JP2631468B2 - Active suspension device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to vibrations applied to a hydraulic suspension cylinder which is disposed in each of four parts of a vehicle and communicates with an appropriate hydraulic source via an active control valve. The present invention relates to an active suspension device capable of performing sprung and unsprung vibration damping depending on vibration.

[Conventional technology]

Conventionally, as an active suspension device which is provided in each part of the four wheels of a wheel and can control a sprung and unsprung vibration by a hydraulic suspension cylinder which is connected to an appropriate hydraulic pressure source through an active control valve, For example, a circuit structure as shown in FIG. 5 has been proposed.

That is, the circuit structure of the active suspension apparatus as the conventional example is such that the active control valve 4 is provided in a passage 3 which communicates between a hydraulic suspension cylinder 1 provided at each of the four wheels and an appropriate hydraulic power source 2. And the hydraulic suspension cylinder 1 has a damping valve 5
Through the gas spring 6.

The active control valve 4 communicates a signal from a detecting means for detecting a so-called sprung motion such as an acceleration sensor or a vehicle height sensor (not shown), and communication between the hydraulic suspension cylinder 1 and the active control valve 4. Passage 3a
The so-called opening / closing control is performed by a command from a controller that inputs a hydraulic pressure P1 upstream of the damping valve 5 and performs arithmetic processing.

The damping valve 5 generates a predetermined damping force when hydraulic oil corresponding to the expansion and contraction operation of the hydraulic suspension cylinder 1 is supplied and discharged between the gas spring 6 and the hydraulic oil.

Therefore, when the vibration frequency applied to the hydraulic suspension cylinder 1 is in the low frequency range, the pressure from the accumulator Q is applied to the hydraulic suspension cylinder 1 by the opening / closing control of the active control valve 4 rather than the function of the gas spring 6. By supplying the oil or discharging the pressure oil on the hydraulic suspension cylinder 1 side to the reservoir tank T, the amount of hydraulic oil supplied to the hydraulic suspension cylinder 1 is controlled, so that the ride comfort and attitude control in the traveling vehicle are so-called active. I can do it.

When the excitation frequency is in a high frequency range,
Due to the switching operability of the active control valve 4, the hydraulic suspension cylinder 1 cannot control the oil amount by the active control valve 4, and exclusively controls the flow of hydraulic oil with the gas spring 6 via the damping valve 5. The damping valve 5
And hydraulic suspension cylinder 1 with gas spring 6
Side, ie unsprung, damping can be achieved.

[Problems to be solved by the invention]

However, in the above-mentioned conventional proposal, the response (or phase) of the active control valve 4 is delayed in the intermediate frequency range with the increase of the excitation frequency. As a result, the cylinder tends to refuel, and the cylinder thrust in the hydraulic suspension cylinder 1 is increased, so that a so-called rugged feeling is generated.

That is, in the hydraulic circuit, when the excitation frequency is in a low frequency range, the riding comfort of the wheels is mainly guaranteed by opening and closing control of the active control valve 4, and the vibration of the sprung vibration can be appropriately controlled. When the excitation frequency increases and enters the intermediate frequency range, a response delay occurs in the active control valve 4, and the normal control of reducing the pressure during extension and increasing the pressure during compression in the vertical vibration of the hydraulic suspension cylinder 1 is as follows. Conversely, when pressure oil release is required, pressure oil charge is caused or a peak of the gain of the active control valve 4 occurs, so that the pressure receiving area of the hydraulic suspension cylinder 1 and the accumulator Q acting on the hydraulic suspension cylinder 1 Pressure (the hydraulic pressure in the passage 3a connecting the hydraulic suspension cylinder 1 and the active control valve 4)
As shown in FIG. 6, the cylinder thrust by the product of P1) is the intermediate frequency region of the excitation frequency (indicated by the symbol N in the figure)
(See the solid line in the figure).

Therefore, the sudden increase in the cylinder thrust of the hydraulic suspension cylinder 1 leads to a so-called rugged feeling,
Deteriorates ride comfort in vehicles.

