JP4747886B2 - Vehicle equipped with a return-promoting cross-linked shock absorber system - Google Patents

Description

  The present invention relates to a shock absorber incorporated in a wheel suspension device of a vehicle such as an automobile, and more particularly to a free-piston cylinder-piston device having four chambers, wherein a pair of rear wheel shock absorbers are used as a pair of front wheel shock absorbers. The present invention relates to an improvement related to a cross-linked shock absorber system connected to a cylinder-piston device in a crossed relationship.

In a vehicle such as a four-wheeled vehicle having a pair of left and right front wheels and a pair of left and right rear wheels, it is in this technical field that each wheel is suspended from a vehicle body by a wheel suspension device incorporating a shock absorber. Is well known. Moreover, a cylinder-piston device having a stepped cylinder and a free piston is combined with such four shock absorbers, and the hydraulic pressures of the left and right shock absorbers for a pair of front wheels are applied to both sides of the free piston so as to oppose each other. In addition to this, the working hydraulic pressures of the left and right shock absorbers for the pair of rear wheels are applied to both sides of the same free piston so as to oppose each other, or the shock absorber on one side of the left and right shock absorbers for the pair of front wheels The difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the other side and the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on the same side of the left and right shock absorbers for the pair of rear wheels The difference can be opposed by a free piston. (That is, the above-described cross-coupled shock absorber system is configured), or a switching valve that switches the operation hydraulic pressure of the four shock absorbers between the parallel communication state and the cross communication state. Switching between the two modes according to the operating state is described in Patent Document 1 below.
JP 2004-322755 A

  The cross-linked shock absorber system is configured as illustrated in FIG. In FIG. 8, 10fl, 10fr, 10rl, and 10rr are the left front wheel, right front wheel, left rear wheel, and right rear wheel of a four-wheel vehicle, respectively, and each wheel is a vehicle body by suspension arms 12fl, 12fr, 12rl, and 12rr, respectively. 14 is suspended so as to be vertically displaceable, and the shock absorbers 16fl, 16fr, 16rl, 16rr respectively cushion the vertical displacement with respect to the vehicle body. Although not shown in the figure, as is well known in the art, the suspension arms 12fl, 12fr, 12rl, and 12rr are arranged in parallel to the shock absorbers 16fl, 16fr, 16rl, and 16rr. A suspension spring also acts, and each wheel is suspended from the vehicle body by a parallel combination of a suspension spring and a shock absorber.

  Oil paths 18fl, 18fr, 18rl, and 18rr are connected to the shock absorbers 16fl, 16fr, 16rl, and 16rr, respectively, and pressure accumulation chambers 20fl, 20fr, 20rl, and 20rr, throttle valves 22fl, 22fr, and so on are respectively connected to these oil paths. 22rl and 22rr are connected.

  The cylinder-piston device 24 slides on a stepped cylinder 30 having a central large diameter cylinder portion 26 and a pair of small diameter cylinder portions 28l and 28r connected to both ends thereof, and a large diameter cylinder portion 26 of the stepped cylinder. And a free piston 36 having a pair of small diameter piston portions 34l, 34r that are connected to both sides of the central large diameter piston portion 32 and slide on a pair of small diameter cylinder portions 28l, 28r of a stepped cylinder. .

  The hydraulic pressure of the shock absorber 16fl is introduced into the hydraulic chamber 38fl of the cylinder-piston device 24 through the oil passage 18fl, and the hydraulic pressure of the shock absorber 16fr is introduced into the hydraulic chamber 38fr of the cylinder-piston device 24 through the oil passage 18fr. The hydraulic pressure of the shock absorber 16rl is introduced into the hydraulic chamber 38rl of the cylinder-piston device 24 via the oil passage 18rl, and the hydraulic pressure of the shock absorber 16rr is introduced into the hydraulic chamber 38rr of the cylinder-piston device 24 via the oil passage 18rr. Yes.

  As is clear from FIG. 8, the hydraulic pressure of the shock absorber for the left and right front wheels is applied to the left and right end faces corresponding to the free piston, and the hydraulic pressure of the shock absorber for the left and right rear wheels is reversed left and right with respect to the free piston. Therefore, when the vehicle turns left, the vehicle body tilts to the right due to centrifugal force, and the hydraulic pressure of the shock absorber for the right front wheel rises higher than the hydraulic pressure of the shock absorber for the left front wheel. When the free piston is urged to the left in the figure, the hydraulic pressure of the shock absorber for the right rear wheel rises higher than that of the left rear wheel, and the free piston is urged to the right in the figure. .

  An example of the state of the force acting on the free piston as the vehicle rolls to the right when the vehicle is turning left is shown in FIG. In this case, if the leftward force in the figure acting on the free piston by the hydraulic pressure in the cylinder chamber 38fr is compared with the rightward force in the figure acting on the free piston by the hydraulic pressure in the cylinder chamber 38fl, As shown by the comparison of the lengths of the two arrows, the left-hand force in the figure is larger than the right-hand force in the figure. To be energized. Similarly, if the force acting on the free piston by the hydraulic pressure in the cylinder chamber 38rr is compared with the rightward force in the diagram acting on the free piston by the hydraulic pressure in the cylinder chamber 38rl, As indicated by the comparison of the lengths of the two arrows, the rightward force in the figure is greater than the leftward force in the figure, so that the free piston moves to the right in the figure due to the resultant force of these two forces. To be energized.

  As described above, the difference between the shock absorber hydraulic pressures of the left and right front wheels due to the roll inclination of the vehicle body and the difference generated between the shock absorber hydraulic pressures of the left and right rear wheels act against each other with respect to the free piston. The difference between the shock absorber oil pressure of the left and right front wheels and the difference between the shock absorber oil pressure of the left and right rear wheels due to the vehicle body turning slightly forward or backward when the vehicle turns. Even if a deviation occurs in the meantime, the displacement of the free piston from the center position remains moderate. Further, depending on the pitching of the vehicle body, there is no difference between the shock absorber hydraulic pressure of the left and right front wheels and the shock absorber hydraulic pressure of the left and right rear wheels, so that no displacement occurs in the free piston.

  On the other hand, as can occur during off-road driving of a vehicle, the warping in which the bounce and the rebound are reversed between the pair of front wheels and the pair of rear wheels and the vehicle body is twisted between the front and the rear. When this happens, the situation is different. That is, now, assuming that the right wheel bounces to the left wheel between the pair of front wheels and the left wheel bounces to the right wheel between the pair of rear wheels, as shown in FIG. If the leftward force in the figure acting on the free piston by the hydraulic pressure in the figure and the rightward force in the figure acting on the free piston in the figure in the cylinder chamber 38fl are compared, the length of the two arrows Since the leftward force in the figure is larger than the rightward force in the figure as shown by comparison, the free piston is urged to the left in the figure by the resultant force of these two forces. At this time, the leftward force in the figure acting on the free piston by the hydraulic pressure in the cylinder chamber 38rr is compared with the rightward force in the figure acting on the free piston by the hydraulic pressure in the cylinder chamber 38rl. For example, as shown by the comparison of the lengths of the two arrows, the leftward force in the figure is greater than the rightward force in the figure, and here again the free piston is shown in the figure by the resultant force of these two forces. Is pushed to the left. Therefore, in this case, the free piston may be displaced to the left end. For the same reason, when the warping is reversed, the free piston may be displaced to the right end in the figure.

