JP2921688B2 - Hydraulic cylinder for suspension - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a hydraulic cylinder suitable for use in an active suspension also serving as an attitude control means.

[Conventional technology]

If the attitude control of the vehicle is actively performed according to the running condition of the vehicle in addition to the change in the stationary load of the vehicle body, the riding comfort of the vehicle is further improved and the steering stability is improved.

Therefore, in recent years, it has been noted that it is effective to execute the attitude control of a vehicle with an active suspension system as a suspension system of the vehicle.

By the way, as a posture control device most suitable for use in this type of active suspension system, for example, a device having a structure as shown in FIG. 2 has been conventionally proposed.

That is, this kind of attitude control device is used for the suspension mechanism I.
And a hydraulic supply / discharge mechanism II. The hydraulic control of the hydraulic supply / discharge mechanism II controls the expansion and contraction of the suspension mechanism I.

Then, the suspension mechanism I has an upper end in four-wheel respective parts of the vehicle to the vehicle body B side, the lower end has a hydraulic cylinder 1 which are respectively connected to the vehicle A side serving suspension arm A _1.

Therefore, by controlling the expansion and contraction of the hydraulic cylinder 1, the vehicle height at each part of the four wheels of the vehicle is adjusted, and the posture of the vehicle is controlled as a whole.

That is, a suspension spring 2 for supporting a load from the vehicle body B is provided in parallel with the hydraulic cylinder 1, and a throttle 3 that performs a predetermined damping action when the hydraulic cylinder 1 expands and contracts is provided in the hydraulic circuit system. And a gas spring 4 that exhibits a predetermined gas spring effect.

On the other hand, as the hydraulic supply / discharge mechanism II connected to the suspension mechanism I, a definite one has not yet been proposed, but at least the control valve 11, the hydraulic source 12, and the tank
13 and a hydraulic source by the selected operation of the control valve 11.
In addition to supplying the hydraulic pressure from the hydraulic cylinder 12 to the hydraulic cylinder 1 or releasing the hydraulic pressure in the hydraulic cylinder 1 to the tank 13, a configuration is adopted in which a neutral state is maintained in which the cylinder hydraulic pressure is maintained.

That is, the controller C, which receives the status signal from the sensor 5 installed on the vehicle body B, ensures that the target pressure calculated by these signals and the actual cylinder pressure detected by the pressure sensor 14 always coincide. And a feedback loop mechanism that operates. Therefore, the control valve 11 receiving the control current i based on this feedback current
Adjusts the cylinder internal pressure so that the vehicle at the time becomes the optimum state by the operation selected by the above.

When adjusting the supply and discharge of the hydraulic oil, the gas spring 4
A shock absorber function by the diaphragm 3 and the diaphragm 3 is exhibited.

Next, FIG. 3 shows an example of the configuration of the hydraulic cylinder 1 and the gas spring 4 that exhibit the above functions.

The hydraulic cylinder 1 are piston 6 is slidably disposed, thereby being divided in the cylinder two vessel chamber V _A, to V _B. The other end of the piston rod 7 to which the piston 6 is fastened projects to the outside of the cylinder.

Further, the piston 6 the vessel chamber V _A, Yes in hole 8 communicating between V _B is perforated in, moreover, the vessel chamber V _A, hydraulic fluid between V _B in normal movement speed region of the piston 6 Has a sufficiently large passage area so that even if the movement occurs, the pressure loss hardly occurs. On the other hand, in the interior of the piston rod 7 is provided with a through hole 9, with connects the outer end of the hole 9 on the sheet discharge side port of the control valve 11, the inner ends are allowed to open the vessel chamber V _B is there.

In contrast, the gas spring 4 is divided into a gas chamber V _G and the oil chamber V _O by the free piston 10 and the interior of which, the oil chamber V _O is common with the cylinder vessel chamber V _B It is connected to the supply / discharge side port.

Although the oil inlet and outlet of the gas spring 4 is formed in the throttle 3, the valve mechanism disposed in the flow path like a normal shock absorber may be used instead of the orifice control mechanism. . Also, previously given pressure gas is sealed in the gas chamber V _G.

Therefore, in the configuration described above, an equivalent body weight and W _e, the cylinder generated force F _e, the spring force F _s, the cylinder pressure as P, the when the vehicle body B is stationary
F _e, F _s, and when the value of each of P and F _c0, F _s0 and _{P 0, W e = F s0} + F c0 = F s0 + A r · P 0 ( where, A _r is the piston rod cross-sectional area) There is a relationship.

