JP2011020567A - Shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize exchanging of a brush by preventing a consumption degree of the brush from preceding a use degree of a vehicle. <P>SOLUTION: A brush consumption degree (Ntotal/Nlimit) as a ratio of a total rotation frequency Ntotal up to a present time to the rotation frequency Nlimit showing a brush service life of an electric motor of an electromagnetic shock absorber and a vehicle use degree (Ytotal/Ytarget) as a ratio of a travel distance Ytotal to a durable travel distance Ytarget of the vehicle are calculated. When the brush consumption degree is larger than the vehicle use degree, a damping force is increased by multiplying target damping force F* by a correction efficient K(>1). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a shock absorber device for a wheel of an automobile or the like, and in particular, a rotor of a brushed motor is rotated by a relative vertical movement of the wheel with respect to the vehicle body to generate an electromagnetic force. The present invention relates to a shock absorber device including an electromagnetic shock absorber that attenuates relative vertical movement.

  Conventionally, an electromagnetic motor that has an electric motor that rotates a rotor by a vertical movement of a wheel with respect to a vehicle body, and that attenuates a relative vertical movement of the wheel with respect to the vehicle body by an electromagnetic force generated by the rotation of the rotor. A shock absorber device having a shock absorber is known. As such an electric motor, Patent Document 1 also proposes a shock absorber device using a motor with a brush.

JP2009-29360A

  However, in the electromagnetic shock absorber, since the rotor of the electric motor is rotated every time the wheel moves relative to the vehicle body, the brush consumption becomes a problem in the configuration using the brushed motor. The consumption of the brush varies depending on the condition of the road and the driving condition. Therefore, the progress of the brush consumption with respect to the travel distance of the vehicle may be early or late. For this reason, the brush may reach the end of its life before the vehicle travel distance reaches the durable travel distance. In such a case, the brush needs to be replaced.

  The present invention has been made in order to cope with the above-described problem, and it is possible to prevent the brush from being consumed earlier than the degree of use (travel distance) of the vehicle so that it is not necessary to replace the brush as much as possible. With the goal.

In order to achieve the above object, a feature of the present invention includes a brushed motor in which a rotor is rotated by a relative vertical movement of a wheel with respect to a vehicle body, and is generated in the brushed motor by the rotation of the rotor. An electromagnetic shock absorber that generates a damping force that suppresses the relative vertical movement of the wheel with respect to the vehicle body by an electromagnetic force, and a damping force control that controls the damping force by adjusting the electromagnetic force generated by the brushed motor. A shock absorber device comprising means,
A brush consumption degree calculating means for estimating a consumption state of the brush of the brushed motor based on the number of rotations of the brushed motor, and calculating a ratio of the estimated consumption state to a life of the brush as a brush consumption degree; Vehicle travel distance information is obtained, and a vehicle use degree calculation means for calculating a ratio of the acquired travel distance to a durable travel distance of the vehicle as a vehicle use degree, and a balance between the calculated brush consumption degree and the vehicle use degree is determined. If the brush consumption degree is determined to be greater than the vehicle use degree by the balance determination means and the balance determination means, the damping force controlled by the damping force control means is corrected to be increased. And a damping force correcting means.

  In the present invention, the rotor of the brushed motor is rotated by the relative vertical movement of the wheel relative to the vehicle body (approach / separation movement between the vehicle body and the wheel) to generate an electromagnetic force, and this electromagnetic force (power generation braking force) The vertical movement of the wheel relative to the car body is attenuated. The damping force control means controls the damping force by adjusting the magnitude of the generated current flowing through the brushed motor, for example.

  The amount of wear (amount of wear) of the brushed motor is governed by the motor rotational speed (total rotational speed at which the rotor rotates). Therefore, the brush consumption state can be estimated from the motor rotation speed. Further, the speed at which the brush wears out also varies depending on the magnitude of the damping force generated by the electromagnetic shock absorber. In other words, as the damping force increases, the relative vertical movement of the wheel with respect to the vehicle body is suppressed. Therefore, the rotation of the brushed motor is suppressed, and the speed at which the brush wears out decreases. Conversely, the damping force decreases. The more the wheel is moved up and down relative to the vehicle body, the more the number of rotations of the brushed motor increases and the speed at which the brush wears out increases.

  If the degree of wear of the brush does not precede the degree of use of the vehicle, it will be possible to replace the brush (including the replacement of the motor with the brush) as little as possible. Therefore, in the present invention, the brush consumption degree calculating means estimates the brush consumption state of the brushed motor based on the rotation speed of the brushed motor, and calculates the ratio of the consumption state to the brush life as the brush consumption degree. . On the other hand, the vehicle usage degree calculating means acquires the travel distance information of the vehicle, and calculates the ratio of the acquired travel distance to the durable travel distance of the vehicle as the vehicle use degree. And a balance determination means determines the balance of a brush consumption degree and a vehicle use degree. If it is determined that the degree of brush consumption is greater than the degree of vehicle use, the damping force correction means corrects the damping force controlled by the damping force control means to be higher. In other words, when it is determined that the brush wear degree is larger than the vehicle use degree, the control amount for controlling the damping force is larger than when the brush wear degree is not judged larger than the vehicle use degree. Correct to the side where the damping force increases. As a result, the rotation of the motor with the brush is suppressed, and the speed at which the brush wears out decreases.

