JP2011084204A - Shock absorber device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress riding comfort from being deteriorated due to the influence of inertia of a reduction gear 35 of an electromagnetic shock absorber 30. <P>SOLUTION: When the electromagnetic shock absorber 30 is compressingly operated, damping force is controlled by adjusting a generated current by a first switching element SW1. On this occasion, a second switching element SW2 is brought into an off-state when a target damping coefficient C is positive, and is brought into an on-state when the target damping coefficient C is negative. When the electromagnetic shock absorber 30 is extendingly operated, the damping force is controlled by adjusting the generated current by a second switching element SW2. On this occasion, the first switching element SW1 is brought into the off-state when the target damping coefficient C is positive, and is brought into the on-state when the target damping coefficient C is negative. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  TECHNICAL FIELD The present invention relates to a shock absorber device for a wheel of an automobile or the like, and more particularly, an electromagnetic type that damps an approach / separation operation between a spring upper part and an unspring part by generating a motor by an approach / separation action between the spring upper part and the spring unsprung part. The present invention relates to a shock absorber device provided with a shock absorber.

  Conventionally, the motor is rotated by the approaching / separating operation between the spring upper part and the spring unsprung part, and the approaching / separating action between the spring upper part and the spring unsprung is attenuated using the induced electromotive force generated by the motor by the rotation. A shock absorber is known from Patent Document 1 and the like. In the shock absorber device proposed in Patent Document 1, if the absolute operating direction of the sprung portion and the direction in which the sprung moves with respect to the unsprung portion are the same direction, the energization terminals of the motor are electrically connected to each other. As a result, a generated current is supplied to the motor to generate a damping force, thereby suppressing the vibration of the sprung portion. Further, if the absolute operating direction of the sprung portion is opposite to the direction in which the sprung moves with respect to the unsprung portion, the motor is prevented from generating a damping force by opening the energization terminals of the motor.

JP2008-273356

  Such an electromagnetic shock absorber needs to convert the approaching / separating operation between the sprung portion and the unsprung portion into the rotating operation of the motor. In this case, in order to obtain realistic damping force characteristics, for example, a speed reducer such as a ball screw mechanism is required. However, the damping force characteristic of the unsprung resonance band deteriorates due to the inertia of the speed reducer, and there is a concern that the riding comfort may deteriorate. FIG. 10 shows a transmission characteristic in which road surface input is transmitted to the sprung portion. In the figure, the thick line represents the transmission characteristic by an electromagnetic shock absorber provided with a reduction gear, and the thin line represents the transmission characteristic by a general hydraulic damper type shock absorber. In addition, the solid line represents the transfer characteristic at low attenuation (soft), and the broken line represents the transfer characteristic at high attenuation (hard). As can be seen from this figure, in the electromagnetic shock absorber, the damping force characteristic is deteriorated in a range larger than the frequency fs, particularly at the time of low damping (soft).

  The present invention has been made to cope with the above-described problem, and an object of the present invention is to suppress deterioration in riding comfort due to the influence of the inertia of the reduction gear.

  In order to achieve the above object, a feature of the present invention is that the motor includes a motor, and an operation conversion mechanism that converts an approach / separation operation between the sprung portion and the unsprung portion into the operation of the motor, An electromagnetic shock absorber that generates a damping force with respect to the approaching / separating operation between the spring upper part and the spring unstressed by the generated current flowing through the motor in accordance with the approaching / separating operation with A first connection path that allows a current flow from one of the terminals to a second terminal that is the other and prohibits a current flow from the second terminal to the first terminal; A second connection path that allows a current flow from the second terminal of the motor to the first terminal and prohibits a current flow from the first terminal to the second terminal; and 1st line provided in the connection path And a second switching element provided in the second connection path, and a power generation current flows through the first connection path when the spring upper part and the spring lower part approach each other. A target damping coefficient of an external circuit through which the generated current flows in the second connection path during the separation operation and a damping force generated by the motor is calculated. If the calculated target damping coefficient is a negative value, the target damping coefficient is calculated. Using the first switching element during the approaching operation of the sprung portion and the unsprung portion so that a target damping coefficient setting means that is set to be replaced with zero and a damping force corresponding to the target damping coefficient are generated. The magnitude of the generated current flowing to the motor is controlled, and the magnitude of the generated current flowing to the motor is controlled using the second switching element during the separation operation of the sprung part and the unsprung part. When the target damping coefficient set by the damping force control means and the target damping coefficient setting means is a positive value, the second switching element is set during the approaching operation between the spring top and the spring bottom. There is provided auxiliary control means for controlling the first switching element to be in an off state during the separation operation between the sprung portion and the unsprung portion.

  In the present invention, the approach / separation operation (approach operation and separation operation) between the sprung portion and the unsprung portion is transmitted to the motor via the motion conversion mechanism. For example, a speed reducer such as a ball screw mechanism can be employed as the motion conversion mechanism. The motor generates an induced electromotive force in accordance with the approach / separation operation between the sprung portion and the unsprung portion. Therefore, by connecting the terminals of the motor to each other, a generated current flows through the motor, and a damping force can be generated with respect to the approaching / separating operation between the spring upper part and the spring lower part. In order to flow this generated current, an external circuit is provided outside the motor. The external circuit includes a first connection path in which current flow from the first terminal to the second terminal of the motor is allowed and current flow from the second terminal to the first terminal is prohibited, and from the second terminal to the second terminal. A second connection path that allows current flow to one terminal and prohibits current flow from the first terminal to the second terminal. A first switching element is provided on the first connection path, and a second switching element is provided on the second connection path. In this case, the generated current of the motor flows through the first connection path during the approaching operation between the sprung part and the unsprung part, and flows through the second connection path during the separating operation between the sprung part and the unsprung part. The first terminal and the second terminal are current-carrying terminals of the motor, and in this case, output terminals for induced electromotive force generated in the motor. Moreover, it is good to provide the resistor (a 1st resistor and a 2nd resistor) which restrict | limits the amount of electric current in a 1st connection path and a 2nd connection path.

