CN1313732C - Piezo-electric compressor with displacement amplifier - Google Patents

Abstract

A compressor ( 300 ) for successive suction and discharge of a compressible fluid, thereby increasing fluid pressure of the compressible fluid in a substantially closed chamber, the compressor ( 300 ) comprising: at least one piezoelectric element ( 22 ); a primary displacement member ( 46 ) coupled to the at least one piezoelectric element ( 22 ); a secondary displacement member ( 44 ) coupled to the piston ; and a non-compressible fluid ( 45 ) disposed to fill a fixed predetermined volume between the primary displacement member ( 46 ) and the secondary displacement member ( 44 ); wherein electrical actuation of the piezoelectric element is controllable to displace the primary displacement member ( 46 ) by a predetermined distance, being coupled via the noncompressible fluid to displace the secondary displacement member ( 44 ) by an amplified distance based upon the fixed predetermined volume.

Description

Piezo Compressor with Displacement Amplifier

technical field

This invention relates to fluid compressors, and more particularly to the use of piezoelectric devices in fluid compressors and pumps.

Background technique

Piston compressors are positive displacement compressors. Positive displacement compressors take in a continuous volume of fluid, enclose it in a well-sealed cavity, and raise it to a higher pressure or compression. Piston compressors use a piston in a cylinder (piston-cylinder assembly) as the compression element to perform this function. The fluid can be gas or liquid, or a mixture of the two, such as refrigerants at different pressures.

Piston compressors use at least two one-way valves in each cylinder, and the one-way valves only open when a predetermined pressure differential acts across the valves. The suction check valve (hereinafter referred to as the suction valve) opens when the fluid pressure in the cylinder drops, allowing fluid to enter the cylinder. The discharge check valve (hereinafter referred to as the discharge valve) opens when the compression ends and the fluid pressure in the cylinder increases to push the fluid out of the cylinder. The continuous suction and discharge of fluid by the cylinder allows the fluid to be continuously discharged under high pressure.

In order for the cylinder to continuously suck in and expel fluid, the piston must reciprocate linearly in the cylinder. Referring to FIG. 1 , which shows a conventional piston compressor, the piston-cylinder assembly includes a suction chamber 11 , a discharge chamber 12 , a suction valve 13 , a discharge valve 14 , a cylinder 15 , a cylinder bore 21 and a piston 16 . Such piston cylinder assemblies are well known to those skilled in the art.

In a piston compressor, the linear reciprocating motion of the piston 16 for sucking in and discharging fluid is performed by a mechanical assembly, such as a rotary motor assembly. The rotary motor assembly includes a rotary motor 19 , a crank 18 and a connecting rod 17 . The rotary motion of the rotary motor 19 is converted into linear up/down or forward/backward motion through the crank 18 and the connecting rod 17, forming the linear reciprocating motion required during the operation of the piston compressor. The downward movement of the piston 16 reduces the pressure in the cylinder bore 21 causing the suction valve 13 to open. As a result, fluid enters the cylinder bore 21 through the suction chamber 11 . The downward movement of the piston 16 is called the suction stroke.

On the other hand, the upward movement of the piston 16 compresses the fluid, increasing the fluid pressure, so that the suction valve 13 is closed and the discharge valve 14 is opened. In this way, fluid is pressed from the cylinder bore 21 into the discharge chamber 12 . The upward movement of the piston 16 is called the discharge stroke.

The rotary motor assembly described above uses several mechanical connections and thus has multiple moving parts. However, such rotary motor assemblies are unnecessarily complex and require maintenance in various aspects such as lubrication and replacement of connections. The non-coaxial mechanical forces acting on the piston 16 also cause additional vibration and noise. Also, the above-mentioned rotary motor assembly is prone to mechanical failure due to wear.

A linear actuator can be used instead of a rotary motor assembly. Linear actuators are well known to those skilled in the art, and piezoelectric elements are used in many such actuators. Typically, piezoelectric elements convert electrical energy into mechanical energy in such actuators. In a piezoelectric actuator, electrical energy is applied to one or more piezoelectric elements, causing the piezoelectric elements to deform, thereby physically actuating at least one other element. A limitation of existing piezoelectric actuators is the relatively small amount of physical deformation of the piezoelectric element. Therefore, the application of piezoelectric actuators is limited to miniature devices. Typically, the displacement range required for such microdevices is from a few micrometers to a few millimeters.

In order to overcome the limitation of relatively small displacement of piezoelectric actuators, in US Patent No. 5,063,542, Petermann et al. described a displacement amplifier for connecting piezoelectric actuators and displacement elements. The piezoelectric actuator has a bellows member that forms an expandable cavity that can be filled with fluid and responds to the linear displacement of the piezoelectric disc, providing amplified linear displacement to the displacement element. However, the problem with the displacement amplifier of Petermann et al. in US Pat. No. 5,063,542 is that the expandable cavity is not fixed, so it is difficult to precisely control the amplified linear displacement. This concept of using piezoelectric actuators in conjunction with hydraulic displacement amplifiers is further described in US Patent 5,074,654 by Alden et al. and in US Patent 5,697,554 by Auwaerter et al. In Alden et al., multiple piezoelectric actuators connected to a hydraulic displacement amplifier are used to control a deformable mirror. In Auwaerter et al., a metering valve for metering fuel injection fluid uses a piezoelectric element connected to a hydraulic displacement amplifier to actuate a valve needle to control the amount of injected fuel.