  As a result, according to the present invention, an imbalance in which the degree of brush consumption progresses compared to the degree of vehicle use is prevented, and it is possible to minimize the need for brush replacement (including replacement of a brushed motor). .

1 is a system configuration diagram of a suspension device including a shock absorber device according to an embodiment of the present invention. It is sectional drawing showing schematic structure of a suspension main body. It is a circuit block diagram of an external circuit. It is a flowchart showing a damping force control routine. It is a flowchart showing a brush consumption state estimation routine. It is a flowchart showing a brush wear balance determination routine. It is a flowchart showing a brush exchange announcement control routine.

  Hereinafter, a suspension device including a shock absorber device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows the system configuration of the suspension device according to the embodiment.

  This suspension device includes four sets of suspension bodies 10FL, 10FR, 10RL, 10RR provided between the wheels WFL, WFR, WRL, WRR and the vehicle body B, and the operations of the suspension bodies 10FL, 10FR, 10RL, 10RR. Suspension electronic control unit 50 for controlling the suspension. Hereinafter, the four sets of the suspension bodies 10FL, 10FR, 10RL, and 10RR and the wheels WFL, WFR, WRL, and WRR are simply collectively referred to as the suspension body 10 and the wheels W unless particularly distinguished from front, rear, left, and right. The suspension electronic control unit 50 is referred to as a suspension ECU 50.

  As shown in FIG. 2, the suspension body 10 is provided between the lower arm LA that supports the wheel W and the vehicle body B, absorbs the impact received from the road surface, enhances the riding comfort, and elastically supports the weight of the vehicle body B. A coil spring 20 serving as a suspension spring and an electromagnetic shock absorber 30 that generates a damping force against vertical vibration of the coil spring 20 are provided in parallel. Hereinafter, in some cases, the upper side of the coil spring 20, that is, the vehicle body B side is referred to as “sprung”, and the lower side of the coil spring 20, that is, the wheel W side is referred to as “unsprung”.

  The electromagnetic shock absorber 30 includes an outer cylinder 31 and an inner cylinder 32 that are coaxially arranged, a ball screw mechanism 35 provided inside the inner cylinder 32, and a rotor (not shown) that rotates by the operation of the ball screw mechanism 35. And an electric motor 40 that generates an induced electromotive force. In the present embodiment, a brushed DC motor is used as the electric motor 40.

  The outer cylinder 31 and the inner cylinder 32 are constituted by coaxial different diameter pipes, and the outer cylinder 31 is provided on the outer periphery of the inner cylinder 32 so as to be slidable in the axial direction. In the figure, reference numerals 33 and 34 denote bearings that slidably support the inner cylinder 32 in the outer cylinder 31.

  The ball screw mechanism 35 includes a ball screw 36 that rotates integrally with the rotor of the electric motor 40, and a ball screw nut 39 that has a female screw portion 38 that engages with a male screw portion 37 formed on the ball screw 36. The ball screw nut 39 is restricted by a rotation stopper (not shown) so that it cannot rotate. Therefore, in this ball screw mechanism 35, the linear motion of the ball screw nut 39 in the vertical axis direction is converted into the rotational motion of the ball screw 35. Conversely, the rotational motion of the ball screw 36 is converted into the vertical axis direction of the ball screw nut 39. Is converted into a linear motion.

  The lower end of the ball screw nut 39 is fixed to the bottom surface of the outer cylinder 31. When an external force is applied to the ball screw 36 to move the outer cylinder 31 in the axial direction, the ball screw 36 rotates. The electric motor 40 is rotated. At this time, the electric motor 40 generates power by generating an induced electromotive force in the electromagnetic coil by causing an electromagnetic coil (not shown) provided in the rotor to cross a magnetic flux generated from a permanent magnet (not shown) provided in the stator. Work as a machine.

  The upper end of the inner cylinder 32 is fixed to the mounting plate 41. The mounting plate 41 is fixed to the motor casing 42 of the electric motor 40, and the ball screw 36 is inserted through a through hole 43 formed in the center thereof. The ball screw 36 is connected to the rotor of the electric motor 40 in the motor casing 42 and is rotatably supported by a bearing 44 in the inner cylinder 32.

  The coil spring 20 is interposed in a compressed state between an annular retainer 45 provided on the outer peripheral surface of the outer cylinder 31 and a mounting plate 46 of the electric motor 40. The suspension body 10 configured in this manner is attached to the vehicle body B via the upper support 26 made of an elastic material on the upper surface of the attachment plate 46.

