JP2515093B2 - Hydro-Machine Suspension - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydropneumatic suspension for improving the riding comfort of an automobile, stabilizing steering, etc., and particularly as a substitute for a suspension spring made of a metal spring. The gas spring characteristics of multiple accumulators used are raised quadratically during bumping to prevent suspension cylinder bottoming, while the rebound side automatically increases the gas spring constant before full rebound. Therefore, the present invention relates to a hydropneumatic suspension that reduces the rebound shock that occurs during a full rebound.

<Prior Art> Conventionally, as a hydropneumatic suspension of this type using a plurality of accumulators, the one shown in the circuit diagram of FIG. 3 has been already known, and this is the main accumulator. Two accumulators a and a sub accumulator b are used, and the hydraulic oil chambers of these accumulators a and b are connected in parallel to the pressure chambers of the suspension cylinder c.

As shown in FIG. 4, the main and sub accumulators a and b are divided into a gas chamber g by dividing the central part by a rubber bellows f.
And the hydraulic chamber h are isolated from each other, the gas chamber g is sealed from the outside, and the hydraulic oil in the hydraulic chamber h can enter and leave the suspension cylinder c.

Here, in general, the gas spring characteristic of the accumulator of the hydropneumatic suspension corresponding to the normal spring characteristic of the metal suspension spring is determined by the gas chamber volume V of the accumulator, the shared load W of the suspension cylinder, and the pressure receiving area A of the piston. It is determined.

Therefore, in the conventional hydropneumatic suspension described above, a gas spring including an on / off valve for intermittently controlling the communication of the sub accumulator b is provided in the middle of the circuit connecting the main accumulator a and the sub accumulator b. A switching valve e for switching the characteristics is provided, and by opening and closing the switching valve e from the outside, it is possible to switch between the use of both the main and auxiliary accumulators a and b and the use of only the main accumulator a. The different gas spring characteristics of high and low stages are obtained according to the traveling conditions during traveling and on rough roads.

Incidentally, in FIG. 3, a switching valve d interposed in the middle of a common circuit connecting the main accumulator a and the sub accumulator b to the working pressure chamber of the suspension cylinder c.
Is a damping force adjusting valve for adjusting each damping force at the time of different gas spring characteristics of the high and low stages, and if it is focused on the point of obtaining the different gas spring characteristics of the high and low stages, there is nothing. It does not have any effect, and is therefore not particularly important in that respect.

Therefore, the main and sub accumulators during normal driving
When using both a and b (when the gas spring repulsive force is soft), the gas spring repulsive force at the reference position, the impact force when the suspension cylinder c fully rebounds at that time, and when driving on rough roads Considering the gas spring repulsive force at the reference position when only the main accumulator a is used (when the spring repulsive force is hard) and the impact force when the suspension cylinder c is fully bumped at that time, the accumulators a and b are considered. It is assumed that the respective volumes are determined, and thereby the different gas spring characteristics of the high and low stages are respectively determined.

With this configuration, during normal traveling, the switching valve e is opened so that the main accumulator a and the sub accumulator b are opened.
By using both of these, the gas spring characteristics by these accumulators a and b are improved along the low repulsive force curve I ′ in FIG. 5 while improving the riding comfort and keeping the gas spring repulsive force near full rebound low. At the time of rebound, it is possible to reduce the impact force caused by the collision of the rebound stopper built in the suspension cylinder c.

Moreover, if the switching valve e is closed and switched to use only the main accumulator a when traveling on a rough road, this time, the gas spring characteristic will be the fifth by the accumulator a only.
By following the high repulsive force curve II ′ in the figure, it is possible to suppress both the posture change of the vehicle body and the impact force at the time of full bump.

<Problems to be Solved by the Invention> However, on the other hand, in consideration of the above points, it is only necessary to set the high and low two-stage gas spring characteristics by the capacities of the main accumulator a and the sub accumulator b. When using a and b, sufficient gas spring repulsion cannot be obtained near the full bump of the suspension cylinder c,
Depending on the condition of the vibration generated between the vehicle body and the wheels, there may be a case where a strong bottoming occurs and a large impact is generated.

In order to solve this point, the accumulators a and b should have a large capacity to increase the pressure receiving area and keep the gas spring repulsive force near the full bump at a required value to reduce the impact during bottoming. However, in reality, it is not possible to employ accumulators a and b having a capacity larger than the necessary maximum in view of the layout of the vehicle, cost and weight requirements.

