JP2012166783A - Vehicular electric damper device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular electric damper device that can improve the riding comfort of the vehicle by optimally attenuating the vertical movement of wheels, is not heat-converted in an early stage, and can always be regenerated.SOLUTION: In the vehicular electric damper device, the relative vertical movement of the wheels with respect to a vehicle body are converted into rotational movement, the vertical movement is attenuated by rotating electric motors 35L, 35R, and the electric motors generate attenuation forces for attenuating the vertical movement of the wheels. The damper device for the vehicle comprises: a displacement speed detection part which calculates a displacement speed at which the wheels are vertically displaced; a drive current setting part which sets target drive currents of the electric motors on the basis of the displacement speed; and motor drive parts 106l, 106R which drive-control the electric motors on the basis of the target drive currents.

Description

  The present invention relates to a vehicle electric damper device provided in a vehicle suspension device.

  2. Description of the Related Art In recent years, in a vehicle suspension device, development of a technique for replacing a generally used hydraulic damper device (hydraulic shock absorber) with an electric damper device has been advanced. The electric damper device attenuates the vertical motion by converting the vertical motion of the wheel relative to the vehicle body into a rotational motion and rotates the electric motor, and the damping force for attenuating the vertical motion of the wheel. Will occur. As such an electric damper device, various devices are known (for example, see Patent Document 1).

  The electric damper device known from Patent Document 1 is such that a linear motion in the vertical direction is converted into a rotational motion by a rack and pinion mechanism to rotate the electric motor.

  By the way, the electric motor is rotated by the vertical movement of the wheel to generate an induced electromotive voltage. At this time, the electric motor can be used as a generator to return the current to the power source, so-called regeneration. A field effect transistor (FET) may be employed for the regeneration circuit. The field effect transistor causes a motor current corresponding to the induced electromotive voltage to flow due to its own resistance effect. As a result, the vertical movement of the wheel is attenuated by the braking force generated by the electric motor. That is, the electric motor becomes a DC generator. When the induced electromotive voltage exceeds the voltage of the power supply (for example, 12 V), a current corresponding to the excess voltage is regenerated in the power supply.

The displacement speed of the wheel in the vertical direction always fluctuates. For example, when the electric motor generates an induced electromotive voltage, the magnitude of the induced electromotive voltage varies according to the displacement speed, that is, the rotational speed of the electric motor.
However, in the electric motor, various mechanical internal losses (also referred to as mechanical loss and viscous resistance) occur, such as frictional resistance of the rotating shaft when the rotor rotates. The loss torque due to internal loss is called viscous torque. Further, the electric motor also has a loss due to the inertia of the rotor of the electric motor itself. The loss torque due to inertia is called inertia torque.
The rotational speed of the electric motor is largely delayed by the influence of viscous torque and inertia torque with respect to the displacement speed at which the wheel is displaced in the vertical direction. As a result, the braking force resulting from the induced electromotive voltage fluctuates, and the riding comfort of the vehicle decreases. For this reason, in order to attenuate the vertical movement of the wheel optimally, at least motor control corresponding to the displacement speed in the vertical direction of the wheel is required.

  Further, even if a direct current resistor using a field effect transistor is connected to the electric motor, current consumption is eventually converted into heat and cannot be accurately controlled. Furthermore, when the induced electromotive force generated in the electric motor exceeds the voltage of the power supply, simply returning the regenerative current corresponding to the excess to the power supply reduces the frequency of returning the regenerative current to the power supply, and the regenerative efficiency is improved. bad.

JP 2005-256922 A

  The present invention provides a technology for an electric damper device for a vehicle that can improve the ride comfort of the vehicle by optimally attenuating the vertical movement of the wheel and that is not promptly converted into heat and that can be always regenerated. The issue is to provide.

  According to the first aspect of the present invention, the vertical motion of the wheel is attenuated by converting the relative vertical motion of the wheel to the vehicle body into a rotational motion and rotating the electric motor, and the vertical motion of the wheel is attenuated. An electric damper device for a vehicle in which the electric motor generates a damping force for detecting a displacement speed at which the wheel is displaced in the vertical direction, and the electric motor based on the displacement speed It has a drive current setting part which sets the target drive current of a motor, and a motor drive part which drives and controls the electric motor with a pulse width modulation signal based on the target drive current.

  According to a second aspect of the present invention, in the first aspect, the displacement speed detection unit is calculated from a value of a displacement amount detection unit that detects a displacement amount by which the wheel is displaced in the vertical direction, and the displacement amount and the displacement speed are calculated. A displacement direction determination unit that determines whether the displacement direction of the wheel is up or down based on at least one of the values, and the drive current setting unit includes a case where the displacement direction is an upward direction and a case of a downward direction In this case, the target drive current is set to a different value.

  According to a third aspect of the present invention, in the first or second aspect, the apparatus includes a displacement acceleration calculation unit that calculates a displacement acceleration in a vertical direction of the wheel from the value of the displacement speed, and the drive current setting unit includes: The target drive current value is corrected in accordance with at least one of a displacement speed and a displacement acceleration.

  According to a fourth aspect of the present invention, in the first aspect, the motor driving unit includes at least two field effect transistors to form one set of arms, and at least two sets of arms to form a bridge circuit. The effect transistor is driven by the pulse width modulation signal and has at least a motor regeneration mode.

In the first aspect of the invention, the displacement speed at which the wheel is displaced in the vertical direction is detected by the displacement speed detector, and the target drive current of the electric motor is set by the drive current setting section based on the displacement speed, Based on this, the motor drive unit controls the drive of the electric motor.
Since the electric motor is driven by the target drive current based on the displacement speed, the electric motor can improve the response of the motor to attenuate the vertical movement of the wheel, and generates an optimum damping force. Therefore, the ride quality of the vehicle can be improved by optimally attenuating the vertical movement of the wheels.
Moreover, since the electric motor is driven by the pulse width modulation signal, only the ON drive signal or the OFF drive signal is used, and the intermediate resistance state between the ON drive and the OFF drive is not used. Because it is not affected by heat, accurate control is possible.

  In the invention which concerns on Claim 2, the displacement direction judgment part judges the displacement direction of a wheel based on the value of at least one of a displacement amount and a displacement speed. Then, the drive current setting unit sets the target drive current to a different value depending on whether the wheel displacement direction is upward or downward. For this reason, the target drive current can be set to a different value and the damping force by the electric motor can be changed depending on the displacement direction of the wheel (that is, the expansion / contraction direction of the vehicle electric damper device). Accordingly, the electric motor can be finely adapted to the vertical movement of the wheel, and the vertical movement can be attenuated more optimally. Therefore, the riding comfort of the vehicle can be further improved.

In the invention which concerns on Claim 3, the displacement acceleration calculating part calculates | requires the displacement acceleration of a wheel from the value of displacement speed. Then, the value of the target drive current is corrected by the drive current setting unit according to the displacement speed and the displacement acceleration.
According to the displacement speed and displacement acceleration, the viscous torque corresponding to the mechanical internal loss of the electric motor itself and the inertia torque corresponding to the loss due to the inertia of the rotor of the electric motor itself change. The value of the target drive current can be corrected according to these loss torques (viscous torque and inertia torque). Since the electric motor is driven by the corrected target driving current, the electric motor responds quickly to the vertical movement of the wheel and generates an optimum damping force to attenuate the vibration of the vehicle. Therefore, the vertical movement of the wheel can be attenuated more optimally, and the riding comfort of the vehicle can be further improved. In particular, the effect is great when the inertia torque of the electric motor increases when the vehicle travels on a rough road surface or the like.

  In the invention according to claim 4, a bridge circuit is configured by a field effect transistor, and the field effect transistor is driven by a pulse width modulation signal, whereby efficient driving with less heat generation can be achieved and the inductance of the electric motor can be achieved. Therefore, even if the induced electromotive voltage of the electric motor is sufficiently smaller than the voltage of the power source, it can be converted to an AC voltage higher than the voltage of the power source, and the regeneration efficiency can be improved.

