JPH0633871A - Active pulsation pressure absorbing device - Google Patents

Abstract

PURPOSE:To obtain a pulsation pressure absorbing device for effectively absorbing the pulsation pressure within a wide frequency range by the simple control for a variable throttle, securing the compactness of a device. CONSTITUTION:In the first constitution, a variable throttle (e) is formed on the downstream side of an accumulator (d) installed midway in a pipe (c) connected from a pulsation source (a), and a controller (g) for carrying out the control for improving the frequency characteristic of the flow rate variation absorbing faculty by an accumulator (d) as a whole is installed. In the second constitution, a variable throttle (e) is installed midway in a branched pipe (c2) to a reservoir from a main pipe (c1) having the pulsation source (a) at one edge, and a controller (g) which carries out the control for the relief of the variation components having an increasing flow rate among the flow rate variation supplied from the pulsation source (a) is installed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active pulse pressure absorbing device which absorbs pulse pressure by actively reducing the pulsating flow rate from a pulsating source such as a pump hydraulic pressure source.

[0002]

2. Description of the Related Art Conventionally, for example, the one shown in FIG. 10 is generally known as a pulse pressure absorbing device for absorbing a pulse pressure due to a pulsating flow rate from a pulsating source such as a pump hydraulic pressure source.

The device shown in FIG. 10 has a pulsation source (hydraulic pump, etc.).
An accumulator is installed in the middle of the main pipe that connects the load at the other end, and a relief valve is installed in the middle of the branch pipe that branches from the main pipe to the reservoir.The relief valve operates the accumulator while regulating the hydraulic pressure. It is designed to absorb fluctuations in oil flow rate.

[0004]

However, in the above-mentioned conventional technique, the pulse pressure absorption capacity depends on the volume change determined by the spring-mass characteristic of the accumulator.
With one accumulator, it is difficult to absorb the pulse pressure outside a specific frequency range. Therefore, if the operating speed of the hydraulic system changes, the number of revolutions of the hydraulic pump changes, and the frequency of the discharge flow rate change changes, causing a deviation from the absorbable frequency range of the accumulator. There was a problem that it would occur.

For example, as shown in FIG. 11, when looking at the frequency characteristics of the fluctuation level of the discharge flow rate, when the peak of the discharge flow rate fluctuation is in the accumulator absorption range, as shown by the dotted line characteristic, the fluctuation level of the discharge flow rate is noise. Vibration is at a level that does not pose a problem, but when the rotational speed changes and the accumulator absorption range deviates to the high frequency side, the fluctuation level of the discharge flow rate is a level at which noise vibration becomes a problem, as indicated by the chain line characteristics. Will rise up to.

That is, the pulsation pressure generated by the pulsation source such as the hydraulic pump normally exists beyond the frequency range that can be absorbed by one accumulator. Therefore, when a large number of accumulators are used, the pulse pressure can be absorbed in a wide frequency range, but in this case, a large number of accumulators are required, which causes a problem that a large device space is required.

The present invention has been made by paying attention to the above problems. While maintaining the compactness of the device, the frequency characteristic of the flow rate fluctuation absorbing ability by one accumulator can be controlled by a simple control for the variable throttle. It is a first object to provide an active pulse pressure absorbing device that effectively absorbs pulse pressure in a wide frequency range by increasing the overall pressure.

[0008] By simply controlling the variable throttle without affecting the load, the fluctuation component of the flow rate fluctuation from the pulsation source, which increases the flow rate, is relieved to effectively absorb the pulse pressure in a wide frequency range. A second object is to provide an active pulse pressure absorber.

[0009]

In order to solve the above-mentioned first problem, in the active pulsation absorber according to claim 1, a variable throttle is provided downstream of the accumulator provided in the middle of the pipe from the pulsation source. A controller for controlling the variable throttle is provided so as to reduce the flow rate fluctuation based on the unsteady flow rate measurement value measured by the unsteady flow rate measuring means.

That is, as shown in the claim correspondence diagram of FIG. 1 (a), a pipe c connecting a pulsation source a at one end and a load b at the other end, and an accumulator d provided in the middle of the pipe c.
A variable throttle e provided downstream of the accumulator d, and a pulsation source a provided downstream of the variable throttle e.
The unsteady flow rate measuring means f for measuring the unsteady flow rate of the discharge oil discharged from the variable throttle e for reducing the flow rate fluctuation based on the unsteady flow rate measurement value measured by the unsteady flow rate measuring means f. And a controller g for controlling the aperture amount.

