JP5187252B2 - Vehicle suspension system - Google Patents

Description

  The present invention relates to a vehicle suspension system including an electromagnetic shock absorber that generates a force in a direction of approaching and separating from an unsprung portion and an unsprung portion.

  In recent years, suspension systems for vehicles include an electromagnetic shock absorber that relies on the force of an electromagnetic motor to generate a force in the direction in which they move toward and away from the unsprung and unsprung parts. An electromagnetic suspension system has been studied. For example, there is a system described in Patent Document 1 below. This electromagnetic suspension system is expected as a high-performance system because of its advantage that vibration damping characteristics based on the so-called skyhook damper theory can be easily realized.

  The electromagnetic suspension system may be provided with a contact-type relay that switches between a state where they are connected and a state where the connection is disconnected between the electromagnetic motor of the shock absorber and the power source. For example, when a failure occurs in which the electromagnetic motor included in the shock absorber cannot be normally driven, the relay disconnects the electromagnetic motor and the power source, and the current flows from the power source to the electromagnetic motor. Is used to prevent wasteful power consumption. However, when the contact type relay is opened and closed under the condition where a large current flows, an arc discharge occurs when the contacts approach or separate from each other, and the arc discharge causes the contact of the relay. May be welded. Therefore, a technique for preventing welding of the contact of the relay exists not only in the suspension system but also in various fields. For example, in the technique described in Patent Document 2 below, the relay is opened and closed only when no current flows through the relay. Further, in the technique described in Patent Document 3, when the discharge voltage of the battery becomes higher than the set value, the supply current to the motor is cut off to protect the contact type relay that exists in the circuit. Composed.

JP 2003-223220 A Japanese Patent Laid-Open No. 11-332095 JP-A-9-247848

  In the above-described electromagnetic suspension system, an electromotive force is generated in an electromagnetic motor included in the shock absorber due to an external input or the like, and a large load is applied to the power source due to the electromotive force. For example, it is possible to prevent a large load from being applied to the power source by disconnecting the connection between the electromagnetic motor and the power source using a contact type relay. In other words, as described above, it is desirable not to open and close the relay in a situation where a large current flows, whereas the connection between the electromagnetic motor and the power source may be disconnected when a large current flows. desired. Therefore, in the electromagnetic suspension system, the timing for switching the opening / closing of the contact relay that switches between the state in which the electromagnetic motor and the power source are connected and the state in which the connection is disconnected is important. It is considered that the practicality of the suspension system including the electromagnetic shock absorber can be improved by optimizing the timing for switching the switching of the relay. This invention is made | formed in view of such a situation, and makes it a subject to improve the practicality of the suspension system provided with the electromagnetic shock absorber.

  In order to solve the above-described problems, a vehicle suspension system of the present invention includes a plurality of contact relays corresponding to the plurality of shock absorbers, and is usually an electromagnetic motor for all of the plurality of shock absorbers. A situation where the power generation current of the electromagnetic motor of one of the plurality of shock absorbers is expected to exceed the set current set in consideration of the occurrence of the welding phenomenon of the relay Below, it is comprised so that the interruption | blocking state which cut | disconnected connection with an electromagnetic motor and a power supply may be implement | achieved with respect to one of the some shock absorbers.

  According to the suspension system of the present invention, it is possible to realize a cut-off state only for a plurality of shock absorbers in which the generated current of the motor is large, so that a large load is not applied to the power source. . Further, for example, at a certain early stage in the process of increasing the generated current of the motor, it is possible to realize a cut-off state with respect to the corresponding shock absorber and prevent welding of the contact of the relay. Having such an advantage makes the suspension system of the present invention highly practical.

Aspects of the Invention

  In the following, some aspects of the invention that can be claimed in the present application (hereinafter sometimes referred to as “claimable invention”) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating the understanding of the claimable inventions, and is not intended to limit the combinations of the constituent elements constituting those inventions to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which some constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

  In each of the following items, item (1) corresponds to claim 1, and the technical feature of item (2) added to claim 1 is claimed in claim 2, claim 1 or claim 2 The technical feature of (4) is added to claim 3, and the technical feature of (5) and (6) is added to claim 3, to claim 4, and claims 1 to Any one of the items 4 to which the technical features of the items (7) and (8) are added is claimed in claim 5, and the product in which the technical features of the item (9) is added to claim 5 is claimed. 6 respectively.

(1) It is provided corresponding to a plurality of wheels, which has an electromagnetic motor, and depends on the force generated by the electromagnetic motor, and the direction in which they approach and separate from the spring upper part and the spring lower part. A plurality of electromagnetic shock absorbers that generate
Connections provided corresponding to the plurality of shock absorbers, each connecting a power source and an electromagnetic motor of a corresponding one of the plurality of shock absorbers to allow current flow between them A plurality of contact type relays that switch between a state and a cut-off state that prevents a current flow between the electromagnetic motor and the power source by disconnecting the power source and the electromagnetic motor;
A relay controller for controlling each of the plurality of relays so as to selectively realize a connected state and a cut-off state for each of the plurality of shock absorbers. A state in which a connected state is realized, and a generated current of an electromagnetic motor included in one of the plurality of shock absorbers is predicted to exceed a set current set in consideration of occurrence of a welding phenomenon of the relay A vehicle suspension system comprising: a relay control device configured to realize a cut-off state with respect to one of the plurality of shock absorbers.

  The suspension system described in this section includes a plurality of contact type relays that switch between a connected state and a disconnected state for each of a plurality of electromagnetic shock absorbers provided corresponding to a plurality of wheels. Yes. That is, according to the suspension system described in this section, it is possible to individually realize either a connected state or a disconnected state for each of the plurality of shock absorbers. It is possible to realize a cut-off state only for the electromagnetic motor with a large generated current so that a large load due to a large electromotive force is not applied to the power source. In addition, the “relay” in the aspect of this section is a contact type as described above, and can be configured to switch between a connected state and a disconnected state by switching ON / OFF.