  Therefore, the damping force can be controlled by adjusting the magnitude of the generated current flowing through the first connection path by controlling the first switching element during the approaching operation between the sprung portion and the unsprung portion. Similarly, by controlling the second switching element during the separating operation between the sprung portion and the unsprung portion, the damping force can be controlled by adjusting the magnitude of the generated current flowing in the second connection path. In order to control such a damping force, the present invention includes target damping coefficient setting means, damping force control means, and auxiliary control means.

  The target damping coefficient setting means calculates a target damping coefficient of the damping force generated by the motor, and sets the target damping coefficient by replacing it with zero if the calculated target damping coefficient is a negative value. That is, if the calculated target attenuation coefficient is a value greater than or equal to zero, that value is set as the target attenuation coefficient, and if the calculated attenuation coefficient is a negative value, the target attenuation coefficient is set to zero. The damping coefficient is an index for generating a damping force, and is represented by the magnitude of the damping force with respect to the approach / separation speed between the sprung portion and the unsprung portion.

  For example, when setting the target damping coefficient based on the skyhook damper theory, if the direction of movement of the sprung and the direction of movement of the sprung to the unsprung direction are the same, the target damping coefficient of the shock absorber is If the value is a positive value and the operating direction of the sprung portion is opposite to the moving direction of the sprung portion relative to the unsprung portion, the target damping coefficient is a negative value. If the target damping coefficient is a positive value, a damping force can be generated in the shock absorber by passing a generated current through the motor. However, if the target damping coefficient is a negative value, Unless it is a suspension, it is not possible to generate a propulsive force that works in the opposite direction to the damping force. Therefore, in the present invention, the target damping coefficient is set to zero when the calculated target damping coefficient is negative so that it can be implemented even with a passive suspension. Since the electromagnetic shock absorber includes a motion conversion mechanism, the inertia force of the motion conversion mechanism affects the damping force. Therefore, the target damping coefficient setting means can set an appropriate target damping coefficient by calculating the target damping coefficient of the damping force generated by the motor. That is, the target damping coefficient is calculated so that a force obtained by subtracting the inertial force of the motion conversion mechanism from the damping force generated by the electromagnetic shock absorber is generated by the motor.

  The damping force control means uses the first switching element to generate power that flows to the motor so that a damping force corresponding to the target damping coefficient set in this way is generated. The magnitude of the current is controlled, and the magnitude of the generated current flowing to the motor is controlled using the second switching element during the separation operation between the sprung part and the unsprung part. When the target damping coefficient is set to zero, the switching element of the corresponding connection path is maintained in the off state so that no generated current flows to the motor, and no damping force is generated in the electromagnetic shock absorber. Like that.

  The target damping coefficient is determined when the direction of movement relative to the unsprung portion of the sprung portion is reversed, that is, when the approaching operation and the separating operation are switched (when the approaching operation is switched to the separating operation, and when the separating operation is moved to the approaching operation). In most cases, the sign (positive / negative) is inverted. At the time of this operation reversal, the direction of the induced electromotive force generated in the motor is reversed, and the connection path through which the generated current flows is switched. For example, when switching from the approaching operation to the separating operation, the generated current flowing through the first connection path changes its direction and flows into the second connection path. When the separation operation is switched to the approaching operation, the generated current flowing through the second connection path changes its direction and flows into the first connection path. Accordingly, the switching element to be controlled by the damping force control means is also switched in accordance with the inversion of the approach / separation operation. Hereinafter, a switching element to be controlled by the damping force control means is referred to as a main control target switching element. The other switching element different from the main control target switching element is referred to as an auxiliary target switching element. For example, if the upper and lower parts of the spring are close to each other, the first switching element is the main control target switching element, the second switching element is the auxiliary target switching element, and the upper part and the lower part of the spring are separated. If so, the second switching element is the main control target switching element, and the first switching element is the auxiliary switching element.

  When the direction of operation with respect to the unsprung portion of the sprung portion is reversed (hereinafter referred to as reversal of expansion / contraction operation), the sign of the target damping coefficient is reversed with a very high probability. Further, at the time of reversing the expansion / contraction operation, the inertia force of the operation conversion mechanism has already been generated and maximized. When the target damping coefficient is set to a positive value, the target damping coefficient is set to zero along with the reversal of the expansion / contraction operation, and the switching element that has been the auxiliary target until then is the main control target. It is turned off by the damping force control means so that the generated current does not flow to the switching motor. At this time, if the auxiliary switching element is turned off and kept on standby before the reversal of the expansion / contraction operation, a damping force can be prevented from being instantaneously generated immediately after the reversal of the expansion / contraction operation. In other words, the inertial force of the motion conversion mechanism has already been generated when the expansion / contraction operation is reversed, and this inertial force tends to act as a damping force when the expansion / contraction operation is reversed, but the auxiliary switching element is turned off in advance. By maintaining the above, the influence of inertial force can be removed.

  Therefore, the auxiliary control means controls the second switching element to be auxiliary to the OFF state when the target damping coefficient is a positive value, and during the close operation of the sprung portion and the unsprung portion. If it is during the separation operation between the spring and the unsprung portion, the first switching element to be assisted is controlled to be in an OFF state. Thereby, it is possible to prevent the damping force from being generated instantaneously immediately after the reversal of the expansion / contraction operation, and to reduce the influence of the inertial force of the motion conversion mechanism. As a result, according to the present invention, it is possible to suppress the ride comfort from deteriorating due to the inertia of the motion conversion mechanism.