  In this way, when the free piston is fully displaced on either side of the cylinder and remains hydraulically acting on it, the hydraulic oil crosses the clearance between the piston and the cylinder, and the left and right cylinder chambers It moves in the middle, causing an imbalance in the amount of hydraulic oil for the pair of left and right shock absorbers. The flow of the hydraulic oil across the clearance between the piston and the cylinder, particularly when the free piston is brought into close contact with one end of the cylinder as illustrated by 40l and 40r in FIG. 9B. When contacted, the hydraulic oil cannot enter between them, and in order to prevent the piston from returning, the contact between the end wall of the piston and the end wall of the cylinder is prevented by something like a ring. More likely to occur.

  The present invention pays attention to the above-mentioned problem, and even when warping of a vehicle in which bound and rebound are reversed between a pair of front wheels and a pair of rear wheels occurs, It is an object of the present invention to prevent deviation from the center position from remaining in the free piston of the cylinder piston device in the coupled shock absorber system.

  In order to solve the above problems, the present invention includes a shock absorber for each of a pair of left and right front wheels and a pair of left and right rear wheels, a central large diameter cylinder portion, and a pair of small diameter cylinder portions connected to both ends thereof. A stepped cylinder, a central large diameter piston portion that slides on the large diameter cylinder portion of the stepped cylinder, and a pair of small diameters that are coupled to both sides thereof and slide on the pair of small diameter cylinder portions. A cylinder-piston device having a piston portion and a free piston, and the hydraulic pressure of the shock absorber on the other side relative to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels Of the left and right shock absorbers of the pair of rear wheels with respect to the hydraulic pressure of the shock absorber on the one side The cylinder-piston device has a cross-linked shock absorber system in which the difference in operating hydraulic pressure of the shock absorber on the other side is opposed to the cylinder-piston device via the free piston. The present invention proposes a vehicle characterized in that a spring for urging the free piston toward the center position with respect to the stepped cylinder is provided.

  The spring is a pair of compression coil springs acting between each of both ends of the stepped cylinder and each of the pair of small diameter piston portions of the free piston, or both ends of the large diameter cylinder portion of the stepped cylinder. And a pair of compression coil springs acting between each of the step portions between the pair of small diameter cylinder portions and the large diameter piston portion of the free piston.

  In this case, an oil passage provided with a communication valve for selectively communicating the left and right shock absorbers of the pair of front wheels by bypassing the cylinder-piston device may be provided. An oil passage provided with a communication valve that bypasses and selectively communicates the left and right shock absorbers of the pair of rear wheels may be provided.

  The difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the one of the left and right shock absorbers of the pair of rear wheels After the difference in operating hydraulic pressure of the other side shock absorber with respect to the operating hydraulic pressure of the other side shock absorber becomes opposite to each other, the operation of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels The difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure and the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of rear wheels The communication valve may be opened when the positive and negative of each other are the same.

  In this case, the communication valve is opened because of the difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the rear of the pair. The absolute value of the difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on the one side of the left and right shock absorbers of the wheel is equal to or less than a predetermined first value. It may be timed.

  Furthermore, the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels When the absolute value of the difference between the operating oil pressure of the shock absorber on the other side with respect to the operating oil pressure of the shock absorber on the one side becomes equal to or less than a predetermined second value smaller than the first value, The communication valve may be closed.

  The communication valve is opened because of the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right sides of the pair of rear wheels One side of the left and right shock absorbers of the pair of front wheels in which the difference in operating hydraulic pressure of the shock absorber on the other side with respect to the operating hydraulic pressure of the shock absorber on the other side of the shock absorbers on the other side is opposite to each other The absolute value of the difference between the hydraulic pressure of the shock absorber on the other side relative to the hydraulic pressure of the shock absorber of the other side and the other side of the shock absorber on the one side of the left and right shock absorbers of the pair of rear wheels After the absolute value of the difference between the hydraulic pressures of the shock absorbers exceeds a predetermined value, the pair of front The difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers and the shock absorber on the one side of the left and right shock absorbers of the pair of rear wheels The difference in operating hydraulic pressure of the shock absorber on the other side with respect to the operating hydraulic pressure may be the same.

  Alternatively, the difference between the hydraulic pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels The communication valve may be opened when the difference between the operating oil pressure of the shock absorber on the other side and the operating oil pressure of the shock absorber on the other side is opposite to each other.

  In this case, the absolute value of the difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers on the pair of rear wheels When the absolute value of the difference between the operating oil pressures of the shock absorbers on the other side and the operating oil pressures on the other side of the shock absorbers is less than a predetermined value, the communication valve is closed. It may come to be.

  Also in this case, the communication valve is opened because the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the above-mentioned The left and right shock absorbers of the pair of front wheels are opposite to each other in the difference in operating hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on the other side of the left and right shock absorbers of the pair of rear wheels. The absolute value of the difference between the hydraulic pressure of the shock absorber on the other side relative to the hydraulic pressure of the shock absorber on one side of the shock absorber and the operation of the shock absorber on the one side of the left and right shock absorbers of the pair of rear wheels The absolute value of the difference between the hydraulic pressures of the shock absorbers on the other side with respect to the hydraulic pressure is a predetermined value or more. There may be later.

  Alternatively, the difference in operating displacement of the shock absorber on the other side relative to the operating displacement of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels After the positive and negative of the difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on the one side of the one side of the pair of front wheels, The difference of the operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber and the shock absorber on the other side with respect to the operating displacement of the shock absorber on one side of the left and right shock absorbers of the pair of rear wheels When the difference in operating displacement is the same, the communication valve is opened. There may be.

  In this case, the communication valve is opened because of the difference between the operating displacement of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the rear of the pair The absolute value of the difference between the operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on the one side of the left and right shock absorbers of the wheel is equal to or less than a predetermined first value. It may be timed.

  The open communication valve may be closed when a predetermined time has elapsed since it was opened.

  Also in this case, the communication valve is opened because of the difference between the operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the pair of front wheels. The difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on the one side of the left and right shock absorbers on the rear wheels is opposite to each other, and the left and right shock absorbers of the pair of front wheels The absolute value of the difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on one side of them and the operating displacement of the shock absorber on the one side of the left and right shock absorbers of the pair of rear wheels After the absolute value of the difference in operating displacement of the shock absorber on the other side with respect to The difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the one of the left and right shock absorbers of the pair of rear wheels The difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on the other side may be the same as each other.

  Furthermore, the difference between the operating displacement of the shock absorber on the other side relative to the operating displacement of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels The communication valve may be opened when the difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on the one side is opposite to each other.

  The opened communication valve may be closed when a predetermined time has elapsed from when it was opened.

  The communication valve is opened because of the difference in operating displacement of the shock absorber on the other side relative to the operating displacement of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right of the pair of rear wheels One side of the left and right shock absorbers of the pair of front wheels in which the difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on the other side is opposite to each other The absolute value of the difference in operating displacement of the shock absorber on the other side relative to the operating displacement of the shock absorber of the other side and the other side of the shock absorber on one side of the left and right shock absorbers of the pair of rear wheels The absolute value of the difference in operating displacement of the shock absorbers may be after a predetermined value or more.

  In any case, the communication valve that bypasses the cylinder-piston device and selectively communicates the left and right shock absorbers of the pair of front wheels or rear wheels is a difference between the hydraulic pressures of the left and right shock absorbers. May be opened when is below a predetermined value.

