36 is read. A first grounding load Fzi1 of each wheel based on the vertical force applied to the wheel is calculated, and in step 30, the second grounding load Fzi2 of each wheel based on the load movement of the vehicle is calculated according to the above equations 38 to 41. Calculated.

  In step 40, it is determined whether or not the first ground load Fzi1 of each wheel is a normal value, that is, vehicle height sensors 58FL to 58RR for detecting information necessary for calculating the first ground load Fzi1. Each sensor is normal, the communication between each sensor and the electronic control devices 56, 54, 52 is normal, the calculation of the vertical force Fsi in the vehicle height control electronic control device 56, the damping force control electronic The calculation of the vertical force Fdi and the vertical inertia force Fwmi in the control device 54 and the calculation of the vertical forces Fstf and Fstr in the active stabilizer device control electronic control device 52 are normal, and the vehicle height control electronic control device. 56, the communication between the damping force control electronic control device 54, the active stabilizer device control electronic control device 52 and the vehicle motion control electronic control device 66 is normal, and the vehicle motion control electronic control device 66 One of whether operation is a normal contact load Fzi1 determination is made, the process proceeds to step 100 when the negative determination has been performed, the process proceeds to step 50 when a positive determination is made.

  In step 50, it is determined whether or not the second ground load Fzi2 of each wheel is a normal value, that is, the longitudinal acceleration sensor 72 and the lateral acceleration sensor for detecting information necessary for calculating the second ground load Fzi2. 74 is normal, the communication between these sensors and the vehicle motion control electronic control device 56 is normal, and the calculation of the second ground load Fzi2 in the vehicle motion control electronic control device 66 is normal. When a positive determination is made, the process proceeds to step 70. When a negative determination is made, the ground load Fzi of each wheel is set to the first ground load Fzi1 in step 60. The

  In step 70, the first grounding load Fzi1 is subjected to fc high-pass filter processing to calculate the first grounding load Fzi1f after the high-pass filtering, and in step 80, the second grounding load Fzi2 is low-pass. By filtering, the second ground load Fzi2f after the low-pass filter processing is calculated, and in step 90, the first ground load Fzi1f after the high-pass filter processing and the second ground load Fzi2f after the low-pass filter processing. The ground contact load Fzi of each wheel is calculated as the sum of. The cut-off frequency fch of the high-pass filter process in step 70 and the cut-off frequency fcl of the low-pass filter process in step 80 are the same frequency.

  In step 100, it is determined whether or not the second ground load Fzi2 of each wheel is a normal value in the same manner as in step 50. If an affirmative determination is made, step 110 is performed. If the contact load Fzi of each wheel is set to the second contact load Fzi2 and a negative determination is made, it is determined in step 120 that the proper calculation of the contact load Fzi of each wheel is impossible. .

  Thus, according to the illustrated first embodiment, the vertical force applied to each wheel by the spring force of the air spring devices 24FL to 24RR based on the target vehicle height Hti and the vehicle height Hi of each wheel by the vehicle height control electronic control device 56. Fsfl to Fsrr are calculated, and the vertical force applied to each wheel by the damping force of each shock absorber based on the damping coefficient Csi of each shock absorber 22FL to 22RR and the stroke speed Hvi of each wheel by the damping force control electronic control unit 54 Fdfl to Fdrr are calculated, and the inertial force Fwmi in the vertical direction of each wheel is calculated based on the mass Mwi of each wheel and the vertical acceleration Xwddi of each wheel, and the active stabilizer device 16 is controlled by the electronic control device 52 for controlling the active stabilizer device. And 18 based on the rotation angles φF and φR of the actuators 20F and 20R and the vehicle height Hi at each wheel position. The vertical forces Fstf and Fstr applied to the left and right front wheels and the left and right rear wheels are calculated by the spring force of the stabilizer devices 16 and 18, and in step 20, the vertical forces Fsi, Fdi, Fstf, Fstr and the inertial force Fwmi are summed. The first ground contact load Fzi1 of the wheel is calculated.

