JPH03516A - Fluid pressure supply device and active type suspension using same device - Google Patents

Abstract

PURPOSE:To prevent a resonant noise and a fatigue destruction or the like owing to the pulse pressure of a discharge pressure, at the above suspension for a vehicle, by connecting at predetermined intervals a plurality of accumulators to the discharge side of a fluid pressure source, and connecting the space between each accumulator by means of an elastic piping. CONSTITUTION:A check valve 4 is connected to the discharge side of a hydraulic pump 1 at a fluid pressure supply device FS, and pulse pressure damping accumulators 6a, 6b connected mutually by means of a rubber hose 5a, are connected to a line pressure piping 5b connected to its output port side. And a filter 7, a check valve 8 are connected in parallel at its lower stream by means of a piping 5c. As a result, a pulse pressure damping effect is obtained by means of accumulators, and at the same time, and seeming spring constant of an operation fluid can be lowered by means of the rubber hose, and resonance due to a pulse movement is prevented, and a noise and a fatigue destruction can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The invention of B provides a fluid pressure supply device for supplying working fluid with reduced pulse pressure to hydraulic equipment, and a method for supplying the working fluid from the fluid pressure supply device to pressure. An active type that uses a fluid pressure supply device that suppresses and controls posture changes such as roll and pitch of the vehicle by supplying fluid pressure to cylinders interposed between the vehicle body and wheels via control valves such as control valves. The present invention relates to a suspension device.

[Conventional technology]

As a conventional active suspension device, there is one described in Japanese Patent Laid-Open No. 62-289420, which was previously proposed by the present applicant.

As shown in FIG. 6, this prior art includes fluid pressure cylinders 42 interposed between each wheel 40 and a vehicle body 41, and a working fluid is supplied to these fluid pressure cylinders 42 by the driving force of an engine. A fluid pressure supply device 43 to be operated, a pressure control valve 44 that controls the operating pressure of each fluid pressure cylinder 42 according to a predetermined command value, and a vertical acceleration detector 45 provided at each wheel position of the vehicle body 41. It is equipped with a control device 46 that outputs a command value for suppressing changes in the posture of the vehicle body to the pressure control valve 44 based on the detected value, and a line pressure pipe 47 and a drain are connected between the pressure control valve 44 and the fluid pressure supply device 43. Piping 48
, and an accumulator 49 for attenuating pulse pressure is connected to the line pressure piping 47.

[Problem to be solved by the invention]

However, in the conventional active suspension device described above, the pressure control valve 44 and the fluid pressure supply device 43 are directly connected via the line pressure piping 47 and the drain piping 48, and the line pressure piping 47 is connected to one accumulator. 49
is connected, and this accumulator 49 is used to attenuate the pulsation pressure in the line pressure piping 47.
No consideration is given to the hydraulic resonance frequency of these piping systems, and this hydraulic resonance frequency becomes relatively high and resonates due to the pulse pressure of the discharge pressure from the fluid supply device 43, causing noise generation, fatigue damage, etc. There were issues that were likely to occur.

Therefore, the present invention has been made by focusing on the above-mentioned problems of the conventional example, and reduces the fluid pressure resonance frequency of the circuit that reduces the pulse pressure of the discharge pressure of the fluid pressure supply device to reduce the generation of noise due to resonance. It is an object of the present invention to provide a fluid pressure supply device that can prevent fatigue failure, etc., and an active suspension device using the same.

[Means to solve the problem]

In order to achieve the above object, the fluid pressure supply device according to claim (1) connects a plurality of accumulators to the discharge side of a fluid pressure source at a predetermined interval, and connects the plurality of accumulators with elastic piping. It is characterized by what it did.

Further, in claim (2), the active suspension device controls a fluid pressure cylinder interposed between each wheel and the vehicle body, and a working fluid pressure from a fluid pressure supply source supplied to the fluid pressure cylinder. In the active suspension device, the fluid pressure supply device includes a fluid pressure source, a plurality of accumulators connected at a predetermined interval to a discharge side of the fluid pressure source, and the plurality of accumulators. It is characterized by consisting of elastic piping that connects between the two.