This means that, as shown in FIG. 7, when the gain (input / output ratio) of the active control valve 4 is such that the vibration frequency applied to the hydraulic suspension cylinder 1 is in the intermediate frequency region (indicated by the symbol N in FIG. 7). The peak position of the gain is smaller than the case where the damping force is large (shown by the solid line in the figure) (see the solid line in the figure). In this case, the frequency shifts to the lower frequency side.

Therefore, the present invention utilizes a frequency characteristic that causes a difference in the characteristic according to the magnitude of the above-described damping force, and maintains a high damping force only in a frequency-dependent damping valve, particularly, only in the unsprung resonance region. In other areas, by adopting a frequency-sensitive damping valve that maintains a low damping force generation state,
While maintaining the dynamic response of the active control valve in the low frequency range where the active control is performed, changing the peak generation state of the gain to suppress the sudden increase in the cylinder thrust, the ride comfort is suppressed by suppressing the so-called rugged feeling. It is another object of the present invention to provide a new active suspension device with improved performance.

[Means for solving the problem]

In order to solve the above-mentioned problem, the configuration of the active suspension device according to the present invention is configured such that hydraulic suspension cylinders disposed in various parts of a vehicle are connected to an appropriate hydraulic source via an active control valve. In the active suspension device, the hydraulic suspension cylinder is communicated with a gas spring via a damping valve that allows a change in a generated damping force depending on an excitation frequency applied to the hydraulic suspension cylinder, and the damping valve is connected to the hydraulic suspension cylinder. A high-cut damping valve that reduces the damping force in the high-frequency region where the vibration frequency to the cylinder is above the unsprung resonance point, and a low-cut damping that reduces the damping force in the low-frequency region below the unsprung resonance point. A valve part is connected to a pipe connecting the hydraulic suspension cylinder and the gas spring. Is obtained by a composed consists those disposed.

(Operation)

When the vibration frequency of the hydraulic suspension cylinder is in a low frequency range, the active control valve can sufficiently respond, so that the open / close control of the active control valve provides good responsiveness, active posture control such as roll control, and sprung mass control. Vibration is controlled.

Further, when the vibration frequency of the hydraulic suspension cylinder is in an intermediate frequency region that causes an undesirable response delay for the active control valve, the vibration frequency of the low-cut damping valve portion of the damping valve depends on the vibration frequency of the hydraulic suspension cylinder. By controlling the generated damping force to a low state by the low-cut operation, the peak value of the gain is shifted to the low frequency side due to the generation of the low damping force of the damping valve, and the gas spring function is activated. This facilitates a sudden increase in cylinder thrust in the hydraulic suspension cylinder, and does not cause a so-called rugged feeling.

Further, when the excitation frequency in the hydraulic suspension cylinder is in the unsprung resonance region on the high frequency side,
Unsprung vibration is damped by the high damping force generated by the damping valve and the gas spring action exclusively depending on the vibration frequency.

〔Example〕

 Hereinafter, the present invention will be described based on illustrated embodiments.

As shown in FIG. 1, the circuit structure of the active suspension device according to the present invention is basically the same as the circuit structure of the previously proposed active suspension device, and includes a hydraulic suspension cylinder 1 and an appropriate hydraulic power source. 2, a passage 3 communicating between the hydraulic suspension cylinder 1 and an appropriate hydraulic source 2, and an active control valve 4 disposed in the passage 3.

A gas spring 6 is connected to the hydraulic suspension cylinder 1 through a damping valve 7. The damping valve 7 is a fixed damping force setting type damping valve 5 according to the present invention. Is replaced with a frequency dependent type in which the valve opening and the like are changed depending on the vibration frequency applied to the hydraulic suspension cylinder 1 and the generated damping force is automatically changed.

When the vibration frequency is in a predetermined high frequency region, that is, near the unsprung resonance point, only the vicinity of the unsprung resonance point is changed to a high damping force state. It is assumed that the state is changed to the occurrence state.

The hydraulic suspension cylinder 1 is disposed in each part of the four wheels of the vehicle, the upper end thereof is connected to the vehicle body side of the vehicle, the lower end thereof is connected to the axle side of the vehicle, and the piston side oil chamber 1a therein is provided with a piston. The rod is inserted through the rod and communicates with the appropriate hydraulic source 2 and the gas spring 6.