  Another feature of the present invention is that, when the target damping coefficient set by the target damping coefficient setting means is zero, the auxiliary control means further performs an approach operation between the sprung portion and the unsprung portion. If so, the second switching element is controlled to be in an on state, and the first switching element is controlled to be in an on state when the sprung portion and the unsprung portion are separated.

  When the target damping coefficient is set to zero, the target damping coefficient is set to a positive value along with the reversal of the expansion / contraction operation, and the switching element that has been the auxiliary target until then is switched to the main control target. Control is performed so that a generated current flows to generate a damping force. At this time, a large damping force can be generated immediately after the reversal of the expansion / contraction operation if the auxiliary switching element is kept in the ON state before the reversal of the expansion / contraction operation. That is, since the inertial force of the motion converting mechanism is maximized when the expansion / contraction operation is reversed, the inertial force can be effectively used as a damping force when the expansion / contraction operation is reversed.

  Therefore, when the target damping coefficient is zero, the auxiliary control means controls the second switching element to be auxiliary to the on state during the approaching operation between the sprung portion and the unsprung portion. If it is during the separation operation from the lower part, the first switching element to be assisted is controlled to be in the ON state. As a result, the inertial force of the motion conversion mechanism can be effectively used as the damping force when the expansion / contraction operation is reversed. As a result, according to the present invention, the ride comfort can be further improved. For example, when the duty ratio (ON period / (ON period + OFF period)) is controlled, the switching element to be assisted is set to 100% duty ratio. Not limited to this, any control may be used as long as the duty ratio is set to an auxiliary duty ratio so that the damping force can be assisted by inertial force.

  Another feature of the present invention is that the target damping coefficient setting means is configured to determine the total target damping coefficient of the entire electromagnetic shock absorber based on at least the vertical speed of the spring top and the approach / separation speed between the spring top and the spring bottom. The target damping coefficient is calculated so that the motor generates a force obtained by subtracting the inertial force of the motion conversion mechanism from the damping force generated by the electromagnetic shock absorber when this total target damping coefficient is set. There is to do.

  In the present invention, when setting the target damping coefficient, the total target damping coefficient of the entire electromagnetic shock absorber is calculated based on at least the vertical speed of the sprung part and the approach / separation speed of the sprung part and the unsprung part. For example, based on the skyhook damper theory, a value obtained by dividing the vertical speed Vu of the spring top by the approach / separation speed Vs between the spring top and the spring bottom, multiplied by the skyhook damping coefficient Cs (Cs · Vu / Vs). ) To calculate the total target damping coefficient for the entire electromagnetic shock absorber. Then, the target damping coefficient is calculated so that a force excluding the inertial force of the motion conversion mechanism is generated by the motor from the damping force generated by the electromagnetic shock absorber when the total target damping coefficient is set. If the calculated target damping coefficient is zero or more, the value is set as the target damping coefficient of the damping force generated by the motor. If the calculated target damping coefficient is a negative value, the target damping coefficient is set. Set to zero. Therefore, according to the present invention, the damping force generated by the motor can be more appropriately controlled, and the riding comfort can be further improved. The vertical speed of the upper part of the spring is the absolute speed at which the upper part of the spring moves in the vertical direction. The approach / separation speed between the upper part of the spring and the lower part of the spring is between the upper part of the spring and the lower part of the spring. The relative speed at which the distance changes, that is, the stroke speed. Accordingly, the target damping coefficient setting means includes detection means for detecting the vertical speed of the sprung portion and the stroke speed.

  In carrying out the present invention, for example, a charging circuit that branches from an external circuit and is connected to the power storage device may be provided, and a part of the generated current of the motor may be supplied to the power storage device to charge the power storage device. .

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 model figure of a suspension apparatus. It is a graph showing a damping force map. It is a graph showing an inertial force map. It is a graph showing the change of stroke displacement, damping force, and inertial force. It is a flowchart showing a damping force control routine. It is a characteristic view of a band pass filter. It is a graph showing a transfer characteristic.

  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 a system configuration of a vehicle suspension apparatus 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. And an electronic control unit 50 for controlling. 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 electronic control unit 50 is referred to as an 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, the upper side of the coil spring 20, that is, the vehicle body B side is referred to as “spring top”, and the lower side of the coil spring 20, that is, the wheel W side is referred to as “spring bottom”.

  The electromagnetic shock absorber 30 includes an outer cylinder 31 and an inner cylinder 32 that are arranged coaxially, a ball screw mechanism 35 that is a reduction gear provided inside the inner cylinder 32, and a rotor (illustrated) by the operation of the ball screw mechanism 35. An electric motor 40 (hereinafter simply referred to as the motor 40) that generates an induced electromotive force. In the present embodiment, a brushed DC motor is used as the 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 corresponds to the motion conversion mechanism of the present invention, and includes a ball screw 36 that rotates integrally with the rotor of the motor 40, and a female screw portion 38 that is screwed into a male screw portion 37 formed on the ball screw 36. And a ball screw nut 39 having 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 motor 40 is rotated. At this time, the motor 40 generates 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, thereby generating a generator. Work as.