  Further, in the aspect of this section, there is a case where “the generated current of the motor is predicted to exceed the set current set in consideration of the occurrence of the welding phenomenon of the relay” (hereinafter, referred to as “the occurrence of the welding phenomenon”). ) ”Means that when the relay is opened and closed while the motor's generated current is flowing through the relay, the relay contacts the relay by arc discharge (hereinafter, simply referred to as“ welding the relay ”). However, it is desirable that the generated current of the motor is large. In other words, it is estimated that the generated current of the motor becomes so large that the relay is welded by arc discharge when the relay is opened and closed while the generated current of the motor is flowing through the relay. It is desirable that In this way, if the above “set current” is determined, at the stage where the generated current of the motor is estimated to be large, a cutoff state is realized with respect to the corresponding shock absorber to prevent welding of the contact of the relay Is possible. When determining whether or not the welding phenomenon occurs, the present invention is not limited to using the generated current of the motor, and various indexes relating to the generated current can be employed. Specifically, as the index, the rotational speed of the motor, the speed of relative movement between the sprung portion and the unsprung portion, unsprung acceleration described in detail later, or the like can be adopted.

  The “force generated by the shock absorber” described in this section is a force for the approaching / separating operation between the sprung portion and the unsprung portion, but this force is not only a resistance force for the approaching / separating operation but also a propulsion for the approaching / separating operation. This also means force, and an electromagnetic “shock absorber” that can generate such force can be used. The specific structure of the shock absorber is not limited, and various electromagnetic shock absorbers that have already been studied can be widely used. Specifically, the unsprung side unit supported by the unsprung portion and the unsprung side unit supported by the unsprung portion and capable of relative movement between the unsprung portion and the unsprung portion according to the approaching and separating operation of the unsprung portion and the unsprung portion. Based on the force of the electromagnetic motor, the force for the relative movement between the unsprung unit and the unsprung unit is generated to generate the force for the approaching and separating operation between the unsprung portion and the unsprung portion. It is possible to adopt a structure to be made.

(2) The relay controller is
When the vertical acceleration of the unsprung portion corresponding to one of the plurality of wheels exceeds a set value, it is determined that the generated current of the electromagnetic motor included in the shock absorber corresponding to the wheel exceeds the set current; The vehicle suspension system according to item (1), which is configured to realize a shut-off state with respect to the shock absorber.

  When the wheel passes through a convex or concave portion of the road surface, that is, a portion where the road surface suddenly rises or falls, the unsprung portion is vigorously moved upward or downward. That is, the electromagnetic motor is rotated at a high speed to generate a large electromotive force and a large generated current flows. The mode described in this section is a mode for determining whether or not the welding phenomenon is occurring based on the unsprung acceleration, and according to the mode of this section, there is a certain possibility that the generated current causes the relay to be welded. It is possible to open the relay before it becomes larger until it is cut off and realize the interrupted state.

(3) The relay controller is
After realizing the shut-off state for one of the plurality of shock absorbers corresponding to one of the plurality of wheels, the unsprung acceleration corresponding to one of the plurality of wheels is set for a set time. The vehicle suspension system according to item (2), wherein the vehicle suspension system is configured to return to a connected state when the value is equal to or less than a set value.

  The mode described in this section is a mode in which the conditions for returning from the blocked state to the connected state are embodied. According to the aspect of this section, based on the unsprung acceleration, in order to return to the connected state with almost no input from the road surface to the wheel, the relay may be welded when switching from the interrupted state to the connected state. It is surely prevented.

(4) The relay controller is
All of the plurality of shock absorbers under a situation where the generated current of the electromagnetic motor included in at least one of the plurality of shock absorbers exceeds the set current and the posture variation speed of the vehicle body exceeds the set speed. The vehicle suspension system according to any one of (1) to (3), wherein each of the plurality of relays is controlled so as to realize a cut-off state with respect to the vehicle.

  In the case where it is estimated that at least one of the plurality of shock absorbers is in a welding phenomenon occurrence situation, and further, “under a situation where the vehicle body posture fluctuation speed exceeds the set speed”, Even with other shock absorbers that are not under the welding phenomenon occurrence situation, there is a high possibility that the welding phenomenon will occur later. In other words, according to the aspect described in this section, it is possible to realize the shut-off state at an earlier stage in the process in which the generated current of the motor becomes larger than the other shock absorbers described above, and more reliably the relay It is possible to prevent welding. “Under the situation where the vehicle body posture fluctuation speed exceeds the set speed” described in this section means that the speed at which the entire vehicle body operates is relatively large, as will be described in detail later.

  (5) The relay control device has a situation in which the posture fluctuation speed of the vehicle body exceeds the set speed when at least one of an index related to the roll speed of the vehicle body, an index related to the pitch speed, and an index related to the bounce speed exceeds a set value. The vehicle suspension system according to item (4), which is configured to determine that the vehicle is in the state.

  The aspect described in this section regards the speed of posture fluctuation of the vehicle body as a combination of various fluctuation speed components based on, for example, the center of gravity position of the vehicle body, and based on each of these fluctuation speed components. This is a mode for determining whether or not the posture variation speed of the vehicle body exceeds the set speed. More specifically, the aspect of this section includes a roll that is a rotational variation around an axis in the front-rear direction passing through the center of gravity of the vehicle body, a pitch that is a rotational variation around the axis in the left-right direction that passes through the center of gravity of the vehicle body, This is a mode in which it is determined whether or not the posture variation speed of the vehicle body exceeds the set speed based on the respective speed-related indexes. As described above, when the posture variation speed of the vehicle body is regarded as a combination of the fluctuation speeds based on the position of the center of gravity of the vehicle body, the sprung speed corresponding to each of the four wheels and the gravity center of each of the four wheels. The roll speed, pitch speed, and bounce speed of the vehicle body can be estimated in consideration of the distance from the position.

  (6) In the relay control device, when the vertical acceleration of the sprung portion corresponding to at least one of the plurality of shock absorbers exceeds a set value, the posture variation speed of the vehicle body exceeds the set speed. The vehicle suspension system according to (4) or (5) configured to be judged to be in a situation.

  For example, when a wheel passes through a convex or concave part of a road surface, vibration with a low frequency and a large amplitude is transmitted from the unsprung part to the unsprung part corresponding to the wheel, and the unsprung part also operates vigorously. May be allowed to In such a case, it is considered that the fluctuation of the sprung corresponding to the wheel is also transmitted to the sprung corresponding to the other wheel, that is, the speed of the posture change of the vehicle body becomes relatively large. That is, as in the aspect of this section, the speed of the posture change of the vehicle body can be estimated based on the vertical acceleration of the sprung portion corresponding to the shock absorber under the welding phenomenon occurrence state.

