JP2011207346A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension device capable of exhibiting system spring rigidity as the whole of the system of the suspension device constituted by an aggregate of a large number of elements at the optimum.SOLUTION: The suspension device includes a system spring rigidity control means 5 for performing control of the system spring rigidity exhibited by the whole of the system of the suspension device 1a by adjusting the mounting state of a vibration suppression means for suppressing vibration transmitted from a wheel 2 or a vehicle body 9 of the vehicle or a vehicle height adjustment means for adjusting the height of the vehicle body 9 to the vehicle body 9. The vibration suppression means or the vehicle height adjustment means is a damper device 6 connected between a wheel 2 side and a vehicle body 9 side and generating the damping force for damping relative movement of the wheel 2 side and the vehicle body 9 side. The system spring rigidity control means 5 is provided on mounting parts 6a, 6b at the wheel 2 side or the vehicle body 9 side of the damper device 6 and controls the system spring rigidity by moving the mounting position of the damper device 6.

Description

  The present invention relates to a suspension apparatus that is provided between a sprung system and an unsprung system and performs a buffering operation of a vehicle, and more particularly, to a suspension apparatus that includes a mechanism that changes spring rigidity.

  As a suspension device, a device that changes a spring stiffness of a main spring by combining a coil spring and a steel torsion bar spring is known. Further, as a suspension device that performs a buffering operation on a traveling vehicle, for example, a technique of an air suspension system that automatically changes a spring constant according to a vehicle speed is disclosed (for example, see Patent Document 1). According to this technique, the spring constant of the air spring is changed by changing the volume of the sub chamber by pushing the piston rod into the cylinder by a predetermined distance according to the vehicle speed. That is, when the vehicle speed is high, the volume of the sub-chamber is reduced, and the piston rod is further pushed into the cylinder to increase the spring constant of the air suspension system. Further, when the vehicle speed is slow, the spring constant of the air suspension system is reduced by increasing the volume of the sub chamber and pulling out the piston rod from the cylinder. In this way, by adjusting the magnitude of the spring constant of the air suspension system according to the vehicle speed, a buffering operation according to the vehicle speed is performed.

  Also disclosed is a technique for configuring an air suspension device including a mount rubber for mounting a piston rod of a hydraulic shock absorber on the vehicle body side and a rod guide provided on a cylinder inner cylinder to support the piston rod (for example, Patent Document 2). According to this technique, an air chamber and a hydraulic shock absorber are integrally provided as an air suspension device, and the upper end of the piston rod of the hydraulic shock absorber is connected to the vehicle body side via the mount rubber. The piston rod is supported by a rod guide. At this time, the movable partition of the actuator is displaced by the air pressure of the air chamber. With such a configuration, the number of parts of the air suspension device can be reduced, and the air suspension device can be stably operated.

JP 2009-61873 A JP 2000-186736 A

  However, the technique disclosed in Patent Document 1 adjusts the spring constant of the air suspension system by moving the position of the piston rod in the cylinder by changing the volume of the sub-chamber according to the vehicle speed. However, it is not considered to control the spring constant of the entire system of the air suspension system. In other words, this technique adjusts the spring constant of the air suspension system by varying the internal pressure of the air spring connected to the sub-chamber.

  However, the suspension system of an automobile is composed of an assembly of many elements, and the adjacent elements of these assemblies interact with each other, and finally the spring characteristics of the entire system of the air suspension system. Is demonstrating. However, the technique disclosed in Patent Document 1 does not consider the spring characteristics of the entire system as an assembly of elements constituting the air suspension system. That is, the spring characteristic of the entire system cannot be obtained only by the spring constant of the sub-chamber. In addition to the vehicle speed, the air suspension system needs to adjust the spring constant depending on the road surface state, etc., but the technique disclosed in Patent Document 1 does not consider the road surface state.

  In the technique disclosed in Patent Document 2, since the mount rubber is formed of a flexible material such as rubber, the mount rubber is used when an external force from the road surface is transmitted to the mount rubber through the piston rod. Is deformed. At the time of such deformation of the mount rubber, the mount rubber has a unique spring constant, so that a reaction force corresponding to the spring constant is generated. That is, since the mount rubber itself has a spring constant, a predetermined reaction force is generated against the external force. Therefore, the air suspension device must be designed in consideration of not only the spring constant of the air spring but also the spring constant of the mount rubber. However, the technique of Patent Document 2 takes into account the addition of the spring constant of the mount rubber. Absent.

  Further, since the rod guide constituting the air suspension device is generally supported so that the piston is slidable, there is a friction force between the rod guide and the piston rod during the stroke of the hydraulic shock absorber. appear. Therefore, since the spring constant of the mount rubber itself and the frictional force between the rod guide and the piston rod influence each other, the system spring constant generated from the entire suspension system (or suspension system) is the air In addition to the spring constant of the spring, it is necessary to add various spring constants generated between the elements. However, the technique of Patent Document 2 does not consider adding the spring constant generated between the elements.