  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 motor 40, and the ball screw 36 is inserted through a through hole 43 formed at the center thereof. The ball screw 36 is connected to the rotor of the 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 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 lower part of the spring (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 to absorb the impact received from the road surface. It enhances the ride comfort and supports 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, the motor 40 generates a resistance force to stop the rotation of the rotor when the rotor rotates and an induced electromotive force is generated in the electromagnetic coil and 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 in the electromagnetic coil of the 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 ECU 50 via an external circuit 100 provided outside the motor 40. The ECU 50 includes a microcomputer as a main part, and performs damping force control by adjusting the amount of current flowing through the 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 position by switching control of the external circuit 100 corresponding to the electromagnetic shock absorber 30. The ECU 50 includes a stroke sensor 61 that detects a vertical separation distance (hereinafter referred to as a stroke S) between the sprung portion and the unsprung portion at each wheel W position, and a vertical acceleration (sprung acceleration) of the sprung portion. A sprung acceleration sensor 62 that detects G) at the position of each wheel W is connected.

  Next, the external circuit 100 will be described with reference to FIG. When the motor 40 is rotated via the ball screw mechanism 35 due to the relative movement of the upper part of the spring (vehicle body B) and the lower part of the spring (wheel W), the external circuit 100 is driven by the induced electromotive force generated by the motor 40. Is a circuit that allows the generated current to flow between the current-carrying terminals (between the first terminal t1 and the second terminal t2), and when the induced electromotive force (induced voltage) of the motor 40 is large, It is also a circuit that charges a part of the power storage device 110 by flowing a part thereof. In the figure, Rm represents the internal resistance of the motor 40 and Lm represents the motor inductance. In this figure, Rm and Lm are described outside the display symbol M of the motor 40, but in reality, Rm and Lm exist between the first terminal t1 and the second terminal t2. .

  The external circuit 100 includes a wiring ab that electrically connects the first terminal t1 and the second terminal t2 of the motor 40 at points a and b, and a wiring cd that electrically connects the points c and d. I have. 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 series 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 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 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 motor 40 and outputs a detection signal representing the measured value ix including information indicating the energization direction to the 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 between the spring top and the spring bottom, the motor 40 generates an induced electromotive force in a direction corresponding to the rotation direction. For example, during the compression operation in which the upper part of the spring and the lower part of the spring approach each other and the electromagnetic shock absorber 30 is compressed, the first terminal t1 of the motor 40 becomes a high potential and the second terminal t2 becomes a low potential. On the contrary, when the electromagnetic shock absorber 30 is extended by separating the sprung portion and the unsprung portion, the second terminal t2 of the motor 40 becomes a high potential and the first terminal t1 becomes a low potential.

  Accordingly, during the compression operation in which the electromagnetic shock absorber 30 is compressed, the first connection path through 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 path dfea flows the generated current 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). In addition, the second resistor R2 becomes a resistance to the generated current flowing from the second terminal t2 to the first terminal t1, 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 a generated current flows through the electromagnetic coil of the motor 40, a power generation brake acts on the motor 40, thereby suppressing relative rotation between the ball screw nut 39 and the ball screw 36. That is, a damping force that suppresses the relative motion between the sprung portion and the unsprung portion 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.

  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 motor 40 increases as the motor rotation speed increases. When the induced electromotive force (induced voltage) exceeds the output voltage (storage voltage) of power storage device 110, a part of the power generated by motor 40 is regenerated in power storage device 110. For example, during the compression operation of the electromagnetic shock absorber 30, the generated current is divided in two directions at the point g, one flows through the first connection path 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 directly through the second connection path dfea, 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.

また、モータ４０で発生する力Ｆは、次式（２）にて表すこともできる。

ここで、Ｌ：ボールねじ３６のリード、Ｋｍ：モータ逆起電力定数、Ｋｔ：モータトルク定数、ｓ：ラプラス演算子である。 Here, the damping force generated in the motor 40 will be described. FIG. 4 shows a model of the suspension device of the present embodiment. In the figure, Mu: sprung mass, Md: unsprung mass, k1: tire spring constant, k2: spring constant of coil spring 20, C: damping coefficient of damping force generated by motor 40, x0: road surface position, x1: unsprung position, x2: sprung position, J: moment of inertia of the ball screw mechanism 35 (including the rotating portion of the motor 40), Rm: motor internal resistance, R: variable resistance, Lm: inductance. The force F generated by the motor 40 is expressed by the following equation (1).

The force F generated by the motor 40 can also be expressed by the following equation (2).

Here, L: lead of the ball screw 36, Km: motor counter electromotive force constant, Kt: motor torque constant, s: Laplace operator.

式（３）、（４）における右辺の第１項がボールねじ機構３５により発生した慣性力の項である。 The equation of motion of the suspension device can be expressed by the following equations (3) and (4).

The first term on the right side in the equations (3) and (4) is the term of inertia force generated by the ball screw mechanism 35.

式中のＣｓは、予め設定した係数（スカイフック減衰係数）である。この式から分かるように、トータル目標減衰係数Ｃｔは、ばね上部の上下速度（以下、ばね上速度と呼ぶ）に比例し、ばね上部のばね下部に対する相対速度（以下、ストローク速度と呼ぶ）に反比例する。また、トータル目標減衰係数Ｃｔは、ばね上部の動作方向と、ばね上部のばね下部に対する動作方向とが同じ方向であれば正の値をとり、ばね上部の動作方向と、ばね上部のばね下部に対する動作方向とが逆方向であれば負の値をとる。 On the other hand, the total target damping coefficient Ct of the damping force generated by the electromagnetic shock absorber 30 is obtained by the following formula (5) based on the skyhook damper theory.

