JP3642155B2 - Suspension control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semi-active suspension control apparatus that controls the damping force of a variable damping force shock absorber in multiple stages based on the vertical displacement speed of a vehicle body.
[0002]
[Prior art]
As a conventional semi-active suspension control device, for example, there is one described in Japanese Patent Laid-Open No. 7-329532 previously proposed by the present applicant. Briefly explaining the damping force variable shock absorber used in this suspension control device, the actuator consisting of a step motor is controlled open according to the on-spring vertical speed as the control input for the pistons built in each shock absorber. When the valve body is rotated or moved relatively by this, the piston-valve body of each fluid path interposed as an orifice in the extension side fluid path and the pressure side fluid path formed between the piston and the valve body Since the opening area is changed, the control amount to this actuator is changed and controlled. The restriction (flow resistance) of the variable orifice changes and the damping force on the expansion side and the compression side is changed individually and continuously. Can be controlled.
[0003]
And in the suspension control device described in the publication, the abnormal noise generated when the control origin of the stepped motor to be controlled is calibrated (hereinafter also referred to as initialization) is masked by road noise or the like. The initialization of the step motor is executed when the vehicle speed exceeds a predetermined value. In this suspension control device, in consideration of the fact that the initialization of the step motor is executed during actual traveling, when a vibration input exceeding a predetermined value, such as vertical acceleration, occurs in the vehicle body during the initialization. Since there is a risk of deviation (step-out) between the actual rotational position of the step motor that is open-controlled and the rotational position of the step motor that is recognized by the control unit that controls it, the step motor is initialized again. I also like to run.
[0004]
[Problems to be solved by the invention]
By the way, such a conventional suspension control device may not receive a normal power supply when the so-called ignition switch is turned off (hereinafter also simply referred to as ignition off), and the ignition switch is turned on (hereinafter simply referred to as ignition on). It also works only during That is, until the vehicle speed reaches a predetermined value or more and initialization is executed, the rotational position of the step motor (= valve element) at the time of the previous ignition off is stored on the control unit side constituting the control means. When the ignition is turned on next time, the rotational position of the step motor is controlled based on the stored rotational position of the step motor.
[0005]
However, if there is an input (disturbance) to the vehicle body such as passengers getting on / off, loading / unloading of luggage, intentionally shaking the vehicle body, etc., until the vehicle speed reaches a predetermined value or more after the ignition switch is turned on. The step motor is rotated together with the valve body by the flow resistance of the fluid passing through the orifice, that is, the fluid force, and the rotation of the step motor memorized on the controller side at the time of the previous ignition off. There is a risk that the position and the current one will deviate. Therefore, until the vehicle speed reaches a predetermined value and the initialization is executed after the ignition is turned on, the step motor is kept in a step-out state, and appropriate damping force control cannot be performed. There is an unresolved issue that the comfort gets worse.
[0006]
In particular, recently, it has been desired to stop the power supply to the actuator including the step motor when the vehicle is stopped even if the ignition switch is in the on state due to the demand for reducing the power consumption. When power supply to the actuator is stopped when the vehicle is stopped, initialization cannot be performed. Therefore, if a large disturbance is input to the vehicle body during this period, the vehicle starts to travel until the vehicle speed reaches a predetermined value. There is an unsolved problem that the step motor remains out of step and the ride quality deteriorates.
[0007]
Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the conventional example, and when the ignition switch is on and the stepping motor occurs when the vehicle is stopped. An object of the present invention is to provide a suspension control device that can perform appropriate damping force control by quickly performing initialization.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a suspension control device according to claim 1 of the present invention is provided by a step motor that is interposed between a vehicle body side member and a wheel side member and is driven in accordance with an input control signal. A damping force variable shock absorber that can set the damping force in multiple stages by changing the throttle through which the fluid passes by controlling the rotation of the valve body, and a sprung vertical speed detecting means that detects the sprung vertical speed of the vehicle body And setting a target rotational position of the valve body in accordance with a damping force that suppresses a change in posture of the vehicle body based on at least a sprung vertical speed detection value detected by the sprung vertical speed detection means, Control means for outputting the control signal to the step motor to perform open loop control so as to move to a target rotational position, and the control means detects a longitudinal speed of the vehicle. Suspension control device comprising vehicle speed detection means and control origin calibration means for calibrating the control origin of the step motor when at least a vehicle speed detection value detected by the vehicle speed detection means is greater than or equal to a preset predetermined vehicle speed value When the ignition switch is on and the vehicle is stopped , Previous Recording Against tep motor Power supply Control interruption means for stopping the control, the control origin calibration means, the control interruption means by the control interruption means Power supply for step motor Disturbance input detection means for detecting that a predetermined disturbance or more is input to the vehicle body during the stop, and when the disturbance input detection means detects that a disturbance is input to the vehicle body, Temporarily canceling the power supply stop by the control interruption means It is characterized by comprising control origin calibration means at the time of disturbance input for performing control origin calibration of the step motor.
[0009]
In the invention according to claim 1, the control interrupting means performs the control while the ignition is on. Power supply for step motor When the disturbance input detection means detects that a disturbance has been input to the vehicle body during stoppage , Temporarily cancel the power supply stop for the step motor By executing the control origin calibration (initialization) of the step motor by the control origin calibration means at the time of disturbance input, step-out of the step motor that would otherwise remain until the vehicle speed reaches a predetermined value is as quickly as possible. However, appropriate damping force control by the damping force variable shock absorber can be started at an early stage.