(7) The vehicle suspension system is
Each of the plurality of shock absorbers is provided corresponding to each of the plurality of shock absorbers, and each of the plurality of shock absorbers drives the electromagnetic motor while controlling an energization current that flows through the electromagnetic motor of the corresponding one. A plurality of driving circuits,
An absorber control device that controls the force generated by each of the plurality of shock absorbers by controlling each of the plurality of drive circuits, and any one of (1) to (6) Vehicle suspension system.

  The aspect described in this section is an aspect in which the suspension system includes a so-called inverter. The inverter may be of any structure that can control the operation of switching elements such as FETs provided for each phase according to the electrical angle of the electromagnetic motor, and can execute PWM (Pulse Width Modulation) control. It is desirable to adopt a simple structure. According to the inverter, it is possible to easily and accurately control the electromagnetic motor. Therefore, the force generated by the shock absorber is controlled by adjusting the energizing current, which is the current flowing through the electromagnetic motor, by the drive circuit. It is possible.

  (8) The vehicle suspension system according to (7), wherein each of the plurality of relays is provided between the power source and each of the plurality of drive circuits.

(9) The absorber controller is
(a) When the relay control device realizes a connection state to any of the plurality of shock absorbers, the drive circuit corresponding to any of the plurality of shock absorbers causes the plurality of shock absorbers to (B) when the relay control device realizes a cut-off state for any of the plurality of shock absorbers, The drive circuit corresponding to any of the shock absorbers is configured to control the power generated by the electromagnetic motor of any of the plurality of shock absorbers to control the force generated by each of the plurality of shock absorbers. The vehicle suspension system according to item (8).

  The aspects described in the above two sections are aspects in which the suspension system includes a plurality of drive circuits, and the places where the plurality of relays are arranged are limited. Since each of the plurality of relays is disposed between the corresponding drive circuit and the power source, even if the interrupted state is realized by the relay, the shock absorber is generated by adjusting the generated current of the motor by the drive circuit. The force can be controlled within a certain range. That is, according to the latter aspect, it is possible to suppress the deterioration of the riding comfort of the vehicle when the blocking state is realized with respect to at least one of the plurality of shock absorbers.

1 is a schematic diagram showing the overall configuration of a vehicle suspension system that is an embodiment of the claimable invention. It is front sectional drawing which shows the spring absorber Assy shown in FIG. It is a circuit diagram of the drive circuit which drives the electromagnetic motor which the actuator shown in FIG. 2 has. It is a figure which shows the relationship between the rotational speed of the electromagnetic motor which the actuator shown in FIG. 2 has, and the rotational torque (energization current) of an electromagnetic motor. It is a figure which shows the time change of the unsprung acceleration and rotation speed of an electromagnetic motor in case a wheel passes the convex part of a road surface. It is a flowchart showing the actuator control program performed by the suspension electronic control unit shown in FIG. It is a flowchart showing the relay control program corresponding to the relay of the right front wheel side performed by the suspension electronic control unit shown in FIG. It is a block diagram regarding the function of the suspension electronic control unit shown in FIG.

  Hereinafter, embodiments of the claimable invention will be described in detail with reference to the drawings. In addition to the following examples, the claimable invention is implemented in various modes including various modifications and improvements based on the knowledge of those skilled in the art, including the mode described in the above [Mode of Invention]. can do. Moreover, it is also possible to constitute the modification of the following Example using the technical matter described in the description of each item of [Aspect of the Invention].

<Configuration of suspension system>
FIG. 1 schematically shows a vehicle suspension system 10 that is an embodiment of the claimable invention. The suspension system 10 includes four independent suspension type suspension devices corresponding to the front, rear, left and right wheels 12, each of which is a spring absorber in which a suspension spring and a shock absorber are integrated. Assy20. The wheel 12 and the spring absorber assembly 20 are generic names, and when it is necessary to clarify which of the four wheels corresponds, as shown in FIG. In some cases, FL, FR, RL, and RR are attached to the front wheel, the right front wheel, the left rear wheel, and the right rear wheel.

  As shown in FIG. 2, the spring absorber assembly 20 is provided between a suspension lower arm 22 that holds the wheel 12 and constitutes a part of the unsprung part, and a mount part 24 that is provided on the vehicle body and constitutes a part of the unsprung part. These are arranged so as to connect them. The spring absorber assembly 20 includes an actuator 30 functioning as an electromagnetic shock absorber and a coil spring 32 as a suspension spring, and these are integrated.

  The actuator 30 includes a screw rod 40 as a male screw portion in which a thread groove is formed, and a ball screw mechanism configured to include a nut 42 as a female screw portion that holds a bearing ball and is screwed with the screw rod 40; An electromagnetic motor 44 (hereinafter sometimes simply referred to as “motor 44”) as a power source and a casing 46 for housing the motor 44 are provided. The casing 46 rotatably holds the screw rod 40 and is connected to the mount portion 24 via an anti-vibration rubber 48 at the outer peripheral portion. The motor 44 has a hollow motor shaft 50, and a screw rod 40 is fixed to the motor shaft 50 at the upper end portion through the inside thereof. That is, the motor 44 applies a rotational force to the screw rod 40.

  The actuator 30 has a cylinder 64 that includes an outer tube 60 and an inner tube 62 that fits into the outer tube 60 and protrudes upward from the upper end portion thereof. The outer tube 60 is connected to the lower arm 22 via a mounting bush 66 provided at the lower end portion thereof, and the inner tube 62 is fixed to the casing 46 at the upper end portion with the threaded rod 40 inserted therethrough. . A nut support cylinder 68 is erected on the inner bottom portion of the inner tube 62, and the nut 42 is fixed to the inner end of the inner tube 62 in a state of being screwed with the screw rod 40.