In order to solve the above-mentioned second problem, in the active type pulse pressure absorber according to claim 2, a variable throttle is provided in the middle of a branch pipe from a main pipe having a pulsation source at one end to a reservoir. A controller for controlling the variable throttle is provided so as to reduce the flow rate fluctuation based on the unsteady flow rate measurement value measured by the steady flow rate measuring means.

That is, as shown in the claim correspondence diagram of FIG. 1B, a main pipe c ₁ connecting a pulsation source a at one end and a load b at the other end, and a main pipe c ₁ provided in the middle of the main pipe c _1. An unsteady flow rate measuring means f for measuring an unsteady flow rate of the discharged oil discharged from the pulsation source a, and a variable throttle e provided in the middle of the branch pipe c ₂ from the main pipe c ₁ to the reservoir h. A controller g for controlling the throttle amount of the variable throttle e so as to reduce the flow rate fluctuation based on the unsteady flow rate measurement value measured by the unsteady flow rate measuring means f.

In the active pulse pressure absorber according to claim 3,
The active valve pressure absorber according to claim 1 or 2, wherein the variable throttle (e) is a servo valve whose throttle amount is controlled by the magnitude of a voltage applied to two laminated piezoelectric elements arranged at both ends of a spool. And

[0014]

The operation of the present invention will be described. During the operation of the pulsation source a accompanied by the flow rate fluctuation, the controller g reduces the flow rate fluctuation propagated to the pipe c from the pulsation source a to the load b based on the unsteady flow rate measurement value from the unsteady flow rate measuring means f. Thus, the diaphragm amount of the variable diaphragm e is controlled. For example, when the unsteady flow rate has a positive amplitude and the capacity of the accumulator d increases, the throttling area of the variable restrictor e is reduced to change −, and when the unsteady flow rate has a negative amplitude, it changes. Gives a change of + to increase the diaphragm area of diaphragm e,
The throttle amount is controlled so that a constant flow rate flows in the pipe c to the load b.

Therefore, when the discharge flow rate from the pulsation source a varies, when the flow rate becomes larger than the average flow rate, the throttle area of the variable throttle e is reduced, and the accumulator d arranged upstream of the variable throttle e. When the inflow flow rate to the variable throttle e increases and the flow rate becomes smaller than the average flow rate, the throttle area of the variable throttle e increases, and the outflow rate from the accumulator d arranged upstream of the variable throttle e increases. By controlling the throttle amount of the diaphragm e, the volume change of the accumulator d becomes large. Moreover, when the fluctuation frequency of the discharge flow rate from the pulsation source a changes, the throttle amount is controlled in response to the change of the frequency, and the volume change of the accumulator d is increased by following the change of the fluctuation frequency of the discharge flow rate. You can

That is, the flow rate fluctuation absorbing ability by the accumulator d determined by the magnitude of the volume change is utilized in the entire range from the low frequency range to the high frequency range, and the frequency characteristic of the flow rate fluctuation absorbing ability by one accumulator d. The pulse pressure is effectively absorbed in a wide frequency range while maintaining the compactness of the device by performing active control that raises the overall.

The operation of the invention according to claim 2 will be described.

During operation of the pulsation source a accompanied by flow rate fluctuation, the controller g propagates from the pulsation source a to the load b to the main pipe c ₁ based on the unsteady flow rate measurement value from the unsteady flow rate measuring means f. The throttle amount of a variable throttle e provided in the middle of the branch pipe c ₂ from the main pipe c ₁ to the reservoir h is controlled so as to reduce the flow rate fluctuation of For example, when the unsteady flow rate has an amplitude of +, the throttling area of the variable throttle e is expanded to give a + change, and when the unsteady flow rate has an amplitude of −, the throttling area of the variable throttle e is reduced. − Change,
The throttle amount is controlled so that a constant flow rate flows through the main pipe c ₁ to the load b.

