JP2011162049A - Shock absorber for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress respective vertical vibrations of an upper part and a lower part of a spring with an easy constitution without using a micro computer. <P>SOLUTION: A resistance value changeover signal output circuit 130 changes damping characteristics of an electromagnetic shock absorber 30 by using a switch signal output to a first resistance circuit 121 and a second resistance circuit 122. The resistance value changeover signal output circuit 130 sets an extension side and a compression side to the medium when inputting a sprung up signal and an unsprung up signal, sets the extension side to the hard and the compression side to the soft when inputting a sprung down signal and an unsprung up signal, sets the extension side to the soft and the compression side to the hard when inputting a sprung down signal and the unsprung up signal, and sets the extension side and the compression side to the medium when inputting the sprung down signal and the unsprung down signal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a shock absorber device for a wheel, and more particularly to an electromagnetic shock absorber that generates electric power by a close / separate operation between an upper part and an unsprung part to attenuate the close / separate action between the upper part and the unsprung part. The present invention relates to a shock absorber device provided.

  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. Such an electromagnetic shock absorber can make the damping force variable by controlling the generated current flowing in the motor. In the suspension device provided with a shock absorber with variable damping force, as shown in FIG. 5, when skyhook control (vibration damping control based on the skyhook damper theory) is performed on the sprung Mu and unsprung Md. Depending on the stroke state of the shock absorber AB, the direction of the required damping characteristic (direction of soft side or hard side) may be reversed between the sprung portion Mu and the unsprung portion Md. For example, during the extension operation in which the shock absorber AB is extended, when both the sprung portion M and the unsprung portion Md are raised, the required damping characteristic of the sprung portion Mu becomes hard (a large damping coefficient). As the lower Md, the required attenuation characteristic is soft (small attenuation coefficient). Therefore, there is a trade-off between required damping characteristics between the unsprung portion Mu and the unsprung portion Md.

JP2008-273356

  Therefore, in the conventional shock absorber device, the required damping force is calculated by a microcomputer using a complicated control theory so as to minimize such a trade-off. For this reason, it is necessary to mount a microcomputer in the damping force control device, and the configuration is complicated and expensive.

  The present invention has been made to cope with the above-described problems, and an object of the present invention is to make it possible to suppress the vertical vibrations of the spring top and the spring bottom with a simple configuration without using a microcomputer.

  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 portion and the spring unstressed when a generated current flows through the motor with the approaching / separating operation with And the second terminal is allowed to allow a current to flow from a first terminal, which is one of the two terminals of the motor, to a second terminal, which is the other of the two terminals of the motor. Current flow from the second terminal to the first terminal is allowed when the first connection path in which current flow from the first terminal to the first terminal is prohibited and the upper part of the spring and the lower part of the spring approach each other. Together with the above A second connection path in which current flow from one terminal to the second terminal is prohibited, a first resistance circuit provided in the first connection path, the electrical resistance value of which can be switched in three ways, and the second connection A motor external circuit having a second resistance circuit provided on the road and having a switchable electric resistance value in three ways, and when the operating direction in the vibration of the sprung resonance frequency region component of the sprung portion is upward. A sprung motion signal output circuit that outputs a sprung down signal when an up signal is output and when it is in the downward direction, and when the operating direction in the vibration of the unsprung resonance frequency region component of the lower spring is in the upward direction An unsprung operation signal output circuit that outputs an unsprung down signal when an up signal is output, and an output signal of the unsprung operation signal output circuit and an output signal of the unsprung operation signal output circuit are input. And Based on the output signal, in that a resistance value switching signal output circuit for outputting a switching signal for switching each resistance value with respect to the first resistor circuit and the second resistor circuit.

  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, a motor external circuit is provided outside the motor. In the motor external circuit, the current flow from the first terminal to the second terminal of the motor is allowed and the current flow from the second terminal to the first terminal is prohibited during the separation operation of the sprung part and the unsprung part. A current flow from the second terminal to the first terminal is allowed and a current flow from the first terminal to the second terminal is prohibited while the first connection path and the spring top and the spring bottom are approaching each other. 2 connection paths. The first connection path is provided with a first resistance circuit that can be switched between three types of electric resistance values: large, medium, and small. The second connection circuit is also provided with a second resistance circuit that can be switched between three types of electric resistance values: large, medium, and small. 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.

  Various motors can be used, but a motor having two terminals, for example, a brushed DC motor using a permanent magnet can be used. In addition, the first resistor circuit and the second resistor circuit may include three resistor elements and switch between them. For example, one fixed resistor provided in series with the first connection path and the second connection path The series switch element provided in series with the fixed resistor, the bypass path bypassing the fixed resistor, and the bypass switch element provided in the bypass path are provided to turn on / off the series switch element and the bypass switch element. By switching the combination of the OFF state, the electrical resistance values of the first connection path and the second connection path can be switched in three ways. The first resistance circuit and the second resistance circuit may be any circuit as long as the electrical resistance value can be switched in at least three ways, and those capable of changing the electrical resistance value steplessly can be used.