  In step 30, the second ground load Fzi2 of each wheel based on the vehicle load movement is calculated based on the longitudinal acceleration Gx and the lateral acceleration Gy of the vehicle, and the first ground load Fzi1 and the second ground load Fzi2 are calculated. When the value is normal, an affirmative determination is made at steps 40 and 50, the first ground load Fzi1 is high-pass filtered at step 70, and the second ground load Fzi2 is low-pass filtered at step 80. In step 90, the ground load Fzi of each wheel is calculated as the sum of the first ground load Fzi1f after the high-pass filter processing and the second ground load Fzi2f after the low-pass filter processing.

  When the first contact load Fzi1 is a normal value but the second contact load Fzi2 is not a normal value, an affirmative determination is made in step 40, but a negative determination is made in step 50, thereby In step 60, the ground load Fzi of each wheel is set to the first ground load Fzi1.

  Furthermore, when the first contact load Fzi1 is not a normal value, but the second contact load Fzi2 is a normal value, a negative determination is made at step 40, but an affirmative determination is made at step 100. Thus, in step 110, the ground load Fzi of each wheel is set to the second ground load Fzi2.

  As described above, since the first ground contact load Fzi1 is estimated based on at least the spring force of the suspension spring, the damping force of the shock absorber, the stabilizer generating force, and the inertia force in the vertical direction of the wheel, road disturbance acts on the wheel. However, in the situation where the ground load of each wheel fluctuates at a high frequency, the first ground load Fzi1 can be accurately estimated as compared with the second ground load Fzi2, and conversely, the second ground load Fzi2 is Since it is estimated based on the longitudinal acceleration Gx and lateral acceleration Gy of the vehicle and is not easily affected by noise, the second in a region where the frequency of the ground load fluctuation of each wheel is low as in the case where the vehicle travels on a flat road. The ground contact load Fzi2 can be estimated relatively accurately.

  Therefore, according to the first embodiment, the ground load Fzi of each wheel is calculated as the sum of the first ground load Fzi1f after the high-pass filter process and the second ground load Fzi2f after the low-pass filter process. In which the ground contact load of each wheel fluctuates at a high frequency, and when the frequency of the ground load variation of each wheel is low, such as when the vehicle travels on a flat road. The ground load Fzi can be accurately estimated.

  In particular, according to the first embodiment shown in the drawing, the cutoff frequency fch of the high-pass filter processing in step 70 and the cutoff frequency fcl of the low-pass filter processing in step 80 are the same frequency or the same frequency. As compared with the case where the cut-off frequency fch of the high-pass filter processing and the cut-off frequency fcl of the low-pass filter processing are different from each other, the ground load Fzi of each wheel can be estimated accurately and easily.

  In the illustrated embodiment 1, the cut-off frequency fch for the high-pass filter processing and the cut-off frequency fcl for the low-pass filter processing are the same, but the cut-off frequencies fch and fcl may be different from each other. Good.

  For example, the cut-off frequency fch of the high-pass filter process is set to a value higher than the cut-off frequency fcl of the low-pass filter process, and the first ground load Fzi1 and the second ground load Fzi2 are bandpass filters for the frequency fcl to fch band. As the sum of the first ground load Fzi1f after the high-pass filter processing, the second ground load Fzi2f after the low-pass filter processing, the first ground load Fzi1bf and the second ground load Fzi2bf after the band-pass filter processing. The ground load Fzi of each wheel may be calculated.

  Conversely, the cut-off frequency fch of the high-pass filter process is set to a value lower than the cut-off frequency fcl of the low-pass filter process, and the first ground load Fzi1 and the second ground load Fzi2 are bandpass for the frequency fch to fcl band. The first grounding load Fzi1bf and the second grounding load Fzi2bf after the band-pass filter processing are obtained by filtering and the sum of the first grounding load Fzi1f after the high-pass filtering and the second grounding load Fzi2f after the low-pass filtering. The ground load Fzi of each wheel may be calculated as a value obtained by subtracting.