Therefore, generally, a small-capacity, small-sized accumulator
Assuming the use of a and b, the gas pressure in the gas chamber g of the main and auxiliary accumulators a and b is set to a high value in advance, and the gas spring repulsive force by these accumulators a and b at the time of full bump is shown in FIG. There is no choice but to raise it so that it approaches the force curve II '.

By doing this, the bottoming that occurs when the suspension cylinder c is fully bumped can be prevented by the gas spring having a high repulsive force, but this is very
Along with this, on the contrary, the repulsive force of the gas spring at the time of full rebound becomes too high, so that the rebound stopper built into the suspension cylinder c violently collides at the time of full rebound, causing a large rebound shock. Occurs.

Therefore, an object of the present invention is to obtain a gas spring characteristic having a spring constant more preferable than riding comfort by using a plurality of accumulators, and to increase the repulsive force of the gas spring at the time of full bump while suppressing the occurrence of impact due to bottoming. And, in the vicinity of full rebound, the gas spring constant is automatically raised to sharply reduce the gas spring repulsion force, and thereby the hydropneumatic suspension that can also reduce the impact generated during full rebound Is to provide.

<Means for Solving Problems> According to the present invention, the above-described object is to provide a vehicle body, a wheel that supports bumps and rebounds with respect to the vehicle body, and a vertically movable wheel, and the bumps and rebounds. A suspension cylinder interposed between the vehicle body and the wheels so as to expand and contract with it, and separated by a partition member into a gas chamber and a hydraulic oil chamber, and the hydraulic oil chamber to the suspension cylinder. With a plurality of accumulators that are hydraulically connected and are arranged in parallel,
At the time of bumping, the hydraulic oil is pumped from the suspension cylinder to the hydraulic oil chamber of each accumulator to increase the gas pressure while compressing each gas chamber by the partition member,
At the time of rebound, on the contrary, the gas spring that expands the gas chamber of each accumulator and pumps the hydraulic oil from each hydraulic oil chamber to the suspension cylinder while lowering the gas pressure in each gas chamber to counter the posture change of the vehicle body. In the hydropneumatic suspension configured to obtain the characteristics, at least one of the plurality of accumulators is set to the maximum expansion state in the rebound region before the suspension cylinder fully rebounds to the rebound side. In order to prevent the supply of hydraulic oil to the suspension cylinder, the gas pressure in the gas chamber at the time of maximum expansion is higher than the hydraulic oil pressure in the suspension cylinder at full rebound,
Further, the remaining accumulator has a full rebound of gas pressure in the gas chamber at the time of maximum expansion so that the hydraulic oil can be continuously supplied to the suspension cylinder even after the hydraulic oil supply from the accumulator becomes zero. It is achieved by configuring the hydraulic pressure in the suspension cylinder to be lower than the hydraulic pressure in that case.

That is, by doing the above, all the accumulators function until the suspension cylinder starts to move to the rebound side and reaches the rebound area near the full rebound, and the rate of decrease in gas pressure under a large gas capacity. Is kept low to keep the gas spring characteristic at a low spring constant.

On the other hand, when the suspension cylinder reaches the rebound area near full rebound, the accumulator that sets the gas pressure in the gas chamber at maximum expansion higher than the hydraulic oil pressure in the suspension cylinder at full rebound will Since the hydraulic oil pressure in the suspension cylinder becomes lower than the gas pressure in the gas chamber, it becomes the most expanded state and the hydraulic oil cannot be supplied to the suspension cylinder, and the original function as the accumulator is lost.

As a result, the hydraulic oil must be supplied to the suspension cylinder only by the accumulator that is set to be lower than the hydraulic oil pressure in the suspension cylinder when the gas pressure in the gas chamber at the time of maximum expansion is fully rebound. The total gas capacity of the accumulator as a whole is reduced, and the gas spring characteristics of the hydropneumatic suspension are automatically switched to a high spring constant.After that, the rate of decrease in the gas pressure of the accumulator due to the extension operation of the suspension cylinder is reduced. When the gas pressure becomes large, the gas pressure rapidly decreases, the repulsive force due to the gas spring of the full rebound of the suspension cylinder is reduced, and the rebound shock is reduced.