  In other words, the spring constant of the air chamber (for example, the sub chamber) of the air suspension is used when adjusting the target spring constant or realizing the vibration damping force when the vehicle performs the desired posture control or vibration suppression control. If the vibration damping force generated by the damping force variable damper that controls the vibration damping force is set to a predetermined value by adjusting the fluid viscosity, adjusting the fluid viscosity, or adjusting the fluid flow path area, the spring of the mount rubber Due to the influence of the constant and the sliding resistance (frictional force) of the piston rod, the suspension system as a whole deviates from the desired spring constant and damping force. As a result, unintended effects may occur in vehicle attitude control and vibration control.

  In other words, considering the spring constant generated by the mount rubber and the frictional force of the piston rod, adjusting the spring rigidity of the suspension system as a whole makes it possible to obtain the target spring constant and damping force (load) for the suspension apparatus as a whole. It is necessary to generate desired vibration suppression control and attitude control for the vehicle, or in the techniques disclosed in Patent Literature 1 and Patent Literature 2, adjusting the spring stiffness as the entire suspension system Can not. Also, with these technologies, the system spring stiffness of the entire suspension system is desired by effectively using the spring constant of the mount rubber and the frictional force of the rod guide without using an air suspension (air spring) or variable damping force damper. Can not be adjusted to the rigidity of. That is, in the suspension device, even if only the spring stiffness of the main spring is changed, the system spring stiffness of the entire system cannot be changed to a desired stiffness.

  The present invention has been made in view of such circumstances, and by effectively utilizing each element of a suspension device constituted by an assembly of a large number of elements and frictional force between the elements, the system as a whole. An object of the present invention is to provide a suspension device that can optimally exhibit the system spring rigidity.

In order to achieve the above object, a suspension apparatus according to claim 1 of the present invention is a vibration suppressing means for suppressing vibration transmitted from a vehicle wheel or a vehicle body, or a vehicle height adjusting means for adjusting the height of the vehicle body. In a suspension device having
System spring stiffness control means is provided for controlling the system spring stiffness that is exhibited in the entire suspension system by adjusting the mounting state of the vibration suppressing means or the vehicle height adjusting means to the vehicle body.

  According to this configuration, since the system spring stiffness control means can adjust the mounting state of the vibration suppressing means or the vehicle height adjusting means to the vehicle body, the frictional force between the elements can be adjusted, and the suspension device It is possible to control the rigidity of the system spring exerted in the entire system. Therefore, in addition to the main spring rigidity inherent to the vibration suppressing means and the vehicle height adjusting means, the system spring rigidity is added by the mount spring rigidity exhibited by the components other than the vibration suppressing means and the vehicle height adjusting means. Control and attitude control can be performed. Thus, fine vibration control and attitude control can be performed according to the running state of the vehicle.

A suspension device according to claim 2 of the present invention is the suspension device according to claim 1,
The vibration suppressing means or the vehicle height adjusting means is a damper device that is connected between the wheel side and the vehicle body side and generates a damping force that attenuates relative movement between the wheel side and the vehicle body side. ,
The system spring stiffness control means is provided in an attachment portion on a wheel side or a vehicle body side of the damper device, and controls the system spring stiffness by moving an attachment position of the damper device.

  According to this configuration, by moving the mounting position of the damper device to the vehicle (wheel side or vehicle body side), not only the load (damping force) exerted by the main spring rigidity of the damper device but also various components It is possible to adjust the rigidity of the system spring that is exhibited as a whole system of the suspension device, including the rigidity of the mount in which the suspension occurs. Therefore, it is possible to improve the accuracy of vehicle vibration control and attitude control. Although the vibration suppressing means has a damper function, the vehicle height adjusting means has a damper function and a vehicle height adjusting function.

  The suspension device according to a third aspect of the present invention is the suspension device according to the second aspect, wherein the system spring stiffness control means sets the mounting position of the damper device in the vehicle front-rear direction, the vehicle width direction, or both directions. The system spring rigidity is controlled by being moved to the position.

  According to this configuration, the mounting position of the damper device can be changed in an arbitrary direction, and accordingly, the inclination state of the damper device to the vehicle body can be changed in an arbitrary direction. Therefore, since the frictional force generated by the sliding generated inside the damper device can be finely changed, the system spring rigidity of the suspension device can be finely adjusted. As a result, the accuracy of vehicle vibration control and attitude control can be further improved.

A suspension device according to a fourth aspect of the present invention is the suspension device according to any one of the first to third aspects, further comprising vibration state detection means for detecting a vibration state of the vehicle,
The system spring stiffness control means controls to reduce the system spring stiffness when the vehicle vibration state detected by the vibration state detection means exceeds a predetermined vibration state.

  According to this configuration, the system spring stiffness control unit can control the system spring stiffness of the suspension device based on the vehicle vibration information detected by the vibration state detection unit, and when the vehicle vibration is large, The ride comfort of the vehicle can be improved by lowering the system spring rigidity of the suspension device.

A suspension device according to a fifth aspect of the present invention is the suspension device according to any one of the first to fourth aspects, wherein a turning state detecting means for detecting a turning state of the vehicle or a posture for detecting a posture state of the vehicle. Including a state detection means;
The system spring stiffness control means has a predetermined attitude state of the vehicle detected by the attitude state detection means when the turning state of the vehicle detected by the turning condition detection means exceeds a predetermined turning state (angle). When the inclination angle of the system is exceeded, control is performed so as to increase the rigidity of the system spring.