  FIG. 4 shows a vehicle ground contact load estimation according to the present invention applied to a vehicle in which a vehicle height control device and a variable damping force type shock absorber are provided on each wheel, and an active stabilizer device is provided on the front wheel side and the rear wheel side. It is a block diagram which shows the electronic control apparatus of Example 2 of an apparatus. In FIG. 4, the same members as those shown in FIG. 2 are denoted by the same reference numerals as those shown in FIG.

  As shown in FIG. 4, in this second embodiment, the vehicle motion control electronic control unit 66 has a weight K calculation and change restriction block 82, and the weight K calculation and change restriction block 82 is the first. The second ground load Fzi2 is set according to the reliability of the first ground load Fzi1 and the second ground load Fzi2 so that the weight of the higher reliability of the ground load Fzi1 and the second ground load Fzi2 is increased. The weight K is calculated with respect to, and the change in the weight K is limited so that a sudden change in the weight K does not occur.

Further, the ground load calculation block 80 of the second embodiment uses the weight K calculated by the weight K calculation and change restriction block 82 to calculate the first ground load Fzi1 and the second ground load Fzi2 according to the following equation 42. The ground load Fzi of each wheel is calculated as a weight sum.
Fzi = Fzi1 (1-K) + Fzi2K (42)

  FIG. 5 is a flowchart showing a calculation routine for the contact load of each wheel in the second embodiment. In FIG. 5, the same step number as the step number shown in FIG. 3 is assigned to the same step as the step shown in FIG.

  In the second embodiment, steps 10 to 50, 100, and 120 are executed in the same manner as in the first embodiment, but when a negative determination is made in step 50, that is, for each wheel. When it is determined that the second ground load Fzi2 is not a normal value, the weight K for the second ground load Fzi2 is set to 0 in step 65, and then the process proceeds to step 140. When an affirmative determination is made. Proceed to step 130.

  If a negative determination is made in step 100, the process proceeds to step 120. If an affirmative determination is made, that is, if it is determined that the second ground contact load Fzi2 of each wheel is a normal value, step 120 is performed. After the weight K for the second ground load Fzi2 is set to 1 at 115, the routine proceeds to step 140.

  In step 130, the average value ΔFza of the absolute value ΔFza (i = fl, fr, rl, rr) of the deviation ΔFzi (i = fl, fr, rl, rr) between the first grounding load Fzi1 and the second grounding load Fzi2 is calculated. Based on the average value ΔFza of absolute values, a weight K for the second ground load Fzi2 is calculated from a map corresponding to the graph shown in FIG.

  In step 140, the weight K is limited by the filtering process for the weight K or the limiting process for the change amount by the guard value. In step 150, the first ground load Fzi1 and the first contact load Fzi1 are calculated according to the above equation 42. The ground load Fzi of each wheel is calculated as the weight sum of the two ground loads Fzi2.

  Thus, according to the illustrated second embodiment, when the first ground load Fzi1 and the second ground load Fzi2 are normal values, an affirmative determination is made in steps 40 and 50, and in step 130 the first The average value ΔFza of the absolute value ΔFzi of the deviation ΔFzi between the grounding load Fzi1 and the second grounding load Fzi2 is calculated, and the second grounding load Fzi2 is based on the average value ΔFza so as to decrease as the average value ΔFza increases. A weight K for is calculated.

  When the first contact load Fzi1 is a normal value but the second contact load Fzi2 is not a normal value, an affirmative determination is made in step 40, but a negative determination is made in step 50, thereby In step 65, the weight K is set to zero. Furthermore, when the first contact load Fzi1 is not a normal value, but the second contact load Fzi2 is a normal value, a negative determination is made at step 40, but an affirmative determination is made at step 100. Thus, in step 115, the weight K is set to 1. In step 150, the ground load Fzi of each wheel is calculated as the weight sum of the first ground load Fzi1 and the second ground load Fzi2 in accordance with the above equation 42.