  As described above, a stepped cylinder having a shock absorber for each of a pair of left and right front wheels and a pair of left and right rear wheels, a central large diameter cylinder part, and a pair of small diameter cylinder parts connected to both ends thereof, and the stepped cylinder A large piston portion in the center that slides on the large-diameter cylinder portion, and a free piston having a pair of small-diameter piston portions that are connected to both sides thereof and slide in the pair of small-diameter cylinder portions of the stepped cylinder. The difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the pair of rear wheels The shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on the one side of the left and right shock absorbers In a vehicle having a cross-coupled shock absorber system in which a difference in hydraulic pressure is opposed to the cylinder-piston device via the free piston, the cylinder-piston device has the free piston connected to the stage. If a spring that biases the attached cylinder toward the center position is provided, when the vehicle warping occurs in which the bound and rebound are reversed between the pair of front wheels and the pair of rear wheels, the piston and the cylinder Even if hydraulic oil moves across the clearance between the left and right cylinder chambers, when the warping of the vehicle stops, the free piston is urged toward the center position relative to the cylinder by the action of the spring. The hydraulic fluid that has moved between the left and right cylinder chambers across the clearance between the cylinders passes through the clearance. While returning to, it can return the free piston to the center position relative to the cylinder.

  A pair of compression coil springs in which the spring acts between each of both ends of the stepped cylinder and each of the pair of small diameter piston portions of the free piston, or both ends of the large diameter cylinder portion of the stepped cylinder and a pair of small diameter cylinders If it is a pair of compression coil springs acting between each of the step portions at the boundary of the portion and the large-diameter piston portion of the free piston, the axial dimension of either or both of the stepped cylinder and the free piston can be set. In consideration of the minimum axial dimension of the compression coil spring when compressed, the present invention can be implemented by a design change that is slightly longer than the conventional design.

  Oil path with a communication valve that selectively connects the left and right shock absorbers of a pair of front wheels by bypassing the cylinder-piston device, or the left and right shock absorbers of a pair of rear wheels by bypassing the cylinder-piston device If an oil passage with a communication valve for communication is provided, when the free piston is pushed back to the center position with respect to the stepped cylinder by a spring, the communication valve is opened to open the piston and cylinder during warping of the vehicle. The hydraulic fluid that has moved between the left and right cylinder chambers across the clearance between them can be easily restored.

  In this case, the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and one of the left and right shock absorbers of the pair of rear wheels After the difference in operating hydraulic pressure of the shock absorber on the other side with respect to the operating hydraulic pressure of the shock absorber on the other side becomes opposite to each other, the operating hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels The difference between the hydraulic pressure of the shock absorber on the other side relative to the hydraulic pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of rear wheels If the communication valve is open when they are the same, the communication valve Without affecting the normal operation of the articulated shock absorber system, the hydraulic fluid that has moved between the left and right cylinder chambers across the clearance between the piston and cylinder during vehicle warping is returned to the original free piston. Can be reliably returned to the central position relative to the cylinder.

  In this case, the communication valve is opened because of the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the pair of rear wheels. The absolute value of the difference between the operating oil pressure of the shock absorber on the other side relative to the operating oil pressure of the shock absorber on one side of the left and right shock absorbers is less than a predetermined first value. If the vehicle recovers from the warped state to the non-warped state, the vehicle does not interfere with the normal operation in which the free piston is pushed back toward the center position with respect to the cylinder by the flow of the associated hydraulic oil. When the warp state of the cylinder almost disappears, it moves between the left and right cylinder chambers across the clearance between the piston and cylinder during warping. Only hydraulic oil can be returned to the original was.

  Also, the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the one side of the left and right shock absorbers of the pair of rear wheels When the absolute value of the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber is less than a predetermined second value smaller than the first value, the communication valve is closed. If the warp state of the vehicle is completely extinguished, the communication valve is closed and the cross-linked shock absorber system is restored to the normal operating state before the warp occurs.

  As described above, the communication valve is opened because of the difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right sides of the pair of rear wheels. The difference in operating hydraulic pressure of the shock absorber on the other side with respect to the operating hydraulic pressure of the shock absorber on the other side of the shock absorbers on the other side is opposite to each other. The absolute value of the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber and the shock on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of rear wheels After the absolute value of the difference between the hydraulic pressures of the absorber exceeds a predetermined value, the left and right shafts of the pair of front wheels The difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the quadrature and the hydraulic pressure of the shock absorber on the one side of the left and right shock absorbers of the pair of rear wheels If the difference in operating hydraulic pressure of the shock absorber on the other side is the same as each other, the communication valve can be opened when the warp advances beyond a certain predetermined degree. .

  The difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the one side of the left and right shock absorbers of the pair of rear wheels If the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber is opposite to each other, if the communication valve is opened, the vehicle will be warped as soon as possible. By opening the communication valve, it is possible to prevent the hydraulic oil from leaking and moving across the free piston.

  Also in this case, the absolute value of the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels When the absolute value of the difference between the operating oil pressure of the shock absorber on the other side and the operating oil pressure of the shock absorber on the other side of the shock absorber on the one side is less than a predetermined value, the communication valve is closed If this is the case, when the warped state of the vehicle is almost extinguished, the communication valve is closed and the cross-linked shock absorber system is restored to the normal operating state before the warp occurs.

  Also in this case, the communication valve is opened because of the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels, and the rear of the pair. One of the left and right shock absorbers of the pair of front wheels, wherein the difference in operating hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on the other side of the left and right shock absorbers of the wheels is opposite to each other The absolute value of the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on the other side and the other hydraulic pressure relative to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of rear wheels The absolute value of the difference in the hydraulic pressure of the shock absorber on the side is after the predetermined value is exceeded. If, when the warp proceeded beyond a certain predetermined degree, it is possible to open the communication valve.

  In addition, the difference in the hydraulic pressure between the left and right shock absorbers of the pair of front wheels or rear wheels corresponds to the difference in the operating displacement between the left and right shock absorbers of the pair of front wheels or rear wheels. The difference between the hydraulic pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the front wheel and the shock absorber on one side of the left and right shock absorbers of the pair of rear wheels The positive / negative relationship between the differences in the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the other and the absolute value of the difference between the two differences or the magnitude of the absolute value of the difference between the absolute values of the two differences The opening / closing of the communication valve can be controlled using the operating displacement of the shock absorber as a parameter instead of the operating oil pressure of the shock absorber. However, since there is a time difference between the change in the hydraulic pressure difference between the left and right shock absorbers and the change in the stroke difference between the left and right shock absorbers, the communication valve is operated based on the change in the stroke difference between the left and right shock absorbers. When opened, the communication valve is preferably closed when a predetermined time has elapsed since the opening.

  FIG. 1 is a schematic view showing a configuration of a main part according to the present invention, that is, a cross-coupled shock absorber system, of a vehicle equipped with a return-promoting cross-linked shock absorber system according to the present invention.