1 is a schematic view of a vehicle including a vehicle suspension device according to the present invention. FIG. 2 is a cross-sectional view of the left vehicle electric damper device shown in FIG. 1. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. FIG. 2 is a schematic diagram of a left displacement amount detection unit illustrated in FIG. 1. FIG. 2 is a control circuit diagram of the left and right electric damper devices shown in FIG. 1. FIG. 6 is a circuit diagram of a bridge circuit in the motor driving unit shown in FIG. 5. 6 is a control flowchart showing an example of an electric motor drive control routine executed by the control circuit shown in FIG. 5. It is a control flowchart which shows the routine of the motor normal rotation control shown by FIG. It is explanatory drawing of the reference drive current map at the time of the motor normal rotation shown by FIG. It is explanatory drawing of the vehicle speed correction map which calculates | requires the vehicle speed correction coefficient according to the vehicle speed shown by FIG. It is explanatory drawing which shows the normal rotation drive control example of the bridge circuit shown by FIG. It is a control flowchart which shows the routine of the motor reverse rotation control shown by FIG. It is explanatory drawing of the reference drive current map at the time of the motor reverse rotation shown by FIG. It is explanatory drawing which shows the example of reverse drive control of the bridge circuit shown by FIG.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
FIG. 1 schematically shows a vehicle equipped with the vehicle suspension device of the present invention as viewed from the back. The vehicle 10 includes a pair of left and right vehicle suspension devices 20L and 20R on the vehicle body 11. The vehicle body 11 has damper housings 11a and 11a on the upper left and right sides. That is, the damper housings 11 a and 11 a are part of the vehicle body 11. The left and right vehicle suspension devices 20L and 20R are employed as a front suspension or a rear suspension of the vehicle 10 (automobile), and the left and right wheels 25L and 25R are suspended from the vehicle body 11.

  The left vehicle suspension device 20L is, for example, a double wishbone suspension including an upper arm 21 and a lower lower arm 22, a wheel support member 23, and an electric damper device 30L for the vehicle.

  The upper arm 21 and the lower arm 22 are connected to the side of the vehicle body 11 so as to be able to swing up and down. The wheel support member 23 is composed of a knuckle for rotatably supporting the wheel 25L, and is connected to the distal end portion of the upper arm 21 and the distal end portion of the lower arm 22 so as to be able to swing up and down. The left vehicle electric damper device 30L (hereinafter, simply referred to as “electric damper device 30L”) is stretched between the damper housing 11a and the lower portion of the wheel support member 23 and acts on the wheel 25L in the vertical direction. It is intended to attenuate the vibrations.

  The right vehicle suspension device 20R has the same configuration as that of the left vehicle suspension device 20L except that it is bilaterally symmetric. The right vehicle electric damper device is denoted by reference numeral 30R. Moreover, 35L is attached | subjected about the left electric motor, and 35R is attached | subjected about the right electric motor.

  FIG. 2 shows a cross-sectional structure of the left vehicle electric damper device 30L shown in FIG. FIG. 3 shows a cross section taken along line 3-3 of FIG. As shown in FIGS. 2 and 3, the electric damper device 30 </ b> L includes a cylinder 31, a rod 32, a rack and pinion mechanism 33, a rod guide 34, an electric motor 35 </ b> L, a coil spring 36, and a dust boot 37.

  The cylinder 31 is a vertically elongated member, and includes a first cylinder 41 and a second cylinder 42. The first and second cylinders 41 and 42 are cylinders arranged coaxially with each other. The first cylinder 41 has a bottom plate 41a at one end, and the other end is open. The bottom plate 41 a has a dish-shaped insulator 43 and mounting bolts 44. The mounting bolt 44 serves as a mounting portion on the cylinder side. Hereinafter, the mounting bolt 44 is referred to as a “cylinder side mounting portion 44”. The second cylinder 42 is open at both ends. One end of the second cylinder 42 is fixed to the open end of the first cylinder 41. The other end of the second cylinder 42 has a bearing 45 (sliding bearing) that supports the rod 32 slidably therein.

  The rod 32 is composed of an elongated round bar arranged coaxially with the cylinder 31, and is slidably accommodated in the cylinder 31, and one end portion 32a projects from the cylinder 31 (from the other end of the second cylinder 42). The protruding one end portion 32a has an annular connecting portion 47 at the tip. Hereinafter, the connecting portion 47 is referred to as a “rod-side mounting portion 47”.

  As shown in FIGS. 1 and 2, the cylinder-side attachment portion 44 is attached to the damper housing 11a. The rod side mounting portion 47 is swingably attached to the lower portion of the wheel support member 23. The rod-side attachment portion 47 may be attached to the lower arm 22 so as to be swingable. In this way, the cylinder 31 is attached to the vehicle body 11, and the one end 32 a of the rod 32 is attached to the wheel support member 23.

  Incidentally, the first cylinder 41 has a bump stopper 48 at the bottom. The bump stopper 48 is made of an elastic material such as rubber and gently interferes when the end surface of the rod 32 approaches the bottom plate 41a of the cylinder 31.

  As shown in FIGS. 2 and 3, the rack and pinion mechanism 33 includes a rack 51 and a pinion 52 that meshes with the rack 51, and is disposed inside the first cylinder 41. The rod 32 has a rack 51. A pinion shaft 53 having a pinion 52 extends in a direction perpendicular to the rod 32, and both ends thereof are rotatably supported by the first cylinder 41 via bearings 54 and 55.

  As described above, the rod 32 is an elongated round bar (cylindrical member). That is, the rod 32 is a member having a circular cross-sectional shape when viewed from the longitudinal direction of the rod. The rack 51 is formed on the outer peripheral surface of the rod 32 having a circular cross section.

  By the way, the rack and pinion mechanism 33 receives a large output from the electric motor 35L, and converts it into a rotational motion at a high speed when the wheel 25L moves up and down at a high speed. Even in this case, the meshing state of the rack 51 and the pinion 52 needs to be reliably maintained. For this reason, each tooth width of the rack 51 and the pinion 52 is set large. That is, the rod 32 has a rack 51 having a large tooth width.

In order to have the rack 51 having a large tooth width on the rod 32, it is conceivable that the cross-sectional shape of the rod 32 (cross-sectional shape when the rod 32 is viewed from the longitudinal direction) is rectangular. However, in the rod 32 having a rectangular cross section, a corner portion on the back surface that does not have the rack 51 protrudes. In this case, the first cylinder 41 that houses the rod 32 must be large.
On the other hand, in the present invention, since the rack 51 is provided on the outer peripheral surface of the rod 32 having a circular cross section, the first cylinder 41 that houses the rod 32 can be reduced in size.

  The rod guide 34 applies a preload to the rack 51 against the pinion 52 by pressing the back surface of the elongated cylindrical rod 32 against the pinion 52. The rod guide 34 includes a contact member 61, a guide portion 62, a compression coil spring 63, an adjustment bolt 64, and a lock nut 65, and is provided in the first cylinder 41.

  The guide portion 62 supports the rod 32 from the opposite side of the rack 51 and guides the rod 32 so as to be slidable in the axial direction. The abutting member 61 is interposed between the rod 32 and the guide portion 62 and directly contacts the outer peripheral surface of the rod 32 to reduce slide resistance. The contact member 61 is made of a material having wear resistance and low frictional resistance. The adjustment bolt 64 adjusts the force pressing the guide portion 62 toward the rod 32, and pushes the guide portion 62 toward the rod 32 via the compression coil spring 63 (adjustment spring 63). There is a slight gap between the guide portion 62 and the adjustment bolt 64 in the adjustment direction of the adjustment bolt 64. The lock nut 65 positions the adjustment bolt 64.

According to the lock guide 34, the adjustment bolt 64 screwed into the first cylinder 41 is used to push the guide portion 62 with an appropriate pressing force through the compression coil spring 63, so that the guide portion 62 preloads (preloads) the rack 51. ) And the rack 51 can be pressed against the pinion 52. That is, by pushing the rack 51 in the meshing direction with respect to the pinion 52, the play (backlash) of meshing between the pinion 52 and the rack 51 can be set to zero or the minimum. Thereby, even if it is a vertical motion like the fine vibration of the rod 32, it can be reliably converted into the rotation of the pinion 52, and a damping force can be generated in the electric motor 35L.
Further, the lock guide 34 can slidably support the rod 32 while restricting the movement of the rod 32 in the longitudinal direction of the pinion shaft 53.