  When the wheel W moves up and down while the vehicle is traveling, the outer cylinder 31 slides in the axial direction with respect to the inner cylinder 32 and the coil spring 20 expands and contracts, thereby absorbing the impact received from the road surface and improving the riding comfort. Increase and support the weight of the vehicle. At this time, the ball screw nut 39 moves up and down with respect to the ball screw 36 to rotate the ball screw 36. For this reason, in the electric motor 40, the rotor rotates to generate an induced electromotive force in the electromagnetic coil, and a resistance force is generated to stop the rotation of the rotor when a generated current flows through the external circuit 100 described later. . This resistance force acts as a damping force of the electromagnetic shock absorber 30. The damping force can be adjusted by adjusting the magnitude of the current flowing through the electromagnetic coil of the electric motor 40 by the external circuit 100 provided for each electromagnetic shock absorber 30.

  Next, a configuration for controlling the operation of the electromagnetic shock absorber 30 will be described. The electromagnetic shock absorber 30 is controlled by the suspension ECU 50 via the external circuit 100. The suspension ECU 50 includes a microcomputer as a main part, and performs damping force control by adjusting the amount of current flowing through the electric motor 40 of the electromagnetic shock absorber 30 by switching control of the external circuit 100. As will be described later, this damping force control is performed independently for each electromagnetic shock absorber 30 at each wheel W position by switching control of the external circuit 100 corresponding to the electromagnetic shock absorber 30. The suspension ECU 50 is connected to a stroke sensor 61 that detects a distance in the vertical direction between the wheel W and the vehicle body B (hereinafter referred to as a stroke S) at each wheel W position. The suspension ECU 50 is connected to a meter ECU 70 that controls instruments such as a vehicle travel distance meter, and acquires information representing the travel distance of the vehicle (vehicle use distance) from the meter ECU 70. Hereinafter, the travel distance acquired from the meter ECU 70 is referred to as travel distance Ytotal.

  Next, the external circuit 100 will be described with reference to FIG. In the figure, Rm represents the internal resistance of the electric motor 40, L represents the motor inductance, and is described outside the display symbol of the electric motor 40. When the rotor of the electric motor 40 is rotated via the ball screw mechanism 35 by the relative movement between the vehicle body B and the wheel W, the external circuit 100 is connected between the terminals of the electric motor 40 by the induced electromotive force generated by the electric motor 40. This circuit allows a generated current to flow between the first terminal t1 and the second terminal t2, and when the induced electromotive force (induced voltage) of the electric motor 40 is large, a part of the generated current is It is also a circuit that charges the power storage device 110 through the power storage device 110.

  The external circuit 100 includes a wiring ab that electrically connects the first terminal t1 and the second terminal t2 of the electric motor 40 at points a and b, and a wiring cd that electrically connects the points c and d. It has. In the figure, since the wiring is a line connecting the points (a, b, c...), The reference numerals are not shown. The wiring ab has a first diode D1 that allows a current flow in the direction from the point a to the point b and prevents a current flow in the direction from the point b to the point a, and a direction in the direction from the point b to the point a. A second diode D2 that allows current flow and blocks current flow in the direction from point a to point b is provided. In the wiring cd, a first switching element SW1, a first resistor R1, a second resistor R2, and a second switching element SW2 are provided in this order from the point c. The first resistor R1 and the second resistor R2 are fixed resistors that set a damping force. In the present embodiment, MOS-FETs are used as the first switching element SW1 and the second switching element SW2, but other switching elements can also be used. Each of the first switching element SW1 and the second switching element SW2 has a gate connected to the suspension ECU 50, and is configured to be turned on / off at a duty ratio set by a PWM (Pulse Width Modulation) control signal from the suspension ECU 50. . The duty ratio in this specification represents an on-duty ratio, that is, a ratio of an on-time of the pulse signal to a time obtained by adding the on-time and off-time of the pulse signal.

  The first terminal t1 and the point a are electrically connected by the wiring t1a, and the second terminal t2 and the point b are electrically connected by the wiring t2b. A current sensor 111 is provided in the wiring t1a. The current sensor 111 detects a current flowing through the electric motor 40 and outputs a detection signal representing a measurement value ix including information indicating the energization direction to the suspension ECU 50.

  Further, the point e between the first diode D1 and the second diode D2 in the wiring ab and the point f between the first resistor R1 and the second resistor R2 in the wiring cd are electrically connected by the wiring ef. It is connected to. A first charging path gi serving as a charging path to the power storage device 110 provided as an in-vehicle power supply battery is branched and provided at a point g that is a connection point between the first switching element SW1 and the first resistor R1. In addition, a second charging path hi serving as a charging path to the power storage device 110 is branched and provided at a point h serving as a connection point between the second switching element SW2 and the second resistor R2. The first charging path gi and the second charging path hi are connected at a point i to a main charging path ij that connects the point i and the positive electrode j of the power storage device 110. Further, the point f and the negative electrode k of the power storage device 110 are connected by a ground line kf. Note that various electric loads provided in the vehicle are connected to the power storage device 110.