[0010]
Further, the suspension control device according to claim 2 of the present invention is characterized in that the disturbance input detecting means is constituted by a vertical acceleration sensor used for detecting a sprung speed of a vehicle body.
[0011]
In the suspension control apparatus according to claim 3 of the present invention, when the disturbance input is detected by the disturbance input detection means during the control origin calibration by the disturbance input control origin calibration means, the control origin calibration means controls the control origin. It is characterized by the fact that re-calibration is performed.
[0012]
【The invention's effect】
According to the suspension control apparatus according to claim 1, Basically, when equipped with a control origin calibration means for calibrating the control origin of the step motor when the vehicle speed detection value is a predetermined vehicle speed abnormality, When the ignition is on and the vehicle stops The power supply to the step motor is stopped When there is a disturbance input consisting of acceleration input exceeding a predetermined value, such as passengers getting on and off, loading or unloading, or deliberately shaking the vehicle body, the control motor's control origin calibration (initialization) is immediately executed. As a result, the stepping motor that would otherwise remain until the vehicle speed reaches a predetermined value is eliminated as quickly as possible, and appropriate damping force control by the damping force variable shock absorber is started early. As a result, the ride comfort can be improved.
[0013]
According to the suspension control apparatus of the second aspect, since the vertical acceleration sensor used for detecting the sprung speed of the vehicle body is applied as the disturbance input detecting means, the disturbance input can be performed without using a separate sensor. The effect that it can detect correctly and can reduce a number of parts is acquired.
[0014]
Further, according to the suspension control device of the third aspect, when the disturbance input is detected during the control origin calibration by the control origin calibration means at the time of disturbance input, the control origin is calibrated again by the control origin calibration means. The effect that control origin calibration can be performed is obtained.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the suspension control device of the present invention will be described below with reference to the drawings.
[0016]
FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, in which damping force variable shock absorbers 3FL to 3RR constituting suspension devices are disposed between wheels 1FL to 1RR and a vehicle body 2, respectively. Step motors 41FL to 41RR for switching the damping force of these damping force variable shock absorbers 3FL to 3RR are controlled by a control signal from the control unit 4 described later.
[0017]
As shown in FIG. 2, each of these damping force variable shock absorbers 3FL to 3RR is configured in a twin tube type gas-filled strut type having a cylinder tube 7 composed of an outer cylinder 5 and an inner cylinder 6. 6 is defined in the upper and lower pressure chambers 9U and 9L by a piston 8 which is in sliding contact with the inside. The piston 8 has a cylindrical lower half 11 molded with a sealing member 9 slidably in contact with the inner cylinder 6 on the outer peripheral surface and a central opening 10 on the inner peripheral surface, and is fitted into the lower half 11. The upper half body 12 is formed. The basic configuration and operation of the damping force variable shock absorbers 3FL to 3RR are the same as or substantially the same as those described in the above-mentioned Japanese Patent Application Laid-Open No. 7-329532 previously proposed by the applicant. As for the detailed contents, the gazette is referred to, and the detailed description thereof is omitted here. In FIG. 2, reference numeral 13 denotes an extension side oil passage, 14 denotes a hole, 27 denotes a pressure side oil passage, 31 denotes a valve body, 35 denotes a piston rod, 36 denotes a vehicle body side member, 37 denotes a bracket, and 38U and 38L. Is a rubber bush, 39 is a nut, 40 is a bracket, 41a is a rotating shaft, 42 is a connecting rod, and 43 is a bumper rubber.
[0018]
The damping force characteristics of the damping force variable shock absorbers 3FL to 3RR are set by the opening area of each orifice formed between the valve body 31 and the piston 8. The rotation angles of the step motors 41FL to 41RR that are rotated relative to each other become a control amount for selectively setting a flow resistance determined by the restriction of the orifice, that is, a damping coefficient, and is a product of multiplying the damping coefficient by the piston speed. The damping force at each valve body position is expressed in the form. Therefore, strictly speaking, the control amount of the present embodiment is a damping coefficient, but from here on, the damping force is simply considered as the control amount.
[0019]
Accordingly, when the rotation angle of the step motor is a position P, as shown in FIG. 3, the position P at which the extension side damping force becomes the maximum damping force is the extension side maximum position P. _TMAX The position P at which the compression side damping force becomes the maximum damping force is the compression side maximum position P. _CMAX However, here, for convenience, the position P corresponding to the intermediate value of the range in which the extension side damping force and the compression side damping force are set to low damping force is set to “0”, and the position changes in the direction in which the extension side damping force increases. Is positive and the change in position in the direction in which the compression side damping force increases is negative, the extension side maximum position P _TMAX Is a plus sign and is simply P _MAX And the compression side maximum position P _CMAX Is a minus sign and simply (-P _MAX ). However, the absolute value of each maximum position | P _MAX | Is not necessarily the same value.
[0020]
Then, the pressure side maximum position (−P _MAx ) To the positive extension side maximum position P _MAX Of the total damping force control range up to and including the positive threshold P with the position P sandwiching “0” _T1 To negative threshold P _C1 The range up to is the extension side low damping force D / F _T0 And compression side low damping force D / F _C0 In particular, a soft range that achieves smoothness in a low-speed traveling state (hereinafter also simply referred to as an SS range), where the position P is larger in the positive direction, that is, the position P is the positive threshold value P. _T1 To the positive maximum extension position P _MAx Is the extension side control range (hereinafter, also simply referred to as HS range) in which the extension side damping force is set high, and the range where the position P is smaller in the negative direction, that is, the position P is the negative threshold value. P _C1 Negative side maximum pressure side position (-P _MAx ) Is a pressure side control range (hereinafter, also simply referred to as SH range) in which the compression side damping force is set high.