An accumulator Q communicated with a piston side oil chamber 1a of the hydraulic suspension cylinder 1 is provided in an appropriate hydraulic source 2.
And a pump P, a relief valve R and a check valve C, and a reservoir tank T.

The accumulator Q is filled with pressurized oil of the pressure set by the relief valve R from the pump P. When the hydraulic pressure in the accumulator Q is insufficient, the accumulator Q is sequentially replenished from the pump P. .

The active control valve 4 is composed of a pressure (or flow rate) control type proportional valve, and a signal from detection means for detecting a so-called sprung motion such as an acceleration sensor and a vehicle height sensor, not shown, and the hydraulic suspension cylinder. The so-called opening / closing control is performed by a command from a controller that inputs a hydraulic pressure P1 in a passage 3a communicating between the first control valve 1 and the active control valve 4 and performs arithmetic processing.

The active control valve 4 is also formed so as to discharge the hydraulic oil from the hydraulic suspension cylinder 1 to the reservoir tank T.

Therefore, by controlling the opening and closing of the active control valve 4, the hydraulic oil is supplied from the accumulator Q of the gas spring 6 or higher to the hydraulic suspension cylinder 1 side to increase the pressure on the hydraulic suspension cylinder 1 side, Reservoir tank T
To lower the pressure on the hydraulic suspension cylinder 1 side.

As a result, for example, when the vehicle height is too low or when the vehicle rolls or nose dive or the like occurs in response to the expansion and contraction movement of the hydraulic suspension cylinder 1, the vehicle height is increased by opening and closing control of the active control valve 4. ,
Alternatively, desired attitude control such as anti-rolling and anti-nose dive can be performed, and the hydraulic oil pressure on the hydraulic suspension cylinder 1 is controlled by the so-called active control of the active control valve 4 in response to the expansion and contraction of the hydraulic suspension cylinder 1. Can be controlled in each case to control sprung vibrations in a running vehicle.

The gas spring 6 communicates the oil chamber 6 a with the hydraulic suspension cylinder 1 via the damping valve 7 so that a desired gas spring effect can be exerted when the hydraulic suspension cylinder 1 expands and contracts.

In the present invention, the damping valve 7 is configured as a so-called self-variable type, and its generated damping force is changed depending on the frequency of vibration applied to the hydraulic suspension cylinder 1.

That is, as shown in FIG. 2, the form of the frequency-dependent damping force change is a frequency region where the vibration frequency applied to the hydraulic suspension cylinder 1 is inconvenient for the active control valve 4 (about 8 to 8 in the vicinity of the unsprung resonance point). 12 Hz) or higher, the so-called high cut action (shown by the I line in the drawing) that reduces the high damping force that has been generated until then, and the vibration frequency applied to the hydraulic suspension cylinder 1 is close to the above-described unsprung resonance point In the frequency range of, a so-called low-cut action is performed to change from the low damping force generation state to the high damping force generation state (see FIG.
The peak state of the damping force obtained by the combination with the form (shown by the II line) is positioned only in the high frequency region (approximately 8 to 12 Hz), which is the region near the unsprung resonance point indicated by the symbol H in FIG. If it is generated, the desired unsprung control can be performed.

Then, with this setting, the hydraulic suspension cylinder 1
In an intermediate frequency region (a region of about 5 to 8 Hz indicated by reference numeral N in FIG. 4) where the excitation frequency with respect to the above causes the peak of the gain of the active control valve 4, the generated damping force in the damping valve 7 is reduced. Therefore, the peak of the gain shifts to the low frequency side (see FIG. 7),
The peak of the thrust of the hydraulic suspension cylinder 1 can be suppressed (see the broken line in FIG. 6).

In the circuit structure described above, the excitation frequency in the hydraulic suspension cylinder 1 is in a low frequency region (fourth region).
(Indicated by the symbol L in the figure), the opening and closing control by the active control valve 4 can be carried out more than the amount of pressure oil flowing into and out of the gas spring 6, so that the sprung mass can be actively damped.