  In general, the absolute value of the deviation ΔFzi between the first contact load Fzi1 and the second contact load Fzi2 increases as the road surface disturbance acts on the wheels and the change in the ground load of each wheel increases, so the average value ΔFza is the road surface disturbance. It represents the degree of fluctuation of the ground load of each wheel due to the action of. As described above, the first ground contact load Fzi1 is estimated based on at least the spring force of the suspension spring, the damping force of the shock absorber, the stabilizer generating force, and the inertia force in the vertical direction of the wheel. In a situation where the ground contact load of each wheel varies at a high frequency, the first ground load Fzi1 accurately reflects the actual ground load compared to the second ground load Fzi2, and conversely the second ground contact. The load Fzi2 is estimated based on the longitudinal acceleration Gx and the lateral acceleration Gy of the vehicle and is not easily affected by noise. Therefore, in a region where the frequency of the ground load variation of each wheel is low, such as when the vehicle is traveling on a flat road. Therefore, the actual ground load is accurately reflected in comparison with the first ground load Fzi1.

  Therefore, according to the second embodiment, when the road surface disturbance is applied to the wheels and the ground load of each wheel fluctuates, the weight of the first ground load Fzi1 is increased to calculate the ground load Fzi of each wheel. In a situation where the frequency of fluctuation of the ground load of each wheel is low, such as when the vehicle is traveling on a flat road, the weight of the second ground load Fzi2 is increased and the ground load Fzi of each wheel is calculated. Whether the road surface disturbance is applied to the wheels and the ground load of each wheel fluctuates at a high frequency, or the ground load fluctuation frequency of each wheel is low, such as when the vehicle is traveling on a flat road. The ground load Fzi of each wheel can be accurately estimated.

  In particular, according to the illustrated embodiment 2, the weight K is calculated as a common value for each wheel based on the average value ΔFza of absolute values of the deviation ΔFzi between the first contact load Fzi1 and the second contact load Fzi2. Therefore, compared to the case where the weight K is calculated for each wheel, the wheel ground load Fzi can be easily estimated.

  Further, according to the second embodiment shown in the drawing, since the weight K change limiting process is performed by the filtering process for the weight K or the change limiting process based on the guard value in Step 140, Thus, a sudden change in the wheel ground contact load Fzi caused by the above can be prevented, whereby a sudden change in the control amount of the vehicle motion control performed using the wheel ground load Fzi can be reliably prevented.

  In the illustrated embodiment 2, the weight K is calculated as a common value for each wheel based on the average value ΔFza of absolute values of the deviation ΔFzi between the first contact load Fzi1 and the second contact load Fzi2. However, as shown in FIG. 7, it may be calculated as a common value for each wheel based on the maximum absolute value ΔFzmax of the deviation ΔFzi.

Further, as shown in FIG. 8, the weight Ki (i = fl, fr, rl, rr) is set for each wheel based on the absolute value of the deviation ΔFzi between the first contact load Fzi1 and the second contact load Fzi2. The ground load Fzi of each wheel may be calculated as a weight sum of the first ground load Fzi1 and the second ground load Fzi2 according to the following equation 43 for each wheel.
Fzi = Fzi1 (1-Ki) + Fzi2Ki (43)

  As shown in FIG. 9, for example, the rate of change or the amount of any of the vertical forces Fsi, Fdi, Fstf, Fstr and the inertial force Fwmi, the vehicle height Hi, the stroke speed Hvi, the vertical acceleration Xwddi of each wheel, etc. The degree of bad road on the road surface is determined based on the rate of change or the amount of change, or other parameters known in the art, and the weight K is the road surface so that the higher the bad road degree, the smaller the weight K. It may be calculated as a value common to each wheel based on the degree of the rough road.

  In the illustrated embodiment 2, if an affirmative determination is made in steps 40 and 50, the absolute value of the deviation ΔFzi between the first ground load Fzi1 and the second ground load Fzi2 in step 130. The weight K for the second ground load Fzi2 is calculated on the basis of the average value ΔFza of the above, but the weight K when affirmative determination is made in steps 40 and 50 is a constant value. Also good.