(Operation) The fluid pressure supply device according to claim (1) includes a plurality of accumulators on the discharge side of a fluid pressure source that supplies working fluid to fluid pressure devices such as a fluid pressure cylinder and a hydraulic motor. Since the connecting elastic piping is provided, the accumulator absorbs the pulsating pressure, and the elastic piping lowers the apparent spring constant of the working fluid and lowers the fluid pressure resonance frequency. By preventing resonance caused by relatively high-frequency pulsations in the discharge pressure of the
Prevents fatigue failure, etc.

In the active suspension device according to claim (2), the fluid pressure supply device that supplies working fluid to the control valve that controls the fluid pressure cylinder includes a plurality of accumulators connected to the discharge side of the fluid pressure source. , and elastic piping connecting these accumulators, it is possible to reduce the pulse pressure and the fluid pressure resonance frequency, as described above, and it is possible to accurately control the fluid pressure cylinder by the control valve. can be done.

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

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention.

In the figure, FS is a fluid pressure supply device, which has a hydraulic pump composed of a fixed cylinder piston pump as a fluid pressure supply source, and the rotation shaft of this hydraulic pump 1 is connected to the output shaft 2a of the engine 2. While being connected and rotationally driven,
The suction side is connected to the oil tank 3, and the discharge side is equipped with a check valve 4.
is connected to the line pressure piping 5 made of a steel tube connected to the output port side of the check valve 4. Two accumulators 6a and 6b for pulsation pressure damping are connected at a predetermined interval to the line pressure piping 5, which is connected to the output port side of the check valve 4. A parallel circuit of a filter 7 and a check valve 8 is connected to a line pressure pipe 5 on the downstream side of the oil tank 3, and a return pipe 10 is connected to an oil tank 3 via an oil cooler 9. Here, the line pressure piping 5 is made of a rubber hose 5a as a flexible elastic piping only between the accumulators 6a and 6b, and the other parts are made of steel tubes 5b and 5c.

The line pressure pipe 5 and the drain pipe 10 are connected via the pressure holding section 11 to the supply pressure port 21a and return boat 21b of the pressure control valve 13 corresponding to each wheel.

The pressure holding unit 11 is inserted between a check valve 14 inserted in the line pressure piping 5 and the line pressure piping 5 and the drain piping 10, and sets the line pressure PL (kg/c4) in a normal state. It is equipped with a relief valve 15 for normal line pressure setting, and a pilot operated check valve 16 to which the line pressure on the downstream side of the check valve 14 is supplied as pilot pressure P. When the pilot pressure P is equal to or higher than the neutral pressure PM of the pressure control valve 13, the pilot-operated check valve 16 is fully opened to establish communication between the input port 161 and the output boat 160, and the pilot pressure PP is When the pressure becomes less than the neutral pressure Ps, the input boat 16i and the output boat 16 become fully closed.
0 is the cutoff state.

The pressure control valve 13 receives a command value I from an attitude change suppression control device 17 that outputs a command value for suppressing changes in the attitude of the vehicle body based on detection signals such as vehicle height, lateral acceleration, vertical acceleration, and longitudinal acceleration. A control pressure Pc corresponding to this command value (■) is output, and this is supplied to a hydraulic cylinder 19 that constitutes an active suspension line inserted between each wheel and the vehicle body to resist changes in the posture of the vehicle body. Generates a biasing force.

The specific structure of this pressure control valve 13 is, as shown in FIG.
2. The poppet 23 and the plunger 24a of the proportional solenoid 24 are coaxially arranged in that order.

The spool 22 has lands 22a and 22b at both ends,
A pressure chamber 22c is formed between the land 22a and a partition wall 21d having a fluid outlet 21c formed in the valve housing 21, and a pressure chamber 22d is formed between the land 22b and the valve housing 21, and the pressure chamber 22d is formed between the land 22b and the valve housing 21. The chamber 22c communicates with the input port 21a via a pilot passage 21e, and the pressure chamber 22d communicates with the control boat 21c via a fluid passage 22e formed in the spool 22. Note that 22f and 22g are springs that center the spool 22.

One end of the poppet 23 is a partition wall 2 that separates a pilot passage 21e from a return passage 21f communicating with a return boat 21b.
It faces a valve seat 21h formed at 1g, and the other end faces an actuator 24b of a plunger 24a of an electromagnetic proportional solenoid 24.