  According to this configuration, the system spring rigidity of the suspension system as a whole can be increased to improve the turning performance and promote the suppression of the posture inclination. Therefore, the operation stability in the running vehicle can be improved. Can be improved.

  According to the present invention, it is possible to optimally exhibit the rigidity of the system spring as a whole system by effectively using each element of the suspension device constituted by an assembly of a large number of elements and the frictional force between the elements. It is possible to provide a suspension device that can

It is a characteristic view which shows the displacement-load characteristic of the system spring in the suspension apparatus which concerns on each embodiment of this invention. FIG. 2 is a characteristic diagram showing a displacement-load characteristic of a system spring when the bottom dead center of characteristic a and characteristic b are matched in the characteristic diagram of FIG. 1. BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the suspension apparatus which concerns on 1st Embodiment of this invention, and its periphery structure, (a) is the block diagram seen through from the back of a vehicle, (b) is the block diagram seen through from the top. FIG. 4 is a schematic diagram of the suspension device of the first embodiment showing a positional relationship among the steering knuckle 4, the actuator 5, and the attachment portion 6 a at the lower end of the damper 6 in the configuration diagram of FIG. It is a flowchart which shows the 1st control method in the suspension apparatus which concerns on each embodiment of this invention. It is a flowchart which shows the 2nd control method in the suspension apparatus which concerns on each embodiment of this invention. FIG. 4 is a schematic diagram of a suspension device according to a second embodiment showing a positional relationship among a steering knuckle 4, an actuator 5, and a mounting portion 6 a at the lower end of a damper 6 in the configuration diagram of FIG. It is a characteristic view which shows the relationship between the displacement (front-back direction and a horizontal direction) of a tire, and the vertical displacement of a suspension apparatus measured about a certain vehicle. It is a block diagram which shows the suspension apparatus which concerns on 3rd Embodiment of this invention, and its periphery structure, (a) is the block diagram seen through from the back of a vehicle, (b) is the block diagram seen through from the top. FIG. 6 is a characteristic diagram showing the effect of suspension characteristics when the suspension device according to the first embodiment of the present invention is mounted on a vehicle. FIG. 6 is a characteristic diagram showing an effect on a sprung response on the vehicle body side when the suspension device according to the first embodiment of the present invention is mounted on a vehicle.

  Since the suspension device of an automobile is composed of an assembly of many elements, adjacent elements influence each other and finally exhibit the suspension characteristics as a system. Specifically, a main spring, a damper, a damper mount, and the like are components of the suspension device. Therefore, the responsiveness of the suspension device as a system is governed not by the spring stiffness of the main spring but by the system spring stiffness of the entire system.

  The suspension device of the present invention is not limited to the spring constant and load adjustable by the active suspension, but includes various elements and elements that constitute the suspension device, such as the spring constant of the mount rubber that constitutes the suspension device and the sliding resistance of the rod guide. It is characterized by controlling the spring stiffness of the entire suspension system (system spring stiffness) by effectively utilizing the reaction force and sliding resistance generated between the two. The spring stiffness (N / m) corresponds to a ratio of contact force (that is, reaction force or load) generated when a certain object is bent. Therefore, the reaction force of the mount rubber and the frictional force of the rod guide are captured as the load generated when the piston rod is stroked when viewed from the suspension system as a whole. Can affect.

  FIG. 1 is a characteristic diagram showing a displacement-load characteristic of a system spring in a suspension device according to each embodiment of the present invention, where the horizontal axis represents displacement and the vertical axis represents load. In FIG. 1, a characteristic a is a displacement-load characteristic of the system spring when the frictional force of the component is small (low friction), and a characteristic b is when the frictional force of the component is large (high friction). It is a displacement-load characteristic of a system spring. The characteristics can be changed between the a1-a2 and a3-a4 in the characteristic a at low friction and between b1-b2 and the b3-b4 in the characteristic b at high friction by a suspension device or a variable damping force damper. This is a characteristic region of main spring stiffness. In the main spring stiffness characteristic region, the load increases (or decreases) in proportion to the amount of displacement based on the main spring stiffness characteristics in both the characteristics a and b.

  Also, the reaction force of the mount rubber and the sliding of the rod guide are between a2-a3 and a4-a1 in the characteristic a at low friction, and between b2-b3 and b4-b1 in the characteristic b at high friction. This is a characteristic region of mount rigidity determined by resistance. In both of the characteristics a and b, the mount rigidity characteristic region increases (or decreases) rapidly depending on the mount rigidity due to the reaction force of the mount rubber and the sliding resistance of the rod guide.

  That is, as shown in FIG. 1, the characteristic of the system spring stiffness has hysteresis caused by the reaction force of the mount rubber, the sliding resistance of the rod guide, etc., and increases or decreases depending on the main spring stiffness, and a predetermined displacement amount is obtained. If exceeded, the load will increase or decrease rapidly depending on the mount stiffness.