  The first charging path gi is provided with a third diode D3 that allows a current flow in the direction from the point g to the point i and prevents a current flow in the direction from the point i to the point g. The second charging path hi is provided with a fourth diode D4 that allows current flow in the direction from the point h to the point i and prevents current flow in the direction from the point i to the point h. That is, the charging circuit is configured to allow charging from the external circuit 100 to the power storage device 110 and to prevent discharging from the power storage device 110 to the external circuit 100.

  Next, the operation of the external circuit 100 will be described. When the rotor is rotated via the ball screw mechanism 35 by the relative movement of the wheel W and the vehicle body B, the electric motor 40 generates an induced electromotive force in a direction corresponding to the rotation direction. For example, during a compression operation in which the wheel W and the vehicle body B approach each other and the electromagnetic shock absorber 30 is compressed, the first terminal t1 of the electric motor 40 becomes a high potential and the second terminal t2 becomes a low potential. Conversely, during the extension operation in which the wheel W and the vehicle body B are separated and the electromagnetic shock absorber 30 is extended, the second terminal t2 of the electric motor 40 is at a high potential and the first terminal t1 is at a low potential.

  Therefore, during the compression operation in which the electromagnetic shock absorber 30 is compressed, the first connection circuit in which the generated current flows from the first terminal t1 to the second terminal t2 through the points c, f, e, and b. A cfeb is formed. Further, during the extension operation in which the electromagnetic shock absorber 30 is extended, the second connection circuit dfea in which the generated current flows from the second terminal t2 to the first terminal t1 through the points d, f, e, and a. Is formed. That is, the circuit through which the generated current flows is different between the compression operation and the expansion operation of the electromagnetic shock absorber 30. In this example, the first resistor R1 becomes a resistance to the generated current flowing from the first terminal t1 to the second terminal t2, and the first switching element SW1 has a large generated current flowing from the first terminal t1 to the second terminal t2. It functions as a current regulator that adjusts the thickness (energization amount). Further, the second resistor R2 becomes a resistance to the generated current flowing from the second terminal t2 to the first terminal t2, and the second switching element SW2 has a magnitude of the generated current flowing from the second terminal t2 to the first terminal t1 ( It functions as a current regulator that adjusts the energization amount.

  When the generated current flows through the electromagnetic coil of the electric motor 40, an electromagnetic force (electric power generation brake) acts on the electric motor 40, thereby suppressing the relative rotation between the ball screw nut 39 and the ball screw 36. That is, a damping force that suppresses relative movement between the vehicle body B and the wheels W is generated. Further, the damping force can be adjusted by adjusting the magnitude of the generated current. Accordingly, the damping force for the compression operation can be set by the resistance value of the first resistor R1 and the duty ratio of the first switching element SW1, and the resistance is increased by the resistance value of the second resistor R2 and the duty ratio of the second switching element SW2. The damping force for the operation can be set. That is, the damping force can be set independently with respect to the compression operation direction and the extension operation direction of the electromagnetic shock absorber 30. In the present embodiment, the resistance value of the first resistor R1 is larger than the resistance value of the second resistor R2, and basically, the damping force for the compression operation is larger than the damping force for the extension operation. It is set to be smaller.

  Further, such adjustment of the damping force can be performed independently by switching control of the external circuit 100 of the electromagnetic shock absorber 30 for each wheel.

  The induced electromotive force generated by the electric motor 40 increases as the motor rotation speed increases. When the induced electromotive force (induced voltage) exceeds the output voltage (storage voltage) of the power storage device 110, a part of the power generated by the electric motor 40 is regenerated in the power storage device 110. For example, during the compression operation of the electromagnetic shock absorber 30, the generated current is shunted in two directions at the point g, one flows through the first connection circuit cfeb as it is, and the other flows through the first charging path gi. Therefore, the power storage device 110 is charged by the generated current that flows through the first charging path gi. Further, when the electromagnetic shock absorber 30 is extended, the generated current is divided in two directions at the point h, one flows through the second connection circuit dfea as it is, and the other flows through the second charging path hi. Accordingly, the power storage device 110 is charged by the generated current that flows through the second charging path hi.

  Next, control of the damping force generated by the electromagnetic shock absorber 30 will be described. FIG. 4 is a flowchart showing a damping force control routine executed by the suspension ECU 50. This damping force control routine is stored as a control program in the ROM of the suspension ECU 50, and is executed independently for each electromagnetic shock absorber 30 of each wheel. The damping force control routine is repeatedly executed at a predetermined short cycle (referred to as a calculation cycle) from when the ignition switch is turned on until it is turned off.