  In FIG. 1, 10fl, 10fr, 10rl, and 10rr are a left front wheel, a right front wheel, a left rear wheel, and a right rear wheel of a four-wheel vehicle, respectively, and each wheel is a vehicle body by suspension arms 12fl, 12fr, 12rl, and 12rr, respectively. 14 is suspended so as to be vertically displaceable, and the shock absorbers 16fl, 16fr, 16rl, 16rr respectively cushion the vertical displacement with respect to the vehicle body. As is well known in the field of this technology, although not shown in the figure, the suspension arms 12fl, 12fr, 12rl, 12rr are arranged in parallel to the shock absorbers 16fl, 16fr, 16rl, 16rr. A suspension spring also acts, and each wheel is suspended from the vehicle body by a parallel combination of a suspension spring and a shock absorber.

  Oil paths 18fl, 18fr, 18rl, and 18rr are connected to the shock absorbers 16fl, 16fr, 16rl, and 16rr, respectively, and pressure accumulation chambers 20fl, 20fr, 20rl, and 20rr, throttle valves 22fl, 22fr, and so on are respectively connected to these oil paths. 22rl and 22rr are connected.

  The cylinder-piston device 24 slides on a stepped cylinder 30 having a central large diameter cylinder portion 26 and a pair of small diameter cylinder portions 28l and 28r connected to both ends thereof, and a large diameter cylinder portion 26 of the stepped cylinder. And a free piston 36 having a pair of small-diameter piston portions 34l, 34r connected to both sides thereof and sliding to a pair of small-diameter cylinder portions 28l, 28r of a stepped cylinder.

  The hydraulic pressure of the shock absorber 16fl is introduced into the hydraulic chamber 38fl of the cylinder-piston device 24 through the oil passage 18fl, and the hydraulic pressure of the shock absorber 16fr is introduced into the hydraulic chamber 38fr of the cylinder-piston device 24 through the oil passage 18fr. The hydraulic pressure of the shock absorber 16rl is introduced into the hydraulic chamber 38rl of the cylinder-piston device 24 via the oil passage 18rl, and the hydraulic pressure of the shock absorber 16rr is introduced into the hydraulic chamber 38rr of the cylinder-piston device 24 via the oil passage 18rr. Yes.

  A compression coil spring 42l interposed between the end wall of the small diameter cylinder portion 28l of the cylinder 30 and the small diameter piston portion 34l of the free piston 36 is provided in the hydraulic chamber 38fl. Is provided with a compression coil spring 42r interposed between the end wall of the small-diameter cylinder portion 28r of the cylinder 30 and the small-diameter piston portion 34r of the free piston 36. The stepped cylinder 30 is formed so as to be symmetrical to the left and right of the central cross section in the axial direction, and the free piston 36 is symmetrical to the left and right of the central cross section in the axial direction of the large-diameter piston portion 32 at the center. The compression coil springs 42l and 42r have the same design. Accordingly, the free piston 36 is elastically biased toward the center position in the axial direction with respect to the stepped cylinder 30 by the pair of springs 42l and 42r.

  By providing the compression coil springs 42l and 42r, the large-diameter cylinder portion 26 of the stepped cylinder and the large-diameter piston portion 32 of the free piston that slides thereon, and the small-diameter cylinder portion 28l of the stepped cylinder are provided. , 28r and the small piston portions 34l, 34r of the free piston sliding on it, there is some clearance, so that when the vehicle is warped between the front and rear wheels as described above, the cylinder chamber 38rr Even if the hydraulic fluid moves through the clearances between the cylinder chamber 38fl, the cylinder chamber 38rr and the cylinder chamber 38rl, or between the cylinder chamber 38rl and the cylinder chamber 38fr, the clearance will flow. If the spring force of the compression coil springs 42l and 42r is designed to an appropriate magnitude with respect to the magnitude of the flow resistance, the time will pass. Is gradually returned to the original transfer in hydraulic fluid between the cylinder chamber through the same clearance with respect to the stepped cylinder can be returned to the free piston in a central position.

  Further, regarding this point, in the embodiment shown in FIG. 1, even if the spring force of the compression coil springs 42l and 42r is reduced with respect to the flow resistance that the clearance exhibits against the flow of the hydraulic oil passing through the clearance, it is free. In order to reliably return the piston to the center position within the preferred time for the stepped cylinder, the cylinder-piston device is bypassed and the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels are bypassed. Oil passages 46f and 46r provided with communication valves 44f and 44r for selectively communicating are provided. In the illustrated embodiment, communication valves are provided for both the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels. Or even if a communication valve is provided only in any one of the left and right shock absorbers of the pair of rear wheels, a certain effect can be obtained.

  The vehicle is provided with an electronic control unit (ECU) 48 using a microcomputer, and the opening and closing of the communication valves 46f and 46r may be controlled by the electronic control unit. The electronic control device 48 is supplied with signals indicating the hydraulic pressure in the hydraulic chambers 38fl, 38fr, 38rl, 38rr from the hydraulic sensors 50fl, 50fr, 50rl, 50rr connected to the oil passages 18fl, 18fr, 18rl, 18rr. A signal indicating the steering angle is supplied from the steering angle sensor 52, and a signal indicating the vehicle speed, the lateral acceleration, the yaw rate, etc. is supplied from a vehicle speed sensor, a lateral acceleration sensor, a yaw rate sensor, etc., not shown in the figure. The throttle valves 22fl, 22fr, 22rl and 22rr are controlled based on the information obtained from the above signal, and the opening and closing of the communication valves 46f and 46r are controlled in the manner exemplified below according to the present invention.

  1, instead of a pair of compression coil springs 42l and 42r acting between both ends of the stepped cylinder 30 and each of the pair of small diameter piston portions 34l and 34r of the free piston 36, FIG. As shown in FIG. 2, a pair of compression coils that act between each of the step portions between the ends of the large-diameter cylinder portion 26 of the stepped cylinder and the pair of small-diameter cylinder portions 28l and 28r and the large-diameter piston portion 32 of the free piston. Springs 54l and 54r may be provided.

  FIG. 3 is a flowchart showing an example of a procedure for controlling the opening and closing of the communication valves 44f and 44r according to the present invention. The control according to the flowchart is started with the start of driving of the vehicle, and may be repeated at a cycle of several tens to several hundreds of milliseconds during the driving of the vehicle. Note that the opening / closing control of the communication valves 44f and 44r according to the present invention solves the problem of the anti-warp operation characteristic inherent in the cross-linked shock absorber system as described above, and acts on the steering angle or the vehicle. The communication valves 44f and 44r are opened when the lateral acceleration is less than a predetermined lower limit value or when the difference between the hydraulic pressures of the left and right shock absorbers of the pair of front wheels or rear wheels is less than a predetermined value. It may be.

  When the control is started, a pair of oil pressures Pfl, Pfr, Prl, Prr in the hydraulic chambers 38fl, 38fr, 38rl, 38rr detected by the hydraulic sensors 50fl, 50fr, 50rl, 50rr are detected in step 10 in step 10. The difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the front wheels is calculated as the difference ΔPf between Pfr and Pfl. The difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the wheel is calculated as a difference ΔPr between Prr and Prl.

  Next, control proceeds to step 30 where it is determined whether the flag Fa is 1 or not. The flag Fa is set to 1 when the control reaches step 70 described later, and has been reset to 0 at the start of the control until then. Accordingly, the answer to step 30 until then is no (N), and the control proceeds to step 40.