  The electric motor 35L is composed of, for example, a DC motor with a brush, and is attached to the outer peripheral portion of the first cylinder 41. An output shaft 35 a (motor shaft 35 a) of the electric motor 35 </ b> L is disposed coaxially with the pinion shaft 53 and is connected to one end of the pinion shaft 53. As the configuration of the connection, for example, there is a connection by serration as shown in FIG. 3 or a connection by coupling (not shown). In this way, the motor shaft 35a is connected to the pinion 52. The configuration in which the motor shaft 35a is connected to the pinion 52 includes “a configuration in which the pinion 52 is formed on the motor shaft 35a”.

  As shown in FIG. 2, the coil spring 36 is a resilient member for absorbing the vibration and impact force in the vertical direction while supporting the weight of the vehicle body acting on the wheel 25L (see FIG. 1). The coil spring 36 is disposed coaxially with the rod 32 at a position away from the electric motor 35L in the longitudinal direction of the rod 32. Both end portions 36 a and 36 b of the coil spring 36 are individually attached to the cylinder 31 and the rod 32.

More specifically, the second cylinder 42 has a first spring receiving seat 71 fixed to a substantially middle portion in the longitudinal direction. The rod 32 has a second spring seat 72 fixed in the vicinity of the rod side mounting portion 47.
The coil spring 36 is disposed so as to surround the second cylinder 42 and the rod 32 protruding from the second cylinder 42. The coil spring 36 is interposed between the first spring receiving seat 71 and the second spring receiving seat 72 and thereby urges the cylinder 31 and the rod 32 in the axial direction and in a direction away from each other.

  The dust boot 37 is a member that covers and seals the open end of the second cylinder 42 and the rod 32 protruding from the open end, and is extendable in the axial direction of the rod 32. By sealing the inside of the cylinder 31 from the outside with the dust boots 37, it is possible to prevent the intrusion of foreign matter and to keep the inside of the cylinder 31 fluid-tight.

By the way, as shown in FIG. 1, the left and right electric damper devices 30L, 30R have displacement amount detection units 80L, 80R, respectively. The left displacement amount detector 80L detects a displacement amount St (not shown) in which the wheel 25L is displaced in the vertical direction relative to the vehicle body 11. The displacement amount St is also referred to as a stroke amount St. The left displacement amount detection unit 80L indirectly detects the displacement amount St of the left wheel 25L, for example, by detecting a swing angle at which the lower arm 22 swings up and down.
Since the right displacement amount detection unit 80R has the same configuration as the left displacement amount detection unit 80L, the same reference numerals are given and description thereof is omitted.

  Hereinafter, the left displacement amount detection unit 80L will be described in detail. FIG. 4 schematically shows the left displacement detector 80L shown in FIG. As shown in FIGS. 1 and 4, the displacement amount detection unit 80 </ b> L includes a housing 81, a swing rod 82, a joint portion 83, a transmission mechanism 84, and a potentiometer 85.

  The housing 81 is attached to the vehicle body 11. The swing rod 82 is attached to the housing 81 so as to be swingable up and down. The joint portion 83 is screwed into the tip of the swing rod 82 and is attached to the lower arm 22 so as to be able to swing up and down. The transmission mechanism 84 transmits the swing motion of the swing rod 82 to the potentiometer 85 and is built in the housing 81.

  The potentiometer 85 detects the swing angle of the swing rod 82 and is built in the housing 81. The potentiometer 85 includes a resistance element 85a and a sliding element 85b. One end of the resistance element 85 a is connected to a constant voltage power source 87 through a fixed resistor 86. The terminal voltage of the constant voltage power supply 87 is constant. The other end of the resistance element 85a is connected to the ground via a fixed resistor 88. The sliding element 85b can slide on the resistance element 85a in accordance with the swing motion of the swing rod 82. A voltage signal obtained by the sliding element 85b (a detection signal from the displacement detection unit 80L) is output from the output terminal 85c. In this way, the displacement amount detection unit 80L can detect the displacement amount St of the wheel 25L illustrated in FIG. 1 via the wheel support member 23 and the lower arm 22.

  Next, control circuits for the left and right electric damper devices 30L and 30R will be described based on FIG. 5 with reference to FIG. FIG. 5 shows control circuits for the left and right electric damper devices 30L and 30R shown in FIG. As shown in FIG. 5, the control circuit includes a battery 101 (DC power supply 101), a main switch 102, a main relay 103, a vehicle speed detection unit 104, two left and right displacement amount detection units 80L and 80R, a control unit 105, and two left and right control units. It consists of motor drive units 106L and 106R.

  The main switch 102 is composed of, for example, an ignition switch. The main relay 103 includes, for example, a normally open contact 103a connected to the battery 101 and an exciting coil 103b that closes the normally open contact 103a. The vehicle speed detection unit 104 is a sensor that detects the traveling speed Vs (vehicle speed Vs) of the vehicle 10. The two left and right displacement amount detection units 80L and 80R are displacement amount detection units individually provided in the electric damper devices 30L and 30R. The two left and right motor drive units 106L and 106R drive the electric motors 35L and 35R individually provided in the electric damper devices 30L and 30R based on the control signal of the control unit 105, respectively.

  The control unit 105 will be described in more detail. The control unit 105 receives the respective detection signals from the vehicle speed detection unit 104, the left and right displacement detection units 80L and 80R, and the left and right current detection units 124L and 124R (details will be described later), and receives two left and right motor drive units. The left and right electric motors 35L and 35R are driven and controlled by controlling 106L and 106R. The control unit 105 includes a one-pulse generation circuit 111, an input interface circuit 112, a control circuit 113, an output interface circuit 114, a watchdog timer circuit 115, and a relay drive circuit 116.

  The one-pulse generation circuit 111 generates a one-pulse signal to the control circuit 113 when the main switch 102 is turned on, and includes, for example, a differentiation circuit. The control circuit 113 is composed of, for example, a microcomputer, receives an input signal via the input interface circuit 112, and issues a control signal via the output interface circuit 114. The watchdog timer circuit 115 monitors a signal with a fixed period received from the control circuit 113, and generates an abnormal signal when the signal is interrupted or when the signal period is disturbed to stop the control circuit 113. The relay drive circuit 116 receives the control signal from the control circuit 113, turns on the main relay 103, and turns off the main relay 103 when an abnormality is detected.

The left motor drive unit 106L includes a gate drive circuit 121, a bridge circuit 122, a booster circuit 123, and a left current detection unit 124L.
The gate drive circuit 121 drives and controls the bridge circuit 122 based on a control signal received from the control circuit 113 via the output interface circuit 114. The bridge circuit 122 is driven by supplying a drive current to the left electric motor 35L.

The booster circuit 123 boosts the voltage of the power supplied from the battery 101 to generate a voltage that is approximately twice as high as the voltage of the battery 101 and supplies it to the gate drive circuit 121. As a result, the gate drive circuit 121 can drive the bridge circuit 122 more quickly and reliably by issuing a high-voltage drive signal to the bridge circuit 122. Accordingly, the response of the damper control by the left electric motor 35L is enhanced. The booster circuit 123 is composed of, for example, a combination of a transistor, a resistor, and a capacitor.
The left current detection unit 124L detects an actual drive current Id (actual current Id) supplied from the bridge circuit 122 to the left electric motor 35L and emits it to the control unit 105. For example, a Hall element or a resistor Consists of.

  The right motor drive unit 106R has substantially the same configuration as the left motor drive unit 106L, and includes a gate drive circuit 121, a bridge circuit 122, a booster circuit 123, and a right current detection unit 124R. The right current detection unit 124R detects the actual drive current Id (actual current Id) supplied from the bridge circuit 122 to the right electric motor 35R and issues the detected drive current Id to the control unit 105.

  FIG. 6 shows a specific circuit of the bridge circuit 122 in the left motor drive unit 106L shown in FIG. The bridge circuit 122 is a so-called H bridge circuit in which four switching elements 131 to 134 formed of N-channel enhancement type field effect transistors (FETs) are connected in an H shape. Since a brushed DC motor is employed as the left electric motor 35L, the bridge circuit 122 having such a configuration is used. That is, two field effect transistors 131 and 132 are combined to form one set of arms, and the other two field effect transistors 133 and 134 are combined to form another set of arms. The bridge circuit 122 is configured by a pair of arms.