  More specifically, the displacement-load characteristic of the system spring when the component friction force is small (low friction) draws a loop like the characteristic a, and when the component friction force is large (high friction). The displacement-load characteristic of the system spring draws a loop like characteristic b. That is, in the displacement-load characteristic of the suspension device, the characteristic a at the time of low friction and the characteristic b at the time of high friction both draw a parallelogram-like characteristic. When the frictional force of the component is 0, there is no sudden load change due to the mount rigidity, so that one proportional characteristic based on the main spring rigidity characteristic is obtained.

  FIG. 2 is a characteristic diagram showing the displacement-load characteristic of the system spring when the bottom dead center of characteristic a and characteristic b is matched in the characteristic diagram of FIG. 1, with the horizontal axis representing displacement and the vertical axis representing load. ing. Comparing characteristics a and b, and looking at the behavior of the displacement movement from the bottom dead center to the top dead center of the suspension device, the difference in the magnitude of the friction force has a large effect on the mount rigidity, and the main spring rigidity It turns out that there is not much influence.

  As a result, when the frictional force of the component is large, the characteristic b0 that is the total inclination from the bottom dead center b1 to the top dead center b3 becomes the system spring rigidity, and the load at the top dead center with the maximum displacement ( That is, the restoring force is increased and the system spring rigidity is increased. When the frictional force of the component is small, the characteristic a0 that is the total inclination from the bottom dead center a1 to the top dead center a3 becomes the system spring rigidity, and the load at the top dead center with the maximum displacement (that is, restoration) Force) is reduced and system spring rigidity is reduced.

  That is, when controlling the system spring stiffness of the suspension device, the mount stiffness (that is, the mount rubber reaction force and the sliding resistance of the rod guide) is changed, and the spring constant and load by the suspension device and damping force variable damper are changed. The system spring stiffness of the entire suspension system can be changed without change.

  Therefore, in the suspension device according to each embodiment of the present invention, a general suspension configured based on constraints such as layout and dimensional tolerance of each component by adding an actuator (system spring stiffness control means). By actively controlling the stiffness of the system spring realized by the device, the suspension device is made to achieve a desired sprung response.

  Hereinafter, several embodiments of a suspension device according to the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, the same elements are denoted by the same reference symbols in principle, and the repeated explanation thereof is omitted.

(First embodiment)
3 (a) and 3 (b) show a suspension device and its peripheral configuration according to the first embodiment of the present invention. FIG. 3A shows a configuration diagram seen through from the rear of the vehicle, and FIG. 3B shows a configuration diagram seen through from above. In FIG. 3 (a), the left arrow in the figure indicates the left side of the vehicle, the right arrow indicates the right side of the vehicle, the upper side in the figure indicates the upper part of the vehicle, the lower side in the figure indicates the lower part of the vehicle, The front side of the vehicle and the front side of the paper indicate the rear side of the vehicle.

  3 (a) and 3 (b), the tire 2 is rotatably fixed to the hub 3 via a wheel (not shown). A steering knuckle 4 is attached to the hub 3. The suspension device 1 a is attached on a damper holding portion 4 a on the upper side of the steering knuckle 4. That is, the suspension device 1a is movable by an actuator (system spring stiffness control means) 5 attached to the upper portion of the damper holding portion 4a and a bush (attachment portion at the lower end of the damper: mount rubber) 6a on the upper portion of the actuator 5. Attached damper (vibration suppression means) 6, coil spring 7 attached in parallel with the damper 6 so as to be stretchable, and attached to the upper part of the damper 6 and the coil spring 7 so as to be movably connected to the vehicle body 9. And a bush (mounting portion at the upper end of the damper: mount rubber) 6b. The damper 6 can also include vehicle height adjusting means for realizing a vehicle height adjusting function in addition to the vibration suppressing function.

  Further, a drive shaft 10 for transmitting the rotational force to the tire 2 is extended between the steering knuckle 4 and the knuckle lower arm 4b. Further, the lower arm 12 is extended from the knuckle lower arm 4 b via the lower ball joint 11 and fixed to the body 9. Further, the tie rod 13 is movably attached from the steering knuckle 4 via the steering knuckle arm 4c so that the tire 2 can be steered.

  As shown in FIG. 3, as means for detecting the operating state of the suspension device 1a, a vibration state detecting means 15 for detecting the vibration state of the vehicle, a turning state detecting means 16 for detecting the turning state of the vehicle, and the vehicle Posture state detecting means 17 for detecting the posture state of the robot. Note that any one of the turning state detection unit 16 and the posture state detection unit 17 may be provided. The vibration state of the vehicle is detected by measuring the acceleration of the vehicle, measuring the expansion / contraction state (suspension displacement) of the damper 6 on the left and right sides of the vehicle, and measuring the lateral acceleration (lateral G). Can do. The vehicle turning state and posture state are detected by measuring the steering angle, measuring the expansion / contraction state (suspension displacement) of the damper 6 on the left and right of the vehicle, and measuring the lateral acceleration (lateral G). Can do.

  FIG. 4 shows a positional relationship among the steering knuckle 4, the actuator 5, and the attachment portion 6a at the lower end of the damper in the configuration diagram of FIG. In FIG. 4, the left side of the figure indicates the front of the vehicle, and the right side of the figure indicates the rear of the vehicle. An actuator 5 is added to the attachment portion 6a at the lower end of the damper, and this actuator 5 is attached to the steering knuckle 4 (actually the damper holding portion 4a) so as to be rotatable. That is, the actuator 5 is disposed at a position that mediates between the attachment portion 6 a at the lower end of the damper and the steering knuckle 4.

