JPH0253624A - Double-acting cylinder - Google Patents

Abstract

PURPOSE:To simply and exactly prevent the cylinder lock within the high frequency vibration range by controlling the working oil flowing through an oil passage formed at the piston part of a double acting cylinder, with a valve which is actuated at an frequency exceeding the working range of a control valve. CONSTITUTION:The control system of a hydraulic suspension system consists of a double acting cylinder 4 having two rods 15 and a control rod 5. In such system when an exciting frequency exceeds the response range of the control system, the piston 16 of the double acting cylinder 4 and both rods 15 are moved. On the other hand, movable masses 20 at both sides of the piston 16 are stopped due to the inertia force. The relative moving moment is generated between the piston 16 and the movable mass 20 so that the vibration of the secondary system is generated due to the damper operating part which consists of the movable mass 20, a spring 22, an oil reservoir 23 and a slot 24. Then the movable mass 20 is separated from a seat part 18 to open an oil passage 17, whereby preventing the cylinder lock.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a double-acting cylinder for use in a hydraulic suspension system in a vehicle.

[Conventional technology]

As is well known in the art, several methods have been proposed as suspension control systems for vehicles, among which a suspension system using double-acting cylinders is shown in the second example.

That is, in this type of suspension, +1jBt is suspended 71 by a double acting cylinder 4 provided between this and the suspension arm 3 of the squeeze wheel 2, and hydraulic oil is supplied to the lower chambers A and B of the cylinder 4. The control valve 5 of the external hydraulic circuit that controls the supply and discharge of the cylinder 4 is detected by the displacement sensor 6 and other various sensors arranged in parallel with the cylinder 4. The sensor 8'C is activated based on the signal of the comparison result between the pressure deviation signal between the lower chambers A and B detected by the comparator 9, and the inertial force applied to the vehicle body l (spring) and the suspension shim arm 3 ( The transmission force of the vibration generated by the unevenness of the running road surface in the spring (spring) or the movement of the system under the spring 11 is controlled by adjusting the load (pressure) generated in the double-acting cylinder 4 and its displacement. It is.

In addition, S indicates a hydraulic source and T indicates a tank.

By the way, generally speaking, the technical requirement for suspensions for commercial vehicles is to achieve a high level of both ride comfort and handling stability. Therefore, in the example shown in Fig. 2, a double-acting cylinder 4 with both lofts is used, and the differential pressure between its internal pressure chambers A and B is controlled to be constant (the output load is not heavy on the spring). Basically, the inertia force is controlled by adding a correction to the inertia force according to its magnitude.

In other words, in order to achieve a comfortable ride, when an external force such as an uneven road surface is applied to the cylinder 4, if the above-mentioned control is not performed on the cylinder 4, the internal pressure of the pressure chamber A will be The pressure increases, and the pressure in pressure chamber B decreases, resulting in an unbalanced state of the set differential pressure between internal pressure chambers A and H.

Therefore, if control is applied to the cylinder 4 to operate the control valve 5 so as to eliminate the unbalance of the internal pressure with respect to the differential pressure set f-, the impact force due to the convex input will be absorbed by the cylinder 4. , it is not transmitted to the sprung portion, resulting in a good riding comfort. Conversely, when concave vibration input is applied to cylinder 4, if tJIW is applied to eliminate the differential pressure imbalance that occurs between pressure chambers A and B, which is the opposite of the previous case, You can get a good ride as well.

On the other hand, when a vehicle turns, for example, a load is transferred from the inner ring to the outer ring due to the inertial force of the heavy body, as is well known. This reduces the load applied to the cylinder 4 on the inner ring side, causing the small side to float, and increases the load on the outer ring side, causing it to sink.

In this poem, if the inner ring side is controlled to increase the internal pressure of pressure chamber A and decrease the internal pressure of pressure chamber B, cylinder 4
A downward force is generated, which can suppress floating. Furthermore, by controlling the pressure chambers A and H in the opposite manner on the outer ring side, an upward force is generated in the cylinder 4, and it is possible to suppress the sinking of the cylinder 4. However, overall,
It can give a flat feeling to the vehicle body posture and improve handling stability.