  Note that the motor driving unit 106L may be configured with at least two field effect transistors to form one set of arms and at least two sets of arms to form the bridge circuit 122. For example, when a three-phase brushless motor is adopted as the left electric motor 35L, the bridge circuit 122 needs to use three sets of arms.

  Each of the four switching elements 131 to 134 receives a drive signal from the gate drive circuit 121 at its gate and performs a switch operation (on / off operation). Hereinafter, the four switching elements (FETs) 131 to 134 are referred to as a first FET 131, a second FET 132, a third FET 133, and a fourth FET 134.

More specifically, the bridge circuit 122 of the left motor driving unit 106L (see FIG. 5) includes a first FET 131 in the upper left stage, a second FET 132 in the lower left stage, a third FET 133 in the upper right stage, and a fourth FET 134 in the lower right stage.
The drain of the upper left first FET 131 and the drain of the upper right third FET 133 are connected to each other and to the positive electrode of the battery 101 (see FIG. 5).
The source of the second FET 132 at the lower left stage and the source of the fourth FET 134 at the lower right stage are connected to each other, connected to the negative electrode of the battery 101, and grounded.
The source of the first FET 131 in the upper left stage and the drain of the second FET 132 in the lower left stage are connected to each other and to one terminal of the left electric motor 35L.
The source of the third FET 133 at the upper right stage and the drain of the fourth FET 134 at the lower right stage are connected to each other and to the other terminal of the left electric motor 35L through the left current detection unit 124L.

By the way, generally, in the field effect transistor, when this transistor is produced, a diode equivalent to that for regeneration is generated. The same applies to the four field effect transistors 131 to 134 described above. For this reason, it is not necessary to incorporate an external regenerative diode in the above-described bridge circuit 122 as in the “conventional bridge circuit employing a bipolar transistor”.
In order to facilitate understanding of the bridge circuit 122, FIG. 6 shows regenerative diodes 135 to 138 provided in the four field effect transistors 131 to 134, respectively. That is, the first regeneration diode 135 is connected to the first FET 131, the second regeneration diode 136 is connected to the second FET 132, the third regeneration diode 137 is connected to the third FET 133, and the fourth regeneration diode 138 is connected to the fourth FET 134.

  The bridge circuit 122 of the right motor drive unit 106R shown in FIG. 5 has the same configuration as the bridge circuit 122 of the left motor drive unit 106L, and the right electric motor 35R is connected instead of the left electric motor 35L. .

  Next, a control flow when the control circuit 113 (see FIG. 5) is a microcomputer will be described based on FIGS. 7 and 8 with reference to FIGS. 1, 5, and 6. FIG. FIG. 7 is a control flowchart showing an example of an electric motor drive control routine executed by the control circuit 113 shown in FIG.

  As shown in FIG. 5, when the main switch 102 is turned on, power is supplied from the battery 101 to the control unit 105. The control unit 105 turns on the normally open contact 103 a of the main relay 103. Electric power is supplied from the battery 101 to the left and right motor drive units 106L and 106R. The control circuit 113 starts control when the main switch 102 is on, and ends control when the main switch 102 is turned off. The one-pulse generation circuit 111 issues a one-pulse reset signal to the control circuit 113 when the main switch 102 is turned on.

First, the control circuit 113 receives a reset signal from the one-pulse generation circuit 111 and resets the system, and then starts control (step ST01).
Next, the displacement amount St detected by the left displacement amount detector 80L, the vehicle speed Vs detected by the vehicle speed detector 104, and the actual current Id detected by the left current detector 124L are read (step ST02).

  Next, it is determined whether or not the read displacement amount St, vehicle speed Vs, and actual current Id are all normal values (step ST03). That is, failure diagnosis of each detection unit is performed. For example, when all the following three conditions are satisfied, it is determined to be normal, and otherwise, it is determined to be abnormal. The first condition is that the value of the displacement amount St is within a predetermined normal range. The second condition is that the value of the vehicle speed Vs is within a predetermined normal range. The third condition is that the value of the actual current Id is within a predetermined normal range based on the control signal from the control circuit 113.

  If it is determined in step ST03 that it is not normal, the main relay 103 is turned off via the relay drive circuit 116 (step ST04). That is, the main relay 103 stops driving the exciting coil 103b and returns the normally open contact 103a to open. As a result, the power supply from the battery 101 to the control unit 105 and the left and right motor drive units 106L and 106R is cut off, and the motor drive control ends.

  If it is determined in step ST03 that it is normal, the displacement speed Sv in the vertical direction of the wheel 25L is calculated from the value of the displacement amount St (step ST05). For example, the displacement speed Sv is obtained by differentiating the value of the displacement amount St with respect to time. The displacement speed Sv is also referred to as a stroke speed Sv.

  Next, based on the value of the displacement speed Sv, it is determined whether the displacement direction of the wheel 25L relative to the vehicle body 11 is up or down (step ST06). When the wheel 25L is displaced upward relative to the vehicle body 11, the electric damper device 30L contracts (the total length Ld of the electric damper device 30L decreases). When the wheel 25L is displaced downward relative to the vehicle body 11, the electric damper device 30L extends (the total length Ld of the electric damper device 30L increases).

When the displacement speed Sv is 0 (Sv = 0), it is determined that the wheel 25L is not displaced up and down, the process returns to step ST02, and a series of control is repeated.
When the value of the displacement speed Sv is positive (Sv> 0), it is determined that the wheel 25L has been displaced downward, the left electric motor 35L is controlled to rotate forward (step ST07), and then the process returns to step ST02. Repeat the series of controls.
If the value of the displacement speed Sv is negative (Sv <0), it is determined that the wheel 25L has been displaced upward, and the left electric motor 35L is reversely controlled (step ST08), and then the process returns to step ST02. Repeat a series of controls.

FIG. 8 is a control flowchart showing a motor normal rotation control routine for executing step ST07 in the electric motor drive control routine shown in FIG.
First, a reference drive current Iex corresponding to the displacement speed Sv is obtained based on a reference drive current map during forward rotation of the motor (step ST11). The reference drive current Iex is a value serving as a reference for the drive current supplied to the left electric motor 35L.

  FIG. 9 is an explanatory diagram of a reference drive current map Mn at the time of forward rotation of the motor in which the horizontal axis is the displacement speed Sv and the vertical axis is the reference drive current Iex to obtain the reference drive current Iex according to the displacement speed Sv. The reference drive current map Mn at the time of forward rotation of the motor is a map when the electric damper device 30L extends (when the displacement direction is downward). For example, when the displacement speed Sv = 0, the reference drive current Iex = It is indicated by a characteristic curve having a characteristic that 0 and Iex increases as Sv increases. According to this characteristic curve, it is understood that Iex has a characteristic that changes in three stages according to the value of Sv. That is, the Iex increase characteristic in a range where Sv increases from 0 to a predetermined Sv1, the Iex increase characteristic in a range where Sv exceeds Sv1 and increases to a predetermined Sv2, and in a range where Sv increases beyond Sv2. The increase characteristic of Iex is different.

  By the way, the output generated by the electric motor 35L, that is, the “damper damping force” corresponds to the drive current that flows through the electric motor 35L. For this reason, the explanatory diagram of the reference drive current map Mn during forward rotation of the motor shown in FIG. 9 is considered as an explanatory diagram of the reference damper damping force map in which the reference driving current Iex on the vertical axis is replaced with the reference damper damping force. be able to.

In FIG. 8, next, a vehicle speed correction coefficient Kv corresponding to the vehicle speed Vs is obtained based on the vehicle speed correction map (step ST12).
FIG. 10 is an explanatory diagram of a vehicle speed correction map Mv for obtaining a vehicle speed correction coefficient Kv corresponding to the vehicle speed Vs, where the horizontal axis is the vehicle speed Vs and the vertical axis is the vehicle speed correction coefficient Kv. The vehicle speed correction map Mv is indicated by, for example, a characteristic curve having the following characteristics. In a range where the vehicle speed Vs increases from 0 to a predetermined Vmin, the vehicle speed correction coefficient Kv is a constant value of 0.1. In a range where the vehicle speed Vs exceeds Vmin and increases to a predetermined Vmax, the vehicle speed correction coefficient Kv increases in proportion from 0.1 to 1.0. In the range where the vehicle speed Vs increases beyond Vmax, the vehicle speed correction coefficient Kv is a constant value of 1.0.

