JP4518008B2 - Suspension device - Google Patents

Description

  The present invention relates to a suspension device including a center cylinder.

Patent Documents 1 to 4 describe a suspension device including (a) a suspension cylinder provided for each of the front, rear, left, and right wheels, and (b) a center cylinder that is operated by the hydraulic pressure of the suspension cylinders. .
Among them, Patent Document 1 discloses (i) (a) a suspension cylinder provided for each of the front, rear, left and right wheels, (b) a center cylinder operated by the hydraulic pressure of the suspension cylinders, and (c) 1 A suspension device including an elastic member that suppresses the operation of the center cylinder when there is a large road surface input to the wheel, and (ii) (a) a return-type suspension cylinder provided for each of the front, rear, left, and right wheels And (b) a diagonal connecting passage connecting the upper and lower chambers of the suspension cylinder in the diagonal ring, and (c) a center cylinder having a hydraulic chamber connected to each of the diagonal connecting passages And (d) a shut-off valve provided between the center cylinder and the diagonal connection passage, and (e) closing the shut-off valve during turning, braking and driving to prevent the operation of the center cylinder. And a suspension device including an operation blocking device.
Patent Document 2 discloses (a) a suspension cylinder provided for each of the front, rear, left and right wheels, (b) a center cylinder operated by the hydraulic pressure of the suspension cylinders, and (c) the center cylinder and the suspension cylinder. The suspension device includes a shut-off valve provided between and an operation blocking device that closes the shut-off valve during turning. The suspension cylinders are connected to the center cylinder in such a manner that the piston is allowed to move during turning and is blocked during braking and driving. Therefore, when the turning is performed, the shut-off valve is closed, whereby the operation of the center cylinder is prevented and the roll accompanying the turning is suppressed.
Special Table 2000-505755 JP 2004-322755 A Japanese Patent Publication No. 6-509997 U.S. Pat. No. 30,240,37

  An object of the present invention is to make vehicle height adjustment well performed in a suspension device including a center cylinder.

The suspension device according to claim 1 includes: (a) a suspension cylinder provided between each wheel holding device and the vehicle body for each of the front, rear, left and right wheels of the vehicle; and (b) the four suspension cylinders. Center cylinders that are connected to each other and operate according to the relationship between these hydraulic pressures, and (c) by controlling the inflow and outflow of hydraulic fluid in each of the four suspension cylinders, A vehicle height adjusting device that adjusts the vehicle height that is a relative position between the hydraulic fluid and (d) the hydraulic fluid flowing in and out of at least one of the four suspension cylinders by the vehicle height adjusting device. When the vehicle height adjustment is performed in such a manner that the center cylinder operates, an operation suppressing device that suppresses the operation of the center cylinder is included.
In this suspension device, the vehicle height is adjusted by the hydraulic fluid flowing in and out of at least one of the four suspension cylinders by the vehicle height adjusting device. However, depending on the number of suspension cylinders through which hydraulic fluid flows in and out, the position where the suspension cylinders are provided, etc., the center cylinder may operate along with the vehicle height adjustment.
When the vehicle height is adjusted in a manner in which the center cylinder operates, a part of the hydraulic fluid that should flow into the suspension cylinder is supplied to the center cylinder, or the suspension cylinder that is not scheduled to supply the operation fluid is Hydraulic fluid is supplied from As a result, inflow and outflow of hydraulic fluid in the suspension cylinder cannot be performed effectively, and it takes a long time for the hydraulic fluid to flow in and out before the actual vehicle height reaches the target vehicle height. The problem that the vehicle height adjustment purpose cannot be achieved occurs.
Therefore, in the suspension device described in this section, when the vehicle height adjustment is performed in such a manner that the center cylinder operates, the operation of the center cylinder is suppressed. As a result, the hydraulic fluid can be effectively flowed in and out of the suspension cylinder, and the vehicle height can be adjusted satisfactorily. This makes it possible to adjust the vehicle height promptly or to achieve the purpose of adjusting the vehicle height.
Inhibiting the operation of the center cylinder includes blocking the operation, decreasing the operating amount, decreasing the operating speed, etc., and reducing the operating amount or reducing the operating speed than when there is no operation suppressing device. Etc.
When the vehicle height adjustment is performed in such a manner that the center cylinder operates, the vehicle height adjustment is performed with the center cylinder scheduled to operate and the center cylinder not operated with the planned operation. There is. This is because when the vehicle height adjustment is performed, it may be impossible to predict in advance that the center cylinder will operate. In any case, it is desirable to suppress the operation of the center cylinder when these vehicle height adjustments are performed.

Patentable invention

  In the following, the invention that is claimed to be claimable in the present application (hereinafter referred to as “claimable invention”. The claimable invention is at least the “present invention” to the invention described in the claims. Some aspects of the present invention, including subordinate concept inventions of the present invention, superordinate concepts of the present invention, or inventions of different concepts) will be illustrated and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating understanding of the claimable invention, and is not intended to limit the set of components constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. Moreover, the aspect which deleted the component from the aspect of each term can also be one aspect of the claimable invention.