  In the present invention, by independently switching the electric resistance values of the two resistance circuits, the magnitude of the generated current flowing in the motor can be adjusted separately for the approaching operation and the separating operation of the spring top and the spring bottom. Can do. For example, if the electrical resistance value is increased, the generated current flowing in the motor can be reduced and the damping force generated by the electromagnetic shock absorber can be reduced. In this case, the damping force can be minimized by setting the electrical resistance value to infinity so that the generated current does not flow. Further, if the electric resistance value is reduced, the generated current flowing through the motor can be increased and the damping force generated by the electromagnetic shock absorber can be increased. In this case, the maximum damping force can be generated by setting the electric resistance value to zero. In addition, if the electrical resistance value is set to the middle, even if there is a trade-off in which the directionality of the required damping characteristic of the unsprung portion and the directionality of the required damping characteristic of the unsprung portion are reversed, it is intermediate between the two required damping characteristics. Damping force can be generated with a good damping characteristic.

  In the present invention, a sprung motion signal output circuit and an unsprung motion signal output circuit are provided to determine the required damping characteristic, and the first characteristic is set based on the output signals of both output circuits to set the damping characteristic. A resistance value switching signal output circuit that outputs a switching signal for switching each electric resistance value to the resistance circuit and the second resistance circuit is provided. The sprung motion signal output circuit outputs a sprung up signal when the motion direction in the vibration of the sprung resonance frequency region component of the sprung portion is upward, and outputs a sprung down signal when the motion direction is downward. On the other hand, the unsprung operation signal output circuit outputs an unsprung up signal when the operating direction in the vibration of the unsprung resonance frequency component of the unsprung portion is upward, and outputs an unsprung down signal when it is downward. To do. The sprung motion signal output circuit includes, for example, a sprung acceleration sensor that detects the vertical acceleration of the sprung portion, and extracts and integrates the signal component in the sprung resonance frequency region from the sprung acceleration sensor signal, thereby integrating the spring. The speed in the vertical direction in the vibration in the upper sprung resonance frequency region may be detected, and a signal corresponding to the operation direction may be output from this speed. Similarly, the unsprung operation signal output circuit includes, for example, an unsprung acceleration sensor that detects the vertical acceleration of the unsprung part, and extracts and integrates the signal component in the unsprung resonance frequency range from the unsprung acceleration sensor signal. Thus, the vertical speed of vibration in the unsprung resonance frequency region of the unsprung part may be detected, and a signal corresponding to the operation direction may be output from this speed. Here, the “operation direction” means the direction in which the sprung portion or the unsprung portion moves within a certain space (absolute space).

  Hereinafter, the direction of motion in the vibration of the sprung resonance frequency region component of the sprung portion upward is simply referred to as the movement of the sprung portion in the upward direction. That the upper part of the spring is simply moved downward, and that the movement direction in the vibration of the unsprung resonance frequency component of the unsprung part is upward. It is referred to as operating, and the fact that the operating direction in the vibration of the unsprung resonance frequency band component of the unsprung portion is downward is simply referred to as that the unsprung portion operates downward.

  Paying attention to the action of the sprung, if the sprung is moving upward, the reverse of the damping characteristic is hard (a large damping coefficient) if the sprung part is moved apart from the sprung part. Moreover, if the damping characteristic is soft (a damping coefficient is small) during the approaching operation between the sprung portion and the unsprung portion, the vibration of the sprung portion can be suppressed. Therefore, in this case, the electrical resistance value of the first resistance circuit may be set to be small, and the electrical resistance value of the second resistance circuit may be set to be large. On the other hand, when the sprung part is moving downward, the approaching action between the sprung part and the unsprung part is reversed so that the damping characteristic is softened when the sprung part is separated from the sprung part. If the damping characteristics are made hard at times, the vibration of the sprung portion can be suppressed. Therefore, in this case, the electrical resistance value of the first resistance circuit may be set large and the electrical resistance value of the second resistance circuit may be set small.

  On the other hand, paying attention to the operation of the unsprung part, if the unsprung part is moving upward, the damping characteristic is softened during the separation operation of the unsprung part and the unsprung part. If the damping characteristic is made hard during the approaching operation between the spring top and the spring bottom, the vibration of the spring bottom can be suppressed. Therefore, in this case, the electrical resistance value of the first resistance circuit may be set large and the electrical resistance value of the second resistance circuit may be set small. On the other hand, when the unsprung part is moving downward, the approaching action between the unsprung part and the unsprung part is reversed so that the damping characteristic is hard during the separating operation between the unsprung part and the unsprung part. If it is time, the vibration of the unsprung portion can be suppressed by making the damping characteristic soft. Therefore, in this case, the electrical resistance value of the first resistance circuit may be set to be small, and the electrical resistance value of the second resistance circuit may be set to be large. Hereinafter, this electrical resistance value to be set is referred to as a required electrical resistance value.