[0021]
According to the damping force characteristic (damping coefficient characteristic) of FIG. 3, the absolute value of the predetermined extension side position value is determined for each predetermined position value that achieves the predetermined extension side attenuation coefficient and the predetermined compression side attenuation having the same absolute value. The value is slightly smaller than the absolute value of the predetermined pressure side position value.
[0022]
On the other hand, a rectangular parallelepiped abutting body 44 as shown in FIG. 4 is provided at the upper end of the valve body 31, and is synchronized with the rotation of the valve body 31 by the rotating shaft 41a of the step motors 41FL to 41RR. Rotate. A stopper plate 45 is housed in an inner hole portion of the upper half 12 that accommodates the abutting body 44, and the abutting body 44 and the stopper plate 45 provide a stopper mechanism 46. It is composed.
[0023]
Two abutting projections 45a and 45b project from the inner hole of the stopper plate 45, and when the abutting body 44 rotates as the rotary shaft 41a of the step motor 41 or the valve body 31 rotates. When the valve body 31 rotates to the position A or the position C, the two restricting end faces 44a or 44b of the abutting body 44 abut on the abutting projection 45a or 45b, and the valve body 31 is further moved. The positive extension side maximum position P is set to the position P of the valve body 31 so as not to rotate. _MAx Or negative pressure side maximum position (-P _MAx In addition, a so-called limiter function is exerted, and at the same time, a step-out correction operation between the rotation angle of the step motor 41 and the position of the valve body 31 is also manifested by a control origin calibration process, so-called initialization process, which will be described later. The detailed configuration and operation of the stopper mechanism 46 will be described in detail later together with the description of the initialization process.
[0024]
In addition, as shown in FIG. 1, the vehicle includes a part of a sprung vertical speed detecting means provided on the vehicle body side corresponding to each wheel 1FL to 1RR position for detecting a sprung vertical speed generated in the vehicle body. And a vehicle speed sensor 52 as vehicle speed detecting means for detecting the vehicle speed in the longitudinal direction of the vehicle.
[0025]
Here, the vertical acceleration sensors 51FR to 51RR correspond to the detected vertical acceleration acceleration values (hereinafter simply referred to as “upper spring acceleration detection values”) of analog voltage values that are positive in the upward direction and negative in the downward direction in accordance with the vertical acceleration acting on the vehicle body at each mounting position. (Also referred to as vertical acceleration on the spring) X _FR "~ X _RR "Is output.
[0026]
The vehicle speed sensor 52 is attached to an output shaft of an automatic transmission, for example, and outputs a pulse signal corresponding to the rotational speed of the output shaft.
As shown in FIG. 5, the vertical acceleration sensors 51FL to 51RR and the vehicle speed sensor 52 are connected to the input side of the control unit 4, and the damping force variable shock absorbers 3FL to 3RR are connected to the output side. Step motors 41FL to 41RR for controlling the damping force are connected.
[0027]
The control unit 4 includes a microcomputer 56 having at least an input interface circuit 56a, an output interface circuit 56b, an arithmetic processing unit 56c, and a storage device 56d, and a vertical acceleration X on a spring of the vertical acceleration sensors 51FL to 51RR. _FL "~ X _RR A / D converters 57FR to 57RR that convert "to a digital value and supply it to the input interface circuit 56a, and step control signals for the step motors 41FL to 41RR output from the output interface circuit 56b are input. Motor drive circuits 59FL to 59RR that convert the pulses to drive the step motors 41FL to 41RR are provided.
[0028]
Here, when the ignition switch 60 is turned on, the microcomputer 56 starts operation by turning on the power of the battery 61. In the arithmetic processing unit 56c, the upper and lower springs are moved upward and downward by arithmetic processing (not shown). Acceleration X _FL "~ X _RR ", For example, as the time integral value, the vertical speed of the vehicle body at the wheel part (also referred to as the sprung vertical speed) X _FL '~ X _RR 'And calculate the sprung vertical speed X _i 'The target rotation angle of the stepping motor according to (i = FL to RR), that is, the target position P of the valve disc _D Is calculated and set, and this target position P _D And current position P _A And a step control amount corresponding thereto is output to the motor drive circuits 59FL to 59RR, and the damping force variable shock absorbers 3FL to 3FL corresponding to the rotation angle of the step motor, that is, the position of the valve body, are output. Open-loop control of 3RR damping force.
[0029]
Further, the arithmetic processing unit 56c performs initialization described later in order to correct the step-out between the rotation angle of the step motor and the position of the valve body in the open loop control of the damping force of the damping force variable shock absorbers 3FL to 3RR. Also responsible for execution of processing.
[0030]
Further, the storage device 56d stores in advance programs and control maps necessary for the arithmetic processing of the arithmetic processing device 56c, and sequentially stores necessary values and arithmetic results in the arithmetic processing process.
[0031]
Furthermore, the motor drive circuits 59FL to 59RR are supplied with electric power from the battery 61 via the motor relay 62, and an NPN transistor as a switching element in which the relay coil 62a of the motor relay 62 is interposed in series therewith. The energization is controlled by 63. A control signal CS output from the output interface circuit 56b of the microcomputer 56 is input to the base of the transistor 63. When the control signal CS is on, the transistor 63 is turned on and the relay coil 62a is energized to close the contact 62b. When the control signal CS is off, the transistor 63 is turned off and the relay is turned on. The coil 62a is de-energized and the contact 62b is opened.