Therefore, in the active suspension device having the above-described circuit structure, even if the vibration frequency in the hydraulic suspension cylinder 1 is in the intermediate frequency range and the active control valve 4 tends to cause a response delay, the damping valve 7 is automatically turned on. A state in which a low damping force is generated, that is, a state in which the hydraulic pressure (P1) on the hydraulic suspension cylinder 1 side is easily released to the gas spring 6 side, is maintained.
Can be changed so that the thrust of the hydraulic suspension cylinder 1 is not abnormally increased, so that the so-called lumpy feeling accompanying the increase in the thrust of the hydraulic suspension cylinder 1 is prevented. be able to.

FIG. 3 shows a specific embodiment of the damping bulk 7 which generates a high damping force only in the vicinity of the unsprung resonance point in the present invention, and attenuates a high frequency region above the vicinity of the unsprung resonance point. A so-called high-cut damping valve portion 7a for lowering the force and a so-called low-cut damping valve portion 7b for lowering the damping force in a low frequency region below the unsprung resonance point are combined in series. part
7a and 7b are disposed in a pipe 10 that communicates the hydraulic suspension cylinder 1 and the gas spring 6 in the present embodiment, and indicates a pressure-side damping force generated when the hydraulic suspension cylinder 1 is compressed. A so-called high cut function and a low cut function are combined, and are housed in a nut 13 screwed to a lower end of an effective bolt 12 that penetrates a central portion of a partition member 11 fixed and caulked in the pipe 10. ing.

The separation leaf valves 70 constituting the damping valve portions 7a and 7b are supported from below by valve discs 71 disposed inside the nut 13, respectively.

Note that a valve disk 71 constituting the lower damping valve portion 7b is caulked and fixed inside the lower end of the nut 13.

Each of the leaf valves 70 is in contact with a respective one of the push valves 73 slidably mounted in the upper block 72 in a vertically slidable manner. Can generate a compression-side damping force when is compressed.

That is, each leaf valve 70 is connected to each lower valve disc.
The center side is supported by the lower surface by a support point c formed in an annular shape on the upper surface of the upper surface 71, and the upper surface of the outer peripheral end is locked to the lower peripheral surface of the upper block 72, respectively. Is a free end which allows downward bending, and the upper surface on the center side is locked to an annular pressing point p formed at the lower end of the push valve 73 above.

The positional relationship between the supporting point c and the pressing point p is such that the pressing point p is located on the inner peripheral side of the supporting point c in the lower high-cut damping valve portion 7a, and the pressing point is located in the upper low-cut damping valve portion 7b. p is set to be on the outer peripheral side of the support point c.

Therefore, as long as no special external force acts on each push valve 73, the outer peripheral end of each leaf valve 70 bends as set, but when an external force such that this push valve 73 is lowered acts on each push valve 73, Since the center of each leaf valve 70 is pressed downward, the bending characteristic of the outer peripheral end of each leaf valve 70 is changed.

That is, in the lower high-cut damping valve portion 7a, the center of the leaf valve 70 is pressed downward, so that the outer peripheral end of the leaf valve 70 is formed on the outer peripheral lower end of the upper block 72 by the so-called principle of Kong. , And a large hydraulic pressure is required to bend the outer peripheral end of the leaf valve 70, that is, a high damping force is expected to be generated when the outer peripheral end of the leaf valve 70 is bent. become.

On the other hand, in the upper low-cut damping valve portion 7b, when the center side of the leaf valve 70 is pressed downward, the outer peripheral end of the leaf valve 70 is separated from the outer peripheral lower end of the upper block 72. Therefore, a large hydraulic pressure is not required for bending the outer peripheral end of the leaf valve 70, that is, when the outer peripheral end of the leaf valve 70 is bent,
A low damping force is expected to be generated.

Incidentally, the above-mentioned external force is obtained by each spool 75 locked on the upper end of each spring 74 whose lower end is in contact with the upper surface of each push valve 73 in each block 72, and the respective spools 75 , Are vertically movably housed in each of the blocks 72.

A pressure chamber R, which is a so-called first-order oil chamber, is formed on the upper surface of each of the spools 75, and the pressure chamber R in the upper low-cut damping valve portion 7b is
The pressure chamber R in the pipe 10 communicates with the passage portion 10a on the side of the hydraulic suspension cylinder 1 through the central oil hole 12a of the perforated bolt 12, and the pressure chamber R in the lower high-cut damping valve portion 7a is It communicates with the passage portion 10a via an upper low-cut damping valve portion 7b.