  Further, in the illustrated second embodiment, when step 65, 115, or 130 is completed, the process of limiting the change in weight K is performed in step 140, but step 140 is omitted. It may also be modified to proceed to step 150 when step 65 or 130 is complete.

  According to the first and second embodiments, the vehicle height control device and the variable damping force type shock absorber are provided on each wheel, and the active stabilizer device is provided on the front wheel side and the rear wheel side. The first ground contact load Fzi1 of each wheel is accurately estimated based on the detected value of the vehicle height sensor used for the control of the vehicle height control device etc. without requiring a load sensor provided corresponding to each wheel. can do.

  Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in each of the above-described embodiments, the vehicle includes a vehicle height adjusting device, a damping force variable shock absorber, and an active stabilizer device. However, the wheel ground load estimating device of the present invention is a vehicle height adjusting device, a damping device. The present invention may be applied to a vehicle that does not include at least one of a force variable shock absorber and an active stabilizer device.

  In each of the above-described embodiments, the vehicle height adjusting device is an air spring type vehicle height adjusting device. However, the vehicle height adjusting device may be any vehicle known in the art such as a hydropneumatic suspension. Although the active stabilizer device may be provided on the front wheel and the rear wheel, the wheel contact load estimating device of the present invention is applied to a vehicle in which the active stabilizer device is provided only on the front wheel or the rear wheel. May be.

  In the above-described embodiments, the vertical force Fsi applied to each wheel by the spring force of the suspension spring, the vertical force Fdi applied to each wheel by the damping force of the shock absorbers 22FL to 22RR, and the spring of the stabilizer device. The arm ratios Kasf, Kasr, Kadf, Kadr, Katf, and Katr are taken into account when calculating the vertical forces Fstf and Fstr applied to the left and right front wheels and the left and right rear wheels by force, but the arm ratio is omitted. May be.

  In each of the above-described embodiments, the vertical forces Fsfl to Fsrr applied to each wheel by the spring force of the air spring devices 24FL to 24RR, and the vertical force Fdfl to be applied to each wheel by the damping force of each shock absorber. Fdrr, the vertical inertia force Fwmi of each wheel, and the vertical forces Fstf and Fstr applied to the left and right front wheels and the left and right rear wheels by the spring force of the active stabilizer devices 16 and 18 are calculated according to the above equations 22 to 32, respectively. However, the spring force of the air spring devices 24FL to 24RR, the damping force of each shock absorber, and the spring force of the active stabilizer devices 16 and 18 are maps (spring characteristic diagram, damping force characteristic diagram, stabilizer force characteristic diagram). ) And the vertical force Fsfl to Fsrr applied to each wheel by the spring force of the air spring devices 24FL to 24RR, each shock absolute The vertical spring forces Fdfl to Fdrr applied to each wheel by the damping force of the bar and the vertical forces Fstf and Fstr applied to the left and right front wheels and the left and right rear wheels by the spring force of the active stabilizer devices 16 and 18 are respectively air spring devices 24FL to 24RR. Or the damping force of each shock absorber, the spring force of the active stabilizer devices 16 and 18 and the corresponding arm ratio.

  Further, vertical forces Fsfl to Fsrr applied to each wheel by the spring force of the air spring devices 24FL to 24RR, vertical forces Fdfl to Fdrr applied to each wheel by the damping force of each shock absorber, and springs of the active stabilizer devices 16 and 18 The vertical forces Fstf and Fstr applied to the left and right front wheels and the left and right rear wheels by the force may be calculated from a map in which the arm ratio is considered.

  In each of the above-described embodiments, the first ground contact load Fzi1 of each wheel is calculated according to the equations 33 to 36 corresponding to the equations 14 and 16 or the equations 37 to 40 corresponding to the equations 18 and 20. For example, the external force Ftni (i = fl, fr, rl, rr) resulting from the turning of the vehicle is calculated based on the longitudinal acceleration Gx and the lateral acceleration Gy of the vehicle. The first ground load Fzi1 may be modified to be calculated according to the corresponding formula.