[0032]
Next, the basic principle of the initialization process executed by the control unit 4 will be described.
In the damping force control of the present embodiment, the rotation angle of the step motor, that is, the control output of the step amount, that is, the control output of the step amount as described above is so-called open in combination with the purpose of simplifying the structure and improving the control response. Loop control. In such open loop control, the presence / absence and magnitude of the step-out cannot be recognized by a normal control routine as is known, so the control input / output is performed by initializing the basic control origin by so-called initialization. Correct the system step-out.
[0033]
Here, a basic initialization process will be briefly described. First, as shown in FIG. _MAX Pressure side maximum position at position C (-P _MAX ) Is a damping force control range, the current position P used in the calculation processing of the damping force control. _A Is an integrated value of the control amount output in the previous calculation process, that is, the step amount S.
[0034]
Therefore, in this embodiment, the position B in the middle of the soft range (SS range) is set to a position value “0”, and initialization is performed using this position value “0” as the control origin. Specifically, as shown in FIG. 4, the step motors 41FL to 41RR are rotated stepwise counterclockwise from the start of initialization, so that one end surface 44a of the abutting body 44 is brought into contact with one protrusion of the stopper plate 45. (In the same figure, the other end surface 44b of the abutting body 44 also abuts against the other abutting protrusion 45b of the stopper plate 45 at the same time.) After that, the rotation angle a shown in FIG. A predetermined number of steps S corresponding to _a The step motors 41FL to 41RR may be rotated clockwise by the amount.
[0035]
Of course, the step motors 41FL to 41RR are rotated stepwise clockwise from the start of initialization so that the other end surface 44b of the abutting body 44 abuts against the other abutting projection 45b of the stopper plate 45 (same as above). In the figure, one end surface 44a of the abutting body 44 also simultaneously abuts against one abutting projection 45a of the stopper plate 45), and then a predetermined number of steps S corresponding to the rotation angle b shown in FIG. _b It is the same even if the step motors 41FL to 41RR are rotated counterclockwise by the same amount.
[0036]
FIG. 6 shows a suspension control calculation process executed by the calculation processing device 56c of the control unit 4 in order to execute this initialization process. The arithmetic processing in FIG. 6 is executed as a preset main program. Further, the current position P updated and stored in the storage device 56d for each arithmetic processing. _A It is assumed that necessary data and information such as are read into the buffer or the like of the arithmetic processing unit 56c every time the arithmetic processing is performed even if there is no special input / output processing step.
[0037]
In this calculation process, first, in step S41, it is determined whether or not the vehicle is stopped. This determination is made based on whether or not the vehicle speed V of the vehicle speed sensor 52 is “0”. When the vehicle speed V is “0”, it is determined that the vehicle is stopped, and the process proceeds to step S42.
[0038]
In step S42, a control flag CF indicating whether or not power is being supplied to the motor drive circuits 59FL to 59RR is being supplied. Not "0" representing Re It is determined whether it is in the set state, and the control flag CF is “ 0 "of Re If it is in the set state, the process jumps to step S45 as it is. If not, the process proceeds to step S43.
[0039]
In step S43, the control signal CS output from the output interface circuit 56b to the transistor 63 is turned off, and then the process proceeds to step S44, the control flag CF is reset to “0”, and then the process proceeds to step S45. .
[0040]
In step S45, the vertical acceleration detected value X of each vertical acceleration sensor 51i (i = FL, FR, RL, RR). _2i ”, And a disturbance threshold value X that causes step-out to step motors 41FL to 41RR whose absolute values are preset. _2i0 ”And whether or not | X _2i ″ | ≦ X _2i0 "", It is determined that the stepping motor 41i of each damping force variable shock absorber 3i is not rotated by the disturbance caused by the vertical movement of the vehicle body, so that the step-out state does not occur. _2i ″ ｜ ＞ X _2i0 If it is "", it is determined that there is a high possibility that the step motor 41i is rotated due to a disturbance, and therefore, the process proceeds to step S46.
[0041]
In this step S46, the control signal CS for the transistor 63 is turned on, and then the process proceeds to step S47, the control flag CF is set to "1" and the initialization flag INT is set to "1", and then the process proceeds to step S48. Transition.
[0042]
In step S48, the initialization process is executed as described above with reference to a table or the like (not shown), and then the process proceeds to step S49. This initialization process continues to be executed with priority over other processes without being hindered by other arithmetic processes such as timer interruption.
[0043]
In step S49, the initialization execution flag SET is set to “1”, and then the process returns to step S41.
On the other hand, when the vehicle speed V of the vehicle speed sensor 52 is a positive value other than “0” in step S41, it is determined that the vehicle is in a traveling state, the process proceeds to step S50, and the control flag CF is “1”. It is determined whether or not it is in the set state. If it is in the set state of “1”, the process jumps to step S53, which will be described later, and if not, the process proceeds to step S51.
[0044]
In step S51, the control signal CS for the transistor 63 is turned on, and then the process proceeds to step S52, the control flag CF is set to “1”, and then the process proceeds to step S53.
[0045]
In step S53, it is determined whether or not the initialization flag INT is set to "1". If it is set to "1", the process proceeds to step S48 to execute initialization processing. After shifting to S54 and executing a damping force control process in order to suppress a change in the posture of the vehicle body that occurs in the vehicle body, the process returns to step S41.
[0046]
Since this damping force control process is the same as or substantially equivalent to the calculation process of FIG. 13 described in, for example, the above-mentioned JP-A-7-329532, a detailed description of the logic is omitted, and Only briefly will be described.