  When this damping force control routine is started, the suspension ECU 50 reads a stroke S that is a vertical separation distance between the wheel W and the vehicle body B detected by the stroke sensor 61 in step S11. Subsequently, in step S12, the stroke S is differentiated by time to calculate the stroke speed Vs. At this time, it is preferable to obtain a stroke speed Vs by performing a band pass filter process and extracting a sprung resonance frequency band component (for example, 0.1 Hz to 3.0 Hz) from the stroke speed signal.

  Subsequently, it is determined from the direction (sign) of the stroke speed Vs whether or not the electromagnetic shock absorber 30 is in a compression operation. When the electromagnetic shock absorber 30 is compressing (S13: Yes), the target damping force F * is calculated as F * = C1 · Vs (S14), and the electromagnetic shock absorber 30 is expanding. In the case (S13: No), the target damping force F * is calculated as F * = C2 · Vs (S15). C1 and C2 are damping coefficients, and the damping coefficient C1 is set smaller than the damping coefficient C2 in order to make the damping force for the compression operation smaller than the damping force for the extension operation.

  Subsequently, in step S16, the suspension ECU 50 checks the setting state of the flag F and determines whether or not F = 1. This flag F represents a balance determination result between the degree of use of the vehicle and the degree of brush consumption of the electric motor 40, and is set by a brush consumption balance determination routine (FIG. 6) described later. The flag F is set to F = 1 when the brush consumption degree is advanced compared to the vehicle use degree, and conversely, the flag F is set to F when the brush wear degree is not advanced compared to the vehicle use degree. = 0 is set. In step S16, the flag F set in the brush wear balance determination routine is read and determined.

  When the flag F is “1”, the suspension ECU 50 reads the correction coefficient K in step S17, and in step S18, the suspension ECU 50 multiplies the target damping force F * by the correction coefficient K (K · F *). The obtained value is set as a new target damping force F *. On the other hand, when the flag F is “0”, the processing of steps S17 and S18 is skipped. That is, the target damping force F * is not corrected. The correction coefficient K is a value larger than “1”, and is calculated in a brush wear balance determination routine described later. Accordingly, in step S17, processing for reading the correction coefficient K calculated in the brush wear balance determination routine is performed.

  Subsequently, in step S19, the suspension ECU 50 calculates a target current i * that is a generated current value for obtaining the target damping force F *. The target current i * is obtained by dividing the target damping force F * by the torque constant. Since the target current i * is for generating a damping force by causing the generated current to flow in a direction that hinders the expansion and contraction operation of the electromagnetic shock absorber 30, its energization direction depends on the operation direction of the electromagnetic shock absorber 30. Different. That is, when the electromagnetic shock absorber 30 is in a compressing operation, the first shock absorber 30 is in a direction of flowing from the first terminal t1 through the first connection circuit cfeb to the second terminal t2, and when the electromagnetic shock absorber 30 is in an extending operation, The direction flows from the second terminal t2 to the first terminal t1 through the second connection circuit dfea.

  Subsequently, the suspension ECU 50 reads the actual current ix detected by the current sensor 111 in step S20. Next, in step S21, the PWM control signal is sent to the first switching element SW1 or the second switching element SW2 to adjust the duty ratio so that the actual current ix becomes equal to the target current i *. Feedback control (for example, PID control) based on deviation Δi (= i * −ix) between * and actual current ix is performed. In this case, the suspension ECU 50 adjusts the duty ratio of the first switching element SW1 when the electromagnetic shock absorber 30 is being compressed, and the second switching element SW2 is when the electromagnetic shock absorber 30 is being extended. Is adjusted so that the generated current flowing through the electric motor 40 becomes equal to the target current i *. For the switching element on the side where the duty ratio is not adjusted (the second switching element SW2 during the compression operation and the first switching element SW1 during the extension operation), the duty ratio may be fixed to 0%, for example. That's fine.

  The suspension ECU 50 repeats such a damping force control routine at a predetermined short cycle. Accordingly, it is possible to generate a damping force having characteristics suitable for the compression direction and the extension direction of the electromagnetic shock absorber 30.

  Next, a process for estimating the consumption state of the brush of the electric motor 40 will be described. The amount of brush consumption is governed by the motor speed (the total speed that the rotor has rotated so far). Therefore, in this embodiment, the brush consumption state is estimated from the motor rotation speed. FIG. 5 is a flowchart showing a brush wear state estimation routine executed by the suspension ECU 50. This brush wear state estimation routine is stored as a control program in the ROM of the suspension ECU 50, and is executed independently for each electromagnetic shock absorber 30 of each wheel.

  When the ignition switch is turned on, a brush wear state estimation routine is started. The suspension ECU 50 first reads a stroke Sn detected by the stroke sensor 61 in step S31. Since this process is repeated at a predetermined calculation cycle, the stroke read this time is represented as stroke Sn in order to distinguish the stroke read this time from the stroke read last time.