  Further, the actuator 30 has a cover tube 70, and the cover tube 70 is connected to the lower surface side of the mount portion 24 through the anti-vibration rubber 72 at the upper end portion with the cylinder 64 inserted. ing. A flange 74 (which functions as an upper retainer) is formed at the upper end of the cover tube 70, and the flange 74 and an annular lower retainer 76 provided on the outer peripheral surface of the outer tube 60. Thus, the coil spring 32 as a suspension spring is supported in a sandwiched state.

  Due to the structure as described above, the actuator 30 includes the sprung unit on the spring unit 40 including the screw rod 40, the motor 44, the casing 46, the inner tube 62, the cover tube 70, etc., the nut 42, the inner tube. 60, the nut supporting cylinder 68 and the like, and the unsprung unit connected to the lower arm 22. The relative rotation is impossible, and the approaching and separating operation between the sprung portion and the sprung portion is performed. The structure is movable in the axial direction, in other words, can be expanded and contracted.

  In the actuator 30, when the sprung portion and the unsprung portion are moved toward and away from each other, the sprung unit and the unsprung unit can move relative to each other in the axial direction, that is, the screw rod 40 and the nut 42 are moved in the axial direction. The relative movement is enabled, and the screw rod 40 rotates relative to the nut 42 with the relative movement. Thereby, the motor shaft 50 also rotates. The motor 44 can apply a rotational torque to the screw rod 40, and the rotational torque can generate a resistance force in a direction that prevents the relative rotation between the screw rod 40 and the nut 42. Is possible. By making this resistance force act as a damping force with respect to the relative movement between the sprung unit and the unsprung unit, and thus as a damping force with respect to the approaching / separating operation between the sprung portion and the unsprung portion, the actuator 30 acts as a shock absorber. It is supposed to function. The actuator 30 is also capable of generating a propulsive force for the relative motion between the sprung portion and the unsprung portion, and executes control based on the so-called skyhook damper theory, pseudo groundhook theory, and the like. Is possible. Furthermore, the rotational torque of the motor 44 can maintain the distance between the spring upper part and the spring lower part at an arbitrary distance. The roll of the vehicle body when turning the vehicle, the pitch of the vehicle body when accelerating / decelerating the vehicle, etc. It is possible to effectively suppress, adjust the height of the vehicle, the so-called vehicle height, and the like.

  In the present suspension system 10, the actuator 30 is controlled by a suspension electronic control unit 140 (hereinafter also referred to as “ECU 140”) as a control device. The ECU 140 is mainly configured by a computer having a CPU, a ROM, a RAM, and the like. The ECU 140 is connected to four inverters [INV] 144 which are provided corresponding to the motors 44 included in the actuators 30 and function as drive circuits for the corresponding motors 44. The inverters 144 are connected to the battery [BAT] 150 via the converter [CONV] 148, and the motor 44 of each actuator 30 receives power from a power supply 152 configured to include the converter 148 and the battery 150. Is supplied.

  The vehicle includes an ignition switch [I / G] 160, a vehicle speed sensor [v] 162 for detecting a vehicle traveling speed (hereinafter sometimes referred to as “vehicle speed”), and a steering wheel operating angle. Operation angle sensor [δ] 168, longitudinal acceleration sensor [Gx] 170 for detecting the actual longitudinal acceleration that is actually generated in the vehicle body, lateral acceleration for detecting the actual lateral acceleration that is actually generated in the vehicle body Sensor [Gy] 172, four sprung vertical acceleration sensors [Gzs] 174 for detecting the vertical acceleration (vertical acceleration) of each mount 24 of the vehicle body corresponding to each wheel 12, and 4 for detecting the vertical acceleration of each wheel 12. Two unsprung vertical acceleration sensors [Gzg] 176, throttle sensor [Sr] 178 for detecting the throttle opening, and master cylinder pressure of the brake Brake pressure sensor [Br] 180 for detecting are provided, which are connected to ECU140 computer. The ECU 140 controls the operation of the actuator 30 based on signals from these switches and sensors. Incidentally, the character [] is a symbol used when the above-mentioned switch, sensor, etc. are shown in the drawing. In addition, the ROM included in the computer of the ECU 140 stores a program related to the control of the actuator 30, various data, and the like.

  As shown in FIG. 3, the motor 44 of each actuator 30 is a three-phase DC brushless motor in which coils are star-connected (Y-connected), and is controlled by the inverter 144 described above. The inverter 144 is a general one as shown in FIG. 3, and a switching element pair composed of a switching element on the high side (high potential side) and a switching element on the low side (low potential side) of a power source is connected to a motor. There are three pairs corresponding to the U phase, V phase, and W phase, which are the three phases of 44. That is, six switching elements HUS, HVS, HWS, LUS, LVS, and LWS are provided. In addition, the switching element control circuit 190 included in the inverter 144 includes a resolver [θ] 192 provided in the motor 44 for detecting the rotation angle of the motor 44 and an actual motor 44 provided in the inverter 144. Three energizing current sensors [I] 194 for measuring an actual energizing current that is a current flowing through each of the phases are connected. The switching element control circuit 190 determines the rotational position (electrical angle) of the motor 44 by the resolver 192, and opens and closes the switching element according to the motor rotational position. The inverter 146 drives the motor 44 by so-called sine wave drive, and the current flowing in each of the three phases of the motor 44 changes in a sine wave shape, and the phase difference differs by 120 ° in electrical angle. In addition, the switching element is controlled. The switching element is controlled by changing the ratio (duty ratio) between the pulse-on time and the pulse-off time by PWM (Pulse Width Modulation) control.

  The direction of the rotational torque generated by the motor 44 may be the same as the direction in which the motor 44 is actually rotating, or vice versa. When the direction of the rotational torque generated by the motor 44 and the rotational direction of the motor 44 are reversed, that is, when the actuator 30 is acting as a resistance force against the relative movement between the wheel and the vehicle body, The force generated by 44 does not necessarily depend on the power supplied from the power source. More specifically, when the motor 44 is rotated by an external force, an electromotive force is generated in the motor 44. When the motor 44 generates a motor force depending on the electromotive force, that is, the actuator 30 starts. In some cases, an actuator force depending on electric power is generated.