  Then, in the first resistance circuit and the second resistance circuit, when the required electrical resistance value of the sprung portion and the required electrical resistance value of the unsprung portion are different (one is large and the other is small), that is, a trade-off. If this occurs, the electrical resistance value may be set to medium. For example, when the sprung up signal and the unsprung up signal are output and when the sprung down signal and the unsprung down signal are output, In both of the separation operations, the required electrical resistance value at the upper part of the spring and the required electrical resistance value at the lower part of the spring are different. In such a case, the trade-off can be dealt with by setting the electric resistance value in the middle.

  Therefore, according to the present invention, it is possible to satisfactorily suppress vertical vibrations in both the sprung portion and the unsprung portion with a simple configuration without using a microcomputer.

  Another feature of the present invention is that the resistance value switching signal output circuit includes a case where the sprung motion signal output circuit outputs a sprung up signal and the unsprung motion signal output circuit outputs a sprung up signal, and When the sprung motion signal output circuit outputs a sprung down signal and the unsprung motion signal output circuit outputs a sprung down signal, the electrical resistance values of the first resistance circuit and the second resistance circuit are calculated. A switching signal to be set therein, and when the sprung motion signal output circuit outputs a sprung up signal and the unsprung motion signal output circuit outputs a sprung down signal, A switching signal for setting the electrical resistance value to be small and the electrical resistance value of the second resistance circuit to be set to be large is output, and the sprung motion signal output circuit outputs a sprung down signal to output the unsprung motion signal output circuit. When outputting the unsprung-up signal is to output a switching signal to set the electric resistance value of the first resistor circuit on a large set the electrical resistance of the second resistor circuit small.

  When the sprung motion signal output circuit outputs a sprung up signal and the unsprung motion signal output circuit outputs a sprung up signal, and the sprung motion signal output circuit outputs a sprung down signal and the unsprung motion signal. When the output circuit outputs an unsprung down signal, the directionality of the required damping characteristic differs between the sprung portion and the unsprung portion. Therefore, the resistance value switching signal output circuit outputs a switching signal for setting the electrical resistance values of the first resistance circuit and the second resistance circuit therein, respectively. Thereby, even if a trade-off occurs in the required damping characteristics between the sprung part and the unsprung part, it is possible to generate a damping force with a suitable damping characteristic in total.

  In addition, when the sprung motion signal output circuit outputs a sprung up signal and the unsprung motion signal output circuit outputs a sprung down signal, the directionality of the required damping characteristic is the same between the sprung portion and the unsprung portion. Become. Therefore, the resistance value switching signal output circuit outputs a switching signal for setting the electrical resistance value of the first resistance circuit to be small and setting the electrical resistance value of the second resistance circuit to be large. As a result, the damping characteristic becomes hard during the separating operation between the sprung portion and the unsprung portion, and the damping characteristic becomes soft during the approaching operation between the sprung portion and the unsprung portion.

  Also, when the sprung motion signal output circuit outputs a sprung down signal and the unsprung motion signal output circuit outputs a sprung up signal, the directionality of the required damping characteristic is the same between the sprung portion and the unsprung portion. Become. Therefore, the resistance value switching signal output circuit outputs a switching signal for setting the electrical resistance value of the first resistance circuit to be large and setting the electrical resistance value of the second resistance circuit to be small. As a result, the damping characteristic becomes soft during the separating operation between the sprung portion and the unsprung portion, and the damping characteristic becomes hard during the approaching operation between the sprung portion and the unsprung portion.

  As a result, vertical vibrations can be satisfactorily suppressed in both the upper and lower parts with a simple configuration.

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 a damping force control apparatus. It is a graph which shows the time change of a stroke. It is a model figure of a suspension apparatus.

  Hereinafter, a suspension device including a vehicle 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 Z, and damping of the suspension bodies 10FL, 10FR, 10RL, 10RR. A damping force control device 100FL, 100FR, 100RL, 100RR for controlling force is provided. The four sets of suspension bodies 10FL, 10FR, 10RL, 10RR, and the four sets of damping force control devices 100FL, 100FR, 100RL, 100RR are all the same. Call it. The wheels WFL, WFR, WRL, and WRR are simply referred to as wheels W.