  In FIG. 8, next, the value of the reference drive current Iex is corrected by the vehicle speed correction coefficient Kv (step ST13). Specifically, the corrected reference drive current Iex is obtained by multiplying the reference drive current Iex obtained in step ST11 by the vehicle speed correction coefficient Kv (Iex = Iex · Kv).

  Next, a correction current I1 for correcting the mechanical internal loss of the electric motor 35L itself is obtained (step ST14). Generally, in the electric motor 35L, various mechanical internal losses (also referred to as mechanical loss and viscous resistance) such as frictional resistance of the rotating shaft when the rotor rotates are generated. In the case of the electric damper device 30L, the load torque of the electric motor 35L, that is, the output torque is increased by this internal loss. The magnitude of the internal loss is a unique value that varies depending on the type and output of the electric motor 35L employed in the electric damper device. A coefficient corresponding to the internal loss is set as a viscosity correction coefficient K1. The viscosity correction coefficient K1 is set in advance to a value corresponding to the electric motor 35L employed. The loss current I1 corresponding to the internal loss is hereinafter referred to as “viscosity correction current I1”.

  Incidentally, since the motor shaft 35a is connected to the wheel 25L via the rod 32 and the rack and pinion mechanism 33 shown in FIG. 2, the viscosity correction current I1 of the electric motor 35L is proportional to the displacement speed Sv of the wheel 25L. For this reason, in step ST14, the viscosity correction current I1 is obtained by multiplying the displacement speed Sv by the viscosity correction coefficient K1.

  Next, the vertical displacement acceleration α of the wheel 25L is calculated from the value of the displacement speed Sv (step ST15). For example, the displacement acceleration α is obtained by differentiating the value of the displacement speed Sv with respect to time.

  Next, a correction current I2 corresponding to the loss due to the inertia of the rotor of the electric motor 35L itself is obtained (step ST16). The rotor which is a mass body always tries to keep the current state due to inertia. The load torque of the electric motor 35L, that is, the output torque is increased by the loss due to the inertia. A coefficient corresponding to the loss due to inertia is defined as an inertia correction coefficient K2. The inertia correction coefficient K2 is set in advance to a value corresponding to the adopted electric motor. The loss current I2 corresponding to the loss due to inertia is hereinafter referred to as “inertia correction current I2”.

  Incidentally, since the motor shaft 35a is connected to the wheel 25L via the rod 32 and the rack and pinion mechanism 33 shown in FIG. 2, the inertia correction current I2 of the left electric motor 35L is proportional to the displacement acceleration α of the wheel 25L. To do. For this reason, in step ST16, the inertia correction current I2 is obtained by multiplying the displacement acceleration α by the inertia correction coefficient K2.

The electric motor 35L generates a load (damping force) of the electric damper device 30L. However, since the viscous torque and inertia torque of the electric motor 35L cannot be directly controlled by the driving current of the electric motor 35L, these torques are reduced. It is necessary to correct. A method for correcting this torque will be described next.
First, after step ST16, it is determined whether or not the value obtained by adding the inertia correction current I2 to the viscosity correction current I1, that is, the value of the total correction current “I1 + I2” is larger than the reference drive current Iex obtained in step ST13. (Step ST17).
When it is determined that the total correction current “I1 + I2” is larger than the reference drive current Iex, the load (damping force) by the electric motor 35L is larger than the required load. In this case, a value Im obtained by subtracting the reference drive current Iex from the total correction current “I1 + I2” is set as the target drive current Im (step ST18). That is, Im = “(I1 + I2) −Iex”. In this way, the target drive current Im supplied to the left electric motor 35L is set. By doing so, it is possible to set the target drive current Im in consideration of excessive loads of the viscous torque and the inertia torque.

  In such a state, since the load is excessive, in order to give an appropriate damping force, the forward rotation control of the electric motor 35L is performed in a control mode in which electric power is supplied from the battery 101, so-called “drive mode”. (Step ST19). That is, feedback control by, for example, PI operation (control by proportional operation and integration operation) is performed so that the actual current Id of the electric motor 35L becomes the target drive current Im. In this way, smooth and responsive damper control can be performed while eliminating the influence of mechanical internal loss of the electric motor 35L itself and the influence of the inertia of the rotor. Thereafter, the control by the motor forward rotation control routine is terminated.

  On the other hand, if it is determined in step ST17 that the total correction current “I1 + I2” is not larger than the reference drive current Iex, a value Ir obtained by subtracting the total correction current “I1 + I2” from the reference drive current Iex is used as the target regeneration current Ir. (Step ST20). That is, “Iex− (I1 + I2)”. In this way, the target regenerative current Ir from the left electric motor 35L is set.

  Next, in a control mode for regenerating power to the battery 101, so-called “regeneration mode”, the electric motor 35L is regeneratively controlled (step ST21). That is, for example, PI control is performed so that the actual current Id regenerated from the electric motor 35L becomes the target regenerative current Ir. In this way, regenerative driving for returning the regenerative current generated by the electric motor 35L to the battery 101, that is, charging is performed. Thereby, energy saving can be achieved. Thereafter, the control by the motor forward rotation control routine is terminated.

The step ST17 will be described in detail. For example, in the following case, the total correction current “I1 + I2” becomes larger than the reference drive current Iex.
When the wheel 25L bounces greatly, the displacement acceleration α of the wheel 25L rapidly increases when the wheel 25L starts to be greatly displaced in the vertical direction. However, the displacement speed Sv of the wheel 25L is in the process of increasing and is still small. As the displacement acceleration α rapidly increases, the total viscous current “I1 + I2” also increases rapidly because the mechanical viscous torque of the electric motor 35L itself and the inertia torque due to the inertia of the rotor are large. On the other hand, since the displacement speed Sv is small, the reference drive current Iex is extremely small. As a result, the total correction current “I1 + I2” temporarily exceeds the reference drive current Iex.

  At this time, since the displacement speed Sv is small, the rotation speed of the electric motor 35L rotated by the linear motion of the rod 32 is also small. For this reason, since the induced electromotive voltage generated by the electric motor 35L is small, the torque (rotation suppression torque) for suppressing the rotation of the motor shaft 35a caused by the induced electromotive voltage is small.

  However, the inertia torque due to the inertia moment of the rotor of the electric motor 35L is extremely large, and hinders the linear motion (vertical movement) of the rod 32. That is, the inertia torque of the electric motor 35L becomes a load, and the damping force for attenuating the vertical movement of the wheel 25L becomes too large. Therefore, at this time, the target drive current Im is set to “(I1 + I2) −Iex” (step ST18), current is supplied from the battery 101 to the electric motor 35L, and the electric motor 35L is actively driven (step ST19) Using viscous torque and inertia torque as loads, it was decided to exhibit the optimum damping effect.

  Thereafter, the displacement speed Sv increases, that is, the damping force required for the electric damper device 30L increases, so that the reference drive current Iex is increased. On the other hand, the displacement acceleration α decreases as the displacement speed Sv increases. For this reason, the total correction current “I1 + I2” decreases and becomes equal to or less than the reference drive current Iex. That is, when the electric motor 35L is driven, the load torque due to the influence of the mechanical viscous torque of the electric motor 35L itself and the inertia torque due to the inertia of the rotor is small. The damping force required for the rod 32 cannot be applied only by this load torque. Accordingly, at this time, the drive current (regenerative current) of the electric motor 35L is controlled so that the portion that cannot be given, that is, “Iex− (I1 + I2)”, and the control torque (damping torque) generated by the electric motor 35L is set. Apply to rod 32. That is, at this time, the target regenerative current Ir is set to “Iex− (I1 + I2)” (step ST20), and the electric motor 35L is regeneratively braked (step ST21) to exert a damping effect.

  Next, a specific example of controlling the bridge circuit 122 in steps ST19 and ST21 of FIG. 8 will be described based on FIG. FIG. 11 is an explanatory diagram illustrating an example of normal rotation drive control of the bridge circuit 122 illustrated in FIG. 6.

FIGS. 11A and 11B show an example of the operation of the bridge circuit 122 when the drive mode is executed in step ST19 of FIG. In the drive mode, the four FETs 131 to 134 receive the following signals.
The first FET 131 receives an off signal (OFF).
The second FET 132 receives a control pulse width modulation signal (PWM signal).
The third FET 133 receives an on signal (ON).
The fourth FET 134 receives an off signal (OFF).
That is, the second FET 132 alternately receives the signal shown in FIG. 11A and the signal shown in FIG.