In other words, while controlling the pressure difference between cylinder pressure chambers A and B to be constant in response to unevenness in the road surface, when inertial force is applied, a deviation of r is applied depending on the magnitude of the inertial force. By adding complement iI, it becomes a higher dimension 11f4 or 11th seven.

Figure 3 (a), (TI), and (c) show such control [
The overall frequency characteristics of the control valve 5, the cylinder type e system, and the like, which are used in a single purpose, are expressed by taking the gain dB on the vertical axis and the wave number ω of 171 on the horizontal axis. , the cylinder mass system both have a characteristic that as the frequency ω increases, the gain dn decreases, so their combined characteristics also have a characteristic that the gain dB decreases on the high frequency side.

Here, the overall gain characteristic is the input displacement of road surface irregularities (x
) to the displacement (xL, ) of the sprung portion. That is, the gain dB is high in the region where the control valve 5 responds, and the unevenness input displacement (X
) with respect to the displacement of a part of the spring 1 (&, (x, , ) is low. In other words, with respect to the displacement of small irregularities (
) The spring is difficult to displace. That is, control j
Due to the operation of P5, hydraulic oil cannot be supplied to or discharged from the cylinder pressure chambers A and B, resulting in the two cylinders 4 being in a dry state.

Therefore, vibrations due to the unevenness in the cylinder 4 cannot be absorbed, and the vibrations are transmitted directly to the spring 11 portion. In other words, the riding comfort in the high frequency range where the control valve 5 cannot respond is 1. I don't have high expectations, and if anything, I think it's getting worse. Of course, the control jt in the JR configuration of such conventional equipment is generally a servo valve, and despite its high response performance, suspension The response of the control block r5, which is the issue here, is not a very high response, and as a control system, l [I I+,.

The scope is as follows.

Therefore, there is a possible way to prevent the cylinder lock state for frequencies in this range υ (the methods shown in FIGS. 4 and 5).

In FIG. 4, the spool 10 and land 11 overlap. In this case, when the cylinder pressure chambers A and B become locked as shown in Figure 1 because they cannot respond to vibrations in the high frequency range.

Hydraulic oil supply and discharge passages 14 heading to cylinder pressure chambers A and B, respectively
The structure is such that oil flows to accumulators +2a and 12b with throttles 13a and l:lb connected to a and +4b to prevent locking.

In FIG. 5, the spool 10 and the land 11 are underlapping. This means that even if the spool IO becomes stuck in the high frequency range as shown in the figure, the double pressure chamber A
The supply and discharge passages between and 8 and these etc. are in communication, and there is no possibility that the cylinder 4 will be in a locked state.

[Problem to be solved by the invention]

However, in the case of the configuration shown in the fourth figure, the accumulators 12a and 12b must be provided separately for the pressure chambers A and H, respectively, and therefore, this accumulator configuration cannot be used as a built-in cylinder type or an external cylinder type. Regardless of which structure is adopted, cylinder 4 and control brake r5
It is expected that the configuration between the Furthermore, cylinder 4. A resonance system will be created between the control 5P5 and the accumulation L/-12a or +2b, and a separate damper will be required to suppress it. Of course, the structure for configuring this damper will be complicated, but the damping pink generated by the damper attached to L will work in the entire frequency range, and as a result, the vibration insulation in the cylinder 4 will be improved. make worse.

According to the configuration of No. 51-A, cylinder 4 does not become locked even in the high frequency range, but this =lG71 means ``8'' In other words, cylinder 4 moves freely in that frequency range. , vibration isolation will not be possible.

Therefore, in order to suppress this vibration, in addition to the accumulators 12a and 12b, it is necessary to provide a spring and a damper in parallel with the cylinder 4, so as to have a damping effect.

However, in this case, similar to the above case, a resonant system is created, and as a result, the damping acts in the entire frequency range of the vibration input, worsening the vibration isolation in the cylinder 4.