Therefore, when there is a fluctuation in the discharge flow rate from the pulsation source a, when the flow rate becomes large, the throttle area of the variable throttle e is expanded to allow a larger amount of flow to escape to the reservoir h, and the flow rate becomes smaller. At this time, the throttle area of the variable throttle e is reduced to suppress the escape to the reservoir h, so that the flow rate fluctuation of the main pipe c ₁ is suppressed by controlling the throttle amount of the variable throttle e. Moreover, when the fluctuation frequency of the discharge flow rate from the pulsation source a changes, the throttle amount is controlled in response to the change of the frequency, and the fluctuation of the flow rate of the main pipe c ₁ is suppressed by following the change of the fluctuation frequency of the discharge flow rate. be able to.

Further, the variable throttle e is provided in the middle of the branch pipe c ₂ from the main pipe c ₁ to the reservoir h,
The influence on the load b can be suppressed without changing the flow resistance of the fluid flowing through the main pipe c ₁ from the pulsation source a to the load b at the time of controlling the throttle amount of the variable throttle e.

That is, by actively controlling the fluctuation component of the flow rate fluctuation from the pulsation source a which increases the flow rate, the pulse pressure is effectively absorbed in a wide frequency range without affecting the load b. To be done.

The operation of the invention according to claim 3 will be described. Since the variable diaphragm e is a servo valve whose diaphragm amount is controlled by the magnitude of the voltage applied to the two laminated piezo elements arranged at both ends of the spool, it can be varied by the laminated piezo element that expands and contracts depending on the magnitude of the applied voltage itself. It is possible to meet the high response demand required when controlling the diaphragm amount of the diaphragm e, and to make the responsiveness the same for both the expansion and contraction of the diaphragm amount of the variable diaphragm e. It is possible to perform throttle amount control that reduces flow rate fluctuations in a wide frequency range.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) The configuration will be described.

FIG. 2 is an overall system diagram showing an active pulse pressure absorbing device of a first embodiment of the present invention corresponding to claim 1. In FIG.

In the active pulse pressure absorber of the first embodiment, a main pipe 3 for connecting a hydraulic pump 1 at one end (corresponding to a pulsation source) and a load 2 at the other end, and the main pipe 3 are arranged in parallel. A bypass pipe 4 (corresponding to a pipe) provided, an accumulator 5 provided in the main pipe 3 connected to the hydraulic pump 1, and a servo valve provided downstream of the accumulator 5 and in the middle of the bypass pipe 4. 6 (corresponding to a variable throttle), and an unsteady flow rate (fluctuation flow rate) of the discharge oil discharged from the hydraulic pump 1 provided downstream of the servo valve 6 and connected to the main pipe 3.
Unsteady flow meter for measuring (equivalent to unsteady flow measuring means)
7 and a controller 9 for applying a control voltage from the voltage source 8 to the servo valve 6 based on the unsteady flow rate measurement value measured by the unsteady flow meter 7.

A fixed throttle 10 is provided in the main pipe 3, and the pressure loss by the fixed throttle 10 is adjusted to be equal to the pressure loss at the neutral position of the servo valve 6.

The servo valve 6 includes a spool 12, a sleeve 13, laminated piezo elements 14 and 15, steel balls 16 and 17, steel ball supports 18 and 19, and laminated piezo element supports 20 and 2.
1 and a housing 22. The spool 12 is sandwiched between the laminated piezoelectric elements 14 and 15 via steel balls 16 and 17. Therefore, the spool 12 is configured to be movable in the axial direction while the control voltage of the voltage source 8 is applied to the laminated piezoelectric elements 14 and 15 to expand and contract, and the force other than the axial direction is released by the steel balls 16 and 17. In addition, the laminated piezo element support bases 20 and 2 for supporting the laminated piezo elements 14 and 15
1 can be fixed at any position in the axial direction of the housing 22, and a predetermined preload can be applied to the laminated piezoelectric elements 14 and 15.

The controller 9 determines a signal to the voltage source 8 according to a control rule described later based on signals from the unsteady flow meter 7 and the rotation angle sensor 23 provided in the hydraulic pump 1. In addition, 24 is a reservoir and 25 is an inverter.

FIG. 3 is a flow chart showing the flow of the servo valve control operation performed by the controller 9.
Each step will be described.

First, at step 101, the ΔT time is read, and at step 102, it is judged whether or not the hydraulic pump 1 is stopped. If "YES", that is, when the hydraulic pump 1 is stopped, the controller 9 is operated. When the control is stopped and the result is "NO", that is, when the hydraulic pump 1 is operating, the process proceeds to step 103.