Implementation of a vehicle wheel ground load estimation device according to the present invention applied to a vehicle in which a vehicle height control device and a damping force variable shock absorber are provided on each wheel, and an active stabilizer device is provided on the front wheel side and the rear wheel side 1 is a schematic configuration diagram illustrating Example 1. FIG. 1 is a block diagram illustrating an electronic control device according to a first embodiment. 3 is a flowchart illustrating a calculation routine for a ground load of each wheel in the first embodiment. Implementation of a vehicle wheel ground load estimation device according to the present invention applied to a vehicle in which a vehicle height control device and a damping force variable shock absorber are provided on each wheel, and an active stabilizer device is provided on the front wheel side and the rear wheel side 10 is a block diagram showing an electronic control device of Example 2. FIG. 7 is a flowchart illustrating a calculation routine for a contact load of each wheel in the second embodiment. It is a graph which shows the relationship between the average value (DELTA) Fza of the absolute value of deviation (DELTA) Fzi of 1st contact load Fzi1 and 2nd contact load Fzi2, and weight K with respect to 2nd contact load Fzi2. It is a graph which shows the relationship between the maximum value (DELTA) Fzmax of the absolute value of deviation (DELTA) Fzi of 1st contact load Fzi1 and 2nd contact load Fzi2, and the weight K with respect to 2nd contact load Fzi2. It is a graph which shows the relationship between the absolute value of deviation (DELTA) Fzi of 1st contact load Fzi1 and 2nd contact load Fzi2, and weight Ki with respect to 2nd contact load Fzi2. It is a graph which shows the relationship between the bad road degree of a road surface, and the weight K with respect to the 2nd ground-contact load Fzi2. It is explanatory drawing which shows the force which acts on a wheel in the two-wheel model of a vehicle.

Explanation of symbols

16, 18 Active stabilizer device 22FL to 22RR Shock absorber 24FL to 24RR Air spring device 52 Electronic control device for active stabilizer device control 54 Electronic control device for damping force control 56 Electronic control device for vehicle height control 58FL to 58RR Vehicle height sensor 60FL to 60RR Position sensor 62FL to 62RR Vertical acceleration sensor 64F, 64R Rotation angle sensor 66 Electronic controller for vehicle motion control 68FL to 68RR Vertical acceleration sensor

Claims (7)

  Estimate the first grounding load of each wheel based on at least the spring force of the suspension spring, the damping force of the shock absorber, and the force generated by the stabilizer, and determine the second grounding load of each wheel based on the longitudinal acceleration and lateral acceleration of the vehicle. A vehicle wheel ground load estimation apparatus for estimating the wheel ground load of each wheel based on the first and second ground loads.   The first ground contact load is used for the frequency region above the first reference value, and the ground contact load of each wheel is calculated using the second ground load for the frequency region less than the second reference value. The vehicle wheel ground load estimation device according to claim 1.   3. The vehicle wheel ground load estimation apparatus according to claim 2, wherein the first and second reference values are the same value.   2. The vehicle wheel ground load estimation apparatus according to claim 1, wherein a ground load of each wheel is calculated as a sum of weights of the first and second ground loads, and the weight is variably set according to a vehicle condition. .   When the estimated accuracy of the first ground load is low, the weight of the first ground load is reduced and the weight of the second ground load is smaller than when the estimated accuracy of the first ground load is high. The vehicle wheel ground load estimation device according to claim 4, wherein the vehicle wheel ground load estimation device is increased.   When the estimation accuracy of the second ground load is low, the weight of the first ground load is increased and the weight of the second ground load is less than when the estimation accuracy of the second ground load is high. 5. The vehicle wheel ground load estimation device according to claim 4, wherein the vehicle wheel ground load estimation device is reduced.   When the deviation of the first and second ground loads is calculated and the magnitude of the deviation is large, the weight of the first ground load is increased compared to when the magnitude of the deviation is small. 5. The vehicle wheel ground load estimation apparatus according to claim 4, wherein the weight of the second ground load is reduced.

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