  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 Z, absorbs the impact received from the road surface, enhances the ride comfort, and elastically supports the weight of the vehicle body Z. 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 Z 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 thus configured is attached to the vehicle body Z 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. Therefore, the motor 40 generates an induced electromotive force in the electromagnetic coil due to the rotation of the rotor, and a resistance force is generated to stop the rotation of the rotor when a generated current flows through the external circuit 110 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 motor 40 by the damping force control device 100 provided for each electromagnetic shock absorber 30.

  Next, the damping force control apparatus 100 will be described. The damping force control apparatus 100 includes a motor external circuit 110 (hereinafter simply referred to as an external circuit 110) for causing a generated current to flow through an electromagnetic coil by an induced electromotive force generated by the motor 40, and a resistance circuit provided in the external circuit 110. A resistance value switching signal output circuit 130 for outputting a switching signal for switching electrical resistance values 121 and 122; a sprung motion signal output circuit 140 for outputting a signal corresponding to the upper and lower motion directions of the sprung portion; And an unsprung operation signal output circuit 150 for outputting a signal corresponding to the operation direction. Each damping force control device 100 includes a sprung acceleration sensor 61 that detects the vertical acceleration (sprung acceleration Gu) of the sprung portion at the position of the wheel W on which the electromagnetic shock absorber 30 is provided, and a sprung portion. Is connected to an unsprung acceleration sensor 62 for detecting the vertical acceleration (unsprung acceleration Gd).

  The damping force control device 100 controls the damping force by adjusting the amount of current flowing through the electromagnetic shock absorber 30 by switching the electrical resistance value of the external circuit 110 according to the operating direction of the spring top and the spring bottom. That is, the damping coefficient of the electromagnetic shock absorber 30 is switched by switching the electric resistance value of the external circuit 110.

  When the motor 40 is rotated via the ball screw mechanism 35 due to the relative movement between the upper part of the spring (vehicle body Z) and the lower part of the spring (wheel W), the external circuit 110 is driven by the induced electromotive force generated by the motor 40. This is a circuit that allows a generated current to flow between the current-carrying terminals (between the first terminal t1 and the second terminal t2). 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 110 includes a wiring ab electrically connecting the first terminal t1 and the second terminal t2 of the motor 40 at points a and b, and a wiring cd electrically connecting 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. A first resistance circuit 121 and a second resistance circuit 122 are provided in series on the wiring cd. The connection point e where the first resistance circuit 121 and the second resistance circuit 122 are connected in the wiring cd is determined by the connection point f and the wiring ef where the first diode D1 and the second diode D2 are connected in the wiring ab. Electrically connected.

  The first resistor circuit 121 includes a first resistor R1 provided in series with the wiring ce, a first bypass path BL1 that connects both ends of the first resistor R1 and bypasses the first resistor R1, and a first resistor The switch element A is provided in the bypass path BL1 and the switch element B is provided in series with the first resistor R1. The second resistor circuit 122 includes a second resistor R2 provided in series with the wiring ed, a second bypass path BL2 that connects between both ends of the second resistor R2 and bypasses the second resistor R2, and a second resistor The switch element C is provided in the bypass path BL2 and the switch element D is provided in series with the second resistor R2. The first resistor R1 and the second resistor R2 are fixed resistors having electric resistance values of r1 ohms and r2 ohms, respectively. In this embodiment, transistors are used as the switch elements A to D. However, other semiconductor switch elements such as MOS-FETs can be used.

  Each of the switch elements A to D has a base connected to the resistance value switching signal output circuit 130 and is turned on when the switching signal output from the resistance value switching signal output circuit 130 is at a high level, and is turned off when the switching signal is at a low level. It is comprised so that. Therefore, the first resistance circuit 121 can be switched in three ways of the electric resistance value of zero, r1, and infinity by switching the on / off states of the switch elements A and B. Similarly, the second resistance circuit 122 can be switched between three types of electric resistance values of zero, r2, and infinity by switching on / off states of the switch elements C and D.

  Next, the operation of the external circuit 110 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, when the electromagnetic shock absorber 30 is extended by separating the upper and lower parts of the spring (when the electromagnetic shock absorber 30 extends), the first terminal t1 of the motor 40 becomes a high potential and the second terminal t2 becomes Low potential. On the other hand, during the compression operation (when the electromagnetic shock absorber 30 is compressed as the sprung portion approaches the unsprung portion) (when the electromagnetic shock absorber 30 contracts with time), the second terminal t2 of the motor 40 becomes a high potential and the first The terminal t1 becomes a low potential.