Therefore, when the vehicle turns or accelerates or decelerates during traveling, an inertial force acts on the vehicle body B to change the vehicle posture.

This is apparently so that the tip of an equivalent vehicle weight W _e is increased or decreased by the variation [Delta] W _e due to inertia force. Therefore, the internal pressure P in the hydraulic cylinders 1 of the wheels, [Delta] W _e = A cylinder pressure change amount [Delta] P ₁ necessary for _r · [Delta] P ₁ becomes relation is satisfied
Is adjusted so that the posture of the vehicle body B does not change at this time while the forces at the respective wheels are kept in a balanced state.

That is, the outer ring side of the turning, with respect to the front wheel during wheel side and the deceleration after the time of acceleration, the weight only variation [Delta] W _e increases, the cylinder pressure is increased by the change amount [Delta] P _1, conversely , inner side during turning, the rear wheel side when the front wheel side and deceleration during acceleration, as the cylinder pressure is reduced by variation [Delta] P _1, by performing the supply and discharge control of the hydraulic oil by the control valve 11 , The body posture can be kept horizontal.

On the other hand, the above-described inertial force does not act on the vehicle body B during the straight traveling at a constant speed. However, when the vehicle body B by uneven ground road surface input during running moves up and down, since a change in the equivalent vehicle weight W _e in proportion to the speed of the upper and lower direction in this case, in the aforementioned control means similar to the means, toシ リ ン ダ P ₂
The vertical movement of the vehicle body can be suppressed by changing only this. That is, _Ar · ΔP ₂ corresponds to the damping force.

Therefore, even when the vehicle B is likely to generate vertical vibrations due to irregular road surface during turning or accelerating or decelerating, the cylinder internal pressure of each wheel is increased or decreased by the change ΔP ₁ and further changed by the change ΔP ₂ By increasing or decreasing, it is possible to measure attitude control and vibration suppression.

By the way, the operation of controlling the increase and decrease of the cylinder internal pressure in such a case has been outlined above, but more specifically, it is performed as follows.

Now, when increasing the cylinder internal pressure, the control current i to the control valve 11 is adjusted by the controller C so that the valve 11
Is selectively operated so that the supply / discharge side port and the hydraulic pressure source port communicate with each other, and hydraulic oil is fed into the oil chamber V _O of the gas spring 4.
Thus, the free piston 10 increases the gas pressure to move the fourth drawing right while compressing the gas chamber V _B, and the pressure in the oil chamber V _O becomes the same as the gas pressure.

At the same time, the cylinder internal pressure also increases. When the signal from the pressure sensor 14 for detecting the cylinder internal pressure matches the target pressure, the current i of the control valve 11 is readjusted, the communication between the two ports is cut off, and the pressure state is maintained.

Conversely, when decreasing the cylinder pressure,
By communicating with the supply and discharge-side port and the tank side port selection operation of the control valve 11, by discharging the working oil from the oil chamber V _O of the gas spring 4 to the tank 13, the gas chamber V _G is expanded Gas pressure drops. Along with this, the cylinder pressure also decreases. When the signal from the pressure sensor 14 matches the target pressure, the connection between the communication ports is cut off as in the above-described operation, and the pressure state at that time is maintained.

[Problems to be solved by the invention]

By the way, in the mechanism having such a configuration, the inertia force acting on the vehicle during the control operation is large, and the hydraulic cylinder which needs the corresponding pressure reduction (change ΔP ₁ ) to maintain the vehicle body posture is irregular. When further decompression (change ΔP ₂ ) is required to suppress the upward movement of the vehicle body due to road surface input, the total decompression (ΔP ₁ + ΔP ₂ ) at that time is equivalent to the cylinder pressure P ₀ at rest. when larger than the value actually the P ₀
Since the pressure reduction width (restriction of piston movement) larger than the value (1) cannot be obtained, the function of suppressing the vertical vibration of the vehicle body at this time is not sufficiently exhibited.

In view of the above, the present invention provides an active suspension that controls the cylinder internal pressure by using a single-acting cylinder and a suspension spring together, in which the internal pressure of the suspension cylinder is reduced to near the control limit in order to secure the stability of the vehicle body posture. The purpose of the present invention is to develop a hydraulic cylinder capable of expecting a sufficient vibration damping effect on vertical vibration of a vehicle body due to road surface input.