  Then, as shown in the directions of arrows b and c (vehicle longitudinal direction) in FIG. 4, the mounting portion 6 a at the lower end of the damper is displaced relatively from the steering knuckle 4 in the vehicle longitudinal direction by the driving force of the actuator 5. Thus, the axial direction of the central axis 6c of the damper 6 is inclined from the arrow d at the neutral time to the direction of the arrow e at the maximum displacement, in the direction of the arrow f at the maximum displacement, and in the opposite direction. Can do. As a result, it is possible to control to increase or decrease the frictional force generated between the inner cylinder and the outer cylinder on the damper side wall (not shown) of the damper 6. That is, when the mounting portion 6a at the lower end of the damper is not displaced and the axial direction of the central axis 6c of the damper 6 is an arrow d, the frictional force generated between the inner cylinder and the outer cylinder on the damper side wall (not shown) of the damper 6 is small. When the mounting portion 6a at the lower end of the damper is displaced in the directions of arrows b and c and the axial direction of the center axis 6c of the damper 6 is inclined in the directions of arrows e and f, the inside of the damper side wall of the damper 6 (not shown) The frictional force generated between the cylinder and the outer cylinder increases. In this way, the mount stiffness due to the frictional force of the damper 6 that can be controlled to increase or decrease is added to the spring stiffness by the coil spring 7, and control to increase or decrease the total system spring stiffness can be performed.

  The actuator 5 may be of any power or type as long as it causes a displacement in the attachment portion 6a at the lower end of the damper. Moreover, even if the displacement direction of the attachment part 6a at the lower end of the damper is a direction perpendicular to the direction shown in FIG. 4, it is sufficient if the frictional force of the damper 6 can be changed.

  Next, the contents of the control method realized by the suspension device 1a having the configuration shown in FIG. 3 will be described. FIG. 5 shows a first control method in the suspension device 1a of the first embodiment. In general, the system spring rigidity of the suspension device 1a is required to be low for the riding comfort of the vehicle and high for the stability of operation. Therefore, the running state of the vehicle is determined to control the system spring stiffness.

  First, in step S1, the vibration state detection unit 15, the turning state detection unit 16, and the posture state detection unit 17 are configured so that the vehicle running state (vibration) is determined by the steering angle of the vehicle, lateral acceleration (lateral G), suspension displacement, and the like. State, turning state, posture state). The speedometer measures (detects) the vehicle speed. Then, the control unit of the actuator (system spring stiffness control means) 5 acquires the detected steering angle, lateral acceleration (lateral G), suspension displacement, vehicle speed, and the like of the detected vehicle.

  Next, in step S2, the controller of the actuator (system spring stiffness control means) 5 determines that the running state of the vehicle is turning, suddenly accelerating, suddenly braking, etc. It is determined whether it is necessary (for example, whether the difference in suspension displacement between the left and right sides of the vehicle exceeds a predetermined value). Here, when the running state of the vehicle is not turning or the like and the stability at the time of running is not particularly required (No in step S2), the process returns to step S1, and the running state of the vehicle is continuously detected. On the other hand, when the traveling state of the vehicle is turning or the like and stability during traveling is required (Yes in step S2), the process proceeds to step S3.

  In step S3, the control unit of the actuator (system spring stiffness control means) 5 displaces the lower end of the damper 6 (the mounting portion 6a at the lower end of the damper) in the direction of increasing the system spring stiffness with respect to the actuator 5. Give instructions. As a result, the actuator 5 greatly displaces the lower end of the damper 6 in the longitudinal direction of the vehicle, so that the axial direction of the central axis 6c of the damper 6 is inclined, the frictional force is increased, and the mount rigidity is increased. As a result, the system spring rigidity of the suspension device increases. As a result, the vehicle can ensure the stability of operation during turning.

  Further, when the tire 2 moves up and down with respect to the body (vehicle body) 9 depending on the road surface state, displacement occurs simultaneously in the longitudinal direction of the vehicle. That is, the longitudinal displacement of the vehicle is determined by the anti-dive scort in which the front portion of the body 9 is lowered, and measures against harshness such as vibration felt on the body 9 depending on the road surface condition. An increase in the frictional force of the damper 6 also occurs due to a change in geometry indicating the positional relationship for determining the position. This may cause an unintended increase in system spring stiffness. In such a case, the mechanism of the suspension device 1a shown in FIG. 3 controls the amount of displacement of the lower end of the damper 6 in the direction in which the frictional force of the damper 6 is reduced, thereby reducing the system spring rigidity, thereby reducing the vibration of the vehicle body. Energy can be reduced (second control method).

  FIG. 6 shows a second control method in the suspension device 1a of the first embodiment shown in FIG. First, in step S11, the vibration state detection unit 15, the turning state detection unit 16, and the posture state detection unit 17 determine the vehicle running state (vibration) according to the steering angle, lateral acceleration (lateral G), suspension displacement, and the like of the vehicle. State, turning state, posture state). The speedometer measures (detects) the vehicle speed. Then, the control unit of the actuator (system spring stiffness control means) 5 acquires the detected steering angle, lateral acceleration (lateral G), suspension displacement, vehicle speed, and the like of the detected vehicle.