Subsequently, in step S32, the suspension ECU 50 calculates the number of rotations ΔN that the electric motor 40 has rotated in the period (calculation cycle) from the previous calculation timing to the current calculation timing by the following equation.
ΔN = (| Sn-Sn-1 |) / L
Here, Sn-1 represents the stroke read at the previous calculation timing. L is the lead of the ball screw 36 of the electromagnetic shock absorber 30. Since the stroke Sn-1 is not obtained at the start of the brush wear state estimation routine, the rotational speed ΔN is set to a fixed value, for example, “0”.

Subsequently, in step S33, the suspension ECU 50 calculates the rotational speed N of the electric motor 40 after the ignition switch is turned on by the following equation.
N = N + ΔN
The initial value of the rotational speed N is “0”. Subsequently, in step S34, the stroke Sn read in step S31 is stored as a stroke Sn-1.

  In step S35, the suspension ECU 50 determines whether or not the ignition switch is turned off, and repeats the processing in steps S31 to S35 until the ignition switch is turned off. Accordingly, the rotational speed ΔN of the electric motor 40 obtained every calculation cycle is accumulated, and the rotational speed N of the electric motor 40 after the ignition switch is turned on is calculated. This rotational speed N corresponds to the distance that the brush of the electric motor 40 slides during the period when the ignition switch is on.

When the suspension EUC 50 detects that the ignition switch is turned off in step S35, the suspension EUC 50 calculates the total rotational speed Ntotal of the electric motor 40 by the following formula in step S36, and the value is a non-volatile provided in the suspension ECU 50. Store in memory (not shown) Ntotal = Ntotal + N
In this case, the total number of revolutions Ntotal up to the previous time is read from the nonvolatile memory, the number of revolutions N in the ignition switch ON period is added to the total number of revolutions Ntotal, and the value is set as a new total number of revolutions Ntotal. Then, the previous total rotation speed Ntotal stored in the nonvolatile memory is rewritten to the new total rotation speed Ntotal calculated this time.

  Subsequently, in step S37, the suspension ECU 50 determines whether or not the rotation speed N during the current ignition switch ON period is greater than the maximum use rotation speed Nmax. The maximum use rotation speed Nmax is a maximum value in the vehicle use history so far during a period in which one ignition switch is turned on, and is stored in the nonvolatile memory. Therefore, in this step S37, the maximum used rotational speed Nmax is read from the nonvolatile memory, and the maximum used rotational speed Nmax is compared with the current rotational speed N. If the current rotational speed N is greater than the maximum used rotational speed Nmax (S37: Yes), in step S38, the current rotational speed N is stored in the nonvolatile memory as the maximum used rotational speed Nmax. That is, the maximum use rotational speed Nmax is rewritten to the current rotational speed N. Then, the brush wear state estimation routine ends. On the other hand, when the current rotation speed N is equal to or less than the maximum use rotation speed Nmax (S37: No), the process of step S38 is skipped, and the brush consumption state estimation routine is ended.

  The total rotation speed Ntotal stored in this way serves as an index representing the brush consumption state of the electric motor 40 and is used in a brush wear balance determination routine (FIG. 6) described later. Further, the maximum use rotation speed Nmax is used in the brush exchange announcement control routine (FIG. 7).

  Next, a process for determining the balance between the degree of use of the vehicle and the degree of wear of the brush will be described. FIG. 6 is a flowchart showing a brush wear balance determination routine executed by the suspension ECU 50. This brush wear balance determination routine is stored as a control program in the ROM of the suspension ECU 50, and is executed independently for each electromagnetic shock absorber 30 of each wheel.

When the ignition switch is turned on, a brush wear balance determination routine is started. First, in step S41, the suspension ECU 50 reads the total rotational speed Ntotal stored in the nonvolatile memory. This total rotation speed Ntotal is information stored in step S36 of the brush wear state estimation routine described above. Subsequently, in step S42, the travel distance Ytotal is read from the meter ECU 70. Subsequently, in step S43, it is determined whether or not the following brush wear balance determination formula is satisfied.
(Ntotal / Nlimit)> (Ytotal / Ytarget)
Here, Nlimit represents the motor rotation speed N corresponding to the life of the brush of the electric motor 40, and Ytarget is a preset durable travel distance of the vehicle.

  In this brush wear balance determination formula, the left side represents the ratio of the current brush wear state to the life of the brush (= brush wear degree). On the other hand, the right side represents the ratio of the travel distance to the current time with respect to the durable travel distance of the vehicle (= the degree of vehicle use). When the value on the left side is larger than the value on the right side, it indicates that the brush consumption level is advanced more than the vehicle usage level. In such a situation, the brush reaches the end of its life before the mileage of the vehicle reaches the durable mileage. On the other hand, when the value on the left side is smaller than the value on the right side, it indicates that the vehicle usage is more advanced than the brush consumption. Therefore, the brush does not reach the end of its life before the vehicle travel distance reaches the durable travel distance.