  Accordingly, during the extension operation in which the electromagnetic shock absorber 30 is extended, the first connection path cefb in which the generated current flows from the first terminal t1 to the second terminal t2 through the points c, e, f, and b. Is formed. In the compression operation in which the electromagnetic shock absorber 30 is compressed, the second connection path through which the generated current flows from the second terminal t2 to the first terminal t1 through the points d, e, f, and a. defa is formed. That is, the circuit through which the generated current flows is different between the expansion operation and the compression operation of the electromagnetic shock absorber 30. In this example, the first resistance circuit 121 serves as a resistance to the generated current flowing from the first terminal t1 to the second terminal t2, and functions as a current regulator that adjusts the magnitude of the generated current. The second resistance circuit 122 serves as a resistance to the generated current flowing from the second terminal t2 to the first terminal t1, and functions as a current regulator that adjusts the magnitude of the generated current.

  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 is generated that suppresses relative movement between the sprung portion and the unsprung portion. Further, the damping force can be adjusted by adjusting the magnitude of the generated current. Therefore, the damping coefficient for the expansion operation of the electromagnetic shock absorber 30 can be switched by switching the electric resistance value of the first resistance circuit 121, and the electromagnetic shock absorber 30 compression operation can be switched by switching the electric resistance value of the second resistance circuit 122. The attenuation coefficient for can be switched. Thereby, it is possible to independently adjust the damping force with respect to the extending operation direction and the compressing operation direction of the electromagnetic shock absorber 30. Further, such adjustment of the damping force can be performed independently by the damping force control device 100 for each wheel.

  The sprung motion signal output circuit 140 includes a band pass filter circuit 141, an integration circuit 142, and a Schmitt trigger circuit 143. A sprung acceleration sensor 61 is connected to the bandpass filter circuit 141. The bandpass filter circuit 141 inputs an output signal (voltage signal) corresponding to the sprung acceleration Gu output from the sprung acceleration sensor 61, and the sprung resonance frequency range (for example, centering on 1 Hz) from the input signal. Only the signal component in the set frequency range is allowed to pass. The output signal of the band pass filter circuit 141 is input to the integration circuit 142. The integration circuit 142 outputs a signal obtained by integrating the acceleration signal that has passed through the bandpass filter circuit 141. Therefore, the integration circuit 142 outputs a voltage signal corresponding to the vertical speed of vibration in the sprung resonance frequency region of the sprung portion. The output signal of the integration circuit 142 is input to the Schmitt trigger circuit 143. The Schmitt trigger circuit 143 outputs a high level signal H when the voltage of the input signal exceeds the first threshold, and outputs a low level signal L when the voltage falls below a second threshold lower than the first threshold. When it is between the second threshold value and the first threshold value, the immediately preceding output state is maintained. The Schmitt trigger circuit 143 outputs a high-level signal H when the vertical speed in the vibration of the sprung resonance frequency region component of the sprung portion is positive by setting the threshold value, and the sprung resonance frequency region component of the sprung portion. The low level signal L is output when the vertical speed of the vibration is negative. Therefore, the Schmitt trigger circuit 143 outputs the high level signal H when the operating direction in the vibration of the sprung resonance frequency component of the sprung portion is upward, and operates in the vibration of the sprung resonance frequency component of the sprung portion. A low level signal L is output when the direction is downward.

  The unsprung operation signal output circuit 150 includes a bandpass filter circuit 151, an integration circuit 152, and a Schmitt trigger circuit 153. An unsprung acceleration sensor 62 is connected to the bandpass filter circuit 151. The bandpass filter circuit 151 receives an output signal (voltage signal) corresponding to the unsprung acceleration Gd output from the unsprung acceleration sensor 62, and from the input signal, the unsprung resonance frequency range (for example, centering on 10 Hz). Only the signal component in the set frequency range is allowed to pass. The output signal of the band pass filter circuit 151 is input to the integration circuit 152. The integration circuit 152 outputs a signal obtained by integrating the acceleration signal that has passed through the band-pass filter circuit 151. Therefore, the integration circuit 152 outputs a voltage signal corresponding to the vertical speed of vibration in the unsprung unsprung resonance frequency region. The output signal of the integration circuit 152 is input to the Schmitt trigger circuit 153. The Schmitt trigger circuit 153 outputs a high level signal H when the vertical speed in the vibration of the unsprung unsprung resonance frequency component is positive, and outputs the high level signal H in the vibration of the unsprung unsprung resonance frequency component. When the speed is negative, the low level signal L is output. Therefore, the Schmitt trigger circuit 153 outputs a high level signal H when the operating direction in the vibration of the unsprung unsprung resonance frequency component is upward, and operates in the vibration of the unsprung unsprung resonance frequency component. A low level signal L is output when the direction is downward.