In step 103, it is judged whether or not a rotation pulse is detected by the rotation angle sensor 23, and "YES".
In the case of, that is, when the rotational speed of the pump is changing, the process proceeds to step 104, and in the case of “NO”, that is, when the rotational speed of the pump is constant, the process proceeds to step 108.

In step 104, the rotation speed N (rpm)
And proceeds to step 105. At step 105, it is determined whether or not the rotation speed N is in the same rotation speed segment as one rotation pulse before. Change to your profile and click "N
In the case of "O", the process proceeds to step 107 and 60 / N (se
c) Calculate the average value Q ₀ of the flow rate from before to the present (Nth rotation), and proceed to step 108.

In step 108, the average flow rate Q _T in ΔT time is calculated, and in the next step 109, the average flow rate Q N in the Nth rotation is calculated from the average value Q _T of fluctuating flow rate in ΔT time.
_The difference ΔQ _T (ΔQ _T = Q _T −Q ₀ ) is subtracted by subtracting _0, and in the next step 110, T−60 / N (sec)
The absolute value of the current difference ΔQ _T is subtracted from the absolute value of the previous difference ΔQ _{T-60 / N} to obtain the difference ε (ε = | ΔQ _{T-60 / N} | − | ΔQ _T |), and step 111 Proceed to.

In step 111, ΔQ _T and ΔQ _{T-60 / N}
If it is "YES", the process proceeds to step 112. If "NO", the process proceeds to step 114, and the flow passage area of the servo valve 6 is held.

In step 112, it is judged whether or not ε> 0. If "YES", the process proceeds to step 113, and if "NO", the process proceeds to step 114, and the flow passage area of the servo valve 6 is reached. Hold.

In step 113, it is judged whether or not ΔQ _T > 0. If “YES”, the process proceeds to step 115, where the flow passage area of the servo valve 6 is reduced by ΔA, and if “NO”, , And proceeds to step 116 to increase the flow passage area of the servo valve 6 by ΔA.

Next, the operation will be described.

(A) When the number of rotations of the hydraulic pump is constant When the hydraulic pump 1 is rotating, the pump rotation angle is detected by the rotation angle sensor 23, and the detected signal is sent to the controller 9. The controller 9 measures in advance the unsteady flow rate generation situation with respect to the pump rotation angle, outputs a control signal according to a control program (FIG. 3) set based on the measurement result, and uses this control signal to generate the voltage source 8 Is operated to apply a control voltage to the laminated piezo elements 14 and 15, and the spool 12 is displaced so that the unsteady flow rate from the hydraulic pump 1 is canceled in the servo valve 6.

At this time, the unsteady flow meter 7 also measures a minute fluctuation amount with respect to the average flow rate from the hydraulic pump 1, and the controller 9 determines a certain time step ΔT (this time step corresponds to the maximum response frequency of the servo valve 6). The value of this average fluctuation is successively calculated every time one cycle is divided into at least several pieces (see FIG. 4 (1)). As a result, the profile of the displacement amplitude with respect to the average flow rate of the hydraulic pump 1 in the time width is obtained.

Normally, in the hydraulic pump 1 as the pulsation source,
Since the piston, the plunger, etc. are used, the deviation profile of the fluctuating flow rate with respect to this average flow rate has periodicity repeated for each plunger (Fig. 4 (1)).
See the right part of).

On the basis of this profile, the servo valve 6 of the bypass pipe 4 can be provided with a profile of a certain average opening area change which reduces the flow rate fluctuation obtained by the method described later (see FIG. 5 (4)). .

First, the minimum area change width ΔA of the throttle due to the front-rear movement of the servo valve 6 is determined and stored in the controller 9. This area change width is determined by the servo valve 6
The maximum change range of the flow rate can be divided into several steps or more.

Next, using the obtained profile, the change amount of − is given to the throttle area of the servo valve 6 by the minimum change width ΔA within the time period in which the change amount of flow has an amplitude of +, and the change amount is −
The minimum change width is ΔA within the increment time with the amplitude of
Calculate a signal pattern that can be given (see FIG. 5).
(See (2)). Hereinafter, the servo valve 6 is moved by this method.