When the suspension ECU 50 determines in step S43 that the brush wear balance determination formula is satisfied (S43: Yes), the suspension ECU 50 determines that the brush wear level is higher than the vehicle use level, and in step S44, flag F Is set to “1”. In step S46, the correction coefficient K is calculated by the following equation. The correction coefficient K is a coefficient that is multiplied by the target damping force F * in step S18 of the damping force control routine described above.
K = (Ntotal / Ytotal) / ((Nlimit−Ntotal) / (Ytarget−Ytotal))
The numerator of the equation representing the correction coefficient K represents the ratio of the brush wear state Ntotal to the travel distance Ytotal, and the denominator represents the remaining usable rotation speed up to the brush life Nlimit relative to the remaining travel distance up to the durable travel distance Ytarget. To express. Therefore, the correction coefficient K is a positive value larger than “1” when the brush consumption degree is larger (advanced) than the vehicle use degree, and the brush consumption degree is larger than the vehicle use degree. It is set to a value that increases (as it progresses).

  On the other hand, if it is determined in step S43 that the brush wear balance determination formula is not satisfied (S43: No), since the brush wear level does not advance beyond the vehicle use level, the flag F is set to “0” in step S45. Set to.

  When the suspension ECU 50 performs the process of step S45 or step S46, the brush wear balance determination routine ends. Then, the suspension ECU 50 changes the target damping force F * in the damping force control routine (FIG. 4) according to the flag F set in the brush wear balance determination routine. That is, when the degree of brush consumption is higher than the degree of vehicle use (F = 1), the target damping force F * is multiplied by the correction coefficient K (> 1) (S18). The damping force in the electromagnetic shock absorber 30 is a force that suppresses the approaching / separating motion between the vehicle body B and the wheel W, and is a force that suppresses the operation of the ball screw mechanism 35 extending and contracting. Therefore, as the magnitude (absolute value) of the target damping force F * increases, the rotation of the electric motor 40 is suppressed and the speed at which the brush wears out becomes slower. As a result, an imbalance in which the degree of brush consumption progresses more than the degree of vehicle use is prevented, and it is possible to eliminate brush replacement (including replacement of the electric motor 40) as much as possible. Further, since the damping force control corresponding to the brush wear balance is performed for each electromagnetic shock absorber 30 of each wheel W, only the electric motor 40 of the specific electromagnetic shock absorber 30 causes the brush consumption to proceed. Can also be prevented.

  Even if the damping force control according to the brush wear balance described above is performed, the brush wear may progress and the need for brush replacement may arise. Therefore, the suspension ECU 50 has a function of announcing the necessity of brush replacement to the driver. FIG. 7 is a flowchart showing a brush replacement announcement control routine executed by the suspension ECU 50. This brush exchange announcement control routine is stored as a control program in the ROM of the suspension ECU 50.

  When the ignition switch is turned on, a brush replacement announcement control routine is started. In step S51, the suspension ECU 50 reads the maximum use rotational speed Nmax. This maximum operating rotational speed Nmax is the maximum value of the rotational speed N in the vehicle usage history so far during the period when the ignition switch is turned on, and the information is stored for each electromagnetic shock absorber 30 in a nonvolatile memory. Is remembered. Accordingly, in this step S51, the maximum use rotational speed Nmax in the four electromagnetic shock absorbers 30 is read from the nonvolatile memory.

  Subsequently, the suspension ECU 50 reads the total rotational speed Ntotal in step S52. This total rotational speed Ntotal is also stored in nonvolatile memory for each electromagnetic shock absorber 30. Therefore, in step S52, the total rotational speed Ntotal in the four electromagnetic shock absorbers 30 is read from the nonvolatile memory.

Subsequently, in step S53, the suspension ECU 50 determines for each electromagnetic shock absorber 30 whether or not the following brush replacement determination formula is satisfied.
λ (Nlimit−Ntotal) ≦ Nmax
Here, λ is a safety factor and is a preset value.

  If the brush replacement determination formula is not satisfied in all four electromagnetic shock absorbers 30 (S53: No), the suspension ECU 50 determines that there is no need for brush replacement, and ends the brush replacement announcement control routine. On the other hand, if at least one of the four electromagnetic shock absorbers 30 satisfies the brush replacement determination formula (S53: Yes), in step S54, the driver is notified of the need for brush replacement. For example, a brush replacement message is displayed on a display provided on the driver's seat front panel. Or, a voice exchange system is used to utter a brush exchange message. Alternatively, the warning rung may simply be turned on. At the same time, the suspension ECU 50 stores, in the nonvolatile memory, an error code indicating wear of the brush, data for specifying the electromagnetic shock absorber 30 that needs to be replaced, and the like.

  When the suspension ECU 50 announces the necessity of brush replacement, the suspension ECU 50 ends the brush replacement announcement control routine. As a result, the driver can know the necessity of brush replacement at the time when the ignition switch is turned on. Also, the brush replacement announcement is made at the stage before the brush reaches the end of its life (the stage where the vehicle can travel a predetermined distance before the brush reaches the end of its life). I can go.