  In the following description, the operation directions of the sprung portion and the unsprung portion are related to the moving direction in the vibration of the resonance frequency range component unless otherwise specified. The signal output from the sprung motion signal output circuit 140 is referred to as a sprung motion signal, and the signal output from the unsprung motion signal output circuit 150 is referred to as a sprung motion signal. As for the sprung operation signal, a signal whose output voltage becomes high level is called a sprung up signal, and a signal whose output voltage becomes low level is called a sprung down signal. As for the unsprung operation signal, a signal whose output voltage is at a high level is called an unsprung up signal, and a signal at which the output voltage is at a low level is called an unsprung down signal.

  FIG. 4 is a graph showing the distance between the sprung portion and the unsprung portion, that is, a change in stroke. In this waveform, a wave with a large period represents vibration of an unsprung resonance frequency band component, and a wave with a small period represents vibration of an unsprung resonance frequency band component. Accordingly, the sprung motion signal indicating the motion direction of the sprung portion is switched at a slow cycle (1 Hz), and the unsprung motion signal indicating the motion direction of the sprung portion is switched at a fast cycle (10 Hz).

  The sprung motion signal output from the sprung motion signal output circuit 140 and the unsprung motion signal output from the unsprung motion signal output circuit 150 are output to the resistance value switching signal output circuit 130. The resistance value switching signal output circuit 130 includes four logic circuits 131, 132, 133, and 134. Each logic circuit 131, 132, 133, 134 receives a sprung motion signal and an unsprung motion signal. The first logic circuit 131 outputs a signal representing the logical product of the positive logic value of the sprung motion signal and the negative logic value of the unsprung motion signal. The second logic circuit 132 outputs a signal representing a negative logical value of a logical product of the negative logical value of the sprung motion signal and the positive logical value of the unsprung motion signal. The third logic circuit 133 outputs a signal representing the logical product of the negative logic value of the sprung motion signal and the positive logic value of the unsprung motion signal. The fourth logic circuit 134 outputs a signal representing a negative logic value of a logical product of the positive logic value of the sprung motion signal and the negative logic value of the unsprung motion signal.

  The output signal of the first logic circuit 131 is input to the base of the switch element A, the output signal of the second logic circuit 132 is input to the base of the switch element B, and the output signal of the third logic circuit 133 is The output signal of the fourth logic circuit 134 is input to the base of the switch element D. Therefore, the resistance value switching signal output circuit 130 is configured to be able to switch on / off states of the switch elements A, B, C, and D in accordance with the operating directions of the sprung portion and the unsprung portion.

  The damping force control apparatus 100 according to the present embodiment adjusts the damping force by switching the damping coefficient of the electromagnetic shock absorber 30 so as to satisfactorily suppress vertical vibration in both the upper and lower portions of the spring. The required damping characteristic (required damping coefficient) required for suppressing the vertical vibration differs depending on the expansion / contraction operation (during extension operation and compression operation) of the electromagnetic shock absorber 30 for each of the upper and lower springs.

When attention is paid only to the sprung portion, the required damping characteristics for suppressing the vibration of the sprung portion are as shown in Table (1). When the upper part of the spring is moving upward, the damping characteristic is hard (large damping coefficient) if the electromagnetic shock absorber 30 is extended (when the upper part of the spring is separated from the lower part of the spring). If the damping characteristics are soft (small damping coefficient) during the compression operation of the shock absorber 30 (at the time of the close movement between the spring top and the spring bottom), the vibration of the spring top can be satisfactorily suppressed. Further, when the sprung portion is moving downward, the damping characteristic is soft when the electromagnetic shock absorber 30 is extended, and the damping characteristic is hard when the electromagnetic shock absorber 30 is compressing. If it makes it, the vibration of a spring top can be suppressed favorably.

On the other hand, when attention is paid only to the unsprung portion, the required damping characteristics for suppressing the vibration of the unsprung portion are as shown in Table (2). When the unsprung part is moving upward, the damping characteristic is soft when the electromagnetic shock absorber 30 is extended, and the damping characteristic is hard when the electromagnetic shock absorber 30 is compressing. The vibration of the unsprung portion can be suppressed satisfactorily. Also, when the unsprung part is operating downward, the damping characteristic is hard when the electromagnetic shock absorber 30 is extended, and the damping characteristic is soft when the electromagnetic shock absorber 30 is compressing. If it makes it, the vibration of a spring top can be suppressed favorably.

  From these two tables, in order to dampen both the sprung portion and the unsprung portion, when the electromagnetic shock absorber 30 is extended, the sprung portion moves upward and the unsprung portion moves downward. It can be understood that the damping characteristic may be set to hard when the spring is moving, and the upper part of the spring is moved downward and the lower part of the spring is moved upward. . Further, when the electromagnetic shock absorber 30 is being compressed, when the upper part of the spring is moving upward and the lower part of the spring is moving downward, the damping characteristic may be set softly. It can be seen that it is sufficient to set the damping characteristic to hard when operating downward and the unsprung part operating upward.