Therefore, the present invention is directed to a hydraulic suspension control system that uses such a double-acting cylinder of both rods and one control valve for controlling the supply and discharge of hydraulic oil to the double-acting cylinder.
Is it possible to prevent cylinder locking in response to high-frequency vibration inputs that cannot be followed by ITA control operations without deteriorating the vibration isolation of the suspension in a wide excitation frequency range? The development of ca is assumed to be 1.1.

(Means for Solving the Problem) According to the present invention, this purpose is achieved by
In a suspension control system that uses a dynamic cylinder and a control valve, the piston of the cylinder has an oil passage that communicates between the cylinder internal pressure chamber partitioned by the piston, and an excitation frequency that exceeds the operating frequency range of the control valve. This can be achieved by a double-acting cylinder having a structure in which a frequency-sensitive valve consisting of a secondary system vibration structure that operates against the valve is provided, and the valve controls the hydraulic oil flowing into the criminal oil passage. I can do it.

(Function) In other words, the frequency sensitive valve of the secondary vibration system that is integrated into the piston part of the double-acting cylinder moves its vibration structure integrally with the piston within the predetermined operating frequency range of the piston operation. Therefore, the oil passage between the cylinder internal pressure chambers is closed 7g.
The machine collapses to keep it in place.

Then, when the vibration frequency reaches an excitation frequency range in which it is impossible to follow the control Jr operation that exceeds this operating frequency, the valve is caused to move all the +tij oil passages due to the vibration of the secondary system of its vibration structure. This acts to allow the flow of hydraulic oil in both pressure chambers nll.

This prevents the cylinder from locking up when the control valve is inoperative, and also eliminates the need for other vibration damping systems such as dampers in the external hydraulic circuit, which reduces the vibration isolation of suspensions that use this system. It works effectively to prevent this.

(Embodiments) Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a JJI diagram of a suspension control system showing an embodiment of the present invention. Common symbols are given to the same components as those in the conventional device described above, and the explanation will be given below. Similarly, the control system consisting of the double-acting cylinder 4 and control valve 5 of both lots I5 and C is used as the basic structure, and the lower chambers A and B of the double-acting cylinder 44 are configured symmetrically with respect to the piston 16. It is.

The piston 16 screwed and fixed to the body at the joint of both rods 15 is provided with at least a pair of oil passages I7 opening in a diagonal direction and communicating between the lower chambers A and 8. The seat part 1 has both sides thereof in contact with the 11fj support mass described later to close the opposite side of the oil passage 17.
8, and the other openings of the oil passages [7 for this oil passage 7 are open ports which communicate with the open perforated grooves 19 extending in the radial direction on the side surface of the piston.

The movable mass 20 is made of metal etc.
It consists of one Is body, is tightly connected to both lots 15 on both sides of the piston 16, has some gap between it and the inner wall of the cylinder 5 to allow the hydraulic oil to pass, and is fixed to both lots 15 on both sides of the piston 16. The end face of the stopper 21 and the piston [6
It is provided so as to be slidable between the end face of the seat portion 18 at. Further, the zero-movement mass 20 is biased in a direction to come into pressure contact with the seat portion 18 by the expanding force of a spring 22 disposed between the end face of the stopper 21 and the movable mass 20.

Furthermore, the assembly of the movable mass 20 and the stopper 2 is carried out on the circumferential surface of the inner rod 15 and the movable mass 2.
0 and the stopper 21, and a small hole 24 facing the chamber 23 is bored in the movable mass 20. As the movable mass 20 moves, hydraulic oil flows from the oil reservoir chamber 23. By regulating the user through the pores 24,
The structure is such that a damper mechanism is exerted against the movement of the movable mass 20.