  As shown in FIG. 11A, when the second FET 132 receives an on signal (ON) of the PWM signal, a positive rotation circuit is formed by the positive electrode of the battery 101, the third FET 133, the electric motor 35L, the second FET 132, and the ground. Is done. As shown in FIG. 11B, when the second FET 132 receives a PWM signal OFF signal (OFF), the electric motor 35L, the first FET 131, and the third FET 133 form a normal closed loop circuit. Thus, when the second FET 132 receives the PWM signal, the bridge circuit 122 is alternately formed with a normal rotation circuit and a normal rotation closed loop circuit. As a result, a drive current (generally a direct current) flows through the electric motor 35L, so that the electric motor 35L is rotated forward.

FIG.11 (c) and FIG.11 (d) have shown the operation example of the bridge circuit 122 when regenerative mode is performed by step ST21 of FIG. In the regeneration mode, the four FETs 131 to 134 receive the next signal.
The first FET 131 receives a PWM signal.
The second FET 132 receives a PWM signal having an inverted waveform from that of the first FET 131 or an off signal (OFF).
The third FET 133 receives an on signal (ON).
The fourth FET 134 receives an off signal (OFF).
That is, the four FETs 131 to 134 alternately receive the signal shown in FIG. 11C and the signal shown in FIG.

  More specifically, as shown in FIG. 11C, the first FET 131 receives the PWM signal ON signal (ON) and the second FET 132 receives the PWM signal OFF signal (OFF) or OFF signal (OFF). Sometimes, the electric motor 35L, the first FET 131, and the third FET 133 form a closed loop circuit. This closed loop circuit is hereinafter referred to as a “dynamic braking circuit”.

  In response to the vertical movement of the wheel 25L, the motor shaft 35a is rotated in the reverse direction via the rod 32 and the rack and pinion mechanism 33, so that an induced electromotive voltage corresponding to the rotational speed is generated in the electric motor 35L. The induced current (regenerative current) flows through the dynamic braking circuit.

  However, in this state, the induced current is too large and needs to be reduced. Therefore, next, as shown in FIG. 11D, the first FET 131 receives the PWM signal OFF signal (OFF), and the second FET 132 receives the PWM signal ON signal (ON) or OFF signal (OFF). In this case, a charging circuit including the ground, the second FET 132, the electric motor 35L, the third FET 133, and the positive electrode of the battery 101 is formed. This charging circuit is hereinafter referred to as a “regenerative braking circuit”.

  The carrier frequency of the PWM signal is a high frequency such as 20 kHz. For this reason, as shown in FIG. 11D, when the first FET 131 receives the OFF signal (OFF) of the PWM signal, the inductance of the electric motor 35L causes the voltage to be higher than the voltage of the battery 101 (for example, 12V). Converted. For example, the regenerative braking circuit is formed because the induced voltage is sufficiently higher than the voltage of the battery 101 even when the induced voltage is low due to the low rotational speed of the electric motor 35L.

  As described above, the bridge circuit 122 is controlled by the PWM signal when the regenerative mode is executed, so that the power generation braking circuit and the regenerative braking circuit are alternately switched in accordance with the PWM cycle. For this reason, the regenerative current can be gradually reduced in accordance with the duty ratio (on / off ratio) of the PWM signal. Accordingly, the electric motor 35L generates an optimum damping force for damping the vertical movement of the wheel 25L. That is, the vertical movement of the wheel 25L can be attenuated at an optimal attenuation rate. The duty ratio of the PWM signal in the regeneration mode may be set so that the electric motor 35L generates an optimum damping force.

  FIG. 12 is a control flowchart showing a motor reverse rotation control routine for executing step ST08 in the electric motor drive control routine shown in FIG. The motor reverse rotation control routine of FIG. 12 has a configuration similar to that of the motor normal rotation control routine shown in FIG. 8, and therefore, the differences will be mainly described and description of other portions will be omitted.

First, a reference drive current Iex corresponding to the displacement speed Sv is obtained based on a reference drive current map during reverse rotation of the motor (step ST111).
FIG. 13 is an explanatory diagram of a reference drive current map Mr at the time of motor reverse rotation in which the horizontal axis is the displacement speed Sv and the vertical axis is the reference drive current Iex to obtain the reference drive current Iex according to the displacement speed Sv. The reference drive current map Mr at the time of reverse rotation of the motor is a map when the electric damper device 30L is contracted (when the displacement direction is upward). For example, when the displacement speed Sv = 0, the reference drive current Iex = 0. And is shown by a characteristic curve with the characteristic that Iex also increases as Sv increases.

According to this characteristic curve, it can be seen that Iex has a characteristic that changes in two steps according to the value of Sv. That is, the increase characteristic of Iex in the range where Sv increases from 0 to a predetermined Sv3 is different from the increase characteristic of Iex in the range where Sv increases beyond Sv3.
As is clear from the above description, the reference drive current map Mr at the time of reverse rotation of the motor shown in FIG. 13 is different in characteristics from the reference drive current map Mn at the time of forward rotation of the motor shown in FIG.

  By the way, the output generated by the electric motor 35L, that is, the “damper damping force” corresponds to the drive current supplied to the electric motor 35L. For this reason, the explanatory diagram of the reference driving current map Mr at the time of the reverse rotation of the motor shown in FIG. 13 is considered as an explanatory diagram of the reference damper damping force map in which the reference driving current Iex on the vertical axis is replaced with the reference damper damping force. Can do.

Step ST112 shown in FIG. 12 is the same as step ST12 shown in FIG.
Step ST113 shown in FIG. 12 is the same as step ST13 shown in FIG.
Step ST114 shown in FIG. 12 is the same as step ST14 shown in FIG.
Step ST115 shown in FIG. 12 is the same as step ST15 shown in FIG.
Step ST116 shown in FIG. 12 is the same as step ST16 shown in FIG.
Step ST117 shown in FIG. 12 is the same as step ST17 shown in FIG.
Step ST118 shown in FIG. 12 is the same as step ST18 shown in FIG.

Step ST119 shown in FIG. 12 has the same configuration as step ST19 shown in FIG. 8, and reversely controls the electric motor 35L in a control mode in which power is supplied from the battery 101, so-called “drive mode”. Thereafter, the control by the motor reverse rotation control routine is terminated.
Step ST120 shown in FIG. 12 is the same as step ST20 shown in FIG.
Step ST121 shown in FIG. 12 has the same configuration as step ST21 shown in FIG. 8, and regenerative control of the electric motor 35L is performed in a control mode for regenerating power to the battery 101, so-called “regeneration mode”. Thereafter, the control by the motor reverse rotation control routine is terminated.

  Next, a specific example of controlling the bridge circuit 122 in steps ST119 and ST121 of FIG. 12 will be described with reference to FIG. FIG. 14 is an explanatory diagram showing an example of reverse drive control of the bridge circuit 122 shown in FIG. The reverse drive control example shown in FIG. 14 is characterized in that drive control in the reverse direction is performed with respect to the forward drive control example shown in FIG. This will be described in detail below.

FIGS. 14A and 14B show an example of the operation of the bridge circuit 122 when the drive mode is executed in step ST119 of FIG. In the drive mode, the four FETs 131 to 134 receive the following signals.
The first FET 131 receives an on signal (ON).
The second FET 132 receives an off signal (OFF).
The third FET 133 receives an off signal (OFF).
The fourth FET 134 receives a control pulse width modulation signal (PWM signal).
That is, the fourth FET 134 receives the signal shown in FIG. 14A and the signal shown in FIG. 14B alternately.

  As shown in FIG. 14A, when the fourth FET 134 receives the on signal (ON) of the PWM signal, a reverse circuit is formed by the positive electrode of the battery 101, the first FET 131, the electric motor 35L, the fourth FET 134, and the ground. The As shown in FIG. 14B, when the fourth FET 134 receives a PWM signal OFF signal (OFF), the electric motor 35L, the first FET 131, and the third FET 133 form a reverse loop circuit. As described above, when the fourth FET 134 receives the PWM signal, a reverse circuit and a reverse closed loop circuit are alternately formed in the bridge circuit 122. As a result, when the drive current (substantially a direct current) flows through the electric motor 35L, the electric motor 35L is reversely rotated.