The proportional solenoid 24 includes a plunger 24a that is slidable in the axial direction, an actuator 24b that is fixed to the poppet 23 side of the plunger 24a, and an excitation coil 24c that applies a downward thrust to the plunger 24a. and
This excitation coil 24C is appropriately excited by a command value I that is a direct current from the posture change suppression control device 17. As a result, a downward thrust is applied to the plunger 24a, and the position of the poppet 23 is controlled via the actuator 24b, thereby controlling the flow rate passing through the valve seat 21h. Then, when the thrust by the proportional solenoid 24 is applied to the poppet 23 and the pressures in both the pressure chambers 22c and 22d are balanced, the spool 22 is in the neutral position and the control port 21C, the input port 21a, and the return port are in a neutral position. It is cut off from the boat 21b.

Here, the relationship between the command value ■ and the control oil pressure Pc output from the control boat 21c is as shown in FIG.
P1418 is output when P is near zero, and when the command value ■ increases in the positive direction from this state, the control output P increases with + to the predetermined proportional gain, and the setting line of the pressure holding part 11 increases. It is saturated at pressure PLII.

The input port 21a of the pressure control valve 13 is connected to the check valve 14 of the pressure holding section 11, the return boat 21b is connected to the input port 16i of the pilot operated check valve 16 of the pressure holding section 11, and the control board 21b is connected to the input port 16i of the pilot operated check valve 16 of the pressure holding section 11. 1-21c is connected to a pressure chamber 19a of a hydraulic cylinder 19 inserted between the vehicle body and each wheel.

Further, an accumulator 25 for accumulating pressure is connected to the line pressure piping 5 between the pressure holding part 11 and the pressure control valve 13, and the pressure chamber 19a of the hydraulic cylinder 19 is connected to the road surface input to the hydraulic cylinder 19. A damping valve 26 and an accumulator 27 are connected to the damping valve 26 and an accumulator 27 for absorbing pressure fluctuations due to unsprung vibrations of the vehicle.

Next, the operation of the above embodiment will be explained. Assuming that the vehicle is now in a stopped state and the ignition switch is in the off state, in this state, the engine 2 is in a stopped state, the hydraulic pump 1 is also in a stopped state, and the line pressure holding part 1 is in a stopped state.
It is assumed that the pressure on the output side of the pressure control valve 13 is approximately maintained at the neutral pressure PH of the pressure control valve 13.

In this state, when the ignition switch is turned on and the engine 2 is started, the rotation speed of the hydraulic pump l increases as the rotation of the output shaft 2a increases, and the hydraulic oil is discharged at a pressure corresponding to the rotation speed. is supplied to the line pressure piping 5.

At this time, the hydraulic fluid discharged from the hydraulic pump 1 generates a pulsating pressure corresponding to the rotation speed of the hydraulic pump 1, but this pulsating pressure is attenuated by the accumulators 6a and 6b, and the hydraulic resonance frequency can be significantly reduced compared to when using

That is, when the fluid pressure supply device FS is represented by an equivalent circuit, it becomes as shown in FIG. Here, KT.

KTc refers to steel tubes 5b on both sides of the elastic pipe 5a,
The appearance of the hydraulic fluid in 5c is the spring constant, Ml, above.

M is the mass of the steel tubes 5b and 5c, and Ko+ is □
2 is the apparent spring constant of the hydraulic oil in the rubber hose 5a,
MH is the mass of the rubber hose 5a, KA, and KAb are the spring constants of the accumulators 6a and 6b.

Then, assuming that the total mass in this equivalent circuit is M and the total spring constant is K, the hydraulic resonance frequency f can be expressed by the following equation.

Then, the spring constant of the hydraulic oil in the rubber hose 5a is □,
) 'CHt is much smaller than the spring constant of the hydraulic fluid in the steel tubes 5b and 5c, so the total spring constant K can be made small, and therefore the hydraulic resonance frequency f can be reduced as shown in Fig. 5. Furthermore, the pulse pressure frequency can be reduced to about 100 Hz, which is lower than the pulse pressure frequency during normal operation of the fluid pressure supply device FS.