According to the embodiment consisting of such a configuration, in the excitation frequency range in which the control system consisting of the cylinder 4 and the control valve 5 can respond, the I+[dynamic mass 20 on both sides of the piston I6 is It moves together with the piston 15 without causing any trouble, and in this state, the expansion force of the spring 22 presses against the seat part 18 and closes the oil passage 17 inside the piston. Since the cylinder 5 functions as a cylinder with sealed double pressure chambers, the supply and discharge of hydraulic oil to the upper and lower chambers A and B is controlled according to the function of the spool 1 () in the control valve 5. On the other hand, when the excitation frequency exceeds the response range of the control valve 5, the control valve 5 does not respond to vibrations in the control system, so the valve 5 is While the hydraulic oil is not supplied to or discharged from the upper and lower chambers A or B by the external oil IL circuit via the external oil IL circuit, the piston 16 and its two rods 15 are damaged in the cylinder 9 which is subjected to relatively high frequency vibration at this time. It tries to move down L depending on the direction of vibration.

At this time, the movable mass 20 has its own inertia,
Since it tries to stop at that position, this piston 16 and O
A slight or relative movement occurs between the f-moving knives 20. That is, 13 hinges 20, springs 22
Vibrations in the secondary system occur due to the joint action of the damper acting portion and the oil reservoir chamber 23 and the pores 2 and 1.

Therefore, the vibration of the secondary system with this relative movement, j
+ (When the moving mass 20 is drawn from the seat part 18, the C1 oil passage 17 is opened, and the flow of the operating 1ffb between the upper chambers A and B is 11゛This can prevent one cylinder from locking up.

(Effects of the Invention) As described above, according to the double-acting cylinder of the present invention, the frequency-sensitive valve consisting of the vibration structure of the secondary system that operates at an excitation frequency that exceeds the operating frequency range of the control valve, Since this control system is designed to control the opening and closing of the oil passage provided between the circular pressure chambers of In addition, as in the conventional device, hydraulic oil is supplied and discharged to and from the equal pressure chamber by the operation of the control valve in the external hydraulic circuit, thereby making it possible to exhibit vibration isolation in the cylinder.

In response to high-frequency vibrations that exceed the above-mentioned response range, the frequency-sensitive valve that senses and operates opens the two pressure chambers through the oil passage, so that the cylinder at this time Oil lock can be prevented. Moreover, the opening frequency of this frequency-sensitive valve can be freely set by changing the spring constant and the weight of the mass part in the vibration structure of the secondary system. By adjusting the damping appropriately, the opening of the oil passage can be adjusted to a certain degree! It is also possible to adjust the valve operation according to the frequency response characteristics of the control valve, the cylinder mass, etc.

It should be noted that the damping action in the vibrating structure needs to be large enough to prevent resonant operation in the structure, but in this case the damping action will not affect the secondary vibrating body inside the piston part. Since this only works, it will not affect the entire control system and will not deteriorate the first vibration isolation property.

In this way, the double-acting cylinder of the present invention has excellent responsiveness!
Even when using the 1vliJ1 valve, which does not have a limit, there is no need to install a spring element to prevent cylinder lock as in conventional devices, and the suspension vibration prevents cylinder lock in the high frequency vibration range. It is possible to maintain extremely good insulation properties.

[Brief explanation of the drawing]

The 113th J is Thursday: 2! A configuration diagram of the main parts of the control system showing an example of a bright double-acting cylinder, and Figure 2 is a configuration diagram showing an example of a suspension system [4, Figures 3 (A), (O), (
C) is a diagram showing the operating characteristics of each main mechanism in the suspension system indicated by L, and FIGS. 4 and 5 are configuration diagrams respectively showing each control system in the above system. (Explanation of symbols) l...+l (body, 2...wheels, 4...double acting cylinder, 5...control system, I5...both parts, 16...
・Piston, 17...oil passage, 18...seat part,
ZO...movable square, 21-fist/stopper, 22...
・Spring, 23...'oil reservoir chamber, 24...pore.

Claims (1)

[Claims] In a suspension control system that uses a double-acting cylinder and a control valve, the piston of the cylinder has an oil passage that communicates between the cylinder internal pressure chambers partitioned by the piston, and an oil passage that communicates with the cylinder internal pressure chamber that exceeds the operating frequency range of the control valve. A frequency sensitive valve comprising a secondary vibration structure that operates in response to an excitation frequency, and the valve is configured to control hydraulic oil flowing into the oil passage. moving cylinder.