Therefore, there is a real need for a linear motor using a piezoelectric element with a controllable displacement amplifier to overcome or at least reduce the complexity, maintenance and mechanical failure problems currently present in reciprocating compressors.

Contents of the invention

It is an object of the present invention to provide a piezoelectric device for use in fluid compressors and pumps.

Accordingly, in one aspect the present invention provides a compressor having a piston-cylinder assembly capable of continuously sucking in and expelling a compressible fluid to increase the pressure of the compressible fluid in a substantially sealed cavity, wherein the piston-cylinder assembly includes a piston, cylinder , a cylinder bore, a suction chamber with a suction valve, and a discharge chamber with a discharge valve, the compressor comprising: at least one piezoelectric element; a main displacement part connected to the at least one piezoelectric element; a slave displacement part connected to the piston; And incompressible fluid filled in the fixed predetermined volume of the main displacement part and the slave displacement part; wherein the electric drive on at least one piezoelectric element can controllably cause the main displacement part to produce a predetermined distance displacement, and the generated predetermined distance Displacement through an incompressible fluid connection causes a displacement of the slave displacement member to an amplified distance dependent on a fixed predetermined volume.

In another aspect, the present invention provides a compressor having a piston-cylinder assembly capable of continuously sucking in and expelling a compressible fluid to increase the pressure of the compressible fluid in a substantially sealed cavity, wherein the piston-cylinder assembly includes a piston, A cylinder, a cylinder bore, a suction chamber with a suction valve, and a discharge chamber with a discharge valve, the compressor includes: at least one piezoelectric element; a main displacement part connected to the at least one piezoelectric element; a slave displacement part connected to the piston; and an incompressible fluid filled within fixed predetermined volumes of the main displacement member and the slave displacement member; wherein, in response to electrical actuation on the at least one piezoelectric element, the displacement of the slave displacement member is amplified according to the displacement of the master displacement member, so The amplified displacement depends on the fixed predetermined volume and the contact area of the primary and secondary displacement elements with the incompressible fluid.

Also, the present invention provides a fluid delivery device with a piston-cylinder assembly capable of continuously sucking and discharging fluid, wherein the piston-cylinder assembly includes a piston, a cylinder, a suction chamber with a suction valve, and a discharge chamber with a discharge valve. The device comprises: at least one piezoelectric element; a main displacement part connected to the at least one piezoelectric element; a slave displacement part connected to the piston; and an incompressible fluid filled in a fixed predetermined volume of the main displacement part and the slave displacement part ; wherein, in response to electrical actuation on at least one piezoelectric element, the displacement of the slave displacement member is amplified according to the displacement of the master displacement member, the amplified displacement being dependent on the fixed predetermined volume and the relationship between the master and slave displacement members and the incompressible fluid the contact area.

Description of drawings

By way of example, the preferred embodiment of the present invention and the other two are described in detail with reference to the accompanying drawings

Example. in:

Figure 1 shows a prior art piston compressor;

Figure 2 shows a compressor according to a first embodiment of the invention;

Figure 3 shows a compressor according to a second embodiment of the invention; and

Figure 4 shows a compressor according to a preferred embodiment of the present invention.

Detailed ways

Referring to FIG. 2, there is shown a piezoelectric compressor 100 according to a first embodiment of the present invention. The piezoelectric compressor 100 includes a piston-cylinder assembly similar to that in a conventional piston compressor as shown in FIG. 1 . However, instead of the conventional linear reciprocating motion provided by the rotary motor 19 , crank 18 and connecting rod 17 , the present piezoelectric compressor 100 uses at least one piezoelectric element 22 directly attached to the piston 16 .

When the driving electric signal is transmitted to the piezoelectric element 22, the piezoelectric element 22 is deformed, so that the piston 16 produces a linear displacement (discharge stroke) upward for a predetermined distance. This causes the fluid pressure in the cylinder bore 21 to increase and the discharge valve 14 to open, allowing compressible fluid to flow from the cylinder bore 21 into the discharge chamber 12 . Then the electric signal is driven to electrically drive the piezoelectric element 22 to generate deformation, so that the piston 16 generates a linear displacement (suction stroke) of a predetermined distance downward. This reduces the fluid pressure in the cylinder bore 21 and the suction valve 13 opens, allowing compressible fluid to flow from the suction chamber 11 into the cylinder bore 21 .

The drive electrical signal delivered to piezoelectric element 22 is generally consistent with the regulatory control usage of piezoelectric element 22 . The driving electrical signal includes a series of voltage or current pulses with a predetermined intensity for driving the piezoelectric element 22 .