At this time, the trigger signal for adjusting the timing of moving the servo valve 6 is a pulse from the rotation angle sensor 23 (several times per rotation), and one signal pattern obtained by one plunger or It can be applied to flow fluctuations after several plungers (see Fig. 4 (1)).

Furthermore, in this hydraulic system, the flow rate fluctuation when an area change is given is also measured downstream of the throttle (see FIG. 4 (2)). Therefore, in the next cycle, the previous area change profile is obtained. Since it is stored and further corrected (see FIG. 5 (3)), the flow rate fluctuation can be further reduced compared to the previous time (see FIG. 4 (3)).
Also, where the fluctuation amplitude of the flow rate was large on the profile due to the previous signal (when there is a tendency for oscillation)
Next time, the area change will be suspended.

By repeating this, finally, the profile of the change in the opening area is suppressed to the minimum step width of the area change, so that the flow rate fluctuation after the servo valve 6 is within the range of the flow fluctuation occurring in the minimum step width of the area change. Can be suppressed,
It is possible to reduce the sound and vibration generated by the flow rate fluctuation in the pipe.

FIGS. 5 (1) to 5 (4) are diagrams showing the state of convergence of the opening area change profile of the servo valve 6 at this time to the final profile, and FIGS. 4 (1) to 4 (4). It is a figure which shows the convergence state of the flow volume change at that time.

(B) When the rotational speed of the hydraulic pump changes First, the flow rate profile obtained in the above-described manner is set at a certain constant rotational speed (N rotation, N + n rotation, N + 2n rotation,
...) (see FIGS. 6 (1) to 6 (3)). The rotation speed K of the pump is calculated each time by the rotation pulse of the rotation angle sensor 23, and the opening area profile given to the servo valve 6 is N−n / 2 ≦ K <N + n / 2, N + n / 2 ≦ K.
<N + 3n / 2, N + 3n / 2 ≦ K <N + 5n / 2, ...
The rotation profiles are used for each rotation range of N, N + n, N + 2n, ...

The input of the profile to the servo valve 6 is triggered by the rotation pulse. When the profile approaches the end and the trigger signal from the rotation angle sensor 23 is input, the next profile is started from that time. If the rotation drops rapidly and the end of the profile is earlier than the trigger signal, it shall return to the beginning of the profile. When the rotation rapidly rises and the trigger signal is input before the end of the profile is reached, the profile is started from the time when the trigger signal is input.

At the time when the rotation pulse is input, if the rotation speed K exceeds the rotation speed of the section of the previous profile, the profile is changed to the corresponding profile and the operation is started.

Even in this case, the control by the signal from the unsteady flow meter 7 downstream of the throttle is also performed, and N to N + n
Even at an intermediate rotation speed of, it converges to an optimum profile that reduces pulsation in a predetermined time.

(C) Fluctuating flow rate reducing action As described above, when the discharge flow rate from the hydraulic pump 1 fluctuates, when the flow rate becomes larger than the average flow rate, the opening area (throttle amount) of the servo valve 6 becomes smaller. The flow rate is reduced and the flow rate into the accumulator 5 arranged upstream of the servo valve 6 is increased,
When the flow rate becomes smaller than the average flow rate, the opening area of the servo valve 6 is enlarged, and the flow rate of the outflow from the accumulator 5 arranged upstream of the servo valve 6 is increased so that the opening area of the servo valve 6 is controlled. By doing so, the volume change of the accumulator 5 becomes large. Moreover, when the fluctuation frequency of the discharge flow rate from the hydraulic pump 1 changes, the opening area is controlled in response to the change of the frequency, and the volume change of the accumulator 5 is increased by following the change of the fluctuation frequency of the discharge flow rate. You can

That is, the flow rate fluctuation absorbing ability of the accumulator 5 which is determined by the magnitude of the volume change is utilized in the entire range from the low frequency range to the high frequency range, and as shown in FIG. 7, one accumulator 5 is used. The frequency characteristic of the flow rate fluctuation absorbing capacity is improved as compared to the conventional one, and the necessary flow rate fluctuation absorbing capacity is obtained in a wide frequency range where noise and vibration are not a problem.

Next, the effect will be described.