  In step 40, it is determined whether or not the product of ΔPf and ΔPr calculated above is negative. This is whether or not the bounce or rebound between the pair of front wheels and the bounce or rebound between the pair of rear wheels are opposite to each other, i.e., between the front and rear wheels of the vehicle. Whether or not the warp state is twisted in the opposite direction is detected. While the answer is no, the control bypasses steps 50 to 70 and returns. However, when the answer is yes (Y), the control proceeds to step 50, and the absolute value of ΔPf is greater than or equal to a predetermined lower limit value δPf. It is determined whether or not. δPf is a value corresponding to a difference between a bound and a rebound between a pair of front wheels, which is inferior to the control described below according to the present invention when the absolute value of ΔPf is a small value below this. is there. While the answer is no, control bypasses steps 60 and 70 and returns, but if the answer is yes, control proceeds to step 60 where the absolute value of ΔPr is greater than or equal to some predetermined lower limit value δPr. It is determined whether or not. δPr also corresponds to the difference between bound and rebound between a pair of rear wheels, which is inferior to the control described below according to the present invention, when the absolute value of ΔPr is a small value below this. Value. While the answer is no, control bypasses step 70 and returns, but if the answer is yes, control proceeds to step 70 where the advance flag Fa is set to 1. When the flag Fa is set to 1, the control proceeds from step 30 to step 80 thereafter.

  In step 80, it is determined whether or not the flag Fb is 1. The flag Fb is set to 1 when the control reaches step 100, which will be described later. Until then, the flag Fb has been reset to 0 at the start of the control. Therefore, the answer to step 80 is no until then, and the control proceeds to step 90.

In step 90, it is determined whether the product of ΔPf and ΔPr is positive. This is because once the vehicle warping occurs, the bounce / rebound between the pair of front wheels and the bounce / rebound between the pair of rear wheels are reversed from each other by a predetermined deviation or more. This is to detect whether or not it has been done. While in answer Ganoderma over, control will be returned to bypass the step 100, if the answer is yes, the control proceeds to step 100, the flag Fb is set to 1. When the flag Fb is set to 1, the control proceeds from step 80 to step 110 thereafter.

  In step 110, it is determined whether or not the flag Fc is 1. The flag Fc is set to 1 when the control reaches step 140, which will be described later, and has been reset to 0 at the start of the control until then. Accordingly, the answer to step 110 until then is no, and control proceeds to step 120.

  In step 120, it is determined whether or not the absolute value of the difference between ΔPf and ΔPr is equal to or smaller than a predetermined relatively small first value δPs. This is to detect whether or not the warped state of the vehicle generated above has been resolved and the free piston has returned to a position that has approached the central position to some extent relative to the stepped cylinder. While the answer is no, control bypasses steps 130 and 140 and returns, but if the answer is yes, control proceeds to step 130 where communication valves 44f and 44r are opened and then control returns to step 140. Then, the flag Fc is set to 1. When the flag Fc is set to 1, the control proceeds from step 110 to step 150 thereafter with the communication valves 44f and 44r kept open.

  In step 150, it is determined whether or not the absolute value of the difference between ΔPf and ΔPr is equal to or smaller than a predetermined second value δPe smaller than the first value δPs. This is because the hydraulic pressure between the shock absorbers of the pair of front wheels and the hydraulic pressure between the shock absorbers of the pair of rear wheels are substantially balanced with each other, and the free piston becomes a stepped cylinder with the communication valves 44f and 44r opened. On the other hand, it is detected whether or not the center position has been returned. While the answer is no, the control bypasses steps 160 and 170 and returns, but when the answer is yes, control proceeds to step 160 where the communication valves 44f and 44r are closed and then control is passed to step 170. The flag Fa, Fb, Fc is set to 0.

  This completes the control of the communication valves 44f and 44r for one warp, and the cross-linked shock absorber system is returned to the normal operating state in which the communication valves 44f and 44r are closed.

  The control as shown in the flowchart of FIG. 3 may be simplified as shown in the flowchart of FIG. In the flowchart of FIG. 4, the steps corresponding to the steps in the flowchart of FIG. 3 are denoted by the same step numbers as in FIG. In this case, if the answer to step 30 is yes, control proceeds to step 110 where it is determined whether or not the flag Fc is 1. Since the flag Fc is initially reset to 0, the answer to step 110 is no, control proceeds to step 130, immediately the communication valves 44f and 44r are opened, and then control proceeds to step 140 where the flag Fc is Set to 1. Thereafter, the control proceeds from step 110 to step 150, and it is determined whether or not the absolute value of the difference between ΔPf and ΔPr is equal to or smaller than a predetermined second value δPe smaller than the first value δPs. The However, in this case, since the signs of ΔPf and ΔPr are opposite to each other, the absolute value of the difference between ΔPf and ΔPr is calculated as the absolute value of ΔPf + ΔP. While the answer is no, control returns by bypassing step 160 and step 170, and when the answer is yes, control proceeds to step 160 where the communication valves 44f and 44r are closed and then flagged at step 170. Fa and Fc are set to 0.

  In the cross-linked shock absorber system shown in FIG. 1, the hydraulic pressure in the hydraulic chambers 38fl, 38fr, 38rl, and 38rr is detected by the hydraulic sensors 50fl, 50fr, 50rl, and 50rr, whereby a pair of front wheels and a pair of rear wheels are detected. However, instead of this, the operation of the left and right shock absorbers of a pair of front wheels and a pair of rear wheels is recognized as shown in FIG. The displacement may be detected by the stroke sensors 56fl, 56fr, 56rl, and 56rr so as to recognize the relative relationship of operation between the left and right shock absorbers of the pair of front wheels and the pair of rear wheels. FIG. 5 is a schematic view similar to FIG. 1 showing another embodiment of a vehicle equipped with such a return-promoting cross-linked shock absorber system according to the present invention. In FIG. 5, parts corresponding to those shown in FIG. 1 are denoted by the same reference numerals as in FIG.

  When the stroke sensors 56fl, 56fr, 56rl, and 56rr are used instead of the hydraulic pressure sensors 50fl, 50fr, 50rl, and 50rr as described above, the strokes of the shock absorbers detected by the stroke sensors are set to Sfl, Sfr, Srl, If Srr, the control corresponding to the control shown in the flowchart of FIG. 3 may be as shown in FIG.

  That is, in steps 210 and 220 in FIG. 6 corresponding to steps 10 and 20 in FIG. 3, ΔSf = Sfr−Sfl and ΔSr = Srr−Srl are substituted for ΔPf = Pfr−Pfl and ΔPr = Prr−Prl. By calculating and using the stroke “S” instead of the pressure “P”, the control is substantially the same as the control described above with reference to FIG. The free piston that is biased from the center position with respect to the stepped cylinder with the movement of the hydraulic oil can be reliably returned to the center position with respect to the stepped cylinder after the warp is eliminated. In the flowchart of FIG. 6, the steps corresponding to the flowchart of FIG. 3 are indicated by step numbers obtained by adding 200 to the step numbers in the flowchart of FIG. A redundant description of each step is omitted to avoid redundancy of the specification.

  However, in the control based on the stroke of each shock absorber, there is a time difference between the change of Pfl to Prr and the change of Sfl to Srr because the accumulator chambers 20fl to 20rr are provided in the hydraulic circuit. Therefore, when the communication valves 44f and 44r are opened when the absolute value of the difference between ΔSf and ΔSr becomes equal to or smaller than δSs in step 320 corresponding to step 120 in FIG. 3, this corresponds to step 150 in FIG. In step 350, if the communication valves 44f and 44r are closed when the absolute value of the difference between ΔSf and ΔSr becomes equal to or less than δSe, there is a risk that the opening period of the communication valves 44f and 44r will be insufficient.