  According to the suspension device of the present embodiment described above, damping force control can be performed with independent characteristics for compression operation and extension operation using a low-cost electromagnetic shock absorber 30 using a brushed motor. it can. When the brush consumption level of the electric motor 40 is higher than the vehicle usage level, a correction coefficient K that increases as the brush consumption level progresses higher than the vehicle usage level is calculated, and this correction coefficient K is used as the target damping force. Since the target damping force F * is corrected by multiplying by F *, an unbalance that the degree of brush consumption progresses more than the degree of vehicle use is prevented. This eliminates the need for brush replacement as much as possible. Further, if the brush wear level is lower than the vehicle usage level, the target damping force F * is returned to the original value, so that the target damping force F * is not excessively increased. As a result, it is possible to achieve both suppression of brush consumption and appropriate damping force control.

  In addition, the ratio of the vehicle travel to the end of the vehicle travel is defined as the ratio of the travel distance to the present time to the durable travel distance of the vehicle, and the ratio of the current brush wear state to the brush life is defined as the brush wear degree. Since the balance of the brush consumption state is determined from the comparison, the balance determination is easy and appropriate.

  In this embodiment, the function of the suspension ECU 50 that performs the processing of steps S31 to S36 in the brush wear state estimation routine and the calculation of the left side of step S43 in the brush wear balance determination routine is used as the brush wear degree calculation means of the present invention. Equivalent to. In the present embodiment, the processing of steps S41 to S42 in the brush wear balance determination routine and the functional unit of the suspension ECU 50 that performs the calculation of the right side of step S43 correspond to the vehicle usage degree calculation means of the present invention. Further, in the present embodiment, the functional unit of the suspension ECU 50 that performs the processing of steps S43 to S45 in the brush wear balance determination routine corresponds to the balance determination means of the present invention. In the present embodiment, the functional unit of the suspension ECU 50 that executes the damping force control routine corresponds to the damping force control means of the present invention. Further, in the present embodiment, the functional unit of the suspension ECU 50 that performs the process of step S46 in the brush wear balance determination routine and the processes of steps S16 to S18 in the damping force control routine corresponds to the damping force correction means of the present invention.

  The suspension device including the shock absorber device according to the present embodiment has been described above. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

  For example, in the present embodiment, the electromagnetic shock absorber 30 generates a damping force by the electric power generation of the electric motor 40, but when a large damping force is required, the power supply device (for example, the power storage device 110). ) To which the electric motor 40 is supplied with power to generate a damping force by the driving force of the electric motor 40 may be added. In the present embodiment, the electric power generated by the electric motor 40 is regenerated to the in-vehicle power supply battery. However, a power storage device is provided in each external circuit 100 and the power storage device is charged with the generated power. The electric motor 40 may be driven using the electric power stored in the electric power.

  In the present embodiment, the target damping force F * is set based on the stroke speed Vs. For example, a sprung acceleration sensor that detects the vertical acceleration of the vehicle body B is additionally provided at each wheel W position. The configuration may be such that the sprung acceleration detected by the sprung acceleration sensor is taken into the suspension ECU 50 and the target damping force F * is set using the stroke speed Vs and the sprung acceleration.

  DESCRIPTION OF SYMBOLS 10 ... Suspension main body, 20 ... Coil spring, 30 ... Electromagnetic shock absorber, 40 ... Electric motor, 50 ... Suspension ECU, 61 ... Stroke sensor, 70 ... Meter ECU, 100 ... External circuit, 110 ... Power storage device, 111 ... Current Sensors, SW1, SW2 ... switching elements, R1, R2 ... resistors, D1, D2, D3, D4 ... diodes, t1, t2 ... terminals, B ... vehicle body, W ... wheels.

Claims (1)

A motor with a brush that rotates the rotor by a vertical movement of the wheel relative to the vehicle body, and a relative vertical movement of the wheel with respect to the vehicle body by electromagnetic force generated by the brushed motor when the rotor is rotated An electromagnetic shock absorber that generates a damping force to suppress
A shock absorber device comprising: damping force control means for controlling the damping force by adjusting an electromagnetic force generated by the brushed motor;
Brush consumption degree calculation means for estimating the consumption state of the brush of the brushed motor based on the number of rotations of the brushed motor, and calculating a ratio of the estimated consumption state to the life of the brush as a brush consumption degree;
Vehicle usage degree calculation means for acquiring vehicle travel distance information and calculating a ratio of the acquired travel distance to a durable travel distance of the vehicle as a vehicle use degree;
A balance determination means for determining a balance between the calculated brush consumption level and the vehicle usage level;
A damping force correcting means for correcting the damping force controlled by the damping force control means to a higher side when the balance determining means determines that the brush wear degree is larger than the vehicle usage degree; A shock absorber device characterized by comprising:

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