[0047]
As described above, the damping force variable shock absorbers 3FL to 3RR of the present embodiment having the damping force characteristic (strictly the damping coefficient characteristic) shown in FIG. With respect to the damping force characteristic of the Skyhook principle in which the speed is taken and the vertical speed on the spring is taken on the vertical axis, when FIG. 3 is viewed from the back side and is rotated forward 90 degrees clockwise (right rotation), the spring Using only the up / down velocity as a control input, it is possible to see a good agreement with the damping force characteristics desired by the Skyhook principle. More preferably, the sprung vertical speed X _i By setting the damping coefficient c linearly with respect to ′, the sprung vertical acceleration X is determined by the damping force D / F represented by the product value of both _i I want to be able to effectively control the excitation force expressed by the product of "and mass M".
[0048]
Therefore, the sprung vertical speed X that is the control input _i The calculation coefficient for calculating the linear attenuation coefficient c with respect to 'is determined by each target position proportional coefficient α in step S25 or step S26 of the calculation process of FIG. ₁ , Α ₂ And the sprung vertical speed X expressed by the damping force characteristic curve of FIG. _i If the damping force D / F with respect to 'is considered to be linearly related to the position P of the step motor, each target position proportional coefficient α ₁ , Α ₂ Respectively, the maximum pressure side position (-P _MAX ) Or maximum extension side position P _MAX Is multiplied by the target position P of the step motor in step S29 or step S33 of the calculation process. _D That is, the rotational position of the valve body that can obtain a desired damping coefficient is calculated. And this target position P _D And the current position P that the control unit must grasp or recognize in the open control. _A The step amount S that should correct the deviation is output, and the target damping force can be obtained by each damping force variable shock absorber 3FL to 3RR.
[0049]
Thus, for example, during low speed traveling, a small excitation force (= sprung vertical speed X _i ') The damping force D / F of each damping force variable shock absorber 3FL to 3RR is set to be small, and the spring moves, that is, the vehicle body moves slowly in response to the input from the road surface, ensuring riding comfort. Is done. On the other hand, during high-speed traveling, the excitation force (= sprung vertical speed X _i ') Becomes larger, so the sprung vertical speed X _i The damping force D / F of each of the damping force variable shock absorbers 3FL to 3RR with respect to 'is set to be large, and thus a large damping effect acts on the spring, that is, the vehicle body, against a large excitation force from the road surface. There is no sense of flickering, and a firm feeling that the vehicle body is following the road surface (wheel) can be obtained. In addition, even at different vehicle speeds, on fine uneven road surfaces such as gravel roads and Belgian roads, excitation force acting on the vehicle body (= sprung vertical speed X _i ') Is also small, so the sprung vertical speed X _i The damping force D / F of each of the damping force variable shock absorbers 3FL to 3RR with respect to 'is set to be small, and the riding comfort is ensured without moving up and down with the excitation force from the road surface.
[0050]
Here, the meaning of the initialization flag INT and the initialization execution flag SET and the exchange of the set state will be described in detail later, and the operation of the initialization process executed in step S48 of the arithmetic process in FIG. 6 will be described. To do.
[0051]
For example, assuming that the final position P of the valve body (that is, the position immediately before the initialization is performed) P is in a position as shown in FIG. 7, the vertical acceleration detection value X is obtained when the arithmetic processing of FIG. 6 is executed. _2i ″ Is disturbance threshold X _O If it is greater than "" or the initialization flag INT is set to "1", the step motors 41FL to 41RR are counterclockwise with respect to the step motors 41FL to 41RR in step S48 of the calculation process of FIG. The step amount S that rotates around and gradually decreases is output as a control signal every predetermined time, thereby being the valve body 31 and simultaneously the abutting body 44, but the step motors 41FL to 41RR are counterclockwise. The rotation angle gradually decreases around the rotation angle, and the compression side maximum position (−P _MAX ) Until the abutment body 44 of the stopper mechanism 46 abuts against the abutment protrusions 45a and 45b of the stopper plate 45, and the rotation stops further.
[0052]
From this state, a predetermined step amount S is applied to the step motors 41FL to 41RR. _a , The stepping motors 41FL to 41RR are rotated clockwise by the rotation angle a to position the position P of the abutting body 44, that is, the valve body 31 to the position value “0”, and the initialization is completed. The flag SET is set to “1”. In this embodiment, when the step motors 41FL to 41RR are rotated counterclockwise and stepwise by a predetermined rotation angle, the motor is held for a predetermined time for each rotation position and the supply voltage is turned off for a predetermined time. The driving force is set to “0”. That is, during this initialization, the driving force of the step motors 41FL to 41RR is intermittent.
[0053]
Further, as shown in FIG. 7, for example, from the final position P to the maximum extension side position P _MAX The assumed maximum overshoot position P reached by the initialization process with the angle up to γ _N To maximum pressure side position (-P _MAX ) Is set to be larger than the angle γ, by setting the angle δ larger than the angle γ, the pressure side maximum position (−P _MAX ).
[0054]
Therefore, according to the calculation process of FIG. 6, the passenger is in a state where the ignition switch 60 is on, the vehicle is stopped, and the power supply to the motor drive circuits 59FL to 59RR is stopped. There is a disturbance input to the vehicle body such as getting on and off, loading / unloading of the baggage or intentionally shaking the vehicle body, which is the current position P of the step motors 41FL to 41RR. _A And the position P stored in the microcomputer 56 constituting the control unit 4 is a large acceleration input that causes a step-out, the process proceeds from step S45 to step S46, and the motor drive circuit 59FL. Step S48 is started after power supply to .about.59RR is started, the initialization as described above is forcibly executed, and the step-out that may have occurred in the step motors 41FL to 41RR due to the disturbance input is as follows. Will be corrected as soon as possible.