  Next, in step S12, the control unit of the actuator (system spring stiffness control means) 5 requires a more relaxed feeling than the current state because the vehicle is running straight and has harshness or the like ( For example, it is determined whether or not the suspension displacement due to harshness or the like exceeds a predetermined value. Here, when the vehicle is not traveling straight and does not require a relaxed feeling (No in step S12), the process returns to step S11 to continuously detect the traveling state of the vehicle. On the other hand, when the traveling state of the vehicle is traveling straight ahead and more relaxed feeling is required than the current state (Yes in step S12), the process proceeds to step S13.

  In step S13, the control unit of the actuator (system spring stiffness control means) 5 displaces the lower end of the damper 6 (the attachment portion 6a at the lower end of the damper) in the direction of decreasing the system spring stiffness with respect to the actuator 5. Give instructions. As a result, the actuator 5 displaces the lower end of the damper 6 in the longitudinal direction of the vehicle, the axial direction of the central axis 6c of the damper 6 is inclined, the frictional force is reduced, and the mount rigidity is lowered. As a result, the system spring rigidity of the suspension device is reduced. As a result, the vehicle can reduce the vibration energy of the vehicle body by reducing the rigidity of the system spring during straight traveling.

(Second Embodiment)
As shown in FIG. 3B, the suspension device 1a according to the first embodiment adds an actuator 5 to the lower end of the damper 6, and the actuator 5 displaces the lower end of the damper 6 in the longitudinal direction of the vehicle. The system spring stiffness of 1a was controlled. In the suspension device 1a of the second embodiment, as in the first embodiment, the actuator 5 is added to the lower end of the damper 6 as shown in FIG. 3B. The system spring stiffness of the suspension device 1a is controlled by shifting in the direction (left-right direction in the drawing in FIG. 3B).

  FIG. 7 shows the relationship between the steering knuckle 4 (damper holding portion 4a), the actuator 5 and the damper 6 of the suspension device 1b of the second embodiment. In FIG. 7, the direction to the left of the arrow is the left side of the vehicle, and the direction to the right of the arrow is the right side of the vehicle. As shown in FIG. 7, the actuator 5 is attached to the attachment portion 6a at the lower end of the damper, and this actuator 5 is attached to the steering knuckle 4 so as to be rotatable. That is, the actuator 5 is disposed at a position that mediates between the attachment portion 6 a at the lower end of the damper and the steering knuckle 4.

  Then, due to the driving force of the actuator 5, as shown in the directions of arrows b and c (left and right directions of the vehicle) in FIG. Since the axial direction of the central axis 6c of the damper 6 can be tilted in the left-right direction as in the first embodiment, the displacement between the inner cylinder and the outer cylinder on the damper side wall (not shown) of the damper 6 It is possible to control the frictional force generated in

  When the lower end of the damper 6 is displaced in the left-right direction by the actuator 5, the lower end of the damper 6 is displaced in the left-right direction of the vehicle relative to the damper holding portion 4 a extending from the steering knuckle 4. As a result, the damper 6 rubs the inner cylinder and the outer cylinder on the side wall of the damper (not shown), and the frictional force increases. In this way, the mount stiffness due to the frictional force of the damper 6 that can be controlled to increase or decrease is added to the spring stiffness by the coil spring 7, and control to increase or decrease the total system spring stiffness can be performed.

  The actuator 5 may be any power or type as long as it causes the damper 6 to be displaced. Further, the displacement direction of the damper 6 is greater in the lateral direction (left-right direction) of the vehicle as in the second embodiment than in the front-rear direction of the vehicle as in the first embodiment.

  Next, the contents of the control method realized by the suspension device 1a of the second embodiment will be described. Generally, the system spring rigidity of the suspension device is required to be low for riding comfort and high for operation stability. Therefore, the running condition of the vehicle is determined to control the system spring stiffness.

  In this case, when it is determined whether or not the traveling vehicle is turning and the stability during traveling is necessary and the system spring rigidity of the suspension device is controlled, the flowchart shown in FIG. Since the same flow is shown, the description thereof is omitted. Further, when the traveling vehicle is traveling straight ahead and it is determined whether or not a feeling of relaxation is necessary, and the system spring stiffness of the suspension device 1a is controlled, it is the same as the flowchart shown in FIG. The description thereof will be omitted.

  Further, when the tire 2 moves up and down with respect to the body 9 depending on the road surface state, the body 9 is simultaneously displaced in the lateral direction. Generally, the displacement amount of the suspension device 1a is larger when the body 9 is displaced in the lateral direction than when the body 9 is displaced in the front-rear direction, and the displacement of the suspension device 1a when the body 9 is displaced in the lateral direction. Quantity tends to be non-linear. FIG. 8 is a characteristic diagram showing the relationship between the vertical displacement of the suspension device 1a with respect to the displacement in the longitudinal direction and the lateral direction of the tire 2 measured for a certain vehicle, and the horizontal axis indicates the displacement of the tire 2 (the longitudinal direction and the lateral direction). The vertical displacement of the suspension device 1a is shown on the vertical axis. That is, as shown in FIG. 8, the vertical displacement amount of the suspension device 1a relative to the displacement amount (front-rear direction and lateral direction) of the tire 2 when the tire 2 moves up and down with respect to the body 9 is It is larger when the body 9 is displaced laterally than when it is displaced, and has a non-linear characteristic.