(1) A suspension cylinder provided between each wheel holding device and the vehicle body for each of the front, rear, left and right wheels of the vehicle;
A center cylinder connected to each of the four suspension cylinders and operated by the relationship between these hydraulic pressures;
A vehicle height adjusting device that adjusts a vehicle height that is a relative position between a wheel and a vehicle body corresponding to each of the suspension cylinders by controlling inflow / outflow of hydraulic fluid in each of the four suspension cylinders;
When the vehicle height adjustment is performed in such a manner that the center cylinder is operated as the hydraulic fluid flows in and out of at least one of the four suspension cylinders by the vehicle height adjusting device. A suspension device comprising: an operation suppressing device that suppresses the operation of the center cylinder (claim 1).
(2) The center cylinder includes: (a) a housing; (b) a center piston slidably fitted to the housing and having a plurality of effective pressure receiving surfaces; and (c) a partition between the housing and the center piston. Four center hydraulic pressure chambers corresponding to each of the effective pressure receiving surfaces of the center piston, and two center hydraulic pressure chambers corresponding to two effective pressure receiving surfaces in the same direction of the center piston, and suspension cylinders of the front wheel suspension cylinders and the left rear wheel is connected to the two center pressure chamber corresponding to the two effective pressure-receiving surface of the two effective pressure-receiving surface and the opposite, respectively, the left front wheel suspension cylinders The suspension device according to item (1), wherein the suspension device is connected to a suspension cylinder of the right rear wheel (claim 2).
In the center cylinder, four center hydraulic chambers are formed by the housing and the center piston. In the center hydraulic pressure chamber corresponding to two effective pressure receiving surfaces in the same direction among the plurality of effective pressure receiving surfaces of the center piston, two wheels of one pair of two pairs of wheels at the diagonal positions of front, rear, left and right suspension cylinder are connected respectively, to the center pressure chamber corresponding to the two effective pressure-receiving surface opposite to that the two effective pressure-receiving surface, suspension cylinders of two-wheel of the other pair are respectively connected. Accordingly, in the center piston, a force corresponding to the hydraulic pressure of the two suspension cylinders in one pair (first force) and a force corresponding to the hydraulic pressure of the other two suspension cylinders (second force). Acts and stops at a position where they balance. Accordingly, when the first force and the second force are not balanced, the center piston is moved, and the center cylinder operates.
For example, in the vehicle height adjustment, when hydraulic fluid is allowed to flow into only one suspension cylinder in order to increase the vehicle height for one of the front, rear, left and right wheels, the center connected to the suspension cylinder The hydraulic pressure in the hydraulic chamber increases. As a result, the center piston is moved in a state where the first force and the second force are not balanced. The same applies to the case where hydraulic fluid is supplied to the suspension cylinders of the two wheels of one pair of the two pairs of wheels that are diagonal to each other, and the center piston is moved.
(3) The center cylinder includes (a) a housing, (b) a center piston slidably fitted to the housing and having a plurality of effective pressure receiving surfaces, and (c) a partition formed by the housing and the center piston. And four center hydraulic pressure chambers corresponding to each of the effective pressure receiving surfaces of the center piston, and four suspension cylinders in the four center hydraulic pressure chambers respectively suppress the movement of the center piston during rolling of the vehicle. (1) or (2) connected when the center piston is allowed to move when the vehicle heights of the two wheels at diagonal positions oscillate in opposite phases. The suspension device described in 1.
(4) Item (1) to Item (3), wherein the vehicle height adjusting device includes a stack-time vehicle height adjusting unit that adjusts the vehicle height in such a manner that the center cylinder operates when the vehicle is stacked. A suspension device according to any one of the preceding claims (Claim 3).
When a vehicle is running on sand, muddy ground, rocky ground, or deep snow, the drive wheels may slip or float and run idle, but this state is said to be stuck. In the suspension device described in this section, the vehicle height adjustment is performed by the stack-time vehicle height adjustment unit mainly when the vehicle is stuck due to a large road surface undulation such as a rocky place. For example, two wheels of one pair of two pairs of wheels at the diagonal positions of the front, rear, left and right wheels ride on the protrusion, and the other two wheels get stuck in the recess and cannot move. This is the case.
(5) The stack height adjustment unit is (a) a stack detection unit for detecting that the vehicle is stacked, and (b) a road surface with which the vehicle is in contact is a road surface with a large undulation. The suspension device according to the item (4), including at least one of the detected irregular terrain detection unit.
About (a) When the absolute value of the rotational speed difference between the left and right drive wheels is larger than the set value, it can be determined that the vehicle is stuck.
| VR-VL |> Vfth
When the drive torque transmitted to the left and right drive wheels is the same, the drive wheel that rides on the protrusion has a larger road surface input (a larger load), so the rotational speed is lower and the drive that gets stuck in the recess. Since the wheel has a smaller road surface input (a smaller load), the rotational speed is higher. Therefore, when the absolute value of these rotational speed differences is larger than the set value, it is considered that the vehicle cannot move.
When a differential device with a differential limiting device is provided between the left and right drive wheels, for example, the ratio of the load applied to one drive wheel of the left and right drive wheels and the load applied to the other drive wheel Is within the predetermined setting range, the driving torque is transmitted so that the rotational speeds of the left and right driving wheels are substantially the same, but if the setting range is exceeded, differential is allowed. When the vehicle is stuck, it is considered that the vehicle is out of the set range. Therefore, even when a differential device with a differential limiting device is provided, it can be determined whether or not they are stacked in the same manner.
The rotational speed may be a peripheral speed (ω · RR: radius of the wheel) as the rotational angular speed ω of the wheel.
Further, the vehicle is being driven, the accelerator pedal is being operated by the driver (or the accelerator opening is greater than or equal to the set value, or the maximum value), and the traveling speed of the vehicle is less than or equal to a set speed that can be considered to be in a stopped state In some cases, it can be said that they are stuck.
About (b) When the warp amount is larger than the set value, the road surface with which the vehicle is in contact is considered to be a road surface with a large undulation. The amount of warp is the sum of the vehicle heights of two wheels of one pair and the vehicle heights of two wheels of the other pair of the two wheels in the diagonal positions of the front, rear, left and right wheels. That is, the absolute value of the difference between the sum of the vehicle heights of the right front wheel and the left rear wheel and the sum of the vehicle heights of the left front wheel and the right rear wheel. Therefore, the expression | (HFR + HRL) − (HFL + HRR) |> Hth
If is established, it can be assumed that the road surface is rough and rough.
In addition, when both that the vehicle is stuck and that it is a rough terrain road are satisfy | filled, it can be determined that it is stuck because it is a rough terrain road.
(6) The road height adjustment unit at the time of stacking eliminates road surface interference that increases the vehicle height of the pair of wheels having the smaller vehicle height out of the two pairs of wheels on the opposite sides of the front, rear, left and right wheels. The suspension device according to (4) or (5), which includes a vehicle height adjusting portion (claim 4).
Of the two pairs of wheels that are diagonal to each other, the two wheels of the pair that rides on the convex portion have a vehicle height that is lower than the two wheels of the pair that fit into the concave portion. If the vehicle height is increased for the two wheels having the smaller vehicle height, that is, the two wheels riding on the convex portion, the interference between the vehicle body and the road surface can be eliminated and the vehicle can easily escape from the stack. For this reason, the pair of two wheels having the smaller vehicle height are set as the vehicle height adjustment target wheels.
In addition, since the rotation speed of the two wheels with the smaller vehicle height is smaller, the two wheels with the smaller rotation speed can be used as the vehicle height adjustment target wheel.
(7) In the operation suppression device, when the vehicle height adjustment for increasing the vehicle height is performed by the road surface interference elimination vehicle height adjustment unit for the two wheels having the smaller vehicle height, The suspension device according to item (6), including a stacking operation suppressing portion that suppresses the operation.
As described above, in the center cylinder, when the vehicle height adjustment is performed to change the vehicle height in the same direction for the two wheels that are diagonal to each other, the center piston is moved. Therefore, when the vehicle height adjustment is performed by the road surface interference elimination vehicle height adjustment unit, it is desirable to suppress the operation of the center cylinder.
As a result, the interference between the vehicle body and the road surface can be eliminated, and the interference between the vehicle body and the road surface can be quickly eliminated.
(8) The one-wheel vehicle height adjustment that suppresses the operation of the center cylinder when the vehicle height adjustment is performed on one of the front, rear, left, and right wheels by the vehicle height adjustment device. When the vehicle height adjustment is performed on two wheels of one pair of the two pairs of wheels at the diagonal positions of the front, rear, left, and right wheels by the time suppression unit and (b) the vehicle height adjustment device The suspension device according to any one of (2) to (7), further including at least one of a diagonal wheel height adjustment suppressing portion that suppresses the operation of the center cylinder.
(9) When the difference between the maximum value and the minimum value among the loads applied to the front, rear, left and right wheels is greater than or equal to a predetermined set value, the operation suppression device is Any one of the items (2) to (8) includes a load imbalance suppression unit that suppresses the operation of the center cylinder when vehicle height adjustment is performed for at least one of the wheels. The suspension device described.
When the vehicle height is adjusted so that the vehicle heights of two wheels having different loads are the same, the hydraulic pressures of the center hydraulic chambers connected to these suspension cylinders are different from each other. . As described above, when the two hydraulic pressures in the center hydraulic pressure chamber are controlled to be different from each other, the force is not balanced in the center piston and is likely to be moved. Therefore, when the load difference is large, it is desirable that the vehicle height adjustment is performed in a state where the operation of the center cylinder is suppressed.