  On the other hand, when the sprung portion and the unsprung portion are operating in the same direction, the required damping characteristics are different both when the electromagnetic shock absorber 30 is extended and compressed. Therefore, in the present embodiment, when there is a trade-off in the directionality of the required damping characteristic between the sprung part and the unsprung part, the required damping characteristic is set to a medium medium between hard and soft.

The damping force control apparatus 100 uses the sprung motion signal indicating the motion direction of the sprung portion and the unsprung motion signal indicating the motion signal of the sprung portion in order to cope with the three required damping characteristics in this way. From the combination, the attenuation characteristics of the electromagnetic shock absorber 30 are switched in three ways by switching the electric resistance values of the first resistance circuit 121 and the second resistance circuit 122. Table (3) shows the states (on / off states) of the switch elements A, B, C, and D set by the resistance value switching signal output circuit 130 from the combination of the sprung motion signal and the unsprung motion signal. ing.

  In the resistance value switching signal output circuit 130, when the sprung up signal and the unsprung up signal are input, the first logic circuit 131 and the third logic circuit 133 output a low level signal, and the second logic circuit 132 is output. The fourth logic circuit 134 outputs a high level signal. Accordingly, the switch elements A and C are turned off, and the switch elements B and D are turned on. For this reason, the electric resistance value of the first resistance circuit 121 is r1 ohms, and the electric resistance value of the second resistance circuit 122 is r2 ohms, and the damping characteristics are both during the expansion operation and the compression operation of the electromagnetic shock absorber 30. Become medium. The electrical resistance values r1 and r2 of the first resistor R1 and the second resistor R2 are set to have a medium attenuation characteristic.

  In addition, when the resistance value switching signal output circuit 130 inputs the sprung up signal and the unsprung down signal, the first logic circuit 131 and the second logic circuit 132 output a high level signal, and the third logic The circuit 133 and the fourth logic circuit 134 output a low level signal. Therefore, the switch elements A and B are turned on, and the switch elements C and D are turned off. For this reason, the electric resistance value of the first resistance circuit 121 is zero, the electric resistance value of the second resistance circuit 122 is infinite, and the damping characteristic is hard when the electromagnetic shock absorber 30 is extended, and when the compression operation is performed. Is soft.

  In addition, when the resistance value switching signal output circuit 130 inputs the sprung down signal and the unsprung up signal, the first logic circuit 131 and the second logic circuit 132 output a low level signal, and the third logic The circuit 133 and the fourth logic circuit 134 output a high level signal. Accordingly, the switch elements A and B are turned off, and the switch elements C and D are turned on. For this reason, the electrical resistance value of the first resistance circuit 121 is infinite, the electrical resistance value of the second resistance circuit 122 is zero, and the damping characteristic is soft during the expansion operation of the electromagnetic shock absorber 30 and during the compression operation. Is hard.

  In addition, when the resistance value switching signal output circuit 130 inputs the sprung down signal and the unsprung down signal, the first logic circuit 131 and the third logic circuit 133 output a low level signal, and the second logic The circuit 132 and the fourth logic circuit 134 output a high level signal. Accordingly, the switch elements A and C are turned off, and the switch elements B and D are turned on. For this reason, the electric resistance value of the first resistance circuit 121 is r1 ohms, and the electric resistance value of the second resistance circuit 122 is r2 ohms, and the damping characteristics are both during the expansion operation and the compression operation of the electromagnetic shock absorber 30. Become medium.

  As described above, when the directivity of the required damping characteristic is the same between the spring upper part and the spring lower part by switching the electric resistance value of the first resistor circuit 121 and the electric resistance value of the second resistor circuit 122, the common When a required attenuation characteristic (hard or soft) is set and a trade-off occurs in the directionality of the required attenuation characteristic, an intermediate attenuation characteristic (medium) is set.

  According to the suspension device of the present embodiment described above, the electrical resistance value of the external circuit 110 is switched by the control of the switch elements A, B, C, and D of the first resistance circuit 121 and the second resistance circuit 122, so that the electromagnetic type The damping characteristic of the shock absorber 30 can be switched. Moreover, since a motor with a DC brush is used as the motor 40, the direction of the generated current flowing in the external circuit is automatically switched according to the motor rotation direction, so that the electromagnetic shock absorber 30 is expanded and compressed. The energization paths (first connection path cefb, second connection path defa) of the external circuit 110 through which the generated current flows can be independently provided. Therefore, independent damping characteristics can be set for the expansion operation and the compression operation of the electromagnetic shock absorber 30. In other words, it is not necessary to always detect the operation direction (extension operation or compression operation) of the electromagnetic shock absorber 30 and perform control so that the damping characteristic is switched every time the operation direction is switched.

