JPH06294375A - Active pulse pressure absorber - Google Patents

Abstract

PURPOSE:To equalize responsiveness of a piston regardless of the piston displacement direction in absorbing of pulse flow rate and also to secure linearity of the displacement of laminated piezo elements by making a piston into a double rod piston, and arranging a first laminated piezo element to which control voltage is alternately applied on the rods on the piston both sides. CONSTITUTION:A piston is made into a double rod piston 28, and a first laminated piezo element 30 and a second laminated piezo element 31 to which control voltage is alternately applied are respectively arranged on rods 28a, 28b on the piston both sides. And they are communicated with each other so that both pressure chambers 26, 27 may hold the same line pressures. Thereby, one side becomes the extension side while the other side becomes the contraction side when both laminated piezo elements 30, 31 are displaced to any sides, and responsiveness of the piston is equalized regardless of the displacement direction in absorbing of pulse flow rate. Moreover, since this absorber has the structure wherein same loads are applied to the extension side and the contraction side of the laminated piezo elements 30, 31, linearity of the displacement to voltage of the laminated piezo elements 30, 31 can be held.

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 absorbing a pulsating flow rate from a pulsating source such as a pump hydraulic pressure source.

[0002]

2. Description of the Related Art Conventionally, as an active noise canceling device for exhaust noise as an active pulse pressure absorbing device of this type, for example, one disclosed in Japanese Patent Laid-Open No. 61-234216 is known.

In the above-mentioned conventional source, an additional sound source is provided in the middle of the exhaust pipe, and the anti-phase wave of the noise emitted from the engine to the exhaust pipe is generated by the additional sound source to effectively cancel the noise. Technology is shown.

[0004]

However, in the above-mentioned conventional active noise canceling device for exhaust noise,
Since the exhaust noise is reduced by the performance of only the additional sound source, the noise in the low frequency response region of the additional sound source remains, and since the additional sound source is installed at the downstream position of the exhaust pipe, It is necessary to accurately grasp the impedance of the pipe and it is difficult to control. Furthermore, since the pressure wave generated by the additional sound source affects the noise source side, it is necessary to provide a pressure sensor on the output side as well.

Therefore, when the pulsation source is a hydraulic pump unit, the above conventional technique cannot be applied as it is. In addition, there is a plan to apply a technique of providing an accumulator in a discharge pipe in a hydraulic pump unit to provide a plurality of pulse pressure reducing accumulators having different capacities for each frequency region from a low frequency region to a high frequency region. In this case, it is disadvantageous in terms of space and cost.

Therefore, the present applicant has previously filed Japanese Patent Application No. 3-522.
No. 51 (filed on March 18, 1991) and Japanese Patent Application No. 3-5
The means for solving the above problem was proposed by the application specification and drawings of No. 5254 (filed on Mar. 20, 1991).

In this prior application, as shown in FIG. 6, a hydraulic pump 1 as a pulsation source and a hydraulic pipe 2 for connecting a load on the other end side, and a hydraulic pipe 2 provided in the middle of the hydraulic pipe 2 are laminated. There is a pulsating pressure absorption unit 4 that applies a voltage to the piezo element 3 to generate a pulsating flow rate, and a hydraulic line 2 between the hydraulic pump 1 and the pulsation pressure absorption unit 4, and the discharge oil discharged from the hydraulic pump 1 An unsteady flow meter 7 for measuring an unsteady flow rate, a controller 8 for controlling an applied voltage to the laminated piezo element 3 so as to cancel a flow rate fluctuation measured by the unsteady flow meter 7, and a power supply 9 are provided, and a pump pulsation is provided. Pulse pressure absorption unit 4
A technique for reducing is shown in. The spring 13
Serves to disperse all of the force due to the line pressure from the hydraulic pump 1 to be applied to the laminated piezoelectric element 3.

However, the above-mentioned prior art also has the problems listed below.

(1) When the displacement of the laminated piezo element 3 is changed by increasing / decreasing the applied voltage, the response speed is determined by the pressure in the conduit, the force of the spring 13 and the force of the laminated piezo element 3, and When the oil in the inside is compressed, an applied voltage is applied to the laminated piezoelectric element 3, and the spring 13 pushes the piston 5 against the pressure of the oil together with the force, and when expanding the oil in the pipeline, the laminated piezoelectric element 3 is compressed. Since the applied voltage is reduced and the spring 13 is pushed back by the pressure of the oil, the response of the piston 5 is different when the applied voltage of the laminated piezo element 3 is increased and extended and when the applied voltage is reduced and contracted. . In addition, since the spring 13 is inserted in parallel with the laminated piezo element 3 so that the spring 13 bears a part of the force applied to the piston 5 by the pressure, when the laminated piezo element 3 is contracted and when it is extended. The load applied at the different points differs, and as shown in FIG. 7, the linearity of the displacement of the laminated piezoelectric element 3 with respect to the voltage is lost.