FIGS. 14C and 14D show an example of the operation of the bridge circuit 122 when the regeneration mode is executed in step ST121 of FIG. In the regeneration mode, the four FETs 131 to 134 receive the next signal.
The first FET 131 receives an on signal (ON).
The second FET 132 receives an off signal (OFF).
The third FET 133 receives the PWM signal.
The fourth FET 134 receives a PWM signal inverted from the third FET 133 or an off signal (OFF).
That is, the four FETs 131 to 134 alternately receive the signal shown in FIG. 14C and the signal shown in FIG.

  More specifically, as shown in FIG. 14C, the third FET 133 receives the PWM signal ON signal (ON) and the fourth FET 134 receives the PWM signal OFF signal (OFF) or OFF signal (OFF). Sometimes, the electric motor 35L, the first FET 131, and the third FET 133 form a closed loop circuit. This closed loop circuit is hereinafter referred to as a “dynamic braking circuit”.

  As the wheel 25L moves up and down, the motor shaft 35a is rotated in the forward rotation direction via the rod 32 and the rack and pinion mechanism 33, so that an induced electromotive voltage corresponding to the rotation speed is generated in the electric motor 35L. The induced current (regenerative current) flows through the dynamic braking circuit.

  Next, as shown in FIG. 14D, when the third FET 133 receives the PWM signal OFF signal (OFF) and the fourth FET 134 receives the PWM signal ON signal (ON) or OFF signal (OFF). A charging circuit is formed which includes the ground, the fourth FET 134, the electric motor 35L, the first FET 131, and the positive electrode of the battery 101. This charging circuit is hereinafter referred to as a “regenerative braking circuit”.

  As described above, the bridge circuit 122 is controlled by the PWM signal when the regenerative mode is executed, so that the power generation braking circuit and the regenerative braking circuit are alternately switched in accordance with the PWM cycle. For this reason, the regenerative current can be gradually reduced according to the duty ratio of the PWM signal. Accordingly, the electric motor 35L generates an optimum damping force for damping the vertical movement of the wheel 25L. That is, the vertical movement of the wheel 25L can be attenuated at an optimal attenuation rate. The duty ratio of the PWM signal in the regeneration mode may be set so that the electric motor 35L emits an optimal damping force.

Next, the operation of the electric damper device 30L configured as described above will be described with reference to FIGS.
When the electric motor 35L generates a drive torque according to the target drive current Im (see FIG. 8), the following action is performed. This drive torque acts to suppress the vertical displacement of the wheel 25L via the rack and pinion mechanism 33 and the rod 32. That is, the vibration in the vertical direction of the wheel 25L is suppressed by the rotation suppression torque. Thus, by converting the relative vertical motion of the wheel 25L with respect to the vehicle body 11 into rotational motion and rotating the electric motor 35L, the vertical motion can be attenuated.

  Further, the rod 32 is linearly moved in the vertical direction by being displaced in the vertical direction of the wheel 25L. The linear motion of the rod 32 is converted into a rotational motion of the motor shaft 35 a by the rack and pinion mechanism 33. As a result, the electric motor 35L generates an induced electromotive voltage according to the rotation speed to be rotated. If torque (rotation suppression torque) for suppressing the rotation of the motor shaft 35a due to the induced electromotive force is generated, a delay due to backlash of the rack and pinion mechanism 33 or the viscous torque and inertia of the electric motor 35L. Delay due to torque will occur.

  In contrast, the electric damper device 30L directly detects or corrects the displacement in the vertical direction of the wheel 25L via the rod 32, and drives and controls the electric motor 35L so that there is no delay. A damping force can be generated. That is, the vibration in the vertical direction of the wheel 25L is suppressed by the rotation suppression torque. Thus, by converting the relative vertical motion of the wheel 25L with respect to the vehicle body 11 to rotational motion and rotating the electric motor 35L, the vertical motion can be attenuated with good responsiveness.

As is clear from the above description, step ST05 shown in FIG. 7 constitutes a “displacement speed detection unit” that detects by calculating the vertical displacement speed Sv of the wheel 25L from the value of the displacement amount St. ing. That is, the displacement speed detector ST05 calculates a displacement speed at which the wheel 25L is displaced in the vertical direction. Such a displacement speed detector ST05 can also be referred to as a displacement speed calculator.
Step ST06 shown in FIG. 7 constitutes a “displacement direction determination unit” that determines whether the displacement direction of the wheel 25L is up or down based on the value of the displacement speed Sv.

Further, steps ST11, ST18, and ST20 shown in FIG. 8 and steps ST111, ST118, and ST120 shown in FIG. 12 include the target drive current Im (target regenerative current Ir) of the electric motor 35L based on the displacement speed Sv. ) Is set. “Drive current setting unit” is configured.
Further, step ST15 shown in FIG. 8 and step ST115 shown in FIG. 12 constitute a “displacement acceleration calculator” that calculates the displacement acceleration α in the vertical direction of the wheel 25L from the value of the displacement speed Sv. .
Further, steps ST12 and ST13 shown in FIG. 8 and steps ST112 and ST113 shown in FIG. 12 constitute a “vehicle speed compatible current correction unit” that corrects the value of the reference drive current Iex according to the vehicle speed Vs. Yes.

  Further, the “drive current setting unit” is configured to set the target drive current Im (including the target regenerative current Ir) to different values depending on whether the displacement direction of the wheel 25L is upward or downward. (Steps ST11, ST18, and ST20 shown in FIG. 8 and steps ST111, ST118, and ST120 shown in FIG. 12).

Further, the “drive current setting unit” is configured to correct the value of the target drive current Im (including the target regenerative current Ir) in accordance with the displacement speed Sv and the displacement acceleration α (shown in FIG. 8). Steps ST14 to ST16, ST18 and ST20, and steps ST114 to ST116, ST118 and ST120 shown in FIG. 12).
Here, steps ST14 to ST16 shown in FIG. 8 and steps ST114 to ST116 shown in FIG. 12 are correction currents I1 and I1 corresponding to the load torque due to the mechanical internal loss of the electric motor 35L itself and the inertia of the rotor. A “correction current setting unit” for obtaining I2 is configured.

The above description is summarized as follows (see FIGS. 1, 4, 7, 8, and 12).
The control unit 105 detects the displacement St by which the wheel 25L is displaced in the vertical direction by the displacement detection unit 80L, and obtains the vertical displacement speed Sv of the wheel 25L by the displacement speed detection unit ST05 from the value of the displacement St. Based on the displacement speed Sv, the target drive current Im (including the target regenerative current Ir) of the electric motor 35L is set by the drive current setting units ST11, ST18, ST20, ST111, ST118, ST120, and the motor drive unit based on the target drive current Im. The electric motor 35L is driven and controlled by 106L.

  Thus, since the electric motor 35L is driven by the target drive current Im (including the target regenerative current Ir) based on the displacement speed Sv, the electric motor 35L is an optimum damping force for attenuating the vertical movement of the wheel 25L. To emit. Therefore, the vertical movement of the wheel 25L can be attenuated optimally.

  Further, in the control unit 105, the displacement direction determination unit ST06 determines the displacement direction of the wheel 25L based on at least one value of the displacement amount St and the displacement speed Sv. The target drive current Im (including the target regenerative current Ir) differs depending on whether the displacement direction of the wheel 25L is upward or downward depending on the drive current setting units ST11, ST18, ST20, ST111, ST118, ST120. Set to value. For this reason, the damping force by the electric motor 35L can be changed by setting the target drive current Im to a different value depending on the displacement direction of the wheel 25L, that is, the expansion / contraction direction of the vehicle electric damper device 30L. Therefore, the vertical movement of the wheel 25L can be attenuated more optimally.

  Further, in the control unit 105, the displacement acceleration calculators ST15 and ST115 obtain the displacement acceleration α of the wheel 25L from the value of the displacement speed Sv. Then, the value of the target drive current Im is corrected according to the displacement speed Sv and the displacement acceleration α by the drive current setting units ST11, ST18, ST20, ST111, ST118, ST120.