  FIG. 4 conceptually shows the relationship between the rotational speed of the motor 44 and the rotational torque of the motor 44 (the energization current of the motor 44). Region (a) in this figure is a region where the direction of rotational torque of motor 44 is the same as the direction of rotation, and region (b) and region (c) are the direction of rotational torque and direction of rotation of motor 44. This is the opposite area. The line that divides the region (b) and the region (c) is a characteristic line when the current-carrying terminals of each phase of the motor 44 are short-circuited, that is, the rotation speed of the motor 44 obtained when so-called short-circuit braking is performed. It is a short circuit characteristic line which shows the relationship between and rotational torque. The region (c) where the rotational torque generated by the motor 44 with respect to the rotational speed is smaller than the rotational torque on the short-circuit characteristic line is the region where the motor 44 generates rotational torque that becomes a resistance force depending on the electromotive force. Incidentally, the area (b) is an area in which the motor 44 receives a supply of electric power from the battery 150 and generates a torque that becomes a resistance force, that is, a so-called reverse braking area. The area (a) is an area in which the motor 44 receives electric power from the battery 150. This is a region that receives the supply of torque and generates a torque as a driving force.

  Note that the inverter 144 has a structure capable of regenerating the power generated by the electromotive force to the battery 150. In other words, when the relationship between the rotational speed ω of the motor 44 and the rotational torque generated by the motor 44 is in the region (c), the generated power based on the electromotive force is regenerated. In the case where the rotational torque generated by the motor 44 and the rotational direction of the motor 44 are reversed, the PWM control of the switching element described above controls the current flowing through each coil of the motor 44 by the electromotive force. Therefore, the magnitude of the rotational torque generated by the motor 44 is changed by changing the duty ratio. That is, the inverter 144 adjusts the current flowing through the coil of the motor 44, that is, the energization current of the motor 44, regardless of whether it is a supply current from a power supply or a generated current generated by an electromotive force. It is structured to control the motor force.

  In addition, between the power supply 152 and each of the four inverters 144, the connection state which connected the inverter 144 and the power supply 152 corresponding to self, and those connections were cut off, and the electric current flow between them was interrupted | blocked Four open / close relays [RY] 200 (four are shown in FIG. 1 and only one is shown in FIG. 3) are provided for switching between the cut-off states. These four open / close relays 200 are contact point type relays. When the ignition switch 160 is turned on, power is supplied from the battery 150 via the ECU 140 and the electromagnetic coil of the relay is energized, the connection state ( When the power supply from the battery 150 is cut off, the cut-off state (open state, OFF state) is established. Each of the four open / close relays 200 is connected to the ECU 140, and the ECU 140 realizes a connected state as a state in which the electric power received from the battery 150 is supplied to the open / close relay 200, and does not supply power. As a result, a cut-off state is realized.

<Control of suspension system>
i) Control of Actuator In the suspension system 10, each of the actuators 30 included in the four spring absorber assemblies 20 can be controlled independently. In each of the spring absorber assemblies 20, the actuator force of the actuator 30 is controlled independently. More specifically, control for attenuating vibrations of the vehicle body and the wheels 12, that is, sprung vibration and unsprung vibration (hereinafter sometimes referred to as “vibration damping control”), and rolling of the vehicle body caused by turning of the vehicle. Control for suppressing (hereinafter sometimes referred to as “roll suppression control”), control for suppressing the pitch of the vehicle body caused by acceleration / deceleration of the vehicle (hereinafter also referred to as “pitch suppression control”), Control executed in parallel. In the vibration damping control, roll suppression control, and pitch suppression control, the actuator force to be generated by the actuator 30 is determined by adding the vibration damping component, roll suppression component, and pitch suppression component, which are the components of the actuator force for each control. Then, the actuator 30 is controlled so as to generate an actuator force having the determined magnitude. In the following description, the actuator force and its component have a positive value corresponding to the force in the direction in which the sprung portion and the unsprung portion approach (bound direction), and the direction that separates the sprung portion and the unsprung portion. It is assumed that the force corresponding to the (rebound direction) force is a negative value.

a) Vibration damping control In the vibration damping control, a vibration damping component F _V of the actuator force is determined so as to generate an actuator force having a magnitude corresponding to the vibration speed in order to attenuate the vibration of the vehicle body and the wheel 12. . In other words, the control is based on both the control based on the so-called skyhook damper theory and the control based on the pseudo groundhook damper theory. Specifically, the vertical operating speed of the vehicle body mount 24 obtained from the spring vertical acceleration detected by the spring vertical acceleration sensor 174 provided on the vehicle mount 24, the so-called absolute spring speed Vs. Based on the vertical movement speed of the wheel 12 obtained from the unsprung longitudinal acceleration detected by the unsprung longitudinal acceleration sensor 176 provided on the lower arm 22, the so-called unsprung absolute speed Vg, vibration damping is performed according to the following equation: The component F _V is calculated.
F _V = Cs · Vs−Cg · Vg
Here, Cs is a gain for generating a damping force in accordance with the vertical operation speed of the mount 24 of the vehicle body, and Cg generates a damping force in accordance with the vertical operation speed of the wheel 12. For gain. That is, Cs and Cg can be considered as damping coefficients for so-called sprung and unsprung absolute vibrations.

b) Roll suppression control When the vehicle turns, the roll moment resulting from the turn separates the sprung and unsprung parts on the turning inner ring side and causes the sprung and unsprung parts on the turning outer ring side to approach each other. It is done. In the roll suppression control, in order to suppress the separation on the turning inner ring side and the approach on the turning outer ring side, the actuator force in the bounce direction is applied to the actuator 30 on the turning inner ring side, and the actuator force in the rebound direction is applied to the actuator 30 on the turning outer ring side. Each is generated as a roll restraining force. Specifically, first, as a lateral acceleration indicating a roll moment received by the vehicle body, an estimated lateral acceleration Gyc estimated based on the steering angle δ of the steering wheel and the vehicle speed v, and a lateral acceleration sensor 172 were measured. Based on the actual lateral acceleration Gyr, a control lateral acceleration Gy ^* , which is a lateral acceleration used for control, is determined according to the following equation.
Gy ^* = K ₁ · Gyc + K ₂ · Gyr (K ₁ , K ₂ : gain)
Such based on the determined control-use lateral acceleration Gy ^*, the roll restrain component F _R is determined according to the following equation.
F _R = K ₃ · Gy ^* (K ₃ : Gain)