As described above, the applied voltage control for the laminated piezo element 3 must be corrected.

(2) Since the force due to the line pressure is applied to the laminated piezo element 3 via the piston 5, the load on the laminated piezo element 3 varies due to the fluctuation of the line pressure, and as shown in FIG. Further, the displacement characteristic of the laminated piezoelectric element 3 with respect to the voltage changes.

Further, since the force due to the line pressure is applied to the laminated piezo element 3 via the piston 5, the piston diameter is made too large to prevent the laminated piezo element 3 from being damaged by an excessive load. As a result, the volume of the hydraulic chamber also becomes small, and the pulsating flow with large amplitude cannot be absorbed.

The present invention has been made by paying attention to the above problems, and in an active pulse pressure absorbing device using a laminated piezoelectric element as a pulse pressure absorbing actuator, regardless of the piston displacement direction when absorbing the pulsating flow rate. A first object is to make the piston responsiveness the same, to secure the linearity of the displacement of the laminated piezo element with respect to the voltage, and to effectively absorb the pulsating flow rate in a wide frequency range by simple control.

In addition to the first problem, the second problem is to eliminate the change in the displacement characteristic of the laminated piezo element with respect to the voltage due to the influence of the fluctuation of the line pressure and to make it possible to absorb the pulsating flow having a large amplitude. And

[0015]

In order to solve the above first problem, in the active pulse pressure absorbing device according to the first claim, the piston is a double rod piston, and the control voltage is alternately applied to the first laminated layer. The piezo element and the second laminated piezo element were respectively arranged on the rods on both sides of the piston.

That is, a fluid pressure circuit for connecting a pulsation source at one end and a load at the other end, and a fluid pressure circuit provided in the middle of the fluid pressure circuit,
A cylinder having a pulsation source side port and a load side port, a first pressure chamber slidably arranged in the cylinder and communicating with the pulsation source side port and the load side port, and fluid is not directly introduced from the pulsation source Both rod pistons that define a cylinder inner chamber in the second pressure chamber, an accumulator that communicates with the second pressure chamber, and a first rod arranged on the first rod side and the second rod side of the two rod pistons, respectively. The laminated piezo element and the second laminated piezo element, the pulsating flow rate equivalent information detecting means for detecting the pulsating flow rate equivalent information generated in the pulsating source, and the pulsating flow rate from the pulsating flow source based on the pulsating flow rate equivalent information detection value It is characterized by further comprising pulsating flow rate absorption control means for alternately applying a control voltage to both the laminated piezoelectric elements so as to cancel them in the pressure chamber.

In order to solve the above-mentioned second problem, in the active pulse pressure absorber according to claim 2, in the active pulse pressure absorber according to claim 1, both the pressure chambers are communicated with each other, and the first pressure chamber is connected. Is provided with a communication passage for guiding the line pressure to the second pressure chamber.

[0018]

The operation of the present invention will be described. When the pulsation source is operating, the pulsation flow rate absorption control means cancels the pulsation flow rate from the pulsation source in the first pressure chamber based on the pulsation flow rate equivalent information detection value from the pulsation flow rate equivalent information detection means. And the control voltage is alternately applied to the second laminated piezoelectric element.

At the time of absorbing the pulsating flow rate, when compressing the fluid in the first pressure chamber, for example, an applied voltage is applied only to the second laminated piezo element so that both rod pistons are made to reduce the volume of the first pressure chamber. The displacement and expansion of the fluid in the first pressure chamber are performed, for example, by applying an applied voltage only to the first laminated piezo element and displacing both rod pistons in a direction to increase the volume of the first pressure chamber. . The volume change of the second pressure chamber due to the volume change of the first pressure chamber during absorption of the pulsating flow rate is absorbed by the accumulator.

That is, in both laminated piezo elements, one of them is an extension side and the other is a contraction side, whichever side is displaced.
Since the spring force does not act as in the prior art, the piston responsiveness is the same regardless of the displacement direction when absorbing the pulsating flow rate.