  In addition, if the direction of the required damping characteristics obtained based on the Skyhook damper theory is the same between the upper and lower springs, the common required damping characteristics (hard or soft) are set, and the required damping characteristics When there is a trade-off in the directionality, an intermediate damping characteristic (medium) is set, so that each vertical vibration between the spring top and the spring bottom can be satisfactorily suppressed. In addition, since the setting of the damping characteristic is switched by a combination of the sprung motion signal and the unsprung motion signal using a logic circuit (resistance value switching signal output circuit 130), a microcomputer is not required, and it is simple. The damping force control apparatus 100 can be configured with a simple configuration. Therefore, cost reduction can be achieved.

  The configuration comprising the electromagnetic shock absorber 30, the damping force control device 100, the sprung acceleration sensor 61, and the unsprung acceleration sensor 62 of the present embodiment corresponds to the vehicle shock absorber device of the present invention. The configuration comprising the sprung motion signal output circuit 140 and the sprung acceleration sensor 61 of the present embodiment corresponds to the sprung motion signal output circuit of the present invention. The configuration comprising the unsprung operation signal output circuit 150 and the unsprung acceleration sensor 62 of the present embodiment corresponds to the unsprung operation signal output circuit 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 first resistor circuit 121 and the second resistor circuit 122 provided in the external circuit 110 are each configured by one fixed resistor and two switch elements. The 1 resistance circuit and the second resistance circuit can employ various configurations as long as the electrical resistance values can be switched to three or more.

  DESCRIPTION OF SYMBOLS 10 ... Suspension main body, 20 ... Coil spring, 30 ... Electromagnetic shock absorber, 40 ... Motor, 61 ... Sprung acceleration sensor, 62 ... Unsprung acceleration sensor, 100 ... Damping force control apparatus, 110 ... Motor external circuit, 121 ... 1st resistance circuit, 122 ... 2nd resistance circuit, 130 ... Resistance value switching signal output circuit, 140 ... Sprung motion signal output circuit, 150 ... Unsprung motion signal output circuit, 141, 151 ... Band pass filter circuit, 142, 152 ... Integral circuit, 143,153 ... Schmitt trigger circuit, 131,132,133,134 ... Logic circuit, cefb ... First connection path, defa ... Second connection path, A, B, C, D ... Switch elements, R1 , R2 ... resistor, D1, D2 ... diode, t1 ... first terminal, t2 ... second terminal, Z ... vehicle body (upper spring), W ... wheel Spring bottom).

Claims (2)

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,
Provided outside the motor, current flow from a first terminal that is one of the two terminals of the motor to a second terminal that is the other of the two terminals of the motor is allowed when the sprung portion and the unsprung portion are separated. And the first connection path in which the flow of current from the second terminal to the first terminal is prohibited, and the current from the second terminal to the first terminal at the time of the close operation of the spring upper part and the spring lower part. A first connection path that allows flow and that prohibits the flow of current from the first terminal to the second terminal, and a first connection path that is provided in the first connection path and that can be switched in three ways. A motor external circuit having a resistance circuit and a second resistance circuit provided in the second connection path and having an electric resistance value switchable in three ways;
A sprung motion signal output circuit that outputs a sprung up signal when the operating direction in the vibration of the sprung resonance frequency region component of the sprung portion is an upward direction and outputs a sprung down signal when the direction is downward;
An unsprung operation signal output circuit that outputs an unsprung up signal when the operating direction in the vibration of the unsprung resonance frequency region component of the unsprung portion is upward, and that outputs an unsprung down signal when it is downward;
An output signal of the sprung motion signal output circuit and an output signal of the unsprung motion signal output circuit are input, and each electrical signal is supplied to the first resistance circuit and the second resistance circuit based on both output signals. A vehicle shock absorber device comprising: a resistance value switching signal output circuit that outputs a switching signal for switching a resistance value. The resistance value switching signal output circuit is
The sprung motion signal output circuit outputs a sprung up signal and the unsprung motion signal output circuit outputs a sprung up signal; and the sprung motion signal output circuit outputs a sprung down signal and When the unsprung operation signal output circuit outputs an unsprung down signal, it outputs a switching signal for setting the electrical resistance values of the first resistance circuit and the second resistance circuit, respectively,
When the sprung motion signal output circuit outputs a sprung up signal and the unsprung motion signal output circuit outputs a sprung down signal, the electric resistance value of the first resistance circuit is set to be small and the second Outputs a switching signal that sets the electrical resistance value of the resistance circuit to a large value.
When the sprung motion signal output circuit outputs a sprung down signal and the unsprung motion signal output circuit outputs a sprung up signal, the electrical resistance value of the first resistance circuit is set to be large and the second 2. The shock absorber device for a vehicle according to claim 1, wherein a switching signal for setting the electric resistance value of the resistance circuit to a small value is output.

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