c) Pitch suppression control When a vehicle nose dive occurs during deceleration such as when the vehicle is braked, the front wheel side spring top and spring bottom are brought closer to each other by the pitch moment that generates the nose dive. The sprung part on the ring side and the unsprung part are separated from each other. In addition, when squat of the vehicle body is generated during acceleration of the vehicle, the sprung moment that generates the squat separates the front wheel spring top and the spring bottom, and the rear wheel spring top and spring bottom. Is approached. In the pitch suppression control, the actuator force is generated as the pitch suppression force in order to suppress fluctuations in the distance between the sprung springs in those cases. Specifically, as longitudinal acceleration indicative of the pitch moment acting on the vehicle body, is employed the actual longitudinal acceleration Gx that is actually measured by the longitudinal acceleration sensor 170, and based on the actual longitudinal acceleration Gx, the pitch restrain component F _P has the following formula Determined according to.
F _P = K ₄ · Gx (K ₄ : Gain)
The pitch suppression control is executed when the throttle opening detected by the throttle sensor 178 or the master cylinder pressure detected by the brake pressure sensor 180 exceeds a set threshold.

d) Target Actuator Force and Motor Operation Control The actuator 30 is controlled based on a target actuator force that is an actuator force that should be generated. In detail, as described above, the vibration damping component F _V of the actuator force, a roll restrain component F _R, the pitch restrain component F _P is determined on the basis of their target actuator is a control target value in accordance with the following equation The force F ^* is determined.
F ^* = F _V + F _R + F _P
Then, the target actuator force F ^* determined as described above is transmitted to the switching element control circuit 190 of the inverter 144, and the target duty ratio is determined based on the target actuator force F ^* . The inverter 144 adjusts the current flowing through the motor 44 by controlling opening and closing of the switching element under the appropriate duty ratio, and generates the target actuator force F ^* .

ii) Control of open / close relay Consider a case where a wheel passes through a convex or concave road surface. For example, when passing through the convex portion of the road surface, the unsprung portion is moved upwards vigorously and the unsprung portion and the unsprung portion approach each other, in other words, the actuator 30 contracts. At that time, a very large electromotive force is generated in the motor 44, and a large load is applied to the converter 148, the battery 150, and the like. Therefore, the ECU 140 turns off the open / close relay 200 corresponding to the actuator 30 having the motor 44 and realizes a cut-off state for the actuator 30 under a situation where the generated current of the motor 44 exceeds the set current. It has become.

Further, when the open / close relay 200 is switched from the ON state to the OFF state in a state where a large generated current is flowing through the open / close relay 200, arc discharge occurs at the moment when the contacts of the open / close relay 200 are separated from each other. As a result, the contacts of the open / close relay 200 may be welded. In other words, it is necessary to estimate that the generated current of the motor 44 becomes so large that a large load is applied to the power supply 152 before the opening / closing relay 200 may be welded. That is, the set current is set in consideration of the occurrence of the welding phenomenon of the open / close relay 200. Specifically, in the present suspension system 10, the generated current of the motor 44 is supplied to the switching relay 200 on the condition that the unsprung longitudinal acceleration Gzg detected by the unsprung longitudinal acceleration sensor 176 exceeds the set value G ₀ . The switching relay 200 is switched from the ON state to the OFF state when it is determined that the current is expected to exceed the set current set in consideration of the occurrence of the welding phenomenon (hereinafter referred to as “the welding phenomenon occurrence state”). It is like that. FIG. 5 shows temporal changes in the unsprung acceleration and the rotation speed (stroke speed) of the motor 44 when the wheel passes through the convexity of the road surface. Since the magnitude of the unsprung acceleration is higher than the magnitude of the rotational speed of the motor 44, it is possible to determine early that the generated current of the motor 44 is increased. As a result, the open / close relay 200 is switched from the ON state to the OFF state so as not to be welded.

When it is estimated that the unsprung longitudinal acceleration Gzg exceeds the set value G ₀ in any of the four actuators 30 and the ECU 140 is in a state of occurrence of a welding phenomenon, the ECU 140 further determines the speed of the posture change of the vehicle body as the set speed. It is determined whether or not the situation is over. Specifically, first, fluctuation speeds based on the position of the center of gravity of the vehicle body, that is, roll speed V _r , pitch speed V _p , and bounce speed V _b are respectively set to threshold speeds V _r0 , V _p0 , V _Judged by whether or not _b0 was exceeded. Each of the roll speed V _r , the pitch speed V _p , and the bounce speed V _b is estimated based on the sprung speeds V _FR , V _FL , V _RR , and V _RL corresponding to each of the four wheels 12. Specifically, the calculation is performed according to the following equation in consideration of the distance of each of the four wheels 12 from the position of the center of gravity.
V _b = (V _FR + V _FL + V _RR + V _RL ) / 4
_{V r = (V FR -V FL} + V RR -V RL) / 4
_{V p = (V FR + V} FL -V RR -V RL) / 4
In the above formula, it is assumed that the distances from the center of gravity of the vehicle body to the four wheels 12 are equal and in unit distance.

Further, whether or not the posture variation speed of the vehicle body exceeds the set speed corresponds to the actuator 30 estimated that the unsprung vertical acceleration Gzg exceeds the set value G ₀ and the welding phenomenon occurs. longitudinal acceleration Gzs of the sprung is determined by whether exceeds the set value G _1. As described above, when the wheel 12 passes through the convex or concave portion of the road surface and the unsprung portion is operated vigorously, the unsprung portion corresponding to the wheel 12 may be operated vigorously. . In such a case, the fluctuation of the sprung corresponding to the wheel 12 is also transmitted to the sprung corresponding to the other wheel, and it is considered that the speed of the posture change of the vehicle body becomes relatively large.

  If it is determined by the above determination that the vehicle body posture fluctuation speed exceeds the set speed, a large power generation current can also flow through the motor 44 of the actuator 30 corresponding to another wheel. It is considered that the nature is high. Therefore, the ECU 140 is configured to realize a cut-off state not only for the actuator 30 estimated to be in a welding phenomenon occurrence state but also for other actuators 30. As a result, the cut-off state can be realized at an earlier stage in the process in which the power generation current of the motor 44 increases with respect to the other actuators 30 described above. In the open / close relay 200 corresponding to those actuators 30, Welding is prevented more reliably.