Further, since the same load is applied to the expansion side and the contraction side of both laminated piezo elements without using a spring, the linearity of displacement of the laminated piezo elements with respect to the voltage is maintained.

The operation of the invention according to claim 2 will be described. The fluid flowing from the pulsation source flows into the second pressure chamber from the first pressure chamber through the communication passage. Therefore, the line pressure component (static pressure component) from the pulsation source is applied to both surfaces of both rod pistons, and the force due to the line pressure is not applied to the laminated piezoelectric element. Therefore, the change of the displacement characteristic with respect to the voltage of the laminated piezo element due to the influence of the line pressure fluctuation is eliminated.

Further, since the load due to the line pressure is not applied to the laminated piezo element, no restriction is imposed on the setting of the piston diameter. Therefore, when the volume of the first pressure chamber is set large, it is possible to absorb the pulsating flow rate having a large amplitude.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. The configuration will be described. FIG. 1 is an overall system diagram showing an active pulse pressure absorbing device of an embodiment of the present invention corresponding to claims 1 and 2, and FIG. 2 is an enlarged detailed view showing a pulse pressure absorbing unit of the embodiment device.

As shown in FIGS. 1 and 2, the active pulse pressure absorber of the embodiment has an input oil passage 23 for connecting a hydraulic unit 21 (corresponding to a pulsation source) at one end and a load 22 at the other end. The output oil passage 24 (corresponding to a fluid pressure circuit) and the input oil passage 23
And a pump-side port 25
A cylinder 25 having a (corresponding to a pulsation source side port) and a load side port 25b, and a first pressure chamber 26 slidably arranged in the cylinder 25 and communicating with the pump side port 25a and the load side port 25b. And both rod pistons 28 defining a cylinder inner chamber in the second pressure chamber 27 into which oil is not directly introduced from the hydraulic unit 21, and the second pressure chamber 2
7 through an accumulator port 25c, a first laminated piezo element 30 and a second laminated piezo element 31 arranged on the first rod 28a side and the second rod 28b side of the rod pistons 28, respectively.
And a rotation angle sensor 32 (corresponding to pulsating flow rate equivalent information detecting means) arranged at the motor shaft position of the hydraulic unit 21.
And a controller 33 and a piezo drive circuit 34 that alternately apply a control voltage to the laminated piezoelectric elements 30 and 31 so as to cancel the pulsating flow rate from the hydraulic unit 21 in the first pressure chamber 26 based on the detected value of the pump rotation angle. (Corresponding to pulsation flow rate absorption control means).

The hydraulic unit 21 includes a pump motor 3
5, a hydraulic pump 36, and an accumulator 37.

As shown in FIG. 2, the two rod pistons 28 are slidably provided between the cylinder 25 and the cylinder 25 through a gap 38 (corresponding to a communicating passage). The gap 38 has a cross-sectional area that does not transmit the dynamic pressure due to the fluctuation of the hydraulic pressure in the first pressure chamber 26 but transmits the static line pressure to the second pressure chamber 27. Also,
First rod 28a, second rod 28b, and cylinder 25
The oil seals are kept by the rod seals 39 and 40.

The first laminated piezo element 30 and the second laminated piezo element 31 are, as shown in FIGS. 1 and 2, a first element frame 41 and a second element frame 42 fixed to a cylinder 25.
And a first steel ball 43 and a second steel ball 44 provided at the ends of the first rod 28a and the second rod 28b, respectively.

Cylinder 25, double rod piston 2
8, first laminated piezo element 30, second laminated piezo element 31
As described above, the pulse pressure absorption unit 45 is configured as shown in FIG.

The operation will be described. When the hydraulic pump 36 rotates, the pump rotation angle is detected by the rotation angle sensor 32 and sent to the controller 33. The controller 33 measures in advance the pulsating flow rate generation state with respect to the pump rotation angle, outputs a control signal according to a control program set based on the measurement result, and activates the piezo drive circuit 34 with this control signal. A control voltage is alternately applied to the first laminated piezo element 30 and the second laminated piezo element 31, and displacement is applied to both rod pistons 28 so as to cancel the pulsating flow rate from the hydraulic unit 21 in the first pressure chamber 26.