In addition, on the outer peripheral side upper surface of each leaf valve 70, the hydraulic oil from the passage portion 10a in the pipe 10 passes through the central oil hole 12a of the perforated bolt 12, and each port 76a of each stopper 76.
And it goes without saying that it flows through each port 72a of each block 72.

An orifice o is provided between each of the pressure chambers R and the passage portion 10a side. The orifice o makes the pressure chamber R a first-order oil chamber. By the selection, it is possible to prevent the above-mentioned first-order oil pressure from being generated in a desired vibration frequency region.

That is, in the upper low-cut damping valve portion 7b, the first-order lag hydraulic pressure can be prevented from being generated immediately before the high-frequency region is reached near the predetermined unsprung resonance point, and the lower high-cut damping valve portion 7b can be prevented. In the valve portion 7a, it is possible to prevent the above-mentioned first-order lag hydraulic pressure from being generated when the high frequency region near the predetermined unsprung resonance point is exceeded.

Further, in the present embodiment, it is assumed that the orifice o is bored in a check valve 78 urged by a non-return spring 77 housed in the stopper 76.

As a result, the hydraulic suspension cylinder 1
When hydraulic oil flows from the side to the gas spring 6 side, that is, from the passage portion 10a to the passage portion 10b opposed across the partition member 11, the primary pressure accumulated in each pressure chamber R via the orifice o is provided. The delayed hydraulic pressure is easily released by the rise of each check valve 78 when the hydraulic oil flows backward in the pipe 10 from the gas spring 6 side to the hydraulic suspension cylinder 1 side.

Therefore, the excitation frequency in the passage portion 10a is in a predetermined high frequency region, that is, in the upper low-cut damping valve portion 7b, until the vicinity of the unsprung resonance point, and the lower high-cut damping valve. In the portion 7a, each of the pressure chambers R until the pressure exceeds the vicinity of the unsprung resonance point.
Generates a first-order oil pressure, which in turn pushes down each spool 75, and through each spring 74,
Each push valve 73 is pushed down.

When the push valves 73 are lowered, the bending rigidity at the outer peripheral end of the leaf valve 70 is reduced in the upper low-cut damping valve portion 7b and the damping force is reduced. In the damping valve portion 7a, the bending rigidity of the outer peripheral end of the leaf valve 70 is increased, so that a high damping force can be generated.

Further, when the excitation frequency in the passage portion 10a approaches a predetermined high frequency region near the unsprung resonance point, first, in the upper low-cut damping valve portion 7b,
No first-order oil pressure is generated in the pressure chamber R, and the spool
75, that is, the push valve 73 is not lowered, the outer peripheral end bending rigidity of the leaf valve 70 is returned to the initial setting state, and a high damping force is generated.

Next, when the above excitation frequency exceeds a predetermined high frequency region near the unsprung resonance point, in the lower high-cut damping valve portion 7a, no first-order lag hydraulic pressure is generated in the pressure chamber R, and the spool 75, That is, the push valve 73
Is not lowered, the flexural rigidity of the outer peripheral end of the leaf valve 70 is returned to the initial set state, and a state where a low damping force is generated.

As described above, in the series installation of the high-cut damping valve portion 7a and the low-cut damping valve portion 7b,
An upstream side, that is, a low-cut damping valve portion 7b on the hydraulic suspension cylinder 1 side is disposed, and a downstream side, that is,
By arranging the damping valve portion 7a for high cut on the gas spring 6 side, when the vibration frequency to the hydraulic suspension cylinder 1 approaches a high frequency region near the unsprung resonance point, the upstream side When the damping valve portion 7b first performs a low-cut operation, and when the excitation frequency is similarly in a high frequency region near the unsprung resonance point, the downstream-side damping valve portion 7a performs a high-cut operation next. As shown in FIG. 4, the peak of the damping force can be reached in a desired high frequency region.

Therefore, according to the damping valve 7 according to the above-described embodiment, as shown in FIG. 4, the vibration frequency applied to the hydraulic suspension cylinder 1 is in a high frequency region near the unsprung resonance point (in FIG. (Shown), the cylinder thrust is kept in a reduced state, and when the excitation frequency is in a high frequency region H near the unsprung resonance point, the cylinder thrust can be raised.