  Incidentally, when the cutoff state is realized with respect to any of the actuators 30, the supply current from the power source 152 to the motor 44 is also stopped, and the motor 44 that the actuator 30 has is a motor that other actuators 30 have. Although the power generation current of 44 cannot be received, the control of the actuator 30 described above is continued. Therefore, the actuator force generated by the actuator 30 in the cut-off state is within the region (c) shown in FIG. 4, that is, within the region where the motor 44 generates a rotational torque that becomes a resistance force depending on the electromotive force. Will be controlled. In the present system 10, even if the cut-off state is realized for any of the four actuators 30, the deterioration of the riding comfort of the vehicle is suppressed.

Incidentally, a cutoff state described above, even unsprung vertical acceleration Gzg is below the set value G _0, is within the set time t ₀ is implemented continuously, unsprung vertical acceleration Gzg is equal to or smaller than the set value G ₀ state Is continued for the set time t ₀ or longer, it is determined that the welding phenomenon is not occurring, and the connection state is restored. That is, in the present system 10, since the input to the wheel 12 from the road surface is almost lost based on the unsprung vertical acceleration, the open / close relay 200 is switched when switching from the cut-off state to the connected state. Welding is reliably prevented.

<Control program>
The control of the actuator 30 as described above is repeatedly executed by the ECU 140 with a short time interval (for example, several milliseconds) while the ignition switch 160 is in the ON state, while the actuator control program shown in the flowchart in FIG. The relay control program shown in the flowchart of FIG. 7 is repeatedly executed by the ECU 140 for the same period as the actuator control program. The control flow will be briefly described below with reference to the flowchart shown in the drawing. The actuator control program is executed for each of the actuators 30 of the spring absorber assembly 20 provided on each of the four wheels 12, and the relay control program is provided for the four opening / closing operations provided corresponding to the four actuators 30. It is executed for each of the relays 200. In the following description, processing by a program for one actuator 30 and one open / close relay 200 (right front wheel side open / close relay 200FR) will be described in consideration of simplification of description.

i) Actuator control program In the process by the actuator control program, first, in step 1 (hereinafter abbreviated as “S1”, the same applies to other steps) to S3, the vibration damping component F is obtained by the method described above. _V , roll suppression component F _R , and pitch suppression component _FP are determined, and in S4, these three components are added together to determine the target actuator force F ^* . In S5, a duty ratio for controlling the motor 44 is determined based on the target actuator force F ^* , and a command based on the duty ratio is transmitted to the inverter 144. By this process, the operation of the motor 44 of each actuator 30 is controlled, so that each actuator 30 generates the required actuator force.

ii) Relay control program In the processing by the relay control program, an actual state flag FL indicating which state is realized between the connected state and the disconnected state is adopted for the corresponding actuator 30FR. The flag value is set to 0 when the connection state is realized, and is set to 1 when the cutoff state is realized. Note that FL, FR, RL, RR may be added to the realization state flag FL as a subscript indicating the wheel position corresponding to each of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel.

In the process according to the relay control program, first, in S11, by whether unsprung acceleration Gzg detected is greater than the set value G ₀ by the unsprung vertical acceleration sensor 176 of the front right wheel 12FR side corresponding to itself, the actuator 30FR motor It is determined whether the generated current of 44 exceeds the set current. Typically, unsprung acceleration Gzg is not less setpoint G ₀ or less, in S23, the opening and closing relay 200FR is connected state is realized is the ON state. On the other hand, when the unsprung acceleration Gzg is larger than the set value G _0, it is determined in S13 to S15 whether or not the posture variation speed of the vehicle body exceeds the set speed. Specifically, in S13, with the right front wheel 12FR sprung detected by sprung vertical acceleration sensor 174 of the side acceleration Gzs is determined whether greater than the set value G ₁ is, step S14 in the manner previously described It is determined in S15 whether or not each of the calculated roll speed V _r , pitch speed V _p , and bounce speed V _b exceeds the threshold speeds V _r0 , V _p0 , and V _b0 , respectively.

Sprung acceleration Gzs is not less setpoint G ₁ or less, and, when the roll velocity V _r, the pitch velocity V _p, any bounce velocity V _b is in each threshold speed V _r0, V _p0, V _b0 below Is determined not to be in a situation where the posture variation speed of the vehicle body exceeds the set speed. In that case, in S16 and subsequent steps, the shut-off state is realized only for the actuator 30FR corresponding to the right front wheel 12FR. Specifically, in S16, the flag value of the realized state flag FL _FR of the front right wheel 12FR side is a 1, in S21, the opening and closing relay 200FR corresponding to the right front wheel 12FR side of the actuator 30FR is OFF.

On the other hand, when the sprung acceleration Gzs is greater than the set value G ₁ or any of the roll speed V _r , pitch speed V _p , and bounce speed V _b is greater than the threshold speed V _r0 , V _p0 , V _b0. Then, it is determined that the posture variation speed of the vehicle body exceeds the set speed. In that case, in S17, each of the realization state flags FL _FR , FL _FL , FL _RR , FL _RL corresponding to all of the four actuators 30 to realize the shut-off state for all of the four actuators 30. The value is set to 1. Next, in this program, the open / close relay 200FR corresponding to the actuator 30FR on the right front wheel 12FR side is turned off, and a cutoff state is realized for the actuator 30FR. For the other actuators 30FL, 30RR, 30RL, it is determined that the flag value of the realization state flag is 1 in S18 in the corresponding relay control program of the open / close relays 200FL, 200RR, 200RL, and in S21 The cut-off state is realized.