[Means for solving the problem]

In order to achieve the above object, the means of the present invention is such that a piston rod is movably inserted into a cylinder via a piston, the piston defines an upper chamber and a lower chamber in the cylinder, and the piston rod A suspension spring arranged in parallel with the cylinder is constantly urged in the direction of extension, and a piston rod has a bypass formed of an axial through hole and a lateral transverse hole, and the bypass is formed by the chamber and the lower chamber. In the active suspension, the bypass communicates with the gas spring via a throttle and selectively communicates with a hydraulic source or a tank via a control valve, and the piston communicates with the upper and lower two chambers. And a compression-side communication hole, and an expansion-side damping force valve and a check valve are provided at the outlet of each communication hole so as to be openable and closable. A shutter for opening and closing the lateral holes vertically movably arranged, the shutter is normally while being supported by the upper and lower two spring is characterized in that it is arranged above the transverse bore.

(Operation)

The bypass passage provided in the piston rod is open when the vehicle height adjustment is at the normal height position, and the piston passes through the piston communication hole regulated by the check valve and the extension side damping force valve. It functions as a free passage for hydraulic oil between the partitioned cylinder upper and lower chambers.

When the piston rod extends near the ascending limit position for body posture control, a shutter that moves downward relative to the piston rod closes the bypass.

With respect to the movement of the piston rod after the bypass passage is closed, that is, the vertical movement of the vehicle body due to the input vibration from the road surface, the movement between the upper and lower chambers is restricted by the check valve and the extension damping valve.

Thus, the damping force exerts a vibration damping action in the piston rod extension region.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

In the hydraulic cylinder of the present invention, as shown in FIG. 1, a piston rod 7 is movably inserted into a cylinder 1 via a piston 6, and the piston 6 connects an upper chamber VA and a lower chamber VB in the cylinder 1. Partition the piston rod 7 into the cylinder 1
Are always urged in the extending direction by the suspension springs 2 arranged in parallel to each other, and the piston rod 7 forms a bypass including an axial through hole 9 and a horizontal transverse hole 19, and the bypass is connected to the upper chamber VA. The bypass communicates with the gas spring 4 via the throttle 3 as in FIG. 3 and selectively communicates with the hydraulic source 12 or the tank 13 via the control valve 11 as in FIG. Further, the piston 6 has two upper and lower chambers V
A growth side communication hole 8b for communicating A and VB and a compression side communication hole 8a are formed, and a growth side damping force valve 16 and a check valve are provided at the outlet of each communication hole.
15 and 15 are provided so as to be freely openable and closable.
A shutter 20 for opening and closing the horizontal hole 19 is disposed on the outer periphery of the shutter so as to be movable up and down, and the shutter 20 is supported by upper and lower two springs 22a and 22b and is usually arranged above the horizontal hole 19. . Hereinafter, a detailed description will be given based on the drawings.

A longitudinal side view showing an embodiment of FIG. 1 according to the present invention, like the conventional shock absorber, the piston 6 that Surihama the hydraulic cylinder 1, the vessel chamber V _A and Yoshitsu V _B in the cylinder
While partitioning the bets, check valve permitting a flow of the hydraulic fluid in the vessel chamber V _A communication hole 8a from the street vessel chamber V _B to the piston 6
15, the extension side damping force gives the flow resistance against the working fluid flowing toward the communication hole 8b from the street vessel chamber V _A to vessel chamber V _B valve 16
And are arranged.

That is, when the piston 6 is fastened to the tip of the piston rod 7 inside the cylinder, the valve spring stopper 17 is sandwiched between the rod tip step and the piston 6,
The check valve 15 is formed by interposing a non-return spring 15b and a non-return valve 15a between one side surface of the stopper 17 and the piston 6, while the inner end surface of a piston nut 18 screwed to the tip of the rod. The inner edge of the leaf valve 16a is sandwiched between the
The expansion valve 16 is formed by arranging the main valve 16b movably in the axial direction between the outer peripheral end face 8 and the leaf valve 16a with the main valve spring 16c interposed therebetween.

A through hole 9 formed in the piston rod 7 for supplying and discharging hydraulic oil is connected to a lateral hole 19 formed in a rod wall above the piston, and the through hole 9 and the lateral hole 19 allow the chamber to be closed.
Bypass passage which communicates the V _A and Yoshitsu V _B is is formed. In addition, these through-holes 9 and lateral holes 19 have a sufficient flow passage cross-sectional area so as to hardly cause resistance to the flow of the hydraulic oil passing therethrough.