Cs in the equation is a preset coefficient (skyhook attenuation coefficient). As can be seen from this equation, the total target damping coefficient Ct is proportional to the vertical speed (hereinafter referred to as sprung speed) of the sprung portion and inversely proportional to the relative speed of the sprung portion relative to the unsprung portion (hereinafter referred to as stroke speed). To do. The total target damping coefficient Ct takes a positive value if the direction of motion of the sprung portion is the same as the direction of motion of the sprung portion relative to the unsprung portion, and takes a positive value. If the movement direction is the opposite direction, a negative value is taken.

従って、モータ４０で発生させるべき減衰力は、電磁式ショックアブソーバ３０で発生させる減衰力からボールねじ機構３５（モータ４０の回転部分を含む）で発生する慣性力を除いた力となり、次式（７）にて表すことができる。尚、電磁式ショックアブソーバ３０の圧縮動作に対する減衰力を正の値にて示している。

この関係式から、モータ４０により発生させる減衰力の減衰係数を目標減衰係数Ｃとして次式（８）により求めることができる。

The force generated by the electromagnetic shock absorber 30 is the sum of the force generated by the motor 40 and the inertial force generated by the ball screw mechanism 35. Therefore, the following relational expression (6) is established.

Accordingly, the damping force to be generated by the motor 40 is a force obtained by subtracting the inertial force generated by the ball screw mechanism 35 (including the rotating portion of the motor 40) from the damping force generated by the electromagnetic shock absorber 30. 7). The damping force for the compression operation of the electromagnetic shock absorber 30 is indicated by a positive value.

From this relational expression, the damping coefficient of the damping force generated by the motor 40 can be obtained as the target damping coefficient C by the following formula (8).

  The electromagnetic shock absorber 30 of the present embodiment can generate a damping force, but cannot generate a propulsive force (negative damping force) generated in a direction opposite to the damping force. Therefore, when the target damping coefficient C has a negative value (C <0), the target damping coefficient C is set to zero (C = 0) so that the damping force is not generated as much as possible. FIG. 5 is a damping force map representing the relationship between the stroke speed and the damping force when the target damping coefficient C is set as described above. In the figure, the second quadrant and the fourth quadrant are regions where the target damping coefficient C is set to zero and the motor 40 cannot generate a damping force. Further, the hatched range in the first quadrant and the third quadrant is a range in which the damping force can be adjusted. On the other hand, the inertial force generated by the ball screw mechanism 35 is a value proportional to the stroke acceleration, as shown in FIG.

  Note that the deterioration in riding comfort due to the inertial force occurs in a frequency band equal to or higher than the frequency fs as shown in FIG. Therefore, in the present embodiment, when calculating the target damping coefficient C, the sensor values detected by the stroke sensor 61 and the sprung acceleration sensor 62 are bandpass filtered, and the sensor values subjected to the bandpass filtering are calculated. The stroke speed, the stroke acceleration, and the sprung speed are obtained by using this, and the target damping coefficient C is calculated from the above equation (8). In this case, as shown in FIG. 9, the pass frequency of the band pass filter is a band from a frequency fs (a value larger than the sprung resonance frequency and smaller than the unsprung resonance frequency) to a preset set frequency fe (for example, 100 Hz). Set to. Note that the target attenuation coefficient C may be bandpass filtered instead of bandpass filtering the sensor value.

  Next, the damping force control in consideration of the influence of the inertial force of the ball screw mechanism 35 will be described. As described above, during the compression operation of the electromagnetic shock absorber 30, the generated current flows through the first connection path cfeb, and the magnitude of the generated current is adjusted by the duty ratio of the first switching element SW1, thereby reducing the damping force. Can be controlled. At this time, the second resistor R2 causes no generated current to flow through the second switching element SW2 regardless of its duty ratio. Accordingly, during the compression operation, the first switching element SW1 is a control target for performing damping force control. Hereinafter, a switching element to be controlled is referred to as a main control target switching element, and a switching element that is not to be controlled is referred to as an auxiliary target switching element. On the other hand, during the extension operation of the electromagnetic shock absorber 30, a generated current flows through the second connection path dfea, and the damping force is controlled by adjusting the magnitude of the generated current with the duty ratio of the second switching element SW2. be able to. At this time, the first resistor R1 causes no generated current to flow through the first switching element SW1 regardless of its duty ratio. Accordingly, during the extension operation, the second switching element SW2 becomes the main control target switching element, and the first switching element SW1 becomes the auxiliary target switching element.

  As shown in FIG. 7, when the expansion / contraction state of the electromagnetic shock absorber 30 is switched, the sign (direction) of the damping force generated by the motor 40 is reversed, but with respect to the inertial force generated by the ball screw mechanism 35, The sign (direction) is not reversed. For example, when the electromagnetic shock absorber 30 is switched from the compression operation to the extension operation, the damping force is switched from positive to negative. At the time of switching, the inertia force has already generated a negative force. That is, an inertial force is generated in the same direction as the damping force after reversing the expansion / contraction operation. On the other hand, when the electromagnetic shock absorber 30 is switched from the expansion operation to the compression operation, the damping force is switched from negative to positive. At the time of switching, the inertia force has already generated a positive force. Also in this case, an inertial force is generated in the same direction as the damping force after the operation reversal.

  Further, as can be seen from the equations (5) and (8), the sign (positive / negative) of the target damping coefficient C of the motor 40 is reversed with a very high probability when the expansion / contraction state of the electromagnetic shock absorber 30 is switched. Therefore, if the value before the reversal of the expansion / contraction operation is set to a positive value, the target damping coefficient C is switched to zero after the reversal of the expansion / contraction operation, and the value before the reversal of the expansion / contraction operation is set to zero (the calculated value is negative). For example, it switches to a positive value after reversing the expansion / contraction operation. When the target damping coefficient C is set to zero, it is a situation where it is desired to generate a propulsive force in the direction opposite to the damping force. In this case, the inertial force interferes with the damping force control. To work. On the other hand, when the target damping coefficient is set to be positive, the inertial force can be effectively used as the damping force.