(1) A servo valve 6 is provided downstream of an accumulator 5 provided in the middle of the main pipe 3 from the hydraulic pump 1, and the flow rate fluctuation is controlled based on the unsteady flow rate measurement value measured by the unsteady flow meter 7. Since the controller 9 for controlling the servo valve 6 is provided so as to reduce the amount, the frequency characteristic of the flow rate fluctuation absorbing ability by one accumulator 5 is entirely controlled by the simple control of the servo valve 6 while maintaining the compactness of the device. By increasing it, pulse pressure can be effectively absorbed in a wide frequency range.

(2) Two laminated piezo elements 1 in which variable diaphragms for changing the opening area are arranged at both ends of the spool 12.
Since the servo valve 6 whose opening area is controlled by the magnitude of the applied voltage to the motors 4 and 15 is used, the high response requirement required when controlling the opening area is provided by the laminated piezo elements 14 and 15 that expand and contract depending on the magnitude of the applied voltage itself. In addition, the response can be made the same in both directions of expansion and contraction of the opening area, and opening area control that reduces flow rate fluctuations in a wide frequency range can be performed with simple control. .

(Second Embodiment) Next, an active pulse pressure absorbing device according to a second embodiment of the present invention corresponding to claim 2 will be described with reference to FIG.

First, the structure will be described.

The active type pulse pressure absorbing device of the second embodiment has a main pipe 3 connecting a hydraulic pump 1 (corresponding to a pulsation source) at one end and a load 2 at the other end, and a main pipe 3 to a reservoir 24. Drain pipe 26 provided in a branched manner (corresponding to a branch pipe)
And 1-2 kH provided in the middle of the drain pipe 26
Servo valve with high z response (equivalent to variable throttle)
6 and 1-2 kH for measuring the unsteady flow rate (fluctuation flow rate) of discharge oil discharged from the hydraulic pump 1 connected to the main pipe 3.
An unsteady flow meter (corresponding to an unsteady flow rate measuring means) 7 having a high response of about z, and a servo valve 6 controlled from a voltage source 8 based on an unsteady flow rate measurement value measured by the unsteady flow meter 7. And a controller 9 for applying a voltage.

If the reservoir side pipe 26a of the drain pipe 26 connected to the output port of the servo valve 6 is long, hydraulic oil in the pipe becomes a resistance element, and it takes time even if the high response servo valve 6 is used. . Therefore, the reservoir side pipe 2
Use 6a as short as possible.

Since the other structures are similar to those of the first embodiment, the corresponding structures are designated by the same reference numerals and the description thereof will be omitted.

Next, the operation will be described.

(B) When the rotational speed of the hydraulic pump is constant (1) Since the hydraulic pump 1 is rotating at a constant rotational speed, the discharged hydraulic oil has a flow rate variation Δ determined by the configuration of the pump.
Q is repeated.

(2) The unsteady flow meter 7 detects the flow rate fluctuation ΔQ and outputs the flow rate fluctuation waveform to the controller 9.

(3) The phase is 180 degrees with respect to the flow rate fluctuation ΔQ detected by the inversion circuit provided in the controller 9.
The power source 8 is supplied with a control signal that causes the valve opening area A such that the flow rate fluctuation is zero with a deviation.

(4) The valve opening area A is as shown in FIG.
When the flow rate fluctuation ΔQ is out of the range of the fluctuation allowable value q, the flow rate fluctuation ΔQ is changed by the area increment ΔA, and the flow rate fluctuation ΔQ is changed to the fluctuation allowable value q.
Learning control is performed so as to search for a value within the range of, and is determined by the result of learning control. When the hydraulic pump 1 is rotating at a constant speed, the flow rate fluctuation ΔQ changes periodically, so once the waveform of the valve opening area A is determined, use it until the flow rate fluctuation waveform changes. You can

(5) The value of the permissible fluctuation value q is selected so that the target noise / vibration level does not matter.

(B) When the rotation speed of the hydraulic pump changes (1) When the rotation speed of the hydraulic pump 1 changes, the frequency range of the discharge flow rate fluctuation deviates, so that the flow rate fluctuation ΔQ is outside the fluctuation allowable value q. turn into.

(2) The unsteady flow meter 7 detects the flow rate fluctuation ΔQ and outputs the flow rate fluctuation waveform to the controller 9.