The shut-off state described above is realized while the state of the unsprung vertical acceleration Gzg is smaller than the set value G ₀ while the state continues for a certain time t ₀ . That is, in S11, the size of the unsprung vertical acceleration Gzg is determined that the setting value G ₀ is less than, in S18, when the flag value of the realized state flag FL is 1, S19 by the following processing, unsprung It is determined whether or not the state in which the magnitude of the vertical acceleration Gzg is smaller than the set value G ₀ has continued for a certain time t ₀ . First, in S19, the time counter is counted up. This counter is used to determine whether or not the set time t _{0 has} elapsed. In S20, the count value C of this counter is compared with a counter threshold value C ₀ corresponding to the set time t ₀ . Incidentally, the counter value C, in S11, if the size of the unsprung vertical acceleration Gzg is determined to have exceeded the set value G _0, are reset in S12. In S20, if the count value C does not reach the counter threshold C _0, the processing of S21 is executed, interrupted state is realized continuously. When the count value C reaches the counter threshold value C ₀ , the flag value of the realization state flag FL is set to 0 in S22, and the connection state is returned to 23.

<Functional configuration of control device>
The ECU 140 that executes the above-described programs can be considered to have various functional units that execute various processes according to the programs. Specifically, as shown in FIG. 8, the ECU 140 controls each of the four actuators 30 by controlling each of the function units that execute the processing by the actuator control program, that is, the inverters 144 as the four drive circuits. An actuator control unit 250 that controls the generated actuator force is provided. The actuator control unit 250 includes a vibration damping control section 252 to determine the vibration damping component F _V by executing the processing in S1, a roll control unit 254 for determining the roll restrain component F _R by executing the process of S2 configured to include a pitch restrain control unit 256 for determining the pitch restrain component F _P by executing the processing in S3.

  The ECU 140 is a functional unit that executes processing by the relay control program, that is, four contact relays to selectively realize the connection state and the cutoff state for each of the four actuators 30. A relay control unit 260 that controls each of the open / close relays 200 is provided. The relay control unit 260 executes the processes of S11 and S18 to S20 and is predicted that the generated current of the motor 44 included in the actuator 30 exceeds the set current set in consideration of the occurrence of the welding phenomenon of the switching relay 200. A welding phenomenon occurrence state determination unit 262 that determines whether or not the vehicle is in a situation where the vehicle body is in a situation in which the vehicle body posture fluctuation speed exceeds the set speed by executing the processes of S13 to S15. It is configured to include a high attitude variation speed state determination unit 264 and a relay switching unit 266 that executes the processing of S21 and S23 and realizes either the connected state or the disconnected state by switching the open / close relay 200. . From the above configuration, the ECU 140 functions as both an absorber control device and a relay control device.

  10: Vehicle suspension system 12: Wheel 20: Spring absorber assembly 22: Lower arm (lower spring) 24: Mount part (upper spring) 30: Actuator (shock absorber) 32: Coil spring (suspension spring) 44: Electromagnetic motor 140 : Suspension electronic control unit (ECU, actuator control device, relay control device) 146: inverter (drive circuit) 148: converter [CONV] 150: battery [BAT] 152: power source 174: sprung vertical acceleration sensor [Gzs] 176: Unsprung vertical acceleration sensor [Gzg] 200: Open / close relay [RY] (reed relay) 250: Actuator control unit 260: Relay control unit 262: Under welding phenomenon occurrence state Judgment unit 264: High posture fluctuation speed condition determination unit 266: Relay switching unit

Claims (6)

Provided for multiple wheels, each having an electromagnetic motor, and depending on the force generated by the electromagnetic motor, generates a force in the direction in which they approach and separate from the spring top and spring bottom. A plurality of electromagnetic shock absorbers,
Connections provided corresponding to the plurality of shock absorbers, each connecting a power source and an electromagnetic motor of a corresponding one of the plurality of shock absorbers to allow current flow between them A plurality of contact type relays that switch between a state and a cut-off state that prevents a current flow between the electromagnetic motor and the power source by disconnecting the power source and the electromagnetic motor;
A relay controller for controlling each of the plurality of relays so as to selectively realize a connected state and a cut-off state for each of the plurality of shock absorbers. A state in which a connected state is realized, and a generated current of an electromagnetic motor included in one of the plurality of shock absorbers is predicted to exceed a set current set in consideration of occurrence of a welding phenomenon of the relay A vehicle suspension system comprising: a relay control device configured to realize a cut-off state with respect to one of the plurality of shock absorbers. The relay controller is
When the vertical acceleration of the unsprung portion corresponding to one of the plurality of wheels exceeds a set value, it is determined that the generated current of the electromagnetic motor included in the shock absorber corresponding to the wheel exceeds the set current; The vehicle suspension system according to claim 1, wherein the suspension system is configured to realize a shut-off state with respect to the shock absorber. The relay controller is
All of the plurality of shock absorbers under a situation where the generated current of the electromagnetic motor included in at least one of the plurality of shock absorbers exceeds the set current and the posture variation speed of the vehicle body exceeds the set speed. The vehicle suspension system according to claim 1 or 2, wherein each of the plurality of relays is controlled so as to realize a cutoff state with respect to the vehicle.   The relay control device has a spring corresponding to at least one of the plurality of shock absorbers when at least one of an index related to the roll speed of the vehicle body, an index related to the pitch speed, and an index related to the bounce speed exceeds a set value. The vehicle suspension system according to claim 3, wherein the vehicle suspension system is configured to determine that the posture variation speed of the vehicle body exceeds the set speed when the upper vertical acceleration exceeds the set value. The vehicle suspension system is
Each of the plurality of shock absorbers is provided corresponding to each of the plurality of shock absorbers, and each of the plurality of shock absorbers drives the electromagnetic motor while controlling an energization current that flows through the electromagnetic motor of the corresponding one. A plurality of driving circuits,
An absorber control device that controls the force generated by each of the plurality of shock absorbers by controlling each of the plurality of drive circuits, and
The vehicle suspension system according to any one of claims 1 to 4, wherein each of the plurality of relays is provided between the power source and each of the plurality of drive circuits. The absorber control device is
(a) When the relay control device realizes a connection state to any of the plurality of shock absorbers, the drive circuit corresponding to any of the plurality of shock absorbers causes the plurality of shock absorbers to (B) when the relay control device realizes a cut-off state for any of the plurality of shock absorbers, The drive circuit corresponding to any of the shock absorbers is configured to control the power generated by the electromagnetic motor of any of the plurality of shock absorbers to control the force generated by each of the plurality of shock absorbers. The vehicle suspension system according to claim 5.

Images