  Due to such a phenomenon, when the tire 2 moves up and down with respect to the body 9 depending on the road surface state, there is a possibility that an unintended increase in system spring rigidity may occur nonlinearly due to the lateral displacement of the body 9. Therefore, in the suspension device 1a of the second embodiment, the lower end of the damper 6 is displaced laterally by the driving force of the actuator 5, thereby controlling the frictional force of the damper 6 more effectively. The vibration energy transmitted to the body 9 is reduced by lowering the system spring rigidity.

(Third embodiment)
In the third embodiment, a suspension device having a configuration in which an actuator is added to the upper end of a damper will be described. FIG. 9 is a configuration diagram showing the suspension device 1b and its peripheral configuration according to the third embodiment of the present invention, where (a) is a configuration diagram seen through from the rear of the vehicle, and (b) is a configuration diagram seen through from above. It is. 9A, the left arrow in the figure indicates the left side of the vehicle, the right arrow indicates the right side of the vehicle, the upper side in the figure indicates the upper part of the vehicle, the lower side in the figure indicates the lower part of the vehicle, and the back side of the paper The front side and the front side of the vehicle indicate the rear side of the vehicle.

  The third embodiment of FIG. 9 differs from the first and second embodiments of FIG. 3 in that the actuator 5 is added to the lower end of the damper 6 constituting the suspension device 1a in the first and second embodiments of FIG. However, in the third embodiment of FIG. 9, the actuator 5 is added to the upper part of the suspension device 1 b so as to contact the body 9. Therefore, only differences from FIG. 3 will be described, and redundant description will be omitted.

  As shown in FIG. 9A, the actuator 5 is disposed at a position that mediates between the upper end of the damper 6 (the mounting portion 6b at the upper end of the damper) and the body 9, and as shown in FIG. By displacing the upper end from the body 9 in the lateral direction and the front-rear direction of the vehicle, the center axis 6c of the damper 6 is eccentric and the frictional force is controlled. The actuator 5 can be of any power or type as long as it causes the damper 6 to be displaced.

  Since the displacement direction of the damper 6 has two degrees of freedom in the front-rear direction and the lateral direction, optimization (minimization) can be achieved particularly when the friction force is lowered to reduce the system spring rigidity. Moreover, in the structure of 3rd Embodiment, since it becomes on-spring arrangement | positioning, it is advantageous at the surface of vibration resistance.

  Next, a control method realized by the suspension device 1b having the configuration of the third embodiment will be described. Since the system spring rigidity of the suspension device is preferably low for riding comfort and high for operational stability, the running state is determined to control the system spring rigidity. In this case, when it is determined whether or not the traveling vehicle is turning and stability during traveling is necessary and the system spring rigidity of the suspension device is controlled, the flowchart shown in FIG. Since the same flow is shown, the description thereof is omitted. Further, when the traveling vehicle is traveling straight ahead and it is determined whether or not a feeling of relaxation is necessary and the system spring stiffness of the suspension device is controlled, the same flowchart as that shown in FIG. 6 is used. Since the flow is shown, the description is omitted.

  Further, when the tire 2 moves up and down with respect to the body 9, it is simultaneously displaced in the longitudinal direction and lateral direction of the vehicle body, and the displacement amount of the suspension device 1b when the vehicle body is displaced in the lateral direction is large and has non-linear characteristics. Prone. Therefore, an unintended increase in system spring rigidity may occur nonlinearly depending on the combination of displacements. However, since the suspension measure of this embodiment is displaced with two degrees of freedom, the friction force can be reduced to almost the same level as the friction force when the damper 6 is a single unit. Vibration energy can be reduced by lowering to the minimum).

"Experimental result"
The suspension devices 1a and 1b according to the respective embodiments described above were incorporated into a vehicle, and the effect on the displacement and load characteristics and the sprung response on the body 9 side was verified as a suspension system. FIG. 10 is a characteristic diagram showing the effect of the suspension characteristics when the suspension device 1a according to the first embodiment of the present invention is mounted on a vehicle. The horizontal axis represents displacement, and the vertical axis represents load. In addition, even in the suspension characteristics when the suspension devices 1a and 1b according to the second and third embodiments are mounted on a vehicle, a characteristic diagram showing the same effect as in the first embodiment can be obtained.

  In FIG. 10, the measurement was performed with the movable part of the actuator 5 at the lower end of the damper 6 at the neutral position (position) d (see FIG. 4) and at the maximum displacement (position) f (see FIG. 4). Although the case is shown, when the lower end of the damper 6 is displaced from the neutral position (position) d to the maximum displacement position (position) f, the characteristic diagram of the parallelogram type also changes continuously and expands in the load coordinate direction. It was confirmed that the friction force continuously increased from the minimum friction force F1 to the maximum friction force F2. Thus, it was found that the system spring stiffness of the suspension device 1a can be changed (controlled) in a range from a value corresponding to the minimum friction force F1 to a value corresponding to the maximum friction force F2.