  According to the displacement speed Sv and the displacement acceleration α, the viscosity correction current I1 corresponding to the load torque (viscous torque) due to the mechanical internal loss of the electric motor 35L itself and the load torque (inertia due to the inertia of the rotor of the electric motor 35L itself). Inertia correction current I2 corresponding to (torque) changes. The value of the target drive current Im (including the target regenerative current Ir) can be corrected according to these correction currents I1 and I2. Since the electric motor 35L is driven by the corrected target drive current Im, the electric motor 35L generates an optimum damping force for attenuating the vertical movement of the wheel 25L. Therefore, the vertical movement of the wheel 25L can be attenuated more optimally.

Further, in the motor driving unit 106L, at least two field effect transistors 131 and 132 (or 133 and 134) constitute one set of arms, and at least two sets of arms constitute a bridge circuit 122, and the field effect The type transistor is driven by a pulse width modulation signal and has at least a motor regeneration mode.
By configuring the bridge circuit 122 with a field effect transistor and driving the field effect transistor with a pulse width modulation signal, it is possible to efficiently drive with less heat generation and to convert the inductance of the electric motor 35L into an AC voltage. Therefore, even if the induced electromotive voltage of the electric motor 35L is sufficiently smaller than the voltage of the power source, it can be converted into an AC voltage higher than the voltage of the power source 101, and the regeneration efficiency can be increased.

In the present invention, when the vehicle 10 is composed of an automobile having four wheels on the front, rear, left, and right, the left and right electric damper devices 30L and 30R are employed only on the two left and right front suspensions, and only the two left and right rear suspensions. Or all four suspensions.
In this case, the motor drive units 106L and 106R are separated from the control unit 105. For this reason, what is necessary is just to provide the motor drive parts 106L and 106R according to the quantity of the electric damper apparatuses 30L and 30R. Thus, since the control unit 105 and the motor driving units 106L and 106R are separated, the configuration of each unit can be simplified, reduced in weight, increased in reliability, and reduced in cost.

The vehicle suspension devices 20L and 20R are not limited to the double wishbone suspension, and may be applied to, for example, a strut suspension.
Moreover, the cylinder 31 is not limited to the structure of the 1st cylinder 41 and the 2nd cylinder 42 which consist of another member, and may be comprised by the single member.
Further, the one end 32 a of the rod 32 may be attached indirectly via the upper arm 21, the lower arm 22, or the like, in addition to the structure directly attached to the wheel support member 23.

  Further, the electric motors 35L and 35R are not limited to brushed DC motors, and may be, for example, brushless motors. The brushless motor has a small mechanical internal loss of the motor itself and a loss due to the inertia of the rotor of the motor itself. When brushless motors are used for the electric motors 35L and 35R, steps ST14 to ST16 shown in FIG. 8 are abolished, and it is optional to appropriately set another correction current value instead of the total correction current “I1 + I2”. It is.

Further, the displacement amount detection units 80L and 80R may be any devices that detect the displacement amount St by which the wheels 25L and 25R are relatively displaced in the vertical direction with respect to the vehicle body 11.
For this reason, the swing rod 82 is not limited to the configuration connected to the lower arm 22, but may be configured to be connected to the upper arm 21, the wheel support member 23, or the electric damper devices 30L and 30R, for example.
Further, the displacement amount detection units 80L and 80R are not limited to the variable resistance type configuration shown in FIG. 4, but may be, for example, a rotary encoder type configuration or a counter electromotive voltage generated in the electric motors 35L and 35R. The required configuration may be used. This counter electromotive voltage is proportional to the rotational speed of the electric motors 35L and 35R. This rotational speed is proportional to the displacement speed Sv of the wheels 25L, 25R. For this reason, the displacement speed Sv can be obtained from the rotational speed.
Further, the displacement amount detection units 80L and 80R may be configured to obtain the rotation angle by a resolver (rotation angle detection means) provided in the electric motors 35L and 35R. The displacement amount St can be obtained from this rotation angle. In this case, since it is not necessary to provide a new displacement amount detection unit, the configuration can be simplified to achieve low cost, high reliability, light weight, and high detection accuracy.

  Further, the displacement speed detection unit is not limited to the configuration in which the displacement speed Sv is calculated (executed in step ST05) from the output value (value of the displacement amount St) of the potentiometer 85 of the displacement amount detection unit 80L. For example, the displacement speed Sv is directly detected by detecting the voltage output from the DC generator in accordance with the displacement speed Sv using a DC generator (tacho generator) or the like instead of the potentiometer 85. Also good.

  Further, the configuration of steps ST12 to ST13 shown in FIG. 8 (configuration of steps ST112 to ST113 shown in FIG. 12), that is, the configuration for correcting the value of the reference drive current Iex according to the vehicle speed Vs is optional. . For example, instead of the vehicle speed Vs, the reference drive current Iex may be corrected by a constant value set appropriately for each vehicle type.

Further, the displacement direction determination unit (corresponding to step ST06 in FIG. 7) determines whether the displacement direction of the wheels 25L and 25R is up or down based on at least one of the displacement amount St and the displacement speed Sv. Good.
For example, when the displacement direction is determined based on the displacement amount St, step ST06 shown in FIG. 7 determines that the wheel 25L is displaced downward when the displacement amount St increases, and the displacement amount St decreases. It is determined that the wheel 25L has been displaced upward.
Further, the displacement direction of the wheels 25L, 25R can be determined from the rotation direction of the electric motors 35L, 35R.

  Further, the control unit 105 may be configured to perform control based on the displacement amount detected by either one of the left and right displacement amount detection units 80L and 80R.

  The vehicle electric damper devices 30L and 30R of the present invention are suitable for use in each suspension device of an automobile.

  DESCRIPTION OF SYMBOLS 10 ... Vehicle, 11 ... Vehicle body, 20L, 20R ... Vehicle suspension device, 23 ... Wheel support member (knuckle), 25L, 25R ... Wheel, 30L, 30R ... Electric damper device for vehicle, 31 ... Cylinder, 32 ... Rod, 32a ... one end of the rod, 33 ... rack and pinion mechanism, 35L, 35R ... electric motor, 35a ... motor shaft, 36 ... coil spring, 36a ... one end of the coil spring, 36b ... other end of the coil spring, 51 ... Rack 52 ... Pinion 80L 80R Displacement detection unit 101 Battery 104 Vehicle speed detection unit 105 Control unit 106L 106R Motor drive unit 124L 124R Current detection unit ST05 Displacement speed Detection unit, ST06 ... displacement direction determination unit, ST11, ST18, ST20, ST111, ST118 ST120 ... drive current setting unit, ST15, ST115 ... displacement acceleration calculator, Im ... target drive current, St ... displacement, Sv ... displacement speed, alpha ... displacement acceleration.

Claims (4)

The vertical motion of the wheel relative to the vehicle body is converted into a rotational motion and the electric motor is rotated to attenuate the vertical motion, and the damping force for attenuating the vertical motion of the wheel is applied to the electric motor. Is an electric damper device for a vehicle in which
A displacement speed detector for detecting a displacement speed at which the wheel is displaced in the vertical direction;
A drive current setting unit for setting a target drive current of the electric motor based on the displacement speed;
A motor drive unit that drives and controls the electric motor with a pulse width modulation signal based on the target drive current;
An electric damper device for a vehicle, comprising: The displacement speed detection unit is calculated from a value of a displacement amount detection unit that detects a displacement amount by which the wheel is displaced in the vertical direction,
A displacement direction determining unit that determines whether the displacement direction of the wheel is up or down based on at least one of the displacement amount and the displacement speed;
2. The vehicle according to claim 1, wherein the drive current setting unit is configured to set the target drive current to a different value depending on whether the displacement direction is upward or downward. Electric damper device. A displacement acceleration calculator for calculating displacement acceleration in the vertical direction of the wheel from the value of the displacement speed;
The said drive current setting part is comprised so that the value of the said target drive current may be correct | amended according to at least one of the said displacement speed and the said displacement acceleration, The Claim 1 or Claim 2 characterized by the above-mentioned. Electric damper device for vehicles.   The motor driving unit includes at least two field effect transistors to form a set of arms, at least two sets of arms to form a bridge circuit, and drives the field effect transistors with the pulse width modulation signal. The vehicular electric damper device according to claim 1, wherein the vehicular electric damper device has at least a motor regeneration mode.

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