  Therefore, in the control according to the flowchart of FIG. 6, when the answer to step 320 is YES and the communication valves 44f and 44r are opened, the timer is set at that time, and a predetermined time is awaited thereafter. In step 350, it is determined that the predetermined time has elapsed, and the communication valves 44f and 44r are closed.

  FIG. 7 is a flowchart showing control when stroke sensors 56fl, 56fr, 56rl, and 56rr are used instead of the hydraulic sensors 50fl, 50fr, 50rl, and 50rr in the control according to the flowchart of FIG. Also in FIG. 7, the steps corresponding to the steps shown in FIG. 4 are indicated by step numbers obtained by adding 200 to the step numbers in FIG. 4, and the control of each step in FIG. The redundant description is omitted to avoid redundancy of the specification.

  While the present invention has been described in detail with respect to several embodiments thereof, it will be apparent to those skilled in the art that various modifications can be made to these embodiments within the scope of the present invention. . For example, as a situation where the free piston does not return to the neutral position, in addition to the above example, the mogul road (for example, the position of the left front wheel and the right rear wheel is higher than the position of the right front wheel and the left rear wheel). This may occur when the vehicle travels on a flat straight road after adjusting the vehicle height on the road surface. That is, on the mogul road, hydraulic oil is supplied to the absorber of the wheel where the vehicle body and the road surface are approaching so that the vehicle body and the road surface do not approach more than a predetermined value (so that the suspension does not hit the bound stopper, etc.) High adjustment is performed, but at this time, the hydraulic oil increases only in one of the hydraulic systems of the left and right wheels. If the vehicle travels on a straight path in this state, the free piston is unlikely to return to the neutral position due to the difference in hydraulic oil amount between the left and right hydraulic systems. After performing the vehicle height adjustment as described above, when it is determined that the vehicle is traveling on a straight path as in the above-described embodiment, the left and right hydraulic systems are connected, the amount of hydraulic oil is equalized, and the free piston Can be returned to the neutral position. In this case, before step 10 and step 20, the presence or absence of the vehicle height adjustment may be confirmed, and the process may proceed to step 10 and step 20 only when the vehicle height adjustment is performed.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the structure of the principal part which concerns on this invention of the vehicle provided with the reset acceleration | stimulation type | mold cross connection type shock absorber system by this invention. Schematic which shows other one Embodiment of the cylinder-piston apparatus replaced with the cylinder-piston apparatus in FIG. The flowchart which shows an example of the point by which the communication valves 44f and 44r in the cross connection type shock absorber system shown in FIG. 1 are controlled according to this invention. The flowchart which shows another example of the point by which the communication valves 44f and 44r in the cross connection type shock absorber system shown in FIG. 1 are controlled according to this invention. Schematic which shows the structure of the principal part which concerns on this invention of other one Embodiment of the vehicle provided with the reset acceleration | stimulation type cross connection type shock absorber system by this invention. The flowchart which shows an example of the point by which the communication valves 44f and 44r in the cross connection type shock absorber system shown in FIG. 5 are controlled according to this invention. 6 is a flowchart showing another example of the manner in which the opening and closing of the communication valves 44f and 44r in the cross-linked shock absorber system shown in FIG. 5 is controlled according to the present invention. Schematic which shows the structure of the principal part relevant to this invention of an example of the vehicle provided with the conventional cross connection type shock absorber system. FIG. 9 is a schematic diagram illustrating the operation of the cylinder-piston device in FIG. 8 when the vehicle is rolled (FIG. A) and when the vehicle is warped (FIG. B).

Explanation of symbols

10fl, 10fr, 10rl, 10rr ... Left front wheel, right front wheel, left rear wheel, right rear wheel, 12fl, 12fr, 12rl, 12rr ... Suspension arm, 14 ... Vehicle body, 16fl, 16fr, 16rl, 16rr ... Shock absorber, 18fl, 18fr, 18rl, 18rr ... oil passage, 20fl, 20fr, 20rl, 20rr ... pressure accumulating chamber, 22fl, 22fr, 22rl, 22rr ... throttle valve, 24 ... cylinder-piston device, 26 ... large diameter cylinder, 28l, 28r ... small diameter Cylinder part, 30 ... cylinder with step, 32 ... large diameter piston part, 34l, 34r ... small diameter piston part, 36 ... free piston, 38fl, 38fr, 38fl, 38rr ... hydraulic chamber, 40l, 40r ... ring, 42l, 42r ... Compression coil spring, 44f, 44r ... communication valve, 46f, 46r ... oil passage, 48 ... electronic control unit (ECU), 50fl, 50fr, 50rl, 50rr ... hydraulic sensor, 52 ... Steering angle sensor, 54l, 54r ... compression coil spring, 56fl, 56fr, 56rl, 56rr ... stroke sensor

Claims (20)