On the other hand, on the bump side of the suspension cylinder, the gas pressure in the gas chamber at the time of maximum expansion is set lower than the hydraulic oil pressure in the suspension cylinder at the time of full rebound. Since all accumulators work, including the accumulator that sets the gas pressure in the gas chamber at the time of maximum expansion higher than the hydraulic oil pressure in the suspension cylinder, the gas spring constant returns to the original spring constant and bottoming The impact force will be alleviated.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a hydropneumatic suspension according to the present invention, where 1 is a main accumulator and 2 is a main accumulator.
Is a sub accumulator, and these main and sub accumulators 1 and 2 are the main and sub accumulators a and b of the conventional example described above.
Similarly to the above, a switching valve for switching the gas spring characteristics indicated by reference numeral 4 for these main / sub accumulators 1 and 2 and a damping switching valve for adjusting damping force shown in reference numeral 5 are provided. At the same time, the suspension cylinder 3 is arranged in the same manner as in the conventional example.

As described above, also in this embodiment, the switching valve 4 for switching the gas spring characteristic and the damping switching valve 5 for adjusting the damping force are used, as in the conventional example described above.

However, the switching valve 4 for switching the gas spring characteristics described above
As described in the conventional example, the main and sub accumulators 1, 2
And the use of only the main accumulator 1 are selected, and the gas spring characteristics are shown in FIG. 2 as a soft and comfortable ride curve I with a low spring constant and a rebound curve II with a high spring constant suitable for running on rough roads. Similarly, the damping switching valve 5 is also the same as in the prior art example, and the gas spring constants (repulsion force curves I, I
It is only for adjusting each damping force when switching I).

Therefore, the switching valves 4 and 5, while using a plurality of accumulators that are comfortable to ride, which is the object of the present invention, while taking a high repulsive force by the gas spring at the time of full bump to suppress the occurrence of impact by bottoming, Also, from the viewpoint of automatically increasing the gas spring constant during the rebound and reducing the impact generated at the time of full rebound, they are not involved in them at all, and in that respect there is absolutely no relation in configuring the present invention. Absent.

On the other hand, in the hydropneumatic suspension of FIG. 1 of the embodiment according to the present invention, the main accumulator 1 is designed to supply hydraulic oil to the suspension cylinder 3 over the entire stroke of the suspension cylinder 3. The gas pressure in the gas chamber g at the time of expansion is configured to be lower than the hydraulic oil pressure in the suspension cylinder at the time of full rebound, and the auxiliary accumulator 2 is set to a predetermined amount for the suspension cylinder 3 to fully rebound to the rebound side. In the front rebound area, the gas at the maximum expansion is higher than the hydraulic oil pressure in the suspension cylinder 3 at the time of full rebound so that the gas chamber g reaches the maximum expansion state and the hydraulic oil cannot be supplied to the suspension cylinder 3. Special feature is that the gas pressure in the chamber g is increased. The has is different from the conventional hydropneumatic suspension at this point.

That is to say, generally speaking, now, the required volume of the accumulator is V ₀ , the required gas chamber volume is V ₁ , the hydraulic fluid volume V ₂
Then, the required volume V _{0 of the} accumulator is "V ₀ = V ₁ +
V ₂ ”and is determined by the required gas chamber volume V ₁ and the hydraulic oil volume V ₂ .

From this, when the hydraulic oil volume becomes V ₂ = 0 as the suspension cylinder 3 moves toward the rebound side and the hydraulic oil in the accumulator runs out, the accumulator becomes a state of only gas in the gas chamber g. After that, the hydraulic oil cannot be supplied according to the stroke of the suspension cylinder 3, and the accumulator does not function.

By utilizing this phenomenon, in this embodiment, of the two main / sub accumulators 1 and 2 used in the circuit configuration, only the sub accumulator 2 is in a predetermined amount before the suspension cylinder 3 fully rebounds. In the gas chamber g at the time of the maximum expansion, the gas chamber g reaches the maximum expansion state in the rebound region, and the hydraulic oil pressure in the suspension cylinder 3 at the time of the maximum expansion exceeds the pressure of the hydraulic oil in the suspension cylinder 3 at the time of full rebound so that the suspension cylinder 3 cannot supply the hydraulic oil That is, the gas pressure was set high.