When absorbing the pulsating flow rate and compressing the oil in the first pressure chamber 26 when the pulsating flow rate is lower than the line flow rate, the voltage applied to the second laminated piezo element 31 is increased to increase the applied voltage to the first laminated piezo element 30. When the pulsating flow rate rises above the line flow rate and the oil in the first pressure chamber 26 is expanded when the oil pressure in the first pressure chamber 26 is decreased by displacing the two rod pistons 28 in a direction to reduce the volume of the first pressure chamber 26, First laminated piezo element 30
Is increased, the applied voltage to the second laminated piezo element 31 is decreased, and both rod pistons 28 are displaced in a direction to increase the volume of the first pressure chamber 26. The volume change of the second pressure chamber 27 due to the volume change of the first pressure chamber 26 at the time of absorbing the pulsating flow rate is absorbed by the accumulator 29.

Specifically, for both rod pistons 28,
When a displacement as shown in FIG. 3 is applied, a voltage as shown in FIG. 4 is applied to the first laminated piezo element 30, and a voltage as shown in FIG. 5 is applied to the second laminated piezo element 31. The waveforms of both voltages are waveforms that are mutually inverted.

That is, both of the laminated piezo elements 30 and 31 have one side to be expanded and the other side to be contracted regardless of the displacement, and the spring force does not act as in the prior art, so that the pulsating flow rate is absorbed. The piston response is the same regardless of the displacement direction.

Further, since the same load is applied to the extension side and the contraction side of both laminated piezo elements 30 and 31 without using a spring, the displacement of both laminated piezo elements 30 and 31 against the voltage is increased. Linearity is maintained.

The oil flowing from the hydraulic unit 21 passes through the gap 38 from the first pressure chamber 26 and the second pressure chamber 2
It flows into 7. Therefore, the line pressure component (static pressure component) from the hydraulic unit 21 is applied to both surfaces of the piston portion of both rod pistons 28, and the laminated piezoelectric elements 30, 3 are formed.
The force due to line pressure is not applied to 1. When the line pressure itself changes, the gap 38 is changed according to the change of the line pressure.
The pressure balance is maintained by the oil flowing through the second pressure chamber 27 into the second pressure chamber 27.

Therefore, the change of the displacement characteristic with respect to the voltage of the laminated piezo elements 30, 31 due to the influence of the fluctuation of the line pressure is eliminated.

The effect will be described. (1) Laminated piezo element 3 as a pulse pressure absorption actuator
In the active pulse pressure absorbing device using 0, 31, the pistons are the double rod pistons 28, and the first laminated piezo elements 30 and the second laminated piezo elements 31 to which the control voltage is alternately applied are connected to the rods 28a on both sides of the pistons. , 28b respectively, the piston response can be made the same regardless of the piston displacement direction at the time of absorbing the pulsating flow rate, and the linearity of displacement of the laminated piezo elements 30, 31 with respect to the voltage can be ensured for simple control. The pulsating flow rate can be effectively absorbed in a wide frequency range.

That is, in controlling the applied voltage to both the laminated piezo elements 30, 31, it is necessary to correct the piston response and the voltage-displacement linearity correction for the non-linearity due to the laminated piezo element being arranged in parallel with the spring. Instead, simple control of applying mutually inverted voltages in accordance with the pulsating flow rate generation state may be performed.

(2) Since the first pressure chamber 26 and the second pressure chamber 27 communicate with each other through the gap 38 so as to maintain the same line pressure, the laminated piezo element 30, which is affected by the fluctuation of the line pressure,
It is possible to eliminate the change in the displacement characteristic with respect to the voltage of 31 and to absorb the pulsating flow having a large amplitude.

As a result of eliminating the change in the displacement characteristic with respect to the voltage of the laminated piezo elements due to the influence of the fluctuation of the line pressure, the applied voltage control to both laminated piezo elements 30 and 31 is simpler because the fluctuation correction of the line pressure is not required. become.

The reason why the pulsating flow having a large amplitude can be absorbed is that the load due to the line pressure is not applied to the laminated piezo elements 30 and 31 so that when the piston diameter is set, the elements are destroyed as in the prior art. No restrictions are imposed. Therefore, the volume of the first pressure chamber 26 can be freely set as needed.

(3) Oil tightness of both pressure chambers 26 and 27 is rod seal 39 for sealing small diameter rods 28a and 28b.
Since it is performed by 40, the influence of friction can be reduced as compared with the case where oil tightness is maintained by the piston seal as in the prior art.

(4) Rod 28 of double rod piston 28
Since the laminated piezo elements 30, 31 are arranged at the ends of the a, 28b via the steel balls 43, 44, the force transmitted from the laminated piezo elements 30, 31 to the two rod pistons 28 is the piston. A force in an extra direction other than the displacement direction is not applied, and the transmission force loss from the element to the piston is suppressed to a small level.