(10) The suspension device according to any one of (1) to (9), wherein the operation suppressing device includes an arbitrary suppressing unit that arbitrarily suppresses the operation of the center cylinder.
(11) The suspension device according to any one of (1) to (10), wherein the operation suppressing device includes a lock portion that arbitrarily locks the operation of the center cylinder.
If the center cylinder is locked and the center cylinder is not operated at any time when the vehicle height adjustment is performed, the vehicle height adjustment can be performed more quickly.
(12) The center cylinder includes: (a) a housing; and (b) a center piston fitted to the housing so as to be relatively movable, and the lock portion includes any relative position of the center piston with respect to the housing. In this case, the suspension device according to the item (11), including an arbitrary position lock portion that prevents movement of the center piston at the position.
(13) The center cylinder includes four center hydraulic chambers respectively connected to the four suspension cylinders, and the operation suppressing device is provided in at least one of the four center hydraulic chambers of the center cylinder. The suspension device according to any one of items (1) to (12), further including an inflow / outflow suppression unit that suppresses the inflow / outflow of the hydraulic fluid.
If the inflow / outflow of the hydraulic fluid in at least one of the four center hydraulic chambers of the center cylinder is suppressed, the operation of the center cylinder can be suppressed. If the inflow / outflow of the hydraulic fluid is blocked, the operation of the center cylinder can be blocked. In this case, the inflow / outflow prevention part is also a lock part.
The inflow / outflow suppression unit may suppress the inflow or the outflow, but it should be avoided that the center hydraulic pressure chamber becomes negative pressure if the outflow is suppressed. It becomes possible to do.
(14) The center hydraulic chamber and each of the suspension cylinders are connected to each other via individual connection passages, and the vehicle height adjusting device includes: (a) a hydraulic pressure source; and (b) the individual connection passages. An individual control passage connected to each of the fluid pressure sources, (c) an individual control valve provided in each of the individual control passages, and (d) each of the individual control valves and a fluid. An individual control valve that controls the inflow / outflow of hydraulic fluid in each of the suspension cylinders corresponding to the individual control valve by controlling the pressure source, and controls the height of the wheel provided with the suspension cylinder A control unit, and the inflow / outflow suppression unit is (e) an operation suppression valve provided in a portion closer to the center cylinder than a connection unit with at least one of the individual connection passages, (f) The vehicle height adjusting device (13) an operation suppression valve control unit that reduces the flow area of the individual connection passage by controlling the at least one operation suppression valve when vehicle height adjustment is performed in a manner in which the cylinder is operated. A suspension device according to claim 7 (Claim 7).
In the open state of the operation suppression valve, the center hydraulic chamber and the suspension cylinder are communicated. In the open state of the individual control valve, the inflow / outflow of the hydraulic fluid in the suspension cylinder is controlled, and the vehicle height of the wheel is controlled. In this state, the hydraulic pressure source, the suspension cylinder, and the center hydraulic pressure chamber are in communication with each other, so that the center cylinder is operated by the hydraulic pressure of the hydraulic pressure source, or hydraulic fluid is interposed between the center cylinder and the suspension cylinder. It may be given or received.
In the closed state of the operation suppression valve, the center hydraulic pressure chamber is shut off from both the suspension cylinder and the hydraulic pressure source. Since the inflow / outflow of the hydraulic fluid in the center hydraulic chamber is blocked, the operation of the center cylinder is blocked. In the opened state of the individual control valve, the vehicle height is adjusted by communicating the suspension cylinder with the hydraulic pressure source, but the center cylinder is not operated. In any case, the operation suppression valve is provided at a position where the center cylinder can be isolated from the suspension cylinder, the hydraulic pressure source, the accumulator and the like in the closed state.
Even if the operation suppression valve and the individual control valve are electromagnetic on-off valves that can be switched between an open state and a closed state by controlling the supply current to the solenoid, the flow path in the open state by controlling the supply current to the solenoid The variable aperture may be a variable aperture.
The hydraulic pressure source includes a high pressure source capable of supplying the hydraulic fluid by pressurizing it and a low pressure source containing the hydraulic fluid at almost atmospheric pressure.
(15) The operation of the center cylinder is permitted when a predetermined release condition is satisfied after the vehicle height adjustment in a mode in which the center cylinder is operated by the vehicle height adjusting device is completed. The suspension device according to any one of items (1) to (14), including a suppression release device.
For example, when the vehicle height adjustment is finished, the operation of the center cylinder can be permitted assuming that the release condition is satisfied.
In addition, operation is permitted when the vehicle height adjustment is completed and the vehicle comes out of the stack, or when the vehicle height adjustment is completed and the road surface in contact with the vehicle becomes a flat road, the operation is permitted. It is possible to do so.
(16) The center cylinder includes (a) a housing, (b) a center piston slidably fitted in the housing, and (c) four center hydraulic pressures partitioned by the housing and the center piston. And the operation suppressing device includes a stroke change limiting portion that limits a change in stroke of the center piston when the center piston is in a predetermined relative position with respect to the housing (1). The suspension device according to any one of Items (15) to (15) (Claim 8).
For example, when the relative position of the center piston with respect to the housing is a predetermined position, the stroke change limiting unit prevents movement of the center piston in one direction and allows movement in the opposite direction. Or the rate of change can be reduced.
The stroke change limiting portion may be (i) a stopper provided at a predetermined position of at least one of the center piston and the housing, or (ii) (a) the above-described operation suppression valve, and (b) the center piston. A position detection device capable of detecting that the relative position with respect to the housing is at a predetermined position, and (c) when the position detection device detects that the position of the center piston has become a predetermined position. An operation suppression valve control unit that suppresses the flow of hydraulic fluid by controlling the operation suppression valve can be included. When the position detecting device detects that the relative position of the center piston with respect to the housing is a predetermined position, the operation suppression valve suppresses the inflow / outflow of the working fluid in the center hydraulic pressure chamber. Thus, the operation of the center cylinder can be suppressed when the center piston is in a predetermined relative position with respect to the housing. The position detection device may be a stroke sensor that detects a stroke of the center piston with respect to the housing, or may be a limit switch that detects that the center piston is in a predetermined position.
(17) The suspension device according to (16), wherein the stroke change control unit includes a movement restricting stopper provided on at least one of the center piston and the cylinder body.
If it comes into contact with the movement restricting stopper, the movement of the center piston in that direction is prevented, but movement in the opposite direction is allowed. As the vehicle height is adjusted, the center piston can be prevented from moving further.
A stopper for reducing the impact when the center piston comes into contact with the housing, that is, a buffer stopper is usually provided. On the other hand, the suspension device described in this section is provided with a movement restricting stopper for limiting the stroke of the center piston so as not to become larger. This movement restriction stopper is larger than the buffer stopper. For example, the center piston is moved in accordance with a change in vehicle height in phase of one wheel or two wheels in a diagonal position, but when the center piston is moved from the neutral position, the normal vehicle height of the wheels is changed. The size, shape, etc. are designed so that they do not come into contact with each other but change into contact when stacked.
The movement restricting stopper can be made of a material that is easily elastically deformed.
(18) A suspension cylinder provided between each wheel holding device and the vehicle body for each of the front, rear, left and right wheels of the vehicle;
A center cylinder connected to each of the fluid chambers of the four suspension cylinders and actuated by the relationship between these fluid pressures;
A vehicle height adjusting device that adjusts a vehicle height that is a relative position between a wheel holding device and a vehicle body corresponding to each of the suspension cylinders by controlling inflow / outflow of hydraulic fluid in each of the four suspension cylinders;
A suspension including an operation suppressing device that suppresses the operation of the center cylinder when hydraulic fluid flows in and out of at least one of the four suspension cylinders by the vehicle height adjusting device. Device (claim 9).
If the operation of the center cylinder is suppressed during the vehicle height adjustment, the vehicle height adjustment can be performed quickly, and the vehicle height adjustment can be performed satisfactorily. Further, in the non-operating state of the center cylinder, a shift from the neutral position of the center piston due to the vehicle height adjustment can be suppressed.
Note that the technical features described in any one of the items (1) to (17) can be adopted for the suspension device described in this item.

Hereinafter, a suspension device according to an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the present suspension device is arranged between the front and rear left and right wheels 4FL, FR, RL, RR between the vehicle body 8 and the wheel holding devices 6FL, FR, RL, RR for holding the wheels 4, respectively. The suspension cylinders 10FL, FR, RL, and RR are provided together with the suspension spring 21. The suspension cylinders 10FL, FR, RL, and RR are operated by hydraulic fluid as fluid. The front, rear, left and right wheels 4FL, FR, RL, and RR are drive wheels, and a vehicle equipped with this suspension device is a four-wheel drive vehicle. Hereinafter, when it is necessary to distinguish between the wheel positions, symbols FL, FR, RL, and RR representing the wheel position are used, and when there is no need to distinguish, the symbols are used without any symbols.
The suspension cylinders 10FL, FR, RL, and RR have the same structure, and each includes a housing 11, a piston 12 fitted inside the housing 11 so as to be relatively movable, and a piston rod 14. The rod 14 is connected to the vehicle body 8 and the housing 11 is connected to the wheel holding device 6 so as not to be relatively movable in the vertical direction. The piston 12 is provided with a communication path 20 that communicates the two liquid chambers 16 and 18 partitioned by the piston 12, and the communication path 20 is provided with a throttle. The throttle generates a damping force corresponding to the relative moving speed of the piston 12 with respect to the housing 11 (the flow rate of the working fluid flowing through the throttle). The suspension cylinder 10 functions as a shock absorber.

As shown in FIG. 1, the piston rod 14 is attached to a spring retainer 22 that holds a suspension spring 21 via an elastic member such as rubber, and the spring retainer 22 is attached to the vehicle body 8 so as not to be relatively movable in the vertical direction. Further, a bound side stopper 24 is attached to the spring retainer 22. The movement limit on the bounce side is defined by the outer upper end surface 26 of the cylinder body 11 coming into contact with the bounce side stopper 24.
On the other hand, a rebound side stopper 28 is provided on the side of the piston 12 where the piston rod 14 is provided. When the inner upper end surface 30 of the main body 11 contacts the rebound side stopper 28, the rebound side movement limit is defined.