Thereby, for example, the same required volume V ₀ of the main accumulator 1 and the sub accumulator 2 is used as shown in FIG. 1, and the hydraulic oil volume V ₂ of the sub accumulator 2 is used.
Is smaller than the hydraulic oil volume V ₂ of the main accumulator 1, the gas chamber volume of the sub accumulator 2 is inevitable.
V ₁ was formed larger than the gas chamber volume V ₁ of the main accumulator 1.

By configuring the sub accumulator 2 as described above, even if the full-bump shock is reduced by setting the gas spring repulsive force at the full-bump to a necessary value, the suspension cylinder 3 is in the full-bump state and a predetermined distance x from the reference position. The hydraulic oil in the sub accumulator 2 does not become zero during the expansion and contraction operation between the main and sub accumulators 1 and 2 while supplying and discharging the hydraulic oil to and from the suspension cylinder 3. The gas spring characteristics are kept at a second level while maintaining a low rate of decrease in gas pressure under the capacity.
A soft riding comfort can be obtained along the soft repulsive force curve I with a low spring constant shown by the solid line in the figure.

On the other hand, when the suspension cylinder 3 reaches the rebound area of the distance x before the predetermined amount of full rebound while moving toward the rebound side, when the hydraulic oil pressure in the suspension cylinder 3 at the time of full rebound is the most expanded. The hydraulic oil volume in the hydraulic oil chamber h of the sub accumulator 2 in which the gas pressure in the gas chamber g is set high becomes zero,
The supply of hydraulic oil from the hydraulic oil chamber h to the suspension cylinder 3 becomes zero, and the sub accumulator 2 does not function.

As a result, the function of only the main accumulator 1 is reduced to reduce the total gas capacity, and the reduction rate of the gas pressure is increased due to the reduction of the gas capacity, and thereafter, the suspension cylinder 3 moves toward the rebound side. The gas pressure of the main accumulator 1 is rapidly reduced while keeping the gas pressure of the sub accumulator 2 constant, and the gas spring characteristic as the hydropneumatic suspension is automatically switched to a high spring constant. It is possible to switch to the hard repulsive force characteristic while following the repulsive force curve III by the broken line parallel to the repulsive force curve II of.

When operating the suspension cylinder 3 from the full-round to the full-bumper side, the hydraulic oil pushed out from the suspension cylinder 3 is first pumped only to the hydraulic oil chamber h of the main accumulator 1 so that the gas in the gas chamber g is By increasing the pressure, the gas chamber g in this main accumulator 1
When the gas pressure inside becomes equal to the gas pressure inside the gas chamber g of the sub accumulator 2, the hydraulic oil from the suspension cylinder 3 is sent in parallel to the main and sub accumulators 1 and 2, and the gas spring characteristic repels. Force curve III to repulsive force curve I
According to, the spring constant of the hardware is initially maintained, and the spring constant of the soft is automatically switched from the middle.

As a result, the gas spring repulsive force at the time of full bumping of the suspension cylinder 3 by the main / sub accumulators 1 and 2 is maintained at a required value, and until both oil and sub accumulators 1 and 2 are fully rebounded. When the gas spring characteristics are made to follow the repulsive force curve I having a low spring constant, that is, the repulsive force due to the gas spring at the time of full rebound is reduced by y compared to the case of the conventional example, and the full rebound of the suspension cylinder 3 The rebound shock can be mitigated by reducing the rod repulsion force.

In the description of the above embodiments, the required volume V ₀ of the main accumulator 1 and the sub accumulator 2 is the same, and the hydraulic oil volume V ₂ of the sub accumulator 2 is set smaller than that of the main accumulator 1 and the suspension is performed. The case where the shape is determined so that the hydraulic oil in the hydraulic oil chamber h of the sub accumulator 2 becomes zero at the time when the cylinder 3 passes the reference position and moves a predetermined distance x toward the rebound side has been described above. As a method of eliminating the hydraulic oil in the hydraulic oil chamber h in the sub accumulator 2 when the sub accumulator 2 is operated for a predetermined distance x, the gas volume in the sub accumulator 2 is controlled, or the sub accumulator 2 is operated.
It is also conceivable to use a porous perforated plate for the stopper of the bellows f (see FIG. 4) inside to reduce the apparent hydraulic oil volume V ₂ and control the inflow / outflow amount of the hydraulic oil.