In addition, when a rubber hose with a spiral tube inside as a reinforcing member is applied as the rubber hose 5a, the rubber hose 5a
By increasing the quality W/LMH, the total mass M increases, and the hydraulic resonance frequency f can be further reduced to about 70)fz as shown by the dotted line in FIG.

In this way, the hydraulic resonance frequency f in the fluid pressure supply device FS
By being able to reduce the pulsation pressure frequency of the hydraulic oil discharged from the hydraulic pump 1 when the engine 2 normally rotates, it is possible to set the frequency to a value lower than the pulsation pressure frequency of the hydraulic oil discharged from the hydraulic pump 1, and it is possible to prevent oil pressure fluctuations due to resonance phenomena.

On the other hand, when the pressure within the line pressure piping 5 increases, the pilot pressure P supplied to the pilot operated check valve 16 also increases accordingly.

Then, the pilot pressure P, the leaf pilot pressure Pr
o That is, at the point when the neutral pressure PM is exceeded, the pilot operated check valve 16 is opened and the return boat 2 of the pressure control valve 13 is opened.
1b is communicated with the oil tank 3. ' After that, when the pressure of the hydraulic oil discharged from the hydraulic pump 1 increases and the line pressure PL on the upstream side of the check valve 14 exceeds the set pressure PL of the relief valve 15, the excess pressure passes through the relief valve 15. Oil tank 3 through doshin piping 7
and the line pressure is maintained at the set pressure PLH.

On the other hand, when the ignition switch is turned on, the attitude change suppression control device 17 is also activated and outputs a command value I to the pressure control valve 13 to suppress changes in the attitude of the vehicle body due to changes in vehicle height due to passengers getting on and off the vehicle. By doing so, the vehicle height is made to match the target vehicle height.

After that, when the vehicle is started, the attitude change suppression control device 1
At step 7, changes in the attitude of the vehicle body due to scut during acceleration, nose dive during deceleration, roll during turning, other pitches, bounces, etc. are detected, and a command value T for suppressing these is output to the pressure control valve 13. This controls the pressure of the hydraulic cylinder 19 and suppresses changes in the attitude of the vehicle body.

Furthermore, when a relatively low frequency vibration input corresponding to the sprung mass resonance frequency range is transmitted from the wheel side to the hydraulic cylinder 19 when driving on a undulating road or a rough road, the internal pressure of the hydraulic cylinder 19 fluctuates in response to this vibration input. As a result, the pressure in the control boat 21C of the pressure control valve 13 also fluctuates. In this state, the pressure chamber 22d of the pressure control valve 13
The pressure will fluctuate, and the posture change suppression control device 1
Based on the command value I from 7 (when the pressure drops below the pressure in the pressure chamber 22c, the spool 22 is lowered and the human-powered boat 21
a and the control port 21c are in communication, and the line pressure P
LH is supplied to the hydraulic cylinder 19. Therefore, the internal pressure of the hydraulic cylinder 19 increases, and the pressure chamber 22 accordingly increases.
The pressure of d increases, the spool 22 rises, and the pressure chamber 22
When the pressure in the pressure chamber 22d becomes equal to the pressure in the pressure chamber 22d, the input boat 21a is closed by the land 22b. on the other hand,
When the pressure in the pressure chamber 22d becomes higher than the pressure in the pressure chamber 22c, the spool 22. is raised, the return boat 21b and the control port 21c are brought into communication, and the hydraulic oil in the hydraulic cylinder 19 is returned to the oil tank 3 via the drain pipe 10. Therefore, the internal pressure of the hydraulic cylinder 19 decreases,
In response to this, the pressure in the pressure chamber 22c decreases and the spool 2
2 descends, and when the pressure in the pressure chamber 22c and the pressure in the pressure chamber 22d become equal, the boat 21 is returned by the land 22a.
b is closed. As a result, vibration input from the road surface transmitted to the hydraulic cylinder 19 is absorbed and prevented from being transmitted to the vehicle body.

Furthermore, when a relatively high-frequency vibration input in the unsprung resonance frequency range is transmitted to the hydraulic cylinder 13 from the wheel side, pressure fluctuations in the pressure chamber 13a of the hydraulic cylinder 13 occur due to this vibration input, but in this case, , a throttle valve 2 is installed in the pressure chamber 13a.
Since the accumulator 27 is connected through 6,
This accumulator 27 absorbs vibration input.