A stepped cylinder having a shock absorber for each of a pair of left and right front wheels and a pair of left and right rear wheels, a central large diameter cylinder portion and a pair of small diameter cylinder portions connected to both ends thereof, and the large diameter of the stepped cylinder A cylinder-piston comprising a central large-diameter piston portion sliding on the cylinder portion and a free piston having a pair of small-diameter piston portions connected to both sides thereof and sliding on the pair of small-diameter cylinder portions of the stepped cylinder A difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels Of the operating pressure of the shock absorber on the other side of the operating pressure of the shock absorber on the other side And a cylinder-piston device having a cross-coupled shock absorber system opposed to each other via the free piston, the cylinder-piston device having the free piston in the center with respect to the stepped cylinder. An oil passage provided with a communication valve that selectively communicates the left and right shock absorbers of the pair of front wheels, bypassing the cylinder-piston device; A hydraulic sensor that detects the hydraulic pressure of the shock absorber and the shock absorber of the pair of rear wheels, and a control device that controls the communication valve based on a detection value of the hydraulic sensor are provided. Of the left and right shock absorbers, the other side with respect to the hydraulic pressure of the shock absorber on one side The difference in operating hydraulic pressure of the shock absorber on the other side with respect to the operating hydraulic pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of rear wheels is opposite to each other. After that, the difference between the operating oil pressure of the shock absorber on the other side with respect to the operating oil pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels The communication valve is configured to open when the difference in operating hydraulic pressure of the shock absorber on the other side with respect to the operating hydraulic pressure of the shock absorber on the one side is the same. . A stepped cylinder having a shock absorber for each of a pair of left and right front wheels and a pair of left and right rear wheels, a central large diameter cylinder portion and a pair of small diameter cylinder portions connected to both ends thereof, and the large diameter of the stepped cylinder A cylinder-piston comprising a central large-diameter piston portion sliding on the cylinder portion and a free piston having a pair of small-diameter piston portions connected to both sides thereof and sliding on the pair of small-diameter cylinder portions of the stepped cylinder A difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels Of the operating pressure of the shock absorber on the other side of the operating pressure of the shock absorber on the other side And a cylinder-piston device having a cross-coupled shock absorber system opposed to each other via the free piston, the cylinder-piston device having the free piston in the center with respect to the stepped cylinder. An oil passage provided with a communication valve for selectively connecting the left and right shock absorbers of the pair of rear wheels, bypassing the cylinder-piston device, and a spring for biasing the position; A hydraulic sensor that detects the hydraulic pressure of the shock absorber of the rear wheel and the shock absorber of the pair of rear wheels, and a control device that controls the communication valve based on a detection value of the hydraulic sensor, and the pair of front wheels Of the left and right shock absorbers on the other side with respect to the hydraulic pressure of the shock absorber on one side The difference in operating hydraulic pressure of the shock absorber on the other side with respect to the operating hydraulic pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of rear wheels is opposite to each other. After that, the difference between the operating oil pressure of the shock absorber on the other side with respect to the operating oil pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels The communication valve is configured to open when the difference in operating hydraulic pressure of the shock absorber on the other side with respect to the operating hydraulic pressure of the shock absorber on the one side is the same. .   The communication valve is opened because of the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right sides of the pair of rear wheels The absolute value of the difference between the operating oil pressure of the shock absorber on the other side with respect to the operating oil pressure of the shock absorber on the one side of the shock absorbers of the other is less than a predetermined first value. The vehicle according to claim 1, wherein the vehicle is configured as described above.   The difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the one of the left and right shock absorbers of the pair of rear wheels When the absolute value of the difference between the hydraulic pressure of the other side shock absorber and the hydraulic pressure of the other side shock absorber is less than a predetermined second value smaller than the first value, the communication valve The vehicle according to claim 3, wherein the vehicle is closed.   The communication valve is opened because of the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right sides of the pair of rear wheels One side of the left and right shock absorbers of the pair of front wheels in which the difference in operating hydraulic pressure of the shock absorber on the other side with respect to the operating hydraulic pressure of the shock absorber on the other side of the shock absorbers on the other side is opposite to each other The absolute value of the difference between the hydraulic pressure of the shock absorber on the other side relative to the hydraulic pressure of the shock absorber of the other side and the other side of the shock absorber on the one side of the left and right shock absorbers of the pair of rear wheels After the absolute value of the difference between the hydraulic pressures of the shock absorbers exceeds a predetermined value, the pair of front The difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers and the shock absorber on the one side of the left and right shock absorbers of the pair of rear wheels The vehicle according to any one of claims 1 to 4, wherein the difference in operating hydraulic pressure of the shock absorber on the other side with respect to the operating hydraulic pressure is equal to each other. A stepped cylinder having a shock absorber for each of a pair of left and right front wheels and a pair of left and right rear wheels, a central large diameter cylinder portion and a pair of small diameter cylinder portions connected to both ends thereof, and the large diameter of the stepped cylinder A cylinder-piston comprising a central large-diameter piston portion sliding on the cylinder portion and a free piston having a pair of small-diameter piston portions connected to both sides thereof and sliding on the pair of small-diameter cylinder portions of the stepped cylinder A difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels Of the operating pressure of the shock absorber on the other side of the operating pressure of the shock absorber on the other side And a cylinder-piston device having a cross-coupled shock absorber system opposed to each other via the free piston, the cylinder-piston device having the free piston in the center with respect to the stepped cylinder. An oil passage provided with a communication valve that selectively communicates the left and right shock absorbers of the pair of front wheels, bypassing the cylinder-piston device; A hydraulic sensor that detects the hydraulic pressure of the shock absorber and the shock absorber of the pair of rear wheels, and a control device that controls the communication valve based on a detection value of the hydraulic sensor are provided. Of the left and right shock absorbers, the other side with respect to the hydraulic pressure of the shock absorber on one side The difference in operating hydraulic pressure of the shock absorber on the other side with respect to the operating hydraulic pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of rear wheels is opposite to each other. When the vehicle is opened, the communication valve is opened . A stepped cylinder having a shock absorber for each of a pair of left and right front wheels and a pair of left and right rear wheels, a central large diameter cylinder portion and a pair of small diameter cylinder portions connected to both ends thereof, and the large diameter of the stepped cylinder A cylinder-piston comprising a central large-diameter piston portion sliding on the cylinder portion and a free piston having a pair of small-diameter piston portions connected to both sides thereof and sliding on the pair of small-diameter cylinder portions of the stepped cylinder A difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels Of the operating pressure of the shock absorber on the other side of the operating pressure of the shock absorber on the other side And a cylinder-piston device having a cross-coupled shock absorber system opposed to each other via the free piston, the cylinder-piston device having the free piston in the center with respect to the stepped cylinder. An oil passage provided with a communication valve for selectively connecting the left and right shock absorbers of the pair of rear wheels, bypassing the cylinder-piston device, and a spring for biasing the position; And a control device for controlling the communication valve based on a detected value of the hydraulic sensor, and a control device for controlling the communication valve based on a detection value of the hydraulic sensor. One side of the left and right shock absorbers on the other side of the wheel with respect to the hydraulic pressure of the shock absorber The difference in operating hydraulic pressure of the shock absorber on the other side with respect to the operating hydraulic pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of rear wheels is opposite to each other. When the vehicle is opened, the communication valve is opened .   Of the left and right shock absorbers of the pair of front wheels, the absolute value of the difference between the hydraulic pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels The communication valve is closed when the absolute value of the difference between the working oil pressures of the shock absorbers on the one side and the working oil pressures on the other side of the shock absorbers on the one side becomes a predetermined value or less. The vehicle according to claim 6 or 7, wherein   The communication valve is opened because of the difference between the hydraulic pressure of the shock absorber on the other side with respect to the hydraulic pressure of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right sides of the pair of rear wheels One side of the left and right shock absorbers of the pair of front wheels in which the difference in operating hydraulic pressure of the shock absorber on the other side with respect to the operating hydraulic pressure of the shock absorber on the other side of the shock absorbers on the other side is opposite to each other The absolute value of the difference between the hydraulic pressure of the shock absorber on the other side relative to the hydraulic pressure of the shock absorber of the other side and the other side of the shock absorber on the one side of the left and right shock absorbers of the pair of rear wheels The absolute value of the operating oil pressure difference between the shock absorbers is after a predetermined value or more. Vehicle according to any one of claims 6 to 8. A stepped cylinder having a shock absorber for each of a pair of left and right front wheels and a pair of left and right rear wheels, a central large diameter cylinder portion and a pair of small diameter cylinder portions connected to both ends thereof, and the large diameter of the stepped cylinder A cylinder-piston comprising a central large-diameter piston portion sliding on the cylinder portion and a free piston having a pair of small-diameter piston portions connected to both sides thereof and sliding on the pair of small-diameter cylinder portions of the stepped cylinder A difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels Of the operating pressure of the shock absorber on the other side of the operating pressure of the shock absorber on the other side And a cylinder-piston device having a cross-coupled shock absorber system opposed to each other via the free piston, the cylinder-piston device having the free piston in the center with respect to the stepped cylinder. An oil passage provided with a communication valve that selectively communicates the left and right shock absorbers of the pair of front wheels, bypassing the cylinder-piston device; A stroke sensor that detects an operating displacement of the shock absorber and the shock absorber of the pair of rear wheels, and a control device that controls the communication valve based on a detection value of the stroke sensor are provided. Against the displacement of the shock absorber on one side of the left and right shock absorbers The difference in operating displacement between the shock absorber on the other side and the difference in operating displacement between the shock absorber on the other side with respect to the operating displacement of the shock absorber on the one side of the left and right shock absorbers of the pair of rear wheels Of the left and right shock absorbers of the pair of front wheels, and the difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the other side of the pair of front wheels and the left and right of the pair of rear wheels The communication valve is opened when the difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on the one side of the shock absorbers is the same . A vehicle characterized by A stepped cylinder having a shock absorber for each of a pair of left and right front wheels and a pair of left and right rear wheels, a central large diameter cylinder portion and a pair of small diameter cylinder portions connected to both ends thereof, and the large diameter of the stepped cylinder A cylinder-piston comprising a central large-diameter piston portion sliding on the cylinder portion and a free piston having a pair of small-diameter piston portions connected to both sides thereof and sliding on the pair of small-diameter cylinder portions of the stepped cylinder A difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels Of the operating pressure of the shock absorber on the other side of the operating pressure of the shock absorber on the other side And a cylinder-piston device having a cross-coupled shock absorber system opposed to each other via the free piston, the cylinder-piston device having the free piston in the center with respect to the stepped cylinder. An oil passage provided with a communication valve for selectively connecting the left and right shock absorbers of the pair of rear wheels, bypassing the cylinder-piston device, and a spring for biasing the position; A stroke sensor for detecting an operating displacement of the shock absorber of the pair of rear wheels and a shock absorber for the pair of rear wheels, and a control device for controlling the communication valve based on a detection value of the stroke sensor. Against the displacement of the shock absorber on one side of the left and right shock absorbers The difference in operating displacement between the shock absorber on the other side and the difference in operating displacement between the shock absorber on the other side with respect to the operating displacement of the shock absorber on the one side of the left and right shock absorbers of the pair of rear wheels Of the left and right shock absorbers of the pair of front wheels, and the difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the other side of the pair of front wheels and the left and right of the pair of rear wheels The communication valve is opened when the difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on the one side of the shock absorbers is the same . A vehicle characterized by   The communication valve is opened because of the difference in operating displacement of the shock absorber on the other side relative to the operating displacement of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right of the pair of rear wheels The absolute value of the difference between the operating displacement of the shock absorber on the other side relative to the operating displacement of the shock absorber on the other side of the shock absorbers of the other is less than a predetermined first value. The vehicle according to claim 10 or 11, wherein the vehicle is configured as described above.   The vehicle according to claim 12, wherein the opened communication valve is closed when a predetermined time elapses from when it is opened.   The communication valve is opened because of the difference between the operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right sides of the pair of rear wheels One side of the left and right shock absorbers of the pair of front wheels in which the difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on the other side is opposite to each other The absolute value of the difference in operating displacement of the shock absorber on the other side relative to the operating displacement of the shock absorber of the other side and the other side of the shock absorber on one side of the left and right shock absorbers of the pair of rear wheels After the absolute value of the difference in operating displacement between the shock absorbers exceeds a predetermined value, The difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on one side of the left and right shock absorbers and the shock absorber on the one side of the left and right shock absorbers of the pair of rear wheels The vehicle according to any one of claims 10 to 13, wherein the difference in operating displacement of the shock absorber on the other side with respect to the operating displacement is equal to each other. A stepped cylinder having a shock absorber for each of a pair of left and right front wheels and a pair of left and right rear wheels, a central large diameter cylinder portion and a pair of small diameter cylinder portions connected to both ends thereof, and the large diameter of the stepped cylinder A cylinder-piston comprising a central large-diameter piston portion sliding on the cylinder portion and a free piston having a pair of small-diameter piston portions connected to both sides thereof and sliding on the pair of small-diameter cylinder portions of the stepped cylinder A difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels Of the operating pressure of the shock absorber on the other side of the operating pressure of the shock absorber on the other side And a cylinder-piston device having a cross-coupled shock absorber system opposed to each other via the free piston, the cylinder-piston device having the free piston in the center with respect to the stepped cylinder. An oil passage provided with a communication valve that selectively communicates the left and right shock absorbers of the pair of front wheels, bypassing the cylinder-piston device; A stroke sensor that detects an operating displacement of the shock absorber and the shock absorber of the pair of rear wheels, and a control device that controls the communication valve based on a detection value of the stroke sensor are provided. Against the displacement of the shock absorber on one side of the left and right shock absorbers The difference in operating displacement between the shock absorber on the other side and the difference in operating displacement between the shock absorber on the other side with respect to the operating displacement of the shock absorber on the one side of the left and right shock absorbers of the pair of rear wheels The vehicle is characterized in that the communication valves are opened when they are opposite to each other . A stepped cylinder having a shock absorber for each of a pair of left and right front wheels and a pair of left and right rear wheels, a central large diameter cylinder portion and a pair of small diameter cylinder portions connected to both ends thereof, and the large diameter of the stepped cylinder A cylinder-piston comprising a central large-diameter piston portion sliding on the cylinder portion and a free piston having a pair of small-diameter piston portions connected to both sides thereof and sliding on the pair of small-diameter cylinder portions of the stepped cylinder A difference between the operating oil pressure of the shock absorber on the other side of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right shock absorbers of the pair of rear wheels Of the operating pressure of the shock absorber on the other side of the operating pressure of the shock absorber on the other side And a cylinder-piston device having a cross-coupled shock absorber system opposed to each other via the free piston, the cylinder-piston device having the free piston in the center with respect to the stepped cylinder. An oil passage provided with a communication valve for selectively connecting the left and right shock absorbers of the pair of rear wheels, bypassing the cylinder-piston device, and a spring for biasing the position; A stroke sensor for detecting an operating displacement of the shock absorber of the pair of rear wheels and a shock absorber for the pair of rear wheels, and a control device for controlling the communication valve based on a detection value of the stroke sensor. Against the displacement of the shock absorber on one side of the left and right shock absorbers The difference in operating displacement between the shock absorber on the other side and the difference in operating displacement between the shock absorber on the other side with respect to the operating displacement of the shock absorber on the one side of the left and right shock absorbers of the pair of rear wheels The vehicle is characterized in that the communication valves are opened when they are opposite to each other .   The vehicle according to claim 15 or 16, wherein the opened communication valve is closed when a predetermined time elapses from when it is opened.   The communication valve is opened because of the difference in operating displacement of the shock absorber on the other side relative to the operating displacement of the shock absorber on one side of the left and right shock absorbers of the pair of front wheels and the left and right of the pair of rear wheels One side of the left and right shock absorbers of the pair of front wheels in which the difference in operating displacement of the shock absorber on the other side with respect to the operating displacement of the shock absorber on the other side is opposite to each other The absolute value of the difference in operating displacement of the shock absorber on the other side relative to the operating displacement of the shock absorber of the other side and the other side of the shock absorber on one side of the left and right shock absorbers of the pair of rear wheels The absolute value of the difference in operating displacement of the shock absorbers after each exceeds a predetermined value. Vehicle according to any one of claims 15 to 17 to.   A communication valve that bypasses the cylinder-piston device and selectively communicates the left and right shock absorbers of the pair of front wheels is opened when the difference between the hydraulic pressures of the left and right shock absorbers is a predetermined value or less. The vehicle according to any one of claims 1, 3 to 6, 8 to 10, 12 to 15, 17, and 18.   A communication valve that bypasses the cylinder-piston device and selectively communicates the left and right shock absorbers of the pair of rear wheels is opened when the difference between the hydraulic pressures of the left and right shock absorbers is less than a predetermined value. The vehicle according to any one of claims 2 to 5, 7 to 9, 11 to 14, and 16 to 18.

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