The predetermined distance x at the time of switching the gas spring constant can be arbitrarily set by changing the hydraulic oil volume V ₂ in the hydraulic oil chamber h of the sub accumulator 2 in accordance with the condition at that time. .

Furthermore, the number of accumulators to be combined with the suspension cylinder 3 does not necessarily have to be two as in the above-described embodiments, and three or more accumulators are used so that at least one of the accumulators can be moved to the rebound side by the suspension cylinder 3. In order to prevent the supply of hydraulic oil to the suspension cylinder 3 and the gas chamber g reaches the maximum expansion state in the rebound area before a predetermined amount of full rebound, the hydraulic oil pressure in the suspension cylinder 3 at the time of full rebound Needless to say, the impact at the time of full rebound can be similarly mitigated by configuring the gas pressure in the gas chamber g at the time of maximum expansion to be high.

<Effects of the Invention> As described above, according to the present invention, a hydrostatic vehicle including a suspension cylinder interposed between a vehicle body and wheels and a plurality of accumulators for supplying and discharging hydraulic oil to and from the suspension cylinder, respectively. In the pneumatic suspension, at least one of the above accumulators is operated by operating the hydraulic oil to the suspension cylinder when the gas chamber reaches the maximum expansion state in the rebound area before the suspension cylinder fully rebounds to the rebound side. The gas pressure in the gas chamber at maximum expansion is higher than the hydraulic oil pressure in the suspension cylinder at full rebound so that the gas spring repulsion at full bump of the suspension cylinder can be prevented. Full force to required value It is possible to reduce the bump shock and also to reduce the full rebound shock by increasing the reduction rate of the gas spring repulsive force from the middle of the suspension cylinder toward the rebound side.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a hydropneumatic suspension to which the present invention is applied, FIG. 2 is a diagram showing a gas spring repulsive force characteristic in the hydropneumatic suspension of the present invention, and FIG. 3 is a conventional hydropneumatic suspension. FIG. 4 is a circuit diagram of the suspension, FIG. 4 is a partial sectional view of the accumulator, and FIG. 5 is a diagram showing a gas spring repulsive force characteristic in a conventional hydropneumatic suspension. 1 ... Main accumulator, 2 ... Sub accumulator, 3 ... Suspension cylinder.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Hirochika 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. Inside the factory (72) Inventor Hiroshi Yamanaka 2548 Tsuchida, Kani-shi, Kayaba Industry Co., Ltd. Gifu North Factory (56) Reference JP-A-53-38022 (JP, A) JP-A-59-53221 (JP, A) Special Open Sho 59-53223 (JP, A) Actual Open Sho 60-152511 (JP, U)

Claims (1)

(57) [Claims] 1. A vehicle body, a wheel supporting a bump and a rebound with respect to the vehicle body so as to be movable up and down, and a space between the vehicle body and the wheel so as to extend and contract with the bump and the rebound. And a plurality of accumulators that are separated by a partition member into a gas chamber and a hydraulic oil chamber, and that are hydraulically connected to the suspension cylinders and are arranged in parallel. At the time of bumping, the hydraulic oil is pumped from the suspension cylinder to the hydraulic oil chamber of each accumulator to increase the gas pressure while compressing each gas chamber by the partition member, while at the time of rebound, conversely,
It is configured to expand the gas chamber of each accumulator and pump the hydraulic oil from each hydraulic oil chamber to the suspension cylinder, while lowering the gas pressure in each gas chamber to obtain the gas spring characteristic that counters the posture change of the vehicle body. In the hydropneumatic suspension described above, at least one of the plurality of accumulators reaches the maximum expansion state in the rebound region before the suspension cylinder fully rebounds to the rebound side and reaches the maximum expansion state to the suspension cylinder. The gas pressure in the gas chamber at the time of maximum expansion is configured to be higher than the hydraulic oil pressure in the suspension cylinder at the time of full rebound so that the hydraulic oil cannot be supplied, and the remaining accumulators are After the hydraulic oil supply from the above accumulator became zero In order to be able to continue supplying hydraulic oil to the suspension cylinder, the gas pressure in the gas chamber at the time of maximum expansion should be lower than the hydraulic oil pressure in the suspension cylinder at the time of full rebound. Characteristic hydropneumatic suspension.