In this running state, when the vehicle is stopped and the ignition switch is turned off, the hydraulic pump 1 of the fluid pressure supply system FS will stop rotating as the engine 2 stops, and its discharge pressure will drop rapidly. However, since the check valves 4 and 14 are inserted in the line pressure piping 5,
The pressure in the pressure control valve 13 and the accumulator 25 does not decrease drastically, but is gradually reduced through the pilot passage 21e and return passage 21f of the pressure control valve 13. When the pressure in the accumulators 25a and 25b becomes less than the neutral pressure PM, the pilot operated check valve 16
is fully open, so hydraulic oil is sealed and maintained within the pressure control valve 13 and the hydraulic cylinder 19 at approximately neutral pressure PM.

Note that in the above embodiment, two accumulators 6
Although the case where the accumulators a and 6b are provided has been described, the present invention is not limited to this. By providing three or more accumulators and connecting them with elastic piping, the pulse pressure can be further reduced and the hydraulic resonance frequency f can be reduced.

Further, in the above embodiment, a case has been described in which the rotational driving force for the hydraulic pump 1 is obtained from the engine, but the invention is not limited to this, and other rotational driving sources such as an electric motor may be applied. Needless to say.

Furthermore, the control valve for the hydraulic suspension is not limited to the pressure control valve 13 described above, and other flow control type servo valves or the like may be used.

Further, in the above embodiments, a case has been described in which hydraulic oil is used as the working fluid, but the present invention is not limited to this, and any working fluid can be used as long as it has a low compressibility.

Furthermore, in the above embodiment, the fluid pressure supply device F
Although the case where S is applied to an active suspension device has been described, it is not limited to this (it is also possible to apply it to a drive device that drives fluid pressure devices such as other fluid pressure cylinders and fluid pressure motors). Needless to say.

〔Effect of the invention〕

As explained above, according to the fluid pressure supply device according to claim (1), a plurality of accumulators are connected to the discharge side of the fluid pressure source, and each accumulator is connected with elastic piping, so that elastic Piping can lower the apparent spring constant of the working fluid and reduce the resonance frequency, preventing resonance phenomena caused by pulsations in the discharge pressure of the fluid pressure source under normal operating conditions, and reducing noise. This has the effect of reliably preventing occurrence of damage to the piping system, damage to the piping system, etc.

Further, according to the active suspension device according to claim (2), pulsation and resonance of the working fluid pressure supplied to a control valve such as a pressure control valve that controls a fluid pressure cylinder that suppresses changes in the attitude of the vehicle body can be prevented. Therefore, accurate attitude change suppression control can be performed, and the effect of improving the ride comfort of the vehicle can be obtained.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing an example of a pressure control valve applicable to the present invention,
Fig. 3 is a characteristic diagram showing the relationship between the control pressure and the command value of the pressure control valve, Fig. 4 is an equivalent circuit diagram of the fluid pressure supply device,
Figure 5 is a characteristic diagram showing the relationship between gain and frequency, and Figure 6 is a characteristic diagram showing the relationship between gain and frequency.
The figure is a system diagram showing a conventional example. In the figure, FS is a fluid pressure supply device, 1 is a hydraulic pump, 2 is an engine, 5 is a line pressure pipe, 5a is a rubber hose, 6a,
6b is an accumulator, 11 is a pressure holding part, 13 is a pressure control valve, 19 is a hydraulic cylinder, 21a is an input port, 2
1b is a return port, and 21C is a control port.

Claims (2)

[Claims] (1) A fluid pressure supply device characterized in that a plurality of accumulators are connected to the discharge side of a fluid pressure source at predetermined intervals, and the plurality of accumulators are connected by elastic piping. (2) An active suspension device that includes a fluid pressure cylinder interposed between each wheel and the vehicle body, and a control valve that controls the working fluid pressure from a fluid pressure supply device supplied to the fluid pressure cylinder. In the fluid pressure supply device, the fluid pressure supply device includes a fluid pressure source, a plurality of accumulators connected at a predetermined interval to the discharge side of the fluid pressure source, and elastic piping connecting the plurality of accumulators. An active suspension device characterized by: