JPS58221033A - Frequency-sensitive shock absorber - Google Patents

Abstract

PURPOSE:To improve running performance and running confortableness by variably controlling the resonance frequency of a resonance value. CONSTITUTION:A resonance value 12 is mounted in the middle of ports 11A, 11B for connecting upper and lower oil chambers 4, 5 formed in a cylinder by a piston 2. The resonance valve 12 is retained at a neutral position through non- linear neutral springs 14 mounted on and under a resonance spool 13, and a spring bearing 16 for the neutral spring 14 is coupled to an operation rod 17 piercing a piston rod 3 and axially slidig, so that the resonance frequency of the resonance valve 12 is changed depending upon the stroke position of the operation rod 17.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shock absorber whose cavitation force changes in a specific frequency range in response to operating conditions.

Japanese Patent Laid-Open Publication No. 1983-1987 (1983) developed a vehicle shock absorber that was designed to improve steering and ride comfort by increasing or decreasing the damping force in a specific vibration frequency range that acts on the vehicle. -126139 and JP-A-55-1
It is disclosed in Japanese Patent No. 26140.

This is achieved by using a resonant valve that causes resonance in a specific vibration frequency range, and by making the passage that bypasses the damping valve listen only when resonance occurs or closes only when resonance occurs, greatly increasing the damping force in a specific resonance frequency range. For example, by weakening the damping force in a specific low frequency range (Fig. 1 (A))
), absorb low-frequency vibrations from the car body to prevent unpleasant vibrations from being transmitted to the car body, or strengthen the damping force in a specific frequency range (Fig. 1 (B)) to prevent rolling of the car body. This prevents nose dives.

However, as can be seen from this, increasing or decreasing attenuation is limited to a specific frequency range, so if the requirements for one range are met, the requirements for other ranges cannot be met. However, even if the ride comfort was improved, there were problems such as poor handling.

In order to solve these problems, the present invention variably controls the natural frequency (oscillation frequency) of the resonance valve according to the driving condition of the vehicle, thereby improving both the handling and ride comfort. To provide a frequency sensitive shock absorber.

Embodiments of the present invention will be described below based on the drawings.

Fig. 2 shows that screws 1 to 2 are slidably housed inside the cylinder 1, and the piston rod 3 of the screws 1 to 2 penetrates the bearing portion 19 and projects to the outside.

The lower end of the cylinder 1 is connected to the axle, and the tip of the piston rod 3 is connected to the vehicle body.

Upper oil chambers 4 and 5 are defined by the screws 1 to 2, and an oil reservoir chamber 7 is formed on the outer periphery of the cylinder 1, which is partitioned by a tire flamm 6T:'.

The oil reservoir chamber 7 compensates for movement of hydraulic oil corresponding to the intrusion volume of the screws and rods 3, and is a GiL air chamber 8 on the outside of the dial frame 6. (Incidentally, a double-tube type Kuyoku I absorber or the like may also be used.) The screws 1 to 2 are provided with passages that communicate the upper and lower oil chambers 4 and 5, and a rebound damping valve 9 and a compression damping valve 1.
o is interposed, and during pressure side operation when the piston rod 3 enters, the hydraulic oil in the lower oil chamber 5 flows to the upper oil chamber 4 via the pressure side damping valve 10, and at this time, a predetermined damping resistance is applied. On the contrary, when the piston rod 3 extends and operates on the extension side, the hydraulic oil in the lower oil chamber 4 flows to the lower oil chamber 5 via the extension damping valve 9, and at this time, a predetermined damping resistance is applied. Ru.

In this way, in order to change the predetermined rebound and compression damping forces according to the operating conditions, a resonance valve 12 is installed in the middle of the communication boats 11A and 11B that pass through the screws 1 to 2 vertically.
is interposed.

The resonance valve 12 has a resonance spool 13 slidably housed in a cylinder hole 18 extending in the axial direction of the piston 2, and nonlinear neutral springs 14A, 14 above and below the resonance spool 13.
B is provided to maintain the resonance valve 12 in a neutral fully open state.

The resonant spool 13 has an annular groove 15 formed on the outer periphery of the central portion thereof, and in the neutral position, communicates the resonant spool 11B with the bow 1-11. Note that the annular groove 15 is always connected to the boat 11 at points other than the resonance point.
In order to maintain communication between A and 11B, a dead band is provided and the groove width is made large.

In this embodiment, the spring bearing 16 of the upper neutral spring 14A passes through the screw and rod 3 in the axial direction.
The spring 14A is connected to an operating rod 17 that moves vertically, and the spring 14A is connected to the operating rod 17 that moves vertically.
, 14B can be compressed to avoid changing the spring constant.

The other end of the operating rod 17 is connected to solenoid actuators 1 and 2.
0, and this solenoid actuator 20 is operated by the drive signal from the control circuit 21.
~Let it be roaked.

The control circuit 21 receives signals from various sensors representative of driving conditions, such as the vehicle speed detection sensor 1 22Δ and the suspension detection sensor 22B, and based on these signals, the control circuit 21 adjusts the damping horn as will be described later. It is variably controlled.