On the other hand, on the outer periphery of the piston 7, there is arranged a shutter 20 formed of a cylindrical ring which can slide freely between the spring stopper 17 and the upper stopper 21 by tightly sliding on the piston. A pair of springs 22a, 2 with approximately equal force
Hanged between 2b. And the shutter 20
Is set at a position above the rod peripheral surface opening position of the lateral hole 19 when the vehicle body B to which the main body is assembled is at a normal vehicle height position.

According to the embodiment having such a configuration, this is used as the above-mentioned suspension mechanism I and the above-described hydraulic supply / discharge mechanism.
With the II assembled and installed between the car body B and the axle A,
Usually have a cylinder volume chamber V _A and Yoshitsu V _B through hole 9 and the transverse bore 19
Since the hydraulic oil is free to move during this time, the check valve 15 and the extension side damping force valve 16 arranged in the piston portion do not work at all.
Accordingly, at this time, the vehicle height can be adjusted in the same manner as in the operation of the conventional mechanism shown in FIGS. 3 and 4.

Meanwhile, when the hydraulic cylinder 1 in the vehicle body attitude control operation during traveling in a state of control limits (pressure P _B = 0 of the vessel chamber V _B), the vehicle body B by vibrating the road surface input is subjected to upward acting force, Thereby, the piston rod 7 is extended upward.

Since the springs 22a and 22b are both compressed by this rod operation, the shutter 20 suspended therefrom has moved generally downward on the outer periphery of the rod 7 with respect to the rod 7, and the shutter 20 has a horizontal hole. Cover the outer peripheral opening end of the 19 rod and close it.

The hydraulic oil in the chamber V _A whose bypass is closed by closing the lateral hole 19 is pushed by the ascending piston 6 and the extension damping valve is provided.
While regulated by 16 through the communication hole 8b to flow into the vessel chamber V _B.

At this time, a damping force based on the pressure difference in the chamber is generated by the flow path resistance to the hydraulic oil, and the vibration damping action against the vehicle body vibration is exerted.

When the vehicle body B moves downward from this state,
The even shutter 20 is in the horizontal hole closed, flows into the vessel chamber V _A side effect oil vessel chamber V _B of the pressure rise through the check valve 15, which like the two vessel chamber V _A, is V _B Since the pressure is equal, the effect of suppressing the vehicle body can be obtained similarly to the conventional mechanism.

〔The invention's effect〕

As described above, according to the hydraulic cylinder of the present invention, the piston portion of the single-acting cylinder is provided with the communication passage between the cylinder chambers regulated by the extension-side damping force valve and the check valve, and the bypass passage of the communication passage is provided with the piston. Provided on the rod, and provided with a shutter slidable in the axial direction supported by a spring on the outer periphery of the rod, and configured to close the bypass passage with the shutter when the cylinder is in the extended state area. Therefore, even when the cylinder moves in the extension direction from the standard state, the extension damping force can be passively generated in response to the external input vibration, so that the suspension cylinder is depressurized to the vehicle height control limit. Also in this case, a sufficient effect of limiting vertical vibration of the vehicle body can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing an embodiment of a hydraulic cylinder of the present invention, FIG. 2 is a configuration diagram showing an example of a conventional active suspension system, and FIG. 3 is an example of a hydraulic cylinder and a gas spring in the above system. FIG. [Description of Signs] 1 ... Cylinder 2 ... Suspension Spring 4 ... Gas Spring 6 ... Piston 7 ... Piston Rod 8 ... Communication Hole 9 ... Through Hole 11 ... Control Valve 15 ... Check valve, 16 ... Extension side damping force valve 19 ... Side hole, 20 ... Shutter 22a, 22b, 22c ... Spring

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16F 9/00-9/58 B60G 17/08

Claims (1)

(57) [Claims] 1. A piston rod is movably inserted into a cylinder via a piston, the piston partitions an upper chamber and a lower chamber in the cylinder, and the piston rod is always suspended by a suspension spring juxtaposed with the cylinder. The piston rod is urged in the extension direction, and a bypass formed of an axial through hole and a lateral transverse hole is formed in the piston rod, the bypass communicates the chamber with the lower chamber, and the bypass is a throttle. In the active suspension, which communicates with the gas spring through the control valve and selectively communicates with the hydraulic pressure source or the tank through the control valve, the piston has the extension communication hole and the compression communication hole communicating the upper and lower chambers. The extension side damping force valve and the check valve are provided at the outlet of each communication hole so as to be openable and closable, and a shutter for opening and closing the side hole is provided on the outer periphery of the piston rod. Movably arranged, the shutter hydraulic cylinder suspension typically while being supported by two upper and lower springs, characterized in that it is arranged above the transverse bore.