(5) Cylinder 25, double rod piston 2
8, first laminated piezo element 30, second laminated piezo element 31
Since the pulsation pressure absorption unit 45 is configured by, etc., it is only necessary to mount the pulsation pressure absorption unit 45 in the middle of the fluid pressure circuit such as the existing hydraulic pipe through which the pulsation flow rate passes, and there is no need for major design changes. Is easy.

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

In the embodiment, an example of the rotation angle sensor for detecting the pump rotation angle is shown as the pulsating flow rate equivalent information detecting means, but various unsteady flowmeters as shown in Japanese Patent Application No. 3-55254 are used. May be.

[0048]

As described above, according to the present invention as set forth in claim 1, in the active pulse pressure absorbing device using the laminated piezoelectric element as the pulse pressure absorbing actuator, the piston is a double rod piston and Since the first laminated piezo element and the second laminated piezo element, to which the control voltage is alternately applied, are arranged on the rods on both sides of the piston, the same piston response can be obtained regardless of the piston displacement direction when absorbing the pulsating flow rate. At the same time, the linearity of the displacement of the laminated piezo element with respect to the voltage can be ensured, and the pulsating flow rate can be effectively absorbed in a wide frequency range by simple control.

According to the present invention of claim 2,
Since both pressure chambers communicate with each other so as to maintain the same line pressure, in addition to the above effects, it is possible to eliminate the change in displacement characteristics with respect to the voltage of the laminated piezo element due to the influence of line pressure fluctuations, and to increase the pulsating flow rate with large amplitude. The effect that absorption is possible is obtained.

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

[Brief description of drawings]

FIG. 1 is an overall system diagram showing an active pulse pressure absorber according to an embodiment of the present invention.

FIG. 2 is an enlarged detailed view showing a pulse pressure absorption unit of the active pulse pressure absorption device of the embodiment.

FIG. 3 is a displacement characteristic diagram of both rod pistons in the embodiment apparatus.

FIG. 4 is a diagram of applied voltage characteristics of the first laminated piezo element in the device of the example.

FIG. 5 is a characteristic diagram of applied voltage of the second laminated piezo element in the device of the example.

FIG. 6 is an overall view showing a prior art active pulse pressure absorber.

FIG. 7 is a voltage-displacement characteristic diagram in a preceding device in which an element and a spring are arranged in parallel.

FIG. 8 is a voltage-displacement characteristic diagram in a preceding device in which a line pressure acts on a piston.

[Explanation of symbols]

 21 hydraulic unit (pulsation source) 22 load 23 input oil passage (fluid pressure circuit) 24 output oil passage (fluid pressure circuit) 25 cylinder 25a pump side port (pulsation source side port) 25b load side port 26 first pressure chamber 27th 2 Pressure Chamber 28 Double Rod Piston 28a First Rod 28b Second Rod 29 Accumulator 30 First Stacked Piezo Element 31 Second Stacked Piezo Element 32 Rotation Angle Sensor (Pulsation Flow Rate Corresponding Information Detection Means) 33 Controller (Pulsation Flow Rate Absorption Control Means) 34 Piezo drive circuit (pulsation flow absorption control means)

Claims (2)

[Claims] 1. A fluid pressure circuit for connecting a pulsation source at one end to a load at the other end, a cylinder provided in the middle of the fluid pressure circuit, the port having a pulsation source side port and a load side port, and the inside of the cylinder. A double-rod piston that is slidably arranged and defines a cylinder inner chamber in a first pressure chamber in which the pulsation source side port and the load side port communicate with each other and a second pressure chamber in which fluid is not directly introduced from the pulsation source. An accumulator communicating with the second pressure chamber, a first laminated piezo element and a second laminated piezo element respectively arranged on the first rod side and the second rod side of the rod pistons, and generated by the pulsation source Pulsating flow rate equivalent information detecting means for detecting the pulsating flow rate equivalent information, and alternately on both the laminated piezoelectric elements so as to cancel the pulsating flow rate from the pulsating source in the first pressure chamber based on the detected value of the pulsating flow rate equivalent information. An active pulsation pressure absorption device comprising: a pulsation flow absorption control means for applying a control voltage to the. 2. The active pulse pressure absorber according to claim 1, further comprising a communication passage that connects the pressure chambers and guides the line pressure of the first pressure chamber to the second pressure chamber. Active pulse pressure absorber.