Individual connection passages 32FL, FR, RL, and RR are connected to the liquid chambers 16 of the suspension cylinders 10FL, FR, RL, and RR, respectively.
In each of the individual connection passages 32FL, FR, RL, RR, the accumulators 34FL, FR, RL, RR and the accumulators 36FL, FR, RL, parallel to each other correspond to the suspension cylinders 10FL, FR, RL, RR, respectively. RR is connected. Spring constant switching valves 38FL, FR, RL, and RR are provided between the suspension cylinders 10FL, FR, RL, and RR and the accumulators 36FL, FR, RL, and RR, respectively.

Each of these accumulators 34 and 36 has a function as a spring, and includes, for example, a housing and a partition member that partitions the inside of the housing, and the individual connection passage 32 is provided in one volume change chamber of the partition member. The other volume change chamber is connected and an elastic body is provided, and the volume of one volume change chamber decreases due to the increase in volume of one volume change chamber, thereby generating elastic force. It can be made to. The accumulators 34 and 36 may be bellows type, bladder type, piston type, or the like.
In this embodiment, the accumulator 34 has a larger spring constant than the accumulator 36. Hereinafter, the accumulator 34 is referred to as a high-pressure accumulator, and the accumulator 36 is referred to as a low-pressure accumulator. The spring constant switching valve 38 is a normally open electromagnetic on-off valve.

  The individual connection passages 32FL, FR, RL, RR are provided with variable throttles 40FL, FR, RL, RR, respectively. As described above, the hydraulic fluid flows into and out of the liquid chamber 16 by the vertical movement of the wheel holding device 6 relative to the vehicle body 8. In this case, the flow area of the individual connection passage 32 is reduced by the variable throttle 40. By being controlled, the damping force generated in the suspension cylinder 10 is controlled. In the present embodiment, a damping force adjusting mechanism is constituted by the variable diaphragm 40 and the like.

  Each of the suspension cylinders 10FL, FR, RL, RR is connected to the center cylinder 48 via individual connection passages 32FL, FR, RL, RR. The center cylinder 48 includes a center piston 50 formed by connecting three pistons, and a cylinder housing 51 that accommodates the center piston 50 in a liquid-tight and slidable manner. The center piston 50 has a first piston 52, a second piston 53, and a third piston 54 in order from the right side of FIG. 1, and the first piston 52 and the second piston 53, and the second piston 53 and the third piston 54 are arranged. They are connected in series by connecting rods 56 and 58, respectively.

The cylinder housing 51 includes a stepped cylinder bore having a large diameter portion and a small diameter portion, and a center piston 50 is fitted into the cylinder bore, whereby four liquid chambers are formed in the housing 51. A second piston 53 is fitted to the large diameter portion of the cylinder bore, and a first piston 52 and a third piston 54 are fitted to the small diameter portion, respectively. Therefore, the diameters of the first piston 52 and the third piston 54 are smaller than the diameter of the second piston 53. The diameters of the first piston 52 and the third piston 54 are the same.
The opposite side of the first piston 52 from the second piston 53 is the first liquid chamber 60, the first piston 52 and the second piston 53 are between the second liquid chamber 61, and the second piston 53 and the third piston 54. Is the third liquid chamber 62, and the third piston 54 is the fourth liquid chamber 63 on the opposite side of the second piston 53. In the first piston 52, the first liquid chamber 60 side is an outer pressure receiving surface 65, and the second liquid chamber 61 side is an inner pressure receiving surface 66. In the second piston 53, the second liquid chamber 61 side is an inner pressure receiving surface 67, the third liquid chamber 62 side is an inner pressure receiving surface 68, and in the third piston 54, the third liquid chamber 62 side is an inner pressure receiving surface. A surface 69 is formed, and the fourth liquid chamber 63 side is an outer pressure receiving surface 70. The first liquid chamber 60 to the fourth liquid chamber 63 correspond to the center hydraulic pressure chamber.

The fluid chamber 16 of the suspension cylinder 10FR of the right front wheel 4FR and the fluid chamber 16 of the suspension cylinder 10FL of the left front wheel 4FL are connected to the first fluid chamber 60 and the fourth fluid chamber 63 via the individual connection passages 32FR and FL, respectively. Is done. As a result, the outer pressure receiving surface 65 of the center piston 50 receives the fluid pressure in the fluid chamber 16 of the suspension cylinder 10FR of the right front wheel 4FR (hereinafter referred to as the fluid pressure of the suspension cylinder), and the outer pressure receiving surface 70 of the left front wheel 4FL. The hydraulic pressure of the suspension cylinder 10FL is received. In the present embodiment, the diameters of the first piston 52 and the third piston 54 are equal, and the pressure receiving areas of the outer pressure receiving surface 65 and the outer pressure receiving surface 70 are also equal.
The suspension cylinder 10RL of the left rear wheel 4RL is connected to the second liquid chamber 61 between the first piston 52 and the second piston 53 adjacent to each other by the individual connection passage 32RL. The suspension cylinder 10RR of the right rear wheel 4RR is connected to the third liquid chamber 62 between the piston 54 and the piston 54 through the individual connection passage 32RR.
On the other hand, the inner pressure receiving surface 66 of the first piston 52 and the inner pressure receiving surface 67 of the second piston 53, which are opposite to each other on both sides of the second liquid chamber 61, are hydraulic pressures of the suspension cylinder 10RL of the left rear wheel 4RL. Receive. However, the force applied to the first piston 52 having the smaller diameter of the two pistons is applied to the portion of the inner pressure receiving surface 67 of the second piston 53 having the larger diameter that has the same pressure receiving area as the inner pressure receiving surface 66 of the first piston 52. Offset by force. Therefore, the effective pressure receiving area of the center piston 50 with respect to the hydraulic pressure of the second liquid chamber 61 is a size obtained by subtracting the pressure receiving area of the inner pressure receiving surface 66 of the first piston 52 from the pressure receiving area of the inner pressure receiving surface 67 of the second piston 53. Become. Similarly, the effective pressure receiving area of the center piston 50 with respect to the hydraulic pressure of the third liquid chamber 62 is a value obtained by subtracting the pressure receiving area of the inner pressure receiving surface 69 of the third piston 54 from the pressure receiving area of the inner pressure receiving surface 68 of the second piston 53. It becomes. That is, the force represented by the product of the hydraulic pressure of the second liquid chamber 61 and the third liquid chamber 62 and the above-described effective pressure receiving area acts on the center piston 50, respectively.

As described above, since the diameter of the first piston 52 and the diameter of the third piston 54 are equal, the effective pressure receiving area of the center piston 50 for the second liquid chamber 61 and the effective pressure receiving area for the third liquid chamber 62 are also equal. Further, in the present embodiment, the effective pressure receiving area for the second liquid chamber 61 and the third liquid chamber 62 of the center piston 50 is equal to the pressure receiving area for the first liquid chamber 60 and the fourth liquid chamber 63. The diameter of the two pistons 53 is determined.
Therefore, in the center piston 50, the two pressure receiving surfaces 65 and 67 on the same side receive forces FFR and FRL corresponding to the hydraulic pressures of the suspension cylinders 10FR and 10RL of the right front wheel 4FR and the left rear wheel 4RL, respectively. The two pressure receiving surfaces 70 and 68 opposite to the pressure receiving surfaces 65 and 67 receive a force corresponding to the hydraulic pressure of the suspension cylinders 10FL and 10RR of the left front wheel 4FL and the right rear wheel 4RR, respectively.
In the center cylinder 48. Return springs 71 and 72 are provided between the outer pressure receiving surface 65 of the center piston 50 and the end surface of the housing 51, and between the outer pressure receiving surface 70 and the end surface of the housing 51, respectively.