  In the damping force control, when the expansion / contraction operation is reversed in a state where the target damping coefficient C is set to zero (a state where the damping force is desired to be zero), a large damping force is required from the moment of the reversal. At this time, in the external circuit 100, the switching element that is the auxiliary target before the reversal of the expansion / contraction operation is switched to the main control target, but a large damping force cannot be generated from the motor 40 at the moment of switching. Therefore, in the present embodiment, the switching element to be assisted is turned on (duty ratio 100%) to stand by before reversing the expansion / contraction operation, and the electromagnetic shock absorber 30 is made large using the inertial force immediately after the reversal of the expansion / contraction operation. Generate a damping force.

  On the other hand, when the expansion / contraction operation is reversed in a state where the target damping coefficient C is set to a positive value (a state in which the damping force is to be generated), it is required not to generate the damping force from the moment of the reversal. The At this time, in the external circuit 100, the switching element that was the auxiliary target before the reversal of the expansion / contraction operation is switched to the main control target, but since the inertial force has already been generated, the inertial force is generated as a damping force when the expansion / contraction operation is reversed. It's easy to do. Therefore, in the present embodiment, the switching element to be assisted is turned off (duty ratio 0%) and placed on standby before reversing the expansion / contraction operation, and the inertial force is removed immediately after reversing the expansion / contraction operation.

  Such control of the switching elements SW1 and SW2 is executed by the ECU 50. Hereinafter, the damping force control process executed by the ECU 50 will be described with reference to the flowchart of FIG. The damping force control routine shown in FIG. 8 is stored as a control program in the ROM of the 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 from when the ignition switch is turned on to when it is turned off.

  When this damping force control routine is started, the ECU 50 reads the stroke S detected by the stroke sensor 61 in step S11, and reads the sprung acceleration G detected by the sprung acceleration sensor 62 in the following step S12. In the subsequent step S13, the ECU 50 performs a band pass filter process on the stroke S and the sprung acceleration G that are sensor values. In this case, a bandpass filter process with characteristics as shown in FIG. 9 is performed. The ECU 50 calculates the stroke speed by first-order differentiation of the filtered stroke S, and calculates the stroke acceleration by second-order differentiation of the stroke S. Also, the sprung speed is calculated by integrating the filtered sprung acceleration G.

  Subsequently, in step S14, the ECU 50 calculates the target attenuation coefficient C by using the equation (8). In subsequent step S15, it is determined whether or not the target attenuation coefficient C is a negative value. If the target attenuation coefficient C is a negative value (C <0), the target attenuation coefficient C is determined in step S16. Replace the value with zero (C = 0). On the other hand, if the target attenuation coefficient C is not a negative value, the process of step S16 is skipped. That is, the value of the target attenuation coefficient C is not changed. Thus, the final target attenuation coefficient C is set.

  Subsequently, in step S17, the ECU 50 determines whether or not the electromagnetic shock absorber 30 is in a compression operation based on the direction of the stroke speed. If the electromagnetic shock absorber 30 is performing compression (S17: Yes), it is determined in step S18 whether the target damping coefficient C is a positive value. As described above, since the target attenuation coefficient C is set to zero when the calculated value is negative, it is determined here whether the target attenuation coefficient C is a positive value or zero. When the target damping coefficient C is a positive value (S18: Yes), in step S19, in order to generate the damping force for the compression operation, the target current that is the target value of the generated current that flows through the first connection path cfeb. i1 * is calculated.

  The damping force generated by the motor 40 is a value obtained by multiplying the damping coefficient by the stroke speed Vs. Further, the generated current flowing in the motor 40 is obtained by converting the damping force into the motor torque and dividing the value by the motor torque constant Kt. Therefore, the target current i1 * flowing through the first connection path cfeb can be obtained by multiplying a value obtained by multiplying the target damping coefficient C by the stroke speed Vs by a preset proportionality 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 direction flows from the first terminal t1 to the second terminal t2 through the first connection path cfeb, 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 path dfea.

  Subsequently, in step S20, the ECU 50 reads a current ix detected by the current sensor 110 (hereinafter referred to as an actual current ix). Subsequently, in step S21, the actual current ix becomes equal to the target current i1 * by feedback control (for example, PID control) based on the deviation Δi (= i1 * −ix) between the target current i1 * and the actual current ix. The PWM control signal is output to the first switching element SW1 that is the main control target to adjust the duty ratio. Thereby, a power generation braking force corresponding to the target damping coefficient C is generated in the motor 40, and this power generation braking force acts as a damping force of the suspension device.

  Subsequently, in step S22, the ECU 50 outputs an off command signal (PMM control signal with a duty ratio of 0%) to the second switching element SW2 to be assisted. Accordingly, the second switching element SW2 is turned off, and the second connection path dfea is maintained in a blocked state. As described above, the process of step S22 is a process of waiting so that the damping force due to the inertial force can be instantaneously interrupted when the expansion / contraction operation is reversed (at the time of the next expansion operation).

  On the other hand, when it is determined in step S18 that the target damping coefficient C is zero, in order to prevent the generation of damping force, in step S23, an off command signal is sent to the first switching element SW1 that is the main control target. (PWM control signal with a duty ratio of 0%) is output to shut off the first connection path cfeb. Subsequently, in step S24, an ON command signal (PMM control signal with a duty ratio of 100%) is output to the second switching element SW2 to be assisted. Therefore, the second switching element SW2 is turned on, and the second connection path dfea is kept in a conductive state (a circuit resistance value is minimized). As described above, the process of step S24 is a process of waiting so that the damping force can be instantaneously generated using the inertia force when the expansion / contraction operation is reversed (at the time of the next extension operation).