(3) When the flow rate variation ΔQ is out of the range of the variation allowable value q, the controller 9 controls the waveform of the valve opening area A by learning by changing it in increments of area ΔA.

(C) Fluctuating flow rate reducing action As described above, when the discharge flow rate from the hydraulic pump 1 fluctuates, when the flow rate increases, the opening area of the servo valve 6 is expanded to increase the flow rate. When the flow rate is reduced to the reservoir 24 and the flow rate is reduced, the opening area of the servo valve 6 is reduced to suppress the release to the reservoir 24. By performing learning control so that the flow rate is within the range, fluctuations in the flow rate of the main pipe 3 can be suppressed. Moreover, when the fluctuation frequency of the discharge flow rate from the hydraulic pump 1 changes, the servo valve 6 with high response is
As a result, the valve opening area A is controlled so as to be within the range of the fluctuation allowable value q by the change of the area step ΔA in response to the change of the frequency, and the change of the discharge flow fluctuation frequency is mainly tracked. Fluctuations in the flow rate of the pipe 3 can be suppressed.

Further, since the servo valve 6 is provided in the middle of the drain pipe 26 from the main pipe 3 to the reservoir 24, the main line 3 flows from the hydraulic pump 1 to the load 2 when the opening area of the servo valve 6 is controlled. The influence on the load 2 can be suppressed without changing the flow resistance of the fluid.

That is, by actively controlling the fluctuation component of the flow rate fluctuation from the hydraulic pump 1 which increases the flow rate, the pulse pressure is effectively absorbed in a wide frequency range without affecting the load 2. To be done.

Next, the effect will be described.

In the second embodiment, the following effect is obtained in addition to the effect of (2) above. (3) A high response servo valve 6 is provided in the middle of the drain pipe 26 from the main line 3 from the hydraulic pump 1 to the reservoir 24, and the flow rate variation ΔQ is based on the unsteady flow rate measurement value measured from the unsteady flow rate diameter 7. Since the controller 9 for controlling the servo valve 6 is provided so as to reduce the fluctuation, the fluctuation component that increases the flow rate among the fluctuations in the flow rate from the hydraulic pump 1 by the simple control of the servo valve 6 without affecting the load 2. By relieving, the pulse pressure can be effectively absorbed in a wide frequency range.

(4) Since the device has no accumulator, a high compactness of the device can be achieved.

Although the embodiments have been described above with reference to the drawings, the specific configuration is not limited to the embodiments, and modifications and additions within the scope of the present invention are included in the present invention. Be done.

For example, in the embodiment, an example in which an unsteady flow meter is used as the unsteady flow rate measuring means has been shown, but a pressure sensor may be used instead of this unsteady flow meter. In this case, the pressure fluctuation ΔP and the flow fluctuation ΔQ are connected by the following relationship in the frequency domain.

ΔP = Z × ΔQ (1) Here, Z is the load impedance of the load system downstream of the hydraulic pump discharge port. Therefore, when the load impedance Z can be measured by giving a known flow rate variation ΔQ from the pump position by a piston or the like connected to the vibration exciter beforehand and measuring ΔP with the pressure sensor, the output of the pressure sensor is used to (1) Since the flow rate fluctuation ΔQ can be estimated using the equation, the control voltage of the controller can be determined so that ΔQ is within a certain range.

In the embodiment, the example of the hydraulic pump is shown as the pulsation source, but the present invention can be applied to the one having a liquid source or a gas source which generates a pulsating pressure due to the pulsating flow rate.

In the embodiment, as the variable throttle, the servo valve in which the spool is stroked by the laminated piezo element to change the opening area is shown, but if the variable throttle is capable of controlling the throttle amount with high response, for example, a spool solenoid is used. It may be a valve or the like.

In the second embodiment, the active pulse pressure absorber without the accumulator is shown. However, as an apparatus with an accumulator added, the flow rate fluctuation is reduced by the control by the variable throttle in the frequency region where the accumulator cannot absorb. Is also good.

[0084]

According to the active type pulse pressure absorber of the present invention as set forth in claim 1, a variable throttle is provided downstream of the accumulator provided in the middle of the pipe from the pulsation source, and the unsteady flow rate measuring means is provided. Since the controller that controls the variable throttle is installed to reduce the flow variation based on the measured unsteady flow rate measurement value, the flow rate variation by one accumulator can be performed by the simple control of the variable throttle while maintaining the compactness of the device. By increasing the frequency characteristic of the absorption capacity as a whole, it is possible to effectively absorb the pulse pressure in a wide frequency range.