The suspension device is provided with a hydraulic fluid supply / discharge device 74. The hydraulic fluid supply / discharge device 74 includes a high pressure source 76, a reservoir as the low pressure source 78, an individual control valve device 80, and the like.
The high-pressure source 76 includes a pump device 84 having a pump 81 and a pump motor 82, a pressure accumulator 86, and the like. The pump device 84, the pressure accumulator 86, and the like are provided in the control passage 88. The hydraulic fluid in the reservoir 78 is pumped up and discharged by the pump 81, and is stored in a pressurized state in the pressure accumulator 86. The accumulator 86 for pressure accumulation is connected to the control passage 88 via a pressure accumulation control valve 90 which is a normally closed electromagnetic on-off valve. A hydraulic pressure sensor 92 is provided in the control passage 88. The hydraulic pressure sensor 92 can detect the discharge pressure and accumulator pressure of the pump 81. In this embodiment, a high pressure source 76, a low pressure source 78, etc. constitute a hydraulic pressure source 98.
A check valve 94 and a silencing accumulator 96 are provided on the discharge side of the pump 81 in the control passage 88. An outflow passage 104 that connects the high pressure side and the low pressure side of the pump 81 is provided, and an outflow control valve 106 is provided in the outflow passage 104.
The outflow control valve 106 is a mechanical on-off valve that uses the discharge pressure of the pump 81 as a pilot pressure. When the pump 81 is not in operation, it is in a communication state, but when the discharge pressure becomes high due to the operation of the pump 81, the communication state is cut off. The pump 81 is a gear pump.

The individual control valve device 80 includes individual control valves 110FL, FR, RL, RR provided in the individual control passages 108FL, FR, RL, RR. The individual control passages 108FL, FR, RL, and RR are passages that connect the control passage 88 and the individual connection passages 32FL, FR, RL, and RR, respectively. The left and right communication valves 112 are provided in the front wheel side left and right communication passages 111 connecting the individual control passages 108FL and FR, and the left and right communication valves 114 are provided in the rear wheel side left and right communication passages 113 connecting the individual control passages 108RL and RR. . The suspension cylinder 10 and the control pressure passage 88 are connected to each other by the individual control passage 108 and the individual connection passage 32.
These individual control valves 110FL, FR, RL, RR, and left and right communication valves 112, 114 are normally closed electromagnetic on-off valves, and the individual control valves 110FL, FR, RL, RR are operated when the left and right communication valves 112, 114 are shut off. By individually controlling each wheel 4FL, FR, RL, RR, the wheel holding device 6FL, FR, RL, RR and the corresponding body part 8 (corresponding to the suspension cylinders 10FL, FR, RL, RR) The vehicle height, which is the distance between the vehicle and the vehicle, can be controlled independently.

  In the present embodiment, a locking valve 120 as an operation suppression valve is provided at a portion 118RL closer to the center cylinder than the connection portion 116RL between the individual connection passage 32RL and the individual control passage 108RL. The locking valve 120 is a normally-open electromagnetic opening / closing valve (electromagnetic control valve), and allows the working fluid to flow in and out of the second fluid chamber 61 and allows the center cylinder 48 to operate in the open state. In the closed state, the inflow / outflow of the working fluid in the second fluid chamber 61 is blocked, the movement of the center piston 50 at that position is blocked, and the operation of the center cylinder 48 is blocked (locked).

  This suspension apparatus is controlled by a suspension ECU 200 mainly including a computer. The suspension ECU 200 includes an execution unit 204, a storage unit 206, an input / output unit 208, and the like. The input / output unit 208 includes a spring constant switching valve 38, a variable throttle 40, a coil of an operation lock valve 120, and a vehicle height adjusting device 74. (Accumulation pressure control valve 90, individual control valve 110, coils of left and right communication valves 112, 114, pump motor 82, etc.) are connected through a drive circuit (not shown), and fluid pressure sensor 92, front, rear, left and right wheels Are connected to a vehicle height sensor 220 for detecting the vehicle height, a stack detection device 222 for detecting that the vehicle is stacked, a vehicle height adjustment mode selection switch 224, a vehicle height adjustment instruction switch 226, etc. .

The stack detection device 222 includes a wheel speed sensor 228 that detects the rotational speeds of the front, rear, left and right wheels. When the absolute value of the rotational speed difference between the left and right wheels (left and right drive wheels) on the front wheel side and the rear wheel side is larger than the set value, it can be determined that the vehicle is stuck. In the four-wheel drive vehicle equipped with the suspension device according to this embodiment, when the drive slip of the drive wheel becomes excessive, the drive slip is applied to the drive wheel so that the drive slip is within a setting range determined by the friction coefficient of the road surface. Although the traction control for controlling the drive torque can be performed, the stack detection device 222 of the present embodiment detects the rotational speeds of the left and right drive wheels without performing the traction control. It can also be applied to a four-wheel drive vehicle in which traction control is not performed.
The vehicle height adjustment mode selection switch 224 is operated by the driver, and the operation of the switch 224 selects either the automatic mode or the manual mode.
The vehicle height adjustment instruction switch 226 is a switch that is operated when the vehicle height is increased, when the vehicle height is decreased, and the like, and is switched by a driver's manual operation.
The storage unit 206 stores a stack height adjustment program and the like represented by the flowchart of FIG.

The operation of the suspension device configured as described above will be described.
In the center cylinder 48, the center piston 50 has a force corresponding to the fluid pressure of the suspension cylinder 10 provided on each wheel (force represented by the product of the fluid pressure and the corresponding pressure-receiving area of the pressure-receiving surface). In principle, they are balanced in a stationary state.
When the vehicle body is pitched, for example, when the distance between the wheel holding device 6 and the vehicle body 8 decreases on the front side of the vehicle and increases on the rear side (for example, when braking), the left and right front wheels 4FL, 4FR suspension cylinders 10FL , 10FR is increased, and the hydraulic pressures of the suspension cylinders 10RL, 10RR of the left and right rear wheels 4RL, 4RR are decreased. Therefore, the hydraulic pressure acting on the outer pressure receiving surfaces 65 and 70 of the first piston 52 and the third piston 54 is increased, and the hydraulic pressure acting on the inner pressure receiving surfaces 67 and 68 of the second piston 52 is decreased. In this case, since the balance of the forces acting on the center piston 50 does not change, the movement of the center piston 50 is suppressed, and the suspension cylinders 10 are equal to each other independently, and a large damping force is generated. The pitching of the vehicle is effectively suppressed.
When rolling on the vehicle body, for example, when the distance between the wheel holding device 6 and the vehicle body 8 increases on the left side of the vehicle and decreases on the right side (for example, when turning left), the left front wheel 4FL, the left rear wheel 4RL The hydraulic pressures of the suspension cylinders 10FL and 10RL are reduced, and the hydraulic pressures of the suspension cylinders 10FR and 10RR of the right front wheel 4FR and the right rear wheel 4RR are increased. Accordingly, the hydraulic pressure acting on the outer pressure receiving surface 70 of the third piston 54 and the inner pressure receiving surface 67 of the second piston 53 is reduced, and the outer pressure receiving surface 65 of the first piston 52 and the inner pressure receiving surface 68 of the second piston 53 are reduced. The fluid pressure acting on the fluid increases. If the balance of the forces acting on the center piston 50 does not change even during rolling, the suspension cylinders 10 are almost independent from each other (extremely speaking, the state where the center cylinder 48 is not present). As the piston 12 moves, a large damping force is generated in each of the suspension cylinders 10 to effectively suppress rolling.

  When an input is applied to one of the front, rear, left, and right wheels from the road surface, for example, a force is applied to reduce the distance between the wheel holding device 6 and the vehicle body 8 to the suspension cylinder 10FL provided on the left front wheel 4FL. (For example, when the left front wheel FL rides on the road bump) or a force that moves the wheels in the same position to the wheels on the diagonal position of the vehicle body 8, for example, the suspension cylinders 10FL, 10RR to the wheel holding device 6 and the vehicle body 8 When a force for reducing the interval is applied, the hydraulic pressures of the suspension cylinders 10FL and 10RR are increased, and the hydraulic pressures of the suspension cylinders 10FR and 10RL are decreased. Accordingly, the hydraulic pressure acting on the outer pressure receiving surface 70 of the third piston 54 and the inner pressure receiving surface 68 of the second piston 52 increases, and the inner pressure receiving surface 67 of the second piston 52 and the outer pressure receiving surface of the first piston 52 are increased. The hydraulic pressure acting on 65 is lowered. Thereby, the center piston 50 moves rightward in FIG. As a result, the volumes of the fourth liquid chamber 63 and the third liquid chamber 62 are increased, and the volumes of the second liquid chamber 61 and the first liquid chamber 60 are decreased. Accordingly, the hydraulic fluid flows out from the suspension cylinders 10FL and 10RR and flows into the suspension cylinders 10FR and 10RL, as if the two suspension cylinders 10FL and 10RR and the two suspension cylinders 10FR and 10RL communicate with each other via the center cylinder 48. Thus, the hydraulic fluid is exchanged between them.

In each of the suspension cylinders 10, the damping characteristic is controlled by controlling the variable throttle 40.
When the flow area of the individual connection passage 32 is reduced by the variable throttle 40, the suspension hardness is hard (a state in which the damping force increases when the vertical relative movement speed between the wheel and the vehicle body is the same). When the flow path area is increased, it becomes soft (a state in which the damping force is reduced when the relative movement speed is the same). The hardness of the suspension is switched in accordance with an operation by a driver of a mode selection switch (not shown), but may be controlled based on the running state of the vehicle.

Further, the spring constant is switched by the control of the spring constant switching valve 38.
When the spring constant switching valve 38 is in the communication state, the two accumulators 34 and 36 are communicated with the liquid chamber 16 so that the spring constant is small, and the spring constant switching valve 38 is shut off. In this case, since the low-pressure accumulator 36 is shut off from the liquid chamber 16 and the high-pressure accumulator 34 is communicated, the spring constant is increased.

The vehicle height corresponding to the four wheels 4FL, FR, RL, RR is controlled by the hydraulic fluid supply / discharge device 74.
The left and right communication valves 112 and 114 and the individual control valve 110 are normally in the illustrated original positions. For example, in the case of increasing the vehicle height, which is the distance between the wheel holding device 6FL and the portion corresponding to the left front wheel 4FL of the vehicle body 8, for the left front wheel 4FL, the pump 81 is operated and the individual control valve 110FL is operated. The communication state is assumed. Since the outflow control valve 106 is shut off by the operation of the pump 81, the hydraulic fluid discharged from the pump 81 is supplied to the suspension cylinder 10FL, and the vehicle height increases. When the actual vehicle height reaches the target value, the individual control valve 110FL is shut off and the operation of the pump 81 is stopped.
In order to reduce the vehicle height, the individual control valve 110FL is in a communication state. Since the pump 81 is in a stopped state, the outflow control valve 106 is in a communication state. The working fluid is caused to flow from the suspension cylinder 10FL to the reservoir 78. When the actual vehicle height reaches the target value, the individual control valve 110FL is turned off.
When the automatic mode is selected by the vehicle height adjustment mode selection switch 224, the vehicle height is changed according to a predetermined condition, and the vehicle height is changed accordingly, and the manual mode is selected. Is changed according to the instruction of the vehicle height adjustment instruction switch 226.

In the present embodiment, when the vehicle is stacked on an uneven road, the vehicle height adjustment at the time of stacking is performed.
The stack is a state in which the drive wheels cannot move due to slipping or slipping. During off-road driving, two pairs of wheels that are diagonally positioned to each other may get stuck in one of the two wheels riding on the convex portion and the other pair of two wheels getting stuck in the concave portion. is there. For example, as shown in FIG. 3, the vehicle height of one pair of two wheels 4FR, 4RL is small (road surface input is large), and the other pair of two wheels 4FL, 4RR is high (road surface input is large). This applies to the case of (smaller). In this case, the vehicle body 8 and the road surface often interfere and cannot move.
Therefore, in this embodiment, the hydraulic fluid is supplied to the suspension cylinders 10FR and 10RL for the wheels 4FR and 4RL having the smaller vehicle height, that is, the wheels 4FR and 4RL riding on the protrusions on the road surface to increase the vehicle height. The vehicle height is adjusted. Thereby, the interference between the vehicle body 8 and the road surface can be eliminated, and the vehicle can be easily pulled out of the stack.

However, when hydraulic fluid is supplied to the suspension cylinders 10FR and 10RL of the pair of wheels 4FR and 4RL that are diagonal to each other, the center cylinder 48 operates and the vehicle height cannot be increased quickly. was there.
For example, when the vehicle height adjustment is performed for each wheel and the vehicle height adjustment for increasing the vehicle height is performed for the wheel 4RL in the open state of the locking valve 120, as shown in FIG. The hydraulic fluid supplied from the hydraulic pressure source 98 is supplied to the suspension cylinder 10RL and also to the second fluid chamber 61. Thereby, in the center cylinder 48, the center piston 50 is moved to the left in the figure. The hydraulic fluid supplied from the hydraulic pressure source 98 is used for the operation of the center cylinder 48. In other words, the hydraulic fluid is not effectively used for vehicle height adjustment.
Due to the movement of the center piston 50, the hydraulic fluid flows out from the suspension cylinder 10FR of the right front wheel 4FR to supply the hydraulic fluid to increase the vehicle height, and it is not necessary to supply the hydraulic fluid to the left front wheel 4FL and the right rear wheel 4RR. The working fluid flows out to the suspension cylinders 10FL, RR.
The same applies when the vehicle height is adjusted for the right front wheel 4FR, and the center piston 50 is moved to the left in the figure.

Therefore, in the present embodiment, when the vehicle height adjustment at the time of stacking is performed, the locking valve 120 is switched to the closed state. When the locking valve 120 is closed, as shown in FIG. 4B, the inflow / outflow of the working fluid in the second fluid chamber 61 of the center cylinder 48 is blocked, and the operation of the center cylinder 48 is locked. The
The center piston 50 is prevented from moving at that position. The hydraulic fluid supplied from the hydraulic pressure source 98 is prevented from being supplied to the center cylinder 48, is effectively used for the suspension cylinder 10, and operates immediately on the suspension cylinders 10FR and RL of the right front wheel 4FR and the left rear wheel 4RL. The liquid can be supplied, and the vehicle height can be adjusted quickly.

The stack height adjustment program shown in the flowchart of FIG. 2 is executed at predetermined time intervals.
In step 1 (hereinafter abbreviated as S1. The same applies to other steps), it is determined whether or not there is a vehicle height adjustment request. It is determined whether or not the vehicle height adjustment instruction switch 226 has been operated by the driver, or whether or not the vehicle is stuck in the automatic mode.
It is considered that the vehicle height adjustment instruction switch 226 is operated because the vehicle is stuck and the driver requests vehicle height adjustment to get out. In addition, if the absolute value of the rotational speed difference between the left and right front wheels 4FR, FL is larger than the set value and the absolute value of the rotational speed difference between the left and right rear wheels 4RR, RL is larger than the set value, it is determined that they are stuck. Is done. Since the vehicle on which the suspension device of the present embodiment is mounted is a four-wheel drive vehicle, a difference between the left and right rotational speeds is detected on each of the front wheel side and the rear wheel side.
| VwFR-VwFL |> Vwth
And | VwRR-VwRL |> Vwth

Next, rough terrain determination is performed in S2. In this embodiment, when the warp amount is larger than the set value, it is determined that the road is rough. The warp amount is an absolute value obtained by subtracting the sum of the vehicle heights of the two wheels of the other pair from the sum of the vehicle heights of the two wheels of one pair of the two pairs of wheels at the diagonal positions. is there.
| (HFR + HRL)-(HFL + HRR) |> Hth
If it is determined that it is rough terrain (when both determinations of S1 and S2 are YES), it may be stuck due to the two wheels at the diagonal positions riding on the protrusion. Recognize. In that case, the locking valve 120 is switched to the closed state in S3. The center piston 50 is prevented from moving at that position, and the operation of the center cylinder 48 is prevented.

In the state shown in FIG. 3, the right front wheel 4FR and the left rear wheel 4RL are wheels on the convex portion, and of the four wheels, the two right front wheels 4FR and the left rear wheel 4RL having a small vehicle height are vehicles. It is considered as a high adjustment target wheel.
In the present embodiment, the vehicle height is adjusted one by one, for example, in order of the right front wheel 4FR and the left rear wheel 4RL.
In S4, the pump motor 82 is activated and the individual control valve 110FR is opened. In S5, it is determined whether or not the vehicle height of the right front wheel 4FR has reached the target vehicle height. When the vehicle height reaches the target vehicle height, the individual control valve 110FR is closed in S6. In S7, it is determined whether there is another wheel height adjustment target wheel. In this case, since the left rear wheel 4RL is also a vehicle height adjustment target wheel, the individual control valve 110RL is opened in S4. When the vehicle height for the left rear wheel 4RL reaches the target vehicle height, the individual control valve 110RL is closed in S6. In this embodiment, since there are no other wheels to be controlled, the determination in S7 is NO, and in S8, the vehicle height adjustment is terminated and the operation of the pump 81 is stopped. In the stack height adjustment, the target vehicle height is set to the maximum vehicle height determined structurally. The vehicle height is increased up to the maximum value in order to move quickly from the stack.
The vehicle height adjustment can be performed simultaneously for the two wheels.

Next, in S9, rough terrain determination is performed. Similar to the execution in S2, it is determined whether or not the warp amount is larger than the set value. The warp amount is the same as long as the shape of the road surface with which the vehicle body 8 is in contact is the same. Since the vehicle body 8 is a rigid body, if the vehicle height of the right front wheel 4FR and the left rear wheel 4RL is increased (the vehicle height increase ΔHFR, ΔHRL) as in the present embodiment, the vehicle of the left front wheel 4FL and the right rear wheel 4RR. The height also changes (ΔHFL, ΔHRR). Between these, the expression ΔHFR−ΔHFL = ΔHRR−ΔHRL (a)
Is established. Since the vehicle body 8 is a rigid body, the inclination angle in the left-right direction on the front wheel side and the inclination angle in the left-right direction on the rear wheel side should be the same.
Also, if this equation is transformed,
ΔHFR + ΔHRL = ΔHRR + ΔHFL (b)
Is established. Therefore, the warp amount after adjusting the vehicle height is
W = | (HFR + ΔHFR + HRL + ΔHRL) − (HFL + ΔHFL + HRR + ΔHRR) |
However, substituting equation (b),
W = | (HFR + HRL) − (HFL + HRR) |
It turns out that it becomes the same as before the vehicle height adjustment.
As long as the road surface with which the vehicle is in contact is the same, that is, unless the vehicle moves, the determination in S9 is YES. If the vehicle moves and the road surface changes, the determination is no.
In this embodiment, by adjusting the vehicle height at the time of stacking, interference between the vehicle body 8 and the road surface is eliminated, so that it is easy to get out of the stack.
When the determination in S9 is NO, the locking valve 120 is opened in S10. The operation of the center cylinder 48 is allowed.
On the other hand, if it is determined in S2 that the road is not rough, normal vehicle height adjustment is performed in S11. The vehicle height is adjusted while the locking valve 120 remains open. Even if the vehicle is in the stacked state, if it is not caused by the fact that the two wheels are on board, S4 and the subsequent steps are not executed.

As described above, when the vehicle height adjustment at the time of stacking is performed, the operation of the center cylinder 48 is locked by closing the locking valve 120, so that the vehicle height adjustment can be performed quickly. Become. As a result, it is possible to achieve the purpose of adjusting the vehicle height, such as improving the running performance and making it possible to easily get out of the stack.
As described above, in this embodiment, the suspension cylinder 10, the hydraulic fluid supply / discharge device 74, the part for storing the vehicle height adjustment program at the time of stacking represented by the flowchart of FIG. The high adjustment device is configured, and the operation suppression device is configured by the locking valve 120, the portion that stores S3 in the flowchart of FIG.
Of the vehicle height adjusting device, a part for storing S2 to 10 and a part for executing S2 constitute a stack-time vehicle height adjusting unit. The stack height adjustment unit is also a cancellation elimination adjustment unit. Furthermore, the operation suppression device is also a lock unit and an inflow / outflow suppression unit. Of the operation suppressing device, an operation suppressing valve control unit is configured by a part that stores S3 of the suspension ECU 200, a part that executes S3, and the like.

In the above embodiment, the target vehicle height is the maximum value determined structurally, but it is not essential to set the maximum value. It can also be set to a value smaller than the maximum value.
In the above embodiment, the lock valve 120 is an electromagnetic on-off valve and is closed by being closed. However, the lock valve is adjusted to adjust the flow area. Possible variable apertures can also be used. If the flow path area is reduced, the time required for adjusting the vehicle height can be shortened compared to the case where the flow path area is not reduced. Further, when the lock valve 120 is switched from the closed state to the open state, if the flow path area is gradually increased, the impact can be reduced as compared with the case of immediately switching from the closed state to the open state. Can do.

Furthermore, in the above-described embodiment, the locking valve 120 is provided in the individual connection passage 32RL. For example, as shown in FIG. 6, the locking portion is also provided on the center cylinder side of the connection portion 116RR of the individual connection passage 32RR. A valve 250 can be provided. That is, it is provided in at least one of the individual connection passages 32RR and 32FL connected to the suspension cylinders 10RR and 10FL of the right rear wheel 4RR and the left front wheel 4FL which are not diagonal to the left rear wheel 4RL.
When the locking valves 120 and 250 are closed, it is desirable that the corresponding center hydraulic pressure chamber does not become negative pressure. That is, it is desirable that the locking valve provided in the individual connection passage connected to the center hydraulic pressure chamber whose volume is reduced by the movement of the center piston 50 be closed, and the center hydraulic pressure chamber is closed by the locking valve. It is desirable to prevent the hydraulic fluid from flowing out.
For example, when the vehicle is stacked by the right front wheel 4FR and the left rear wheel 4RL riding on the protrusions and the vehicle height is adjusted during stacking, the fluid pressure in the first fluid chamber 60 and the second fluid chamber 61 is reduced. Get higher. A force for moving the center piston 50 to the left in the drawing is applied. If the operation of the center cylinder 48 is permitted, the center piston 50 is moved to the left. In this case, the working fluid is allowed to flow out from the third liquid chamber 62 and the fourth liquid chamber 63. Therefore, it is desirable that the locking valve 250 provided corresponding to the third liquid chamber 62 is closed.
In addition, when the left front wheel 4FL and the right rear wheel 4RR ride on the protrusions and the vehicle is stacked and the vehicle height is adjusted during stacking, the hydraulic pressure in the third liquid chamber 62 and the fourth liquid chamber 63 is reduced. Get higher. A force for moving the center piston 50 to the right in the figure is applied. If the center piston 50 is moved to the right, the hydraulic fluid is allowed to flow out from the first liquid chamber 60 and the second liquid chamber 61, and the locking liquid provided corresponding to the second liquid chamber 61 is used. It is desirable that the valve 120 be closed.
In this way, the locking valve that is switched to the closed state is the one provided in the individual connection passage to which the suspension cylinder provided in the wheel fitted in the recess is connected when stuck during rough terrain traveling. It is desirable. Of the two pairs of wheels at the diagonal positions, the wheel with the higher sum of the vehicle heights is the wheel that has entered the recess.

Further, three locking valves can be provided, or four, that is, can be provided corresponding to each of the individual connection passages. When two or more lock valves are provided, the lock valve to be switched to the closed state (closed state switch target valve) is selected based on the warp amount, and the wheel with the higher vehicle height is selected. Only the lock valve corresponding to the center hydraulic chamber to which the suspension cylinder of the selected wheel is connected can be closed. In addition, all the locking valves can be closed.
Further, when two or more locking valves are provided and all the locking valves are closed, the hydraulic fluid is allowed to flow into the center hydraulic pressure chamber in parallel with the locking valves. It is also possible to provide a check valve for preventing the hydraulic fluid from flowing out of the center hydraulic pressure chamber. Thereby, it is possible to suppress the center hydraulic pressure chamber from becoming a negative pressure.

In the above embodiment, the operation of the center cylinder 48 is locked by closing the lock valve 120 when the stack height adjustment program S3 is executed. The movement can also be restricted in a state in which the piston 50 reaches a predetermined position. An example is shown in FIG.
In this embodiment, movement restricting stoppers 310 and 311 are provided at the step portions of the large diameter portion and the small diameter portion of the housing 51 of the center cylinder 48, respectively. As shown in FIG. 5 (a), the movement restricting stoppers 310 and 311 have the stoppers 310 and 311 in the normal travel when the center piston 50 is assumed to be in the neutral position when the center cylinder 48 is in an inoperative state. Although it does not contact 311, it is designed to contact just before stacking. In other words, during normal travel, hydraulic fluid may be exchanged between the suspension cylinder and the center cylinder and the center piston 50 may be moved as the vehicle height changes. Even if it is fully bounced, the center piston 50 does not come into contact with the stoppers 310 and 311. On the other hand, when the vehicle is stacked, the vehicle has a size and shape that can come into contact with the stoppers 310 and 311 immediately before.
In the state where the center piston 50 is in contact with the stopper 310, the leftward movement in FIG. 5 is allowed, but the rightward movement is prevented. Further, in the state where the center piston 50 is in contact with the stopper 311, the rightward movement in FIG. 5 is allowed, but the leftward movement is prevented.

Therefore, when the vehicle is stacked in the state shown in FIG. 3, since the hydraulic pressure of the suspension cylinders 10FR and 10RL is increased, the center piston 50 is moved to the left as shown in FIG. It contacts the stopper 311. In this state, even if hydraulic fluid is supplied to the suspension cylinders 10FR and 10RL in order to increase the vehicle height of the right front wheel 4FR and the left rear wheel 4RL, the center piston 50 does not move further to the left. . As a result, the hydraulic fluid from the hydraulic pressure source 98 can be effectively supplied to the suspension cylinders 10FR and 10RL, and the vehicle height can be adjusted quickly.
In the present embodiment, the stoppers 310, 311 and the like constitute a stroke change limiting unit.

  The stoppers 310 and 311 can also be provided on the pressure receiving surfaces 67 and 68 of the second piston 53. Further, it can be provided on the pressure receiving surface 65 of the first piston 51 and the pressure receiving surface 70 of the third piston 54, or on the end surfaces corresponding to the first liquid chamber 60 and the fourth liquid chamber 63 of the cylinder housing 51.

In the above-described embodiment, when the vehicle height adjustment is performed when the vehicle is stacked, the locking valve 120 is switched to the closed state. In the case where the vehicle height adjustment is performed with a large load difference, at least one of the locking valves 120 and 250 can be switched to the closed state. This is because the possibility that the center piston 50 moves also in these cases is high.
Further, even when the vehicle height is adjusted while the vehicle is stopped, at least one of the locking valves 120 and 250 can be switched to the closed state. If at least one of the locking valves 120 and 250 is closed, the vehicle height can be adjusted quickly. Furthermore, the movement of the center piston 50 due to the vehicle height adjustment can be suppressed, and the deviation of the center piston 50 from the neutral position when the center cylinder 48 is in an inoperative state can be reduced.
The suspension device is a four-wheel drive vehicle, and the left and right front wheels 4FL and 4FR and the left and right rear wheels 4RL and 4RR each have an engine drive torque that is different from that of a differential device (hereinafter referred to as LSD). It can also be mounted on a vehicle that is transmitted via a limited slip differential gear. According to the differential device with differential restriction, the relative rotation between the left wheel and the right wheel is restricted, and the wheel with the smaller rotation speed (the wheel on the high load side) and the wheel with the larger one (the wheel on the low load side) Greater torque is distributed. According to the suspension device of the present invention, even a vehicle that does not include a differential device with a differential limit can easily come out of the stack, but a vehicle that includes an operating device with a differential limit. If applied to the above, it is possible to further improve the running performance.
Furthermore, the present invention is not limited to a four-wheel drive vehicle, and can be applied to a vehicle in which two wheels are non-drive wheels. It can implement in the aspect which gave.

It is a figure showing the suspension apparatus which is one Example of this invention. It is a flowchart showing the vehicle height adjustment program at the time of a stack | stuck memorize | stored in the memory | storage part of suspension ECU of the said suspension apparatus. It is a figure which shows the state of the said suspension apparatus in case the vehicle is stuck. It is the figure which showed the flow of the hydraulic fluid during vehicle height adjustment compared with the case where the action | operation of a center cylinder is a locked state, and the case where it is not so. It is a figure which compares and shows the movement of the center piston in the said center cylinder by the case where it is stuck during middle high-speed driving | running | working. It is a figure showing a part of suspension apparatus which is another one Example of this invention.

Explanation of symbols

10: Suspension cylinder 48: Center cylinder 120, 250: Lock valve 220: Vehicle height sensor 310, 311: Stopper

Claims (9)

A suspension cylinder provided between each wheel holding device and the vehicle body for each of the front, rear, left and right wheels of the vehicle;
A center cylinder connected to the four suspension cylinders and operating according to the hydraulic relationship of the four suspension cylinders;
A vehicle height adjusting device that adjusts a vehicle height that is a relative position between a wheel and a vehicle body corresponding to each of the suspension cylinders by controlling inflow / outflow of hydraulic fluid in each of the four suspension cylinders;
When the vehicle height adjustment is performed in such a manner that the center cylinder operates as the hydraulic fluid flows into and out of at least one of the four suspension cylinders by the vehicle height adjustment device, A suspension device comprising: an operation suppressing device that suppresses the operation of the center cylinder. The center cylinder is (a) a housing, (b) a center piston slidably fitted to the housing and having a plurality of effective pressure receiving surfaces, and (c) partitioned by the housing and the center piston, Four center hydraulic pressure chambers corresponding to each of the effective pressure receiving surfaces of the center piston, and the two center hydraulic pressure chambers corresponding to the two effective pressure receiving surfaces in the same direction of the center piston are respectively suspended by the right front wheel. connected cylinder and the suspension cylinders for the rear left wheel, the two center pressure chamber corresponding to the two effective pressure-receiving surface of the two effective pressure-receiving surface and the opposite, respectively, the right rear wheel and the left front wheel suspension cylinders The suspension device according to claim 1, wherein the suspension device is connected to the suspension cylinder.   The suspension device according to claim 2, wherein the vehicle height adjusting device includes a stack-time vehicle height adjusting unit that adjusts the vehicle height in such a manner that the center cylinder operates when the vehicle is stacked.   A road surface interference-resolving vehicle in which the vehicle height adjusting unit at the time of stacking increases the vehicle height of two wheels of a pair having a smaller vehicle height among the two pairs of wheels at the diagonal positions of the front, rear, left and right wheels. The suspension device according to claim 3, comprising a height adjustment portion.   The suspension device according to any one of claims 1 to 4, wherein the operation suppressing device includes a lock portion that arbitrarily locks the operation of the center cylinder.   The center cylinder includes four center hydraulic chambers respectively connected to each of the four suspension cylinders, and the operation suppressing device is configured to flow in hydraulic fluid in at least one of the four center hydraulic chambers. The suspension device according to any one of claims 1 to 5, including an inflow / outflow suppression unit that suppresses outflow.   The center hydraulic chamber and each of the suspension cylinders are respectively connected via individual connection passages, and the vehicle height adjusting device is connected to (a) a hydraulic pressure source and (b) the individual connection passages, respectively. On the other hand, an individual control passage connected to the fluid pressure source, (c) an individual control valve provided in each of the individual control passages, and (d) each of the individual control valves and a fluid pressure source. By controlling the inflow / outflow of the hydraulic fluid in each of the suspension cylinders corresponding to the individual control valve, and controlling the vehicle height of the wheel provided with the suspension cylinder; The inflow / outflow suppression portion includes (e) an operation suppression valve provided in a portion closer to the center cylinder than the connection portion with at least one of the individual connection passages, and (f) the The center is adjusted by the vehicle height adjusting device. An operation suppression valve controller that reduces the flow area of the individual connection passage by controlling the at least one operation suppression valve when vehicle height adjustment is performed in a manner in which the Linda is operated. The suspension device described.   The center cylinder includes (a) a housing, (b) a center piston slidably fitted in the housing, and (c) four center hydraulic chambers partitioned by the housing and the center piston. 8. The operation suppression device includes a stroke change limiting unit that limits a change in stroke of the center piston when the center piston is at a predetermined relative position of the housing. Suspension device as described in one. A suspension cylinder provided between each wheel holding device and the vehicle body for each of the front, rear, left and right wheels of the vehicle;
A center cylinder that is connected to each of the four suspension cylinders and operates according to a hydraulic pressure relationship between the four suspension cylinders;
A vehicle height adjusting device that adjusts a vehicle height that is a relative position between a wheel and a vehicle body corresponding to each of the suspension cylinders by controlling inflow / outflow of hydraulic fluid in each of the four suspension cylinders;
A suspension including an operation suppressing device that suppresses the operation of the center cylinder when hydraulic fluid flows in and out of at least one of the four suspension cylinders by the vehicle height adjusting device. apparatus.

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