[0055]
Then, after the initialization process in step S48 is completed, the process returns to step S41. If the vehicle continues to be stopped, the process proceeds to step S42, and the control flag CF is set to “1” in step S47. Therefore, the process proceeds to step S43, the control signal CS is turned off, power supply to the motor drive circuits 59FL to 59RR is stopped, and then the control flag CF is reset to “0” in step S44, and then to step S45. Transition. Therefore, when a disturbance is input again after the previous initialization process is completed, the initialization process is executed each time.
[0056]
However, as a real problem, during low speed traveling such as when the vehicle is stopped or immediately after the ignition is turned on, noise accompanying rotation and / or stop of the step motors 41FL to 41RR by the initialization process, or There is a possibility that noise or the like that abuts the abutting body 44 against the abutting protrusions 45a and 45b of the stopper plate 45 may be transmitted as abnormal noise to the vehicle interior. Therefore, in this embodiment, when there is no disturbance input that causes step-out to the stepping motors 41FL to 41RR while the vehicle is stopped, that is, when there is no acceleration input, the vehicle speed is the same as in JP-A-7-329532. The stepping motor is initialized when the road noise transmitted to the vehicle interior increases to a certain degree by increasing the speed to a certain degree.
[0057]
Specifically, a vehicle speed at which a noise level such as road noise transmitted to the vehicle interior as needed becomes larger than a noise level transmitted to the vehicle interior as the step motors 41FL to 41RR are initialized is a predetermined vehicle speed value. V ₀ The vehicle speed detection value V detected by the vehicle speed sensor 52 is the predetermined vehicle speed value V. ₀ When it is above, execution of initialization of each step motor 41FL-41RR is permitted.
[0058]
That is, the initialization flag INT is set / cleared by an individual calculation process, and the vehicle speed detection value V is set to a predetermined vehicle speed value V. ₀ When this is the case, it may be a necessary condition for setting the initialization flag INT to “1”. That is, in such a traveling state at the vehicle speed, it may be considered that the noise transmitted to the vehicle interior as the step motors 41FL to 41RR are initialized is masked by the road noise transmitted to the vehicle interior. When various problems described later are cleared and the initialization is completed, the initialization completion flag END is set to “1”.
[0059]
On the other hand, initialization is executed when the vehicle speed becomes higher than the set vehicle speed in this way, or when initialization is executed while the vehicle is stopped, the vehicle starts before the initialization is completed. In such a case, if the input to the shock absorber from the road surface acting during initialization or the input to the shock absorber accompanying the vehicle body swing is large, the piston speed of the variable damping force shock absorber is considered to increase. As a result, the step motor may step out due to the fluid force passing through the orifice as described above.
[0060]
Therefore, in the present embodiment, in order to obtain the accurate position “0” of the step motor, it is determined whether the initialization of the step motor may be executed or whether the initialization that is being executed may be completed. An initialization monitoring process executed by the arithmetic processing unit 56c of the microcomputer 56 is shown in FIG.
[0061]
This initialization monitoring process is executed as a timer interrupt process every predetermined time ΔT (for example, 3.3 msec). First, in step S1, the spring vertical acceleration X _2i ″ (I = FL to RR) and the vehicle speed V of the vehicle speed sensor 52 are read, and then in step S2, the vehicle speed V is the predetermined vehicle speed value V. ₀ When it is above, it transfers to step S3, and when that is not right, it transfers to step S19. In step S3, if the initialization completion flag END is in a reset state of “0”, the process proceeds to step S5. If not, the process returns to the main program. In step S5, the process proceeds to step S6 when the initialization flag INT is set to “1”, and the process proceeds to step S7 otherwise.
[0062]
Here, in step S7, the absolute value | X of the sprung vertical acceleration detected value | X _2i ″ | Is the preset predetermined vertical acceleration value X that causes the stepping motor to step out. _2i0 If it is smaller than "", the process proceeds to step S8, and if not, the process proceeds to step S4. In step S8, the timer counter CNT is incremented by "1" and then the process proceeds to step S9. The counter CNT is the predetermined count value CNT ₀ If so, the process proceeds to step S10. If not, the process returns to the main program.
[0063]
In step S10, the initialization flag INT is set to “1” and then the process proceeds to step S11. After the initialization execution flag SET is reset to “0”, the process proceeds to step S12 and the timer counter CNT is cleared. Then, the process returns to the main program.
[0064]
On the other hand, in the step S6, the absolute value | X of the sprung vertical acceleration detected value | X _2i ″ | Is a preset disturbance threshold value X _2i0 If it is equal to or greater than "", the process proceeds to step S13. Otherwise, the process proceeds to step S14. In step S13, the initialization temporary completion flag NEND is set to "1" and then the process proceeds to step S14. If the initialization execution flag SET is “1”, the process proceeds to step S15. If not, the process returns to the main program.
[0065]
In step S15, the initialization flag INT is reset to “0” and then the process proceeds to step S16. If the initialization temporary completion flag NEND is in the reset state of “0”, the process proceeds to step S17. Then, the process proceeds to step S18. In step S17, the initialization completion flag END is set to “1”, and then the process proceeds to step S18. The initialization temporary completion flag NEND is reset to “0”, and then the process returns to the main program.