Next, we will explain the operation in more detail, including the operation.The resonance valve 12 housed inside the screw 1-2 causes resonance movement when the reciprocating vibration frequency of the piston 2 and its rigid vibration frequency match. Wake up.

The natural frequency of the resonance valve 12 is the mass of the resonance spool 13,
It is determined based on the spring constants of the neutral springs 14A and 14B.

The nonlinear neutral springs 14A and 14B change their spring characteristics, in other words, the spring constant, depending on the amount of compression, and the proportional relationship between load and displacement becomes nonlinear.
When the spring bearing 16 is moved and the spring constant is changed by scrolling 7, the natural frequency of the resonance valve 12 changes.

The resonance valve 12 has a neutral spring 14△ except at the resonance point.

14B holds the resonance spool 13 in the neutral position, and the annular groove 15 communicates the boats 11A and 11B in an open state, so the generated damping force is low in this state.

The sprung mass vibration when the car body is rolling is usually 1.5
The vibration is at a low frequency of ~2l-1z, but the sprung mass vibration received from the road surface when driving at medium to high speeds is 12-15)-1z, so for example, when driving at high speed, the car has a good ride comfort and prevents rolling. In order to improve steering stability, control circuit 2
The solenoid actuator 20 is driven by the signal from 1 to rotate the operating lever 17 to the neutral spring 14A.
, 14B are reduced to set the natural frequency of the resonance valve 12 to 1.5 to 2 Hz.

In other words, when the vibration from the road surface is received while driving at high speed, the generated damping force is weak because the resonance valve 12 remains active. )
Prevent Y Riruno.

On the other hand, the mid-term break is rolling during "-norring" ()■
When the boat tilts to the right), it resonates with this []-ring vibration fh frequency, and the resonance spool 13 is largely displaced, thereby cutting off communication between the boats 11Δ and 11B.

At this time, the photogenic damping force is regulated by the rebound and compression side damping valves 9 and 10, and this damping force must be set strongly in advance.
3. In particular, it is possible to prevent the rolling of the vehicle body.

4. When trying to cause low-frequency bouncing (vertical vibration of the vehicle body) in 1, it can be effectively prevented by increasing the damping force under such conditions through resonance.

Also, when the weight of the vehicle changes (changes due to the load), the vibration frequency of the spring F changes, but in order to increase the damping force and prevent bottoming out when the vehicle is loaded, this shooting frequency must be changed. The operating rod 17 is stroked via the solenoid actuator 20 in response to a signal from the control circuit 21, and the spring constants of the neutral springs 14Δ and 14B of the resonance valve 12 are switched so as to have a resonance point corresponding to the resonance point. As a result, the damping force against sprung mass vibrations when the vehicle is loaded is increased, and handling stability is improved with priority given to ride comfort.

By the way, in this embodiment, the resonance valve 12 is an example in which a normally closed type valve that is open except for the resonance point is installed, but a normally closed type valve that opens at the resonance point and weakens the damping force is installed. Of course, it is also convenient to provide the resonance valve 12.

In this case, the central outer peripheral portion of the resonant spool 13 is made into a land, and an annular groove (small diameter portion) is formed at both ends thereof.

When this normally-closed resonance valve 12 is used, the frequency of sprung mass vibration increases in proportion to the vehicle speed, even when driving on the same road surface. By controlling the resonance frequency to gradually increase according to the speed, it is possible to effectively absorb sprung mass vibrations from low speeds to high speeds. When these occur, the resonance valve 12 closes to suppress them.

As described above, according to the present invention, the resonance frequency of the -C resonance valve is variably controlled according to the external operating force, so that the damping time 11 of the shock absorber can be prevented from changing depending on the operating state. The ride comfort and handling stability of a vehicle can be improved under a wider range of driving conditions, where the required damping characteristics are contradictory.
We can improve together below.

[Brief explanation of the drawing]

Fig. 1 (△>, (B) is a polygonal explanatory diagram of the damping force change characteristics of a conventional device in relation to frequency, and Fig. 2 is a sectional view showing an embodiment of the present invention. 1. ... Cylinder, 2... Piston, 3... Piston rod, 4, 5... Oil chamber, 9, 10... Damping valve,
11A. 11B... Boat, 12... Resonant valve, 13... Resonant spool, 14... Nonlinear neutral spring, 16... Spring receiver, 17... Operating rod, 20... Solenoid actuator, 21 ...Control circuit, 22A, 22B・
...Sen9゜Patent applicant Kayaba Kogyo Co., Ltd.7o 1111ゑΔ Fig. 2

Claims (1)

[Claims] A resonance valve is provided in the middle of the boat that communicates the upper and lower oil chambers defined in the cylinder by screws 1 to 4.
The IL swing spool is held in the neutral position via non-linear neutral springs installed above and below, and the spring bearing of the neutral spring is connected to the operating rod that slides in the C-axis direction through the piston rod. A frequency-sensitive shock absorber characterized in that the resonant frequency of the resonant valve is variable depending on the position of the resonant valve.