  FIG. 11 is a characteristic diagram showing the effect on the sprung response on the body 9 side when the suspension device 1a according to the first embodiment of the present invention is mounted on a vehicle. Shows the effective value of sprung acceleration. That is, when the sprung response that the suspension device 1a exerts on the body 9 side is measured in a state where the lower end of the damper 6 is displaced from the neutral position (position) d to the maximum displacement position (position) f by the movable part of the actuator 5, As shown in FIG. 11, it was confirmed that the sprung response changes. The resonance frequency (frequency indicating the peak of each mountain-shaped graph in FIG. 11) rises more at the maximum displacement f than the neutral time d, and the sprung acceleration effective value (in FIG. 11) at the resonance frequency. The peak of each mountain-shaped graph is larger. From this, it was found that the spring stiffness is higher at the maximum displacement f than at the neutral d. As shown in FIG. 10, it was found that the spring rigidity can be enhanced as shown in FIG. 11 by enlarging the parallelogram type characteristic diagram in the load coordinate direction (increasing the frictional force). And the characteristic which shows the effect similar to 1st Embodiment also with respect to the effect on the sprung response by the side of the body 9 when the suspension apparatus 1a, 1b which concerns on 2nd and 3rd embodiment of this invention is mounted in a vehicle. The figure could be obtained.

  That is, when the vibration frequency from the road surface exceeds the predetermined frequency by displacing the lower end of the damper 6 from the neutral position (position) d to the maximum displacement position (position) f, the effective value of the on-spring acceleration of the suspension device 1a is From the effective value of the sprung acceleration at neutral d, the effective value of the sprung acceleration at maximum displacement f is increased. This is because the resonance frequency rises by displacing the lower end of the damper 6 from the neutral time (position) d to the maximum displacement time (position) f, and the effective value of sprung acceleration at the resonance frequency increases. The characteristic that the system spring rigidity is increased is shown, and it is shown that the control for increasing or decreasing the vibration energy on the body 9 side is possible.

  As described above, the suspension devices 1a and 1b according to the embodiments of the present invention actively utilize the frictional force that originally acts as a damping element when operating the mechanical portion, and the suspension devices 1a and 1b The system spring stiffness that determines the characteristics is changed. This makes it possible to effectively control the equivalent system spring stiffness, which is highly effective in suspension characteristics, without changing the single spring stiffness of the suspension devices 1a, 1b. It is possible to achieve stability together.

  Although the present invention has been specifically described based on the three embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, the positional relationship between the damper 6 and the actuator 5 is not limited to the above-described embodiments, and any positional relationship between the damper 6 and the actuator 5 is included in the present invention as long as the mechanism displaces the damper 6. .

  According to the suspension devices 1a and 1b of the present invention, the system spring stiffness can be variably controlled only by using the frictional force and reaction force of various components, so that the suspension device 1a and 1b can be effectively used from a general-purpose vehicle to a luxury vehicle. be able to.

1a, 1b Suspension device 2 Tire (wheel)
3 Hub 4 Steering knuckle 4a Damper holding part 5 Actuator (system spring stiffness control means)
6 Damper (vibration suppression means, vehicle height adjustment means)
6a Damper lower end mounting part 6b Damper upper end mounting part 9 Body (vehicle body)
15 vibration state detection means 16 turning state detection means 17 posture state detection means

Claims (5)

In a suspension device having vibration suppressing means for suppressing vibration transmitted from a vehicle wheel or a vehicle body, or vehicle height adjusting means for adjusting the height of the vehicle body,
Suspension comprising system spring stiffness control means for controlling the system spring stiffness exerted in the entire suspension system by adjusting the mounting state of the vibration suppressing means or the vehicle height adjusting means to the vehicle body. apparatus. The vibration suppressing means or the vehicle height adjusting means is a damper device that is connected between the wheel side and the vehicle body side and generates a damping force that attenuates relative movement between the wheel side and the vehicle body side. ,
2. The system spring stiffness control means is provided at a wheel-side or vehicle-body-side mounting portion of the damper device, and controls the system spring stiffness by moving the mounting position of the damper device. The suspension device described in 1.   3. The system spring stiffness control means controls the system spring stiffness by moving the mounting position of the damper device in the front-rear direction or the vehicle width direction of the vehicle, or in both directions. Suspension device. Comprising vibration state detection means for detecting the vibration state of the vehicle,
2. The system spring stiffness control unit controls the system spring stiffness to decrease when the vehicle vibration state detected by the vibration state detection unit exceeds a predetermined vibration state. 4. The suspension device according to any one of items 3 to 3. A turning state detecting means for detecting a turning state of the vehicle, or a posture state detecting means for detecting a posture state of the vehicle;
The system spring stiffness control means is configured such that when the turning state of the vehicle detected by the turning state detection means exceeds a predetermined turning state, or the posture state of the vehicle detected by the posture state detection means is a predetermined inclination angle. The suspension device according to any one of claims 1 to 4, wherein the suspension is controlled so as to increase the rigidity of the system spring when the value exceeds.

Images