[0066]
On the other hand, in step S19, if the initialization flag INT is in the reset state of “0”, the process proceeds to step S4, and if not, the process proceeds to step S6. In step S4, the timer counter CNT is cleared and then the process returns to the main program.
[0067]
The operation of the arithmetic processing of FIG. 8 will be briefly described in view of the correlation with the arithmetic processing of FIG.
First, when there is no disturbance input when the ignition is on and the vehicle is stopped, the vehicle speed V detected based on the pulse signal of the vehicle speed sensor 52 is the predetermined vehicle speed value V. ₀ Unless this is the case, the process proceeds from the step S2 to the step S4 through the step S19. As a result, the timer counter CNT is simply cleared to return to the main program, so the initialization flag INT is maintained at “0”. Thus, the initialization process shown in FIG. 6 is not executed.
[0068]
On the other hand, the vehicle speed V is equal to the predetermined vehicle speed value V. ₀ If it becomes above, it will transfer to step S3, and since the initialization completion flag END is still maintained to "0", it will transfer to step S5, and then the initialization flag INT will still be maintained to "0", and it will transfer to step S7. .
[0069]
Here, the sprung vertical acceleration X acting on the vehicle body _2i ″ Is the predetermined vertical acceleration value X that causes the stepping motor to step out _2i0 If it is smaller than "", the process proceeds to step S8, where the timer counter CNT is incremented, and the timer counter CNT is incremented by the predetermined count value CNT. ₀ That is, the vehicle speed V is the predetermined vehicle speed value V. ₀ Above and sprung vertical acceleration X _2i ″ Is the predetermined vertical acceleration value X _2i0 A state smaller than ″ is a predetermined time (= CNT ₀ .DELTA.T) If the operation continues, the process proceeds from step S9 to step S10, the initialization flag INT is set to "1". At the same time, the initialization execution flag SET is reset to "0" in step S11, and then the process proceeds to step S12 and the timer counter CNT is cleared.
[0070]
As a result, the vehicle has the predetermined vehicle speed value V ₀ Assuming that the vehicle is continuously traveling on a relatively stable road at a higher vehicle speed, the initialization process in step S48 of the calculation process of FIG. 6 is executed. Thus, the vehicle speed V is the predetermined vehicle speed value V ₀ Even if the initialization of the step motor is executed during traveling as described above, the noise transmitted to the vehicle interior due to the initialization is masked by the road noise transmitted to the vehicle interior, so that the passenger feels abnormal noise. There is nothing. In addition, since the vehicle has traveled stably on a relatively flat good road for the predetermined time T or more, during the initialization that is subsequently performed, the above-mentioned detachment is caused by the fluid force accompanying a large road surface input or vehicle body swing input. The possibility that a tone will occur is small.
[0071]
On the other hand, when the ignition is on and the disturbance is input while the vehicle is stopped, the initialization is executed and the vehicle speed V is the predetermined vehicle speed value V. ₀ Even if it is smaller, if the initialization flag INT is once set to "1" and the initialization completion flag END is still "0", the process proceeds to step S6 in any case. Here, since the initialization flag INT is reset to “0” when the initialization process is completed in the arithmetic process of FIG. 6, this state indicates that the initialization is being executed in any case. Inside, the sprung vertical acceleration X acting on the vehicle body _2i "Is the disturbance threshold value X that causes the stepping motor to step out. _2i0 If it is equal to or greater than "", the process proceeds to step S13, and the initialization temporary completion flag NEND is set to "1". Therefore, the initialization process by the arithmetic process of FIG. 6 is completed, and the initialization execution flag SET is set. When set to “1”, the process proceeds from step S14 to step S15 of the arithmetic processing of FIG. 8 to reset the initialization flag INT to “0”, and the initialization temporary completion flag NEND is reset to “0”. That is, the sprung vertical acceleration X that causes the stepping motor to step out during initialization. _2i Only when ″ has not occurred, the process proceeds to step S17, where the initialization completion flag END is set to “1.” At this time, the initialization process has been completed without any problem. In any case, the flow of returning to the main program as it is from step S3 is repeated and initialization is not executed again.
[0072]
On the other hand, a sprung vertical acceleration X that causes the stepping motor to step out during the initialization. _2i When the initialization temporary completion flag NEND is set to “1”, the initialization completion flag END remains reset to “0” after the initialization is executed at that time. When the initialization flag INT is set to "1" again after satisfying the above conditions, the initialization process is performed again by the arithmetic processing of Fig. 6. During this time, the step motor is stepped out. Vertical acceleration X on spring _2i ”Occurs, and if the initialization temporary completion flag NEND is set to“ 1 ”, the condition is satisfied until the initialization completion flag END is set to“ 1 ”. The initialization is repeatedly executed until the initialization is completed without any problem.
[0073]
Therefore, according to the present invention, although the initialization is executed for the disturbance generated while the ignition is on and the vehicle is stopped, the vehicle starts before it is completed, or passengers get on and off or load Up-and-down acceleration X that causes the stepping motor to step out by unloading or deliberately shaking the vehicle body _2i If "" occurs, the initialization is repeated after waiting for the time when the predetermined condition is satisfied, so that the position "0" of the step motor is surely released, and as a result, appropriate damping force control is ensured. can do.