According to the active type pulse pressure absorbing device of the present invention as defined in claim 2, a variable throttle is provided in the middle of a branch pipe from a main pipe having a pulsation source at one end to a reservoir to measure an unsteady flow rate. Since the controller that controls the variable throttle is installed to reduce the flow rate fluctuation based on the unsteady flow rate measurement value measured from the means, the flow rate from the pulsation source can be reduced by the simple control of the variable throttle without affecting the load. Relieving the fluctuation component of the fluctuation that increases the flow rate has the effect of effectively absorbing the pulse pressure in a wide frequency range.

According to a third aspect of the present invention, in the active pulse pressure absorber according to the first or second aspect of the present invention, two laminated piezoelectric elements in which variable throttles are arranged at both ends of the spool are provided. Since the servo valve controls the throttle amount according to the magnitude of the applied voltage, the laminated piezo element that expands and contracts depending on the magnitude of the applied voltage can meet the high response requirements required when controlling the throttle amount of the variable throttle. At the same time, the response can be made the same in both directions of expansion and contraction of the variable throttle amount, and throttle amount control that reduces flow rate fluctuations over a wide frequency range can be performed with simple control. The effect is obtained.

In particular, this is a very useful technique when applied to a vehicle-mounted hydraulic control system which requires highly accurate hydraulic control.

[Brief description of drawings]

1 (a) is a diagram corresponding to the claims of the active pulse pressure absorber of the invention of claim 1, and FIG. 1 (b) is the active pulse pressure absorber of the invention of claim 2; It is a claim corresponding figure of an apparatus.

FIG. 2 is an overall system diagram showing an active pulse pressure absorber of the first embodiment.

FIG. 3 is a flowchart showing a flow of servo valve control operation performed by the controller of the first embodiment device.

FIG. 4 is a diagram showing a converged state of flow rate changes when the rotational speed of the hydraulic pump is constant.

FIG. 5 is a diagram showing a state where the opening area change profile of the servo valve converges to the final profile.

FIG. 6 is a diagram showing a flow rate change profile when the rotational speed of the hydraulic pump changes.

FIG. 7 is a frequency characteristic of the flow rate fluctuation absorbing ability of the accumulator.

FIG. 8 is an overall system diagram showing an active pulse pressure absorber according to a second embodiment.

FIG. 9 is a time chart showing a flow rate characteristic and a throttle area characteristic in the second embodiment device.

FIG. 10 is an overall system diagram showing a conventional pulse pressure absorber.

FIG. 11 is a frequency characteristic diagram of the discharge flow rate fluctuation level in the conventional device.

[Explanation of symbols]

a Pulsation source b Load c Piping c ₁ Main piping c ₂ Branch piping d Accumulator e Variable throttle f Unsteady flow rate measuring means g Controller h Reservoir

Claims (3)

[Claims] 1. A pipe connecting a pulsation source at one end and a load at the other end, an accumulator provided in the middle of the pipe, a variable throttle provided downstream of the accumulator, and a downstream of the variable throttle. An unsteady flow rate measurement unit that is provided to measure the unsteady flow rate of the discharge oil discharged from the pulsation source, and reduces the flow rate fluctuation based on the unsteady flow rate measurement value measured from the unsteady flow rate measurement unit. An active pulse pressure absorbing device, comprising: a controller that controls a throttle amount of the variable throttle. 2. A main pipe connecting a pulsation source at one end and a load at the other end, and an unsteady flow rate provided in the middle of the main pipe for measuring an unsteady flow rate of discharge oil discharged from the pulsation source. Measuring means; a variable throttle provided in the middle of the branch pipe from the main pipe to the reservoir; and the variable throttle so as to reduce the flow rate fluctuation based on the unsteady flow rate measurement value measured by the unsteady flow rate measuring means. An active pulse pressure absorbing device comprising: a controller for controlling the throttling amount of the. 3. The variable valve is a servo valve in which the throttle amount is controlled by the magnitude of the voltage applied to the two laminated piezoelectric elements arranged at both ends of the spool. 2. The active pulse pressure absorber according to 2.