  When the ECU 50 performs step S22 or step S24, the ECU 50 once ends the damping force control routine. Then, the damping force control routine is repeated at a predetermined short cycle. When such a process is repeated, if the expansion / contraction operation of the electromagnetic shock absorber 30 is reversed and the compression operation is switched to the expansion operation, “No” is determined in step S17. In this case, the ECU 50 determines in step S25 whether or not the target damping coefficient C is a positive value. If the target damping coefficient C is a positive value, in step S26, a target current i2 * that is a target value of the generated current flowing through the second connection path dfea is calculated in order to generate a damping force for the extension operation. . The target current i2 * is obtained by multiplying a value obtained by multiplying the target damping coefficient C by the stroke speed Vs by a proportional constant.

  Subsequently, the ECU 50 reads the actual current ix detected by the current sensor 110 in step S27, and in step S28, feedback control based on a deviation Δi (= i2 * −ix) between the target current i2 * and the actual current ix ( For example, the duty ratio is adjusted by outputting a PWM control signal to the second switching element SW2 that is the main control target so that the actual current ix becomes equal to the target current i2 * by PID control. Thereby, a power generation braking force corresponding to the target damping coefficient C is generated in the motor 40, and this power generation braking force acts as a damping force of the suspension device.

  In this case, immediately before the expansion / contraction operation of the electromagnetic shock absorber 30 is reversed, the target damping coefficient C is set to zero with a very high probability, and the second switching element SW2 is maintained in the ON state in step S24. Yes. Therefore, immediately after the expansion / contraction operation of the electromagnetic shock absorber 30 is reversed, the inertia force generated before that can be used as the damping force. That is, the direction of the damping force generated after the expansion / contraction operation of the electromagnetic shock absorber 30 is reversed is the same direction as the inertial force generated before that, and a large damping force is instantaneously generated immediately after the reversal of the expansion / contraction operation. Is required. Therefore, the second switching element SW2 is kept on in preparation for reversal of the expansion / contraction operation so that the generation of the damping force is not delayed, and the second switching element SW2 is switched from the on state to the duty ratio by current feedback when the expansion / contraction operation is reversed. By shifting to control, the inertial force can be used as a damping force immediately after reversal.

  Subsequently, in step S29, the ECU 50 outputs an off command signal (PMM control signal with a duty ratio of 0%) to the first switching element SW1 to be assisted. Accordingly, the first switching element SW1 is turned off, and the first connection path cfeb is maintained in a blocked state. The process of step S29 is a process of waiting so that the damping force and the inertial force can be instantaneously interrupted when the expansion / contraction operation is reversed (at the time of the next compression operation).

  On the other hand, when it is determined in step S25 that the target damping coefficient C is zero, in order to prevent the generation of a damping force, in step S30, an off command signal is sent to the second switching element SW2 that is the main control target. (PWM control signal with a duty ratio of 0%) is output to shut off the second connection path dfea. In this case, immediately before the expansion / contraction operation of the electromagnetic shock absorber 30 is reversed, since the second switching element SW2 is maintained in the OFF state in step S22, the generated current does not flow through the second connection path dfea. The generation of damping force can be reliably eliminated. In the subsequent step S31, the ECU 50 outputs an ON command signal (PMM control signal with a duty ratio of 100%) to the first switching element SW1 to be assisted. Therefore, the first switching element SW1 is turned on, and the first connection path cfeb is maintained in a conductive state (a state in which the circuit resistance value is minimized). The process of step S31 is a process of waiting so that the damping force can be instantaneously generated using the inertial force when the expansion / contraction operation is reversed (next compression operation).

  When the ECU 50 performs step S29 or step S31, the ECU 50 once ends the damping force control routine. Then, the damping force routine is repeated at a predetermined short cycle. When such a process is repeated, if the expansion / contraction operation of the electromagnetic shock absorber 30 is reversed and the expansion operation is switched to the compression operation, “Yes” is determined in step S17. In this case, the ECU 50 determines whether or not the target damping coefficient C is a positive value in step S18. If the target damping coefficient C is a positive value, the duty ratio of the first switching element SW1 that is the main control target is controlled in steps S19 to S21 in order to generate a damping force. Immediately before the inversion, the target damping coefficient C is set to zero with a very high probability, and the first switching element SW1 is maintained in the on state (S31). For this reason, a large damping force can be generated in the electromagnetic shock absorber 30 by using the inertial force generated before the extension operation is reversed as a damping force immediately after the extension operation is reversed.

  On the other hand, when it is determined in step S18 that the target damping coefficient C is zero, in order to prevent the generation of damping force, in step S23, an off command signal is sent to the first switching element SW1 that is the main control target. (PWM control signal with a duty ratio of 0%) is output to shut off the first connection path cfeb. In this case, immediately before the expansion / contraction operation of the electromagnetic shock absorber 30 is reversed, since the first switching element SW1 is maintained in the OFF state in step S29, the generated current does not flow through the first connection path cfeb. The generation of damping force can be reliably eliminated.

  According to the suspension device of the present embodiment described above, the total target damping coefficient of the entire electromagnetic shock absorber 30 is calculated from the skyhook damper theory, and is generated in the electromagnetic shock absorber 30 when the total target damping coefficient is set. The target damping coefficient C is calculated so that the motor 40 generates a force obtained by removing the inertial force generated by the ball screw mechanism 35 from the damping force. In this case, when the target damping coefficient C takes a negative value, the target damping coefficient C is replaced with zero. If the target damping coefficient C is a positive value, the motor 40 generates a target damping force by adjusting the duty ratio of the switching element to be controlled so that the generated current of the motor 40 becomes equal to the target current. At the same time, the switching element to be assisted is put on standby in an off state. Accordingly, it is possible to reliably prevent the generated current from flowing when the next expansion / contraction operation of the electromagnetic shock absorber 30 is reversed, so that no damping force is generated. On the other hand, when the target damping coefficient C is set to zero (when the calculated value of the target damping coefficient C is negative), the switching element that is the main control target is turned off so that no damping force is generated. At the same time, the switching element to be assisted is placed on standby in an on state. Accordingly, when the next expansion / contraction operation of the electromagnetic shock absorber 30 is reversed, the inertia force of the ball screw mechanism 35 can be used as a damping force, and a large damping force can be generated immediately after the reversal of the expansion / contraction operation. As a result, it is possible to suppress the ride comfort from being deteriorated by the inertia of the ball screw mechanism 35. In addition, since a single-phase brush motor is used as the motor 40 of the electromagnetic shock absorber 30, a simple system including the motor drive circuit (external circuit 100) can be configured to reduce the cost. be able to.

  Note that the processing of steps S14 to S16 performed by the ECU 50 in the damping force control routine corresponds to the target damping coefficient setting means of the present invention. Further, the processing of steps S19 to S21, step S23, steps S26 to S28, and step S30 performed by the ECU 50 in the damping force control routine corresponds to the damping force control means of the present invention. Further, the processing of step S22, step S24, step S29, and step S31 performed by the ECU 50 in the damping force control routine corresponds to the auxiliary control means of the present invention. The configuration including the electromagnetic shock absorber 30, the external circuit 100, the ECU 50, the stroke sensor 61, and the sprung acceleration sensor 62 of the present embodiment corresponds to the shock absorber device 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, in steps S24 and S31 of the damping force control routine, the auxiliary switching element is placed on standby at a duty ratio of 100%. Immediately after the expansion / contraction operation of the electromagnetic shock absorber 30 is reversed. As long as inertial force can be assisted, the duty ratio is not necessarily set to 100%, and may be set to a preset auxiliary duty ratio (≠ 0%).

  In the present embodiment, a brush motor is used as the motor 40 for generating a damping force. However, a brushless motor may be used. Further, a linear solenoid type direct acting motor may be used.

  DESCRIPTION OF SYMBOLS 10 ... Suspension main body, 20 ... Coil spring, 30 ... Electromagnetic shock absorber, 40 ... Motor, 50 ... Electronic control unit (ECU), 61 ... Stroke sensor, 62 ... On-spring acceleration sensor, 100 ... External circuit, 110 ... Power storage Device, 111 ... Current sensor, 121, 122 ... Voltage sensor, SW1, SW2 ... Switching element, R1, R2 ... Resistor, D1, D2, D3, D4 ... Diode, t1 ... First terminal, t2 ... Second terminal, B: body (upper spring), W: wheel (lower spring), cfeb: first connection path, dfea: second connection path.

Claims (3)

A motor and an operation conversion mechanism for converting the approach / separation operation between the spring upper part and the spring unsprung into the operation of the motor; An electromagnetic shock absorber that generates a damping force with respect to the approaching / separating operation between the sprung portion and the unsprung portion,
The flow of current from the first terminal that is one of the two terminals of the motor to the second terminal that is the other is allowed and the flow of current from the second terminal to the first terminal is prohibited. A first connection path and a second connection path in which current flow from the second terminal of the motor to the first terminal is allowed and current flow from the first terminal to the second terminal is prohibited And a first switching element provided in the first connection path, and a second switching element provided in the second connection path, wherein the first connection path is provided when the spring upper part and the spring lower part are moved closer to each other. An external circuit through which a generated current flows and a generated current flows in the second connection path during the separating operation between the sprung portion and the unsprung portion;
A target damping coefficient setting means for calculating a target damping coefficient of the damping force generated by the motor, and setting the target damping coefficient by replacing it with zero if the calculated target damping coefficient is a negative value;
In order to generate a damping force according to the target damping coefficient, the magnitude of the generated current flowing to the motor is controlled using the first switching element during the close operation of the sprung portion and the unsprung portion, Damping force control means for controlling the magnitude of the generated current that flows to the motor using the second switching element when the sprung portion and the unsprung portion are separated.
When the target damping coefficient set by the target damping coefficient setting means is a positive value, the second switching element is controlled to be in an off state during the approaching operation between the sprung portion and the unsprung portion, A shock absorber device comprising: auxiliary control means for controlling the first switching element to be in an OFF state when the sprung portion and the unsprung portion are separated.   The auxiliary control unit further turns on the second switching element when the target damping coefficient set by the target damping coefficient setting unit is zero when the upper and lower springs are approaching each other. 2. The shock absorber device according to claim 1, wherein the first switching element is controlled to be in an ON state when the state is controlled and the spring upper portion and the spring lower portion are separated. The target damping coefficient setting means includes
The total target damping coefficient of the entire electromagnetic shock absorber is calculated based on at least the vertical speed of the upper part of the spring and the approaching / separating speed between the upper part of the spring and the unsprung part, and when the total target damping coefficient is set, the electromagnetic 3. The shock absorber device according to claim 1, wherein a target damping coefficient is calculated so that a force obtained by removing an inertial force of the motion conversion mechanism is generated by the motor from a damping force generated by the type shock absorber. .

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