As a result, the peak position of the cylinder thrust in the hydraulic suspension cylinder 1 can be set to a region other than the intermediate frequency region N. Therefore, the peak position of the cylinder thrust in the conventional example shown by the solid line in FIG. (Indicated by reference numeral N in the figure), and it becomes possible to prevent the so-called rugged feeling in the intermediate frequency region N.

Then, in the predetermined high frequency region H, the unsprung vibration can be suppressed by the generation of the high damping force described above.

〔The invention's effect〕

As described above, according to the present invention, in an active suspension device in which a hydraulic suspension cylinder provided between an axle side of a vehicle and a vehicle body side of a vehicle is connected to an appropriate hydraulic source via an active control valve, The so-called active control of the active control valve can control the sprung attitude in the low frequency range of the vehicle vibration and the sprung vibration, as well as the hydraulic oil when the hydraulic suspension cylinder is connected to the gas spring. The low-damping force is generated by the operation of the low-cut damping valve even in the intermediate frequency range where the generated damping force depends on the vibration frequency of the hydraulic suspension cylinder and causes an undesired phase delay for the active control valve. Abnormally increase the thrust of the hydraulic suspension cylinder. Vibration, and the occurrence of ruggedness of the vehicle can be prevented, the ride comfort in the vehicle can be maintained in a good state, and the excitation in the high frequency region near the unsprung resonance point where the active control valve cannot respond. Even in the state, the unsprung vibration can be damped by the damping valve and the gas spring, and there is an advantage that the riding comfort and steering stability in the vehicle can be obtained.

Further, according to the present invention, the damping valve can be adjusted to the excitation frequency near the unsprung resonance point from each of the low-cut and high-cut damping valve portions without significantly changing the basic circuit structure from the conventionally proposed one. By providing a two-stage valve, there is an advantage that it is advantageous in terms of assembling work or economically.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a basic structure of an active suspension device according to the present invention, FIG. 2 is a characteristic diagram of a generated damping force of a damping valve according to the present invention, and FIG. 3 is a diagram showing a variable damping valve according to the present invention. FIG. 4 is a partially enlarged sectional view showing a specific example of a high-cut damping valve portion and a low-cut damping valve portion. FIG. 4 is a characteristic diagram of a cylinder thrust of a hydraulic suspension cylinder according to the present invention. FIG. FIG. 6 is a circuit diagram showing the device, FIG. 6 is a characteristic diagram showing the relationship between the vibration frequency of the hydraulic suspension cylinder and the thrust of the hydraulic suspension cylinder in the active suspension device together with the conventional and the present invention, and FIG. Frequency of hydraulic suspension cylinder and gain of active control valve It is a characteristic diagram showing the relationship. 1 ... Hydraulic suspension cylinder 2 ... Appropriate hydraulic source, 3,3a ... Path 4 ... Active control valve 5 ... Damping valve, 6 ... Gas spring 7 ... Frequency dependent damping valve 7a ... High cut Damping valve part 7b for low-cut damping valve part 10 Pipe piping 10a, 10b Passage part 11 Partition wall member 12, Perforated bolt 13 Nut 70 70 Leaf valve 71 Valve Disc, 72… Block 73… Push valve, 74… Spring 75… Spool, 76… Stopper 77… Non-return spring 78… Check valve, C… Check valve P… Pump, Q… Accumulator R: relief valve, T: reservoir tank

Claims (1)

(57) [Claims] In an active suspension system in which hydraulic suspension cylinders disposed at various parts of a vehicle are connected to an appropriate hydraulic source via an active control valve, the hydraulic suspension cylinder is added to the hydraulic suspension cylinder. The damping valve is connected to a gas spring via a damping valve that allows the generated damping force to be changed depending on the vibration frequency, and the vibration frequency applied to the hydraulic suspension cylinder is higher than the vicinity of the unsprung resonance point. The hydraulic suspension cylinder and the gas spring are connected to a high-cut damping valve portion that reduces the damping force in a frequency region and a low-cut damping valve portion that reduces the damping force in a low frequency region below the unsprung resonance point. Active suspension characterized by being comprised in the piping Down apparatus.