[0074]
From the above, each of the vertical acceleration sensors 51FL to 51RR corresponds to the sprung vertical speed detection means of the suspension control device of the present invention. Similarly, the control unit corresponds to the control means, and the vehicle speed sensor 52 and the control unit 4 Step S1 of FIG. 8 executed in FIG. 8 corresponds to the vehicle speed detecting means, and steps S41 to S44 in FIG. 6 correspond to the control interruption means, and step S48 of FIG. , S49 and S53 and the calculation process of FIG. 8 correspond to the control origin calibration means, step S45 in FIG. 6 corresponds to the disturbance input detection means, and the steps in the calculation process of FIG. S46 to S49 correspond to control origin calibration means at the time of disturbance input.
[0075]
In the above-described embodiment, the case where the change in the posture of the vehicle body due to the vibration input from the road surface has been described has been described. However, the present invention is not limited to this, and a vehicle movement state such as a braking state is detected. You may make it perform the control which suppresses this together.
[0076]
In the above-described embodiment, the case where the digital vehicle speed V is output from the vehicle speed sensor 52 has been described. However, the present invention is not limited to this. A / D conversion may be performed and input to the microcomputer 56. Further, a pulse signal corresponding to the vehicle speed is input from the vehicle speed sensor 52 to the microcomputer 56, and the number of pulses per unit time is calculated by the arithmetic processing unit 56c of the microcomputer 56. Alternatively, the vehicle speed V may be calculated from the pulse interval. In this case, the vehicle stop determination at step S21 in the suspension control process of FIG. 6 is determined by whether or not the pulse signal from the vehicle speed sensor 52 is input. can do.
[0077]
Furthermore, in the above-described embodiment, the case where the microcomputer 56 is used for control has been described. However, the present invention is not limited to this, and an electronic circuit such as an arithmetic circuit may be combined.
[0078]
Furthermore, in the above-described embodiment, the case where the vertical acceleration sensors 51FL to 51RR are provided at the positions of the wheels 1FL to 1RR of the vehicle body 2 has been described. The vertical acceleration may be estimated from the values of other vertical acceleration sensors.
[0079]
Still further, in the above embodiment, the sprung vertical acceleration detection value X _2i Although the case where the presence / absence of disturbance input is detected based on the absolute value of ″ has been described, the present invention is not limited to this. It is also possible to apply an acceleration switch, and further detect the presence or absence of disturbance input by detecting the stroke or stroke speed of the damping force variable shock absorbers 3FL to 3RR when the vehicle is stopped and whether or not this exceeds a predetermined value. You may do it.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of a suspension control device of the present invention.
2 is a front view, partly in section, showing an example of a damping force variable shock absorber employed in the suspension control device of FIG. 1;
FIG. 3 is an explanatory diagram showing a damping force characteristic with respect to the position of the valve body of the damping force variable shock absorber.
4 is an explanatory diagram of a stopper mechanism provided in the damping force variable shock absorber shown in FIG. 2; FIG.
FIG. 5 is a block diagram illustrating an example of a controller.
FIG. 6 is a flowchart showing a calculation process of initialization (control origin calibration) executed by a controller as an embodiment of the suspension control apparatus of the present invention.
FIG. 7 is an explanatory diagram of the action of initialization (control origin calibration) by the arithmetic processing of FIG. 6;
FIG. 8 is a flowchart showing calculation processing of initialization (control origin calibration) permission and condition setting control executed by a controller as an embodiment of the suspension control apparatus of the present invention.
[Explanation of symbols]
1FL ~ 1RR wheel
2 body
3FL-3RR Variable damping force shock absorber
4 Control unit
8 Piston
11 Lower half
12 Upper half
13 Extension side oil passage
14 Pressure side oil passage
31 Disc
35 piston rod
41FL to 41RR step motor
44 Bumper
45 Stopper plate
46 Stopper mechanism
51FR to 51RR Vertical acceleration sensor
52 Vehicle speed sensor
56 Microcomputer
59FL to 59RR Motor drive circuit

Claims (3)

The valve body is rotationally controlled by a step motor that is interposed between the vehicle body side member and the wheel side member and is driven according to the input control signal, so that the damping force is changed by changing the throttle through which the fluid passes. Based on a variable shock absorber that can be set in multiple stages, a sprung vertical speed detecting means for detecting a sprung vertical speed of the vehicle body, and at least a sprung vertical speed detection value detected by the sprung vertical speed detecting means Open loop control by setting a target rotation position of the valve body according to the damping force that suppresses the posture change of the vehicle body and outputting the control signal to the step motor so as to move the valve body to the target rotation position And a control unit configured to detect in advance a vehicle speed detection unit that detects a longitudinal speed of the vehicle, and at least a vehicle speed detection value detected by the vehicle speed detection unit is preset. In the suspension control apparatus having a control origin calibration means for controlling the origin calibration of the step motor when it is higher than a predetermined vehicle speed value, when the vehicle ignition switch is an on is stopped, before kiss A control interruption means for stopping power supply to the stepping motor is provided, and the control origin calibration means detects a disturbance input detection for detecting that a predetermined disturbance or more is input to the vehicle body while the power supply to the step motor is stopped by the control interruption means. And when the disturbance input is detected by the disturbance input detection means, the control origin calibration at the time of disturbance input is performed by temporarily canceling the power supply stop by the control interruption means and performing the control origin calibration of the step motor. And a suspension control device.  The suspension control device according to claim 1, wherein the disturbance input detection unit includes a vertical acceleration sensor used for detecting a sprung speed of a vehicle body.  2. The control origin calibration means recalibrates the control origin when a disturbance input is detected by the disturbance input detection means during the control origin calibration means during the disturbance input. Or the suspension control apparatus of 2.

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