When the driving electric signal is continuously transmitted to the piezoelectric element 22, the piezoelectric element 22 is electrically driven to produce opposite deformations in the respective directions of performing the suction stroke or the discharge stroke. Accordingly, the linear reciprocating motion of the piezoelectric element simultaneously causes the linear reciprocating motion of the piston 16 required to operate the piezoelectric compressor 100 . The operation of the piston-cylinder assembly in piezoelectric compressor 100 is similar to that of a conventional piston compressor. The advantage of the piezoelectric compressor 100 is that there are fewer moving parts and mechanical failures are less likely to occur. The piezoelectric compressor is suitable as a small or micro compressor, and is used in occasions that require continuous and stable dynamic operation while bearing a fixed load. Likewise, the piezoelectric compressor is suitable as a fluid delivery device, such as a pump. When used as a pump, the fluid delivered may be compressible or incompressible.

Referring to FIG. 3, there is shown an improved piezoelectric compressor 200 according to a second embodiment of the present invention. In addition to using at least one piezoelectric element 22, a displacement amplifying device, such as a spring 32, is added. Typical linear displacements achieved by piezoelectric elements range from a few microns to a few millimeters. In a specific application, such a small displacement is difficult to form a sufficient linear reciprocating motion, so that the piezoelectric compressor cannot work with a large enough capacity. The spring 32 can be used as a displacement amplifier to convert the linear reciprocating motion of the piezoelectric element 22 into an amplified linear reciprocating motion. Accordingly, the linear reciprocating motion of the piston 16 is also amplified, thereby increasing the amount of compressible fluid per suction and discharge stroke, thereby increasing the capacity of the piezoelectric compressor 200 . However, this amplified linear reciprocating motion with the spring 32 may not be easy to control, and may also form harmonics, which may finally hinder the linear reciprocating motion of the piezoelectric element 22 . This also depends on the inherent mechanical spring rate of the spring 32, which decreases with continued use.

Referring to FIG. 4 , it shows a super piezoelectric compressor 300 according to a third embodiment of the present invention. In addition to the advantage of the compressor having greater linear reciprocating motion of the piston 16, the linear reciprocating motion of the piston 16 can be better controlled at the same time. Such a function can be achieved by the super piezoelectric compressor 300 by using a hydraulic displacement amplifier. The hydraulic displacement amplifier includes a main displacement part 46 connected to the piezoelectric element 22 , a slave displacement part 44 connected to the piston 16 , and an incompressible fluid 45 filled in fixed predetermined volumes of the main displacement part 46 and the slave displacement part 44 . In this way, the incompressible fluid 45 connects the primary displacement member 46 and the secondary displacement member 44 . Such incompressible fluid 45 may be hydraulic oil or compressor lubricating oil. The displacement part 44 is then connected with the piston 16 through the piston rod 42 . The contact area of the primary displacement member 46 with the incompressible fluid 45 is generally larger than the contact area of the slave displacement member 44 with the incompressible fluid 45 .

When the driving electric signal is transmitted to the piezoelectric element 22, the piezoelectric element 22 deforms the main displacement member 46 and produces a displacement of a small predetermined distance. However, displacement by the incompressible fluid 45 from the displacement member 44 amplifies the predetermined distance, and thus the displacement of the piston 16 by the piston rod 42 amplifies the predetermined distance. The degree of amplification of the displacement of the slave displacement member 44 depends on the fixed predetermined volume and the size/surface area of the master and slave displacement members.

The relationship between the amplified displacement and the surface area of the main displacement part 46, the displacement of the main displacement part 46 predetermined distance and the displacement from the displacement part 44 is as follows:

$\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; A</span>}}{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; l</span>}$

Where L is the amplified displacement of the slave displacement component 44 , and l is the displacement of the predetermined distance of the primary displacement component 46 . A is the contact area between the primary displacement component 46 and the incompressible fluid 45 , and a is the contact area between the secondary displacement component 44 and the incompressible fluid 45 .

The baffle plate 47 is connected with the piston spring 43, and the spring is connected with the slave displacement part 44 again. The baffle plate 47 and the piston spring 43 jointly urge the slave displacement member 44 to perform linear reciprocating motion. This also causes the piston 16 to perform linear reciprocating motion.

The hydraulic displacement amplifier not only has the function of amplifying the linear displacement of the piezoelectric element 22, but also can better control the linear reciprocating motion of the piston 16.

The piezoelectric compressors 100 , 200 and 300 in FIG. 2 , FIG. 3 and FIG. 4 are all described and illustrated in a vertical orientation manner, and each has a specific explanation. However, those skilled in the art can understand that operating the piezoelectric compressors 100 , 200 and 300 in other directions does not depart from the scope of the present invention. In addition, piezoelectric compressors may also be used in multiples, in different arrangements, and in other than compressor and pump situations, all without departing from the scope of the present invention. It should be understood that various adjustments and improvements can be made by those skilled in the art without departing from the scope of the present invention.

Claims (21)

1. A compressor having a piston-cylinder assembly capable of continuously sucking in and expelling a compressible fluid, thereby increasing the fluid pressure of said compressible fluid in a substantially sealed cavity, wherein said piston-cylinder assembly comprises a piston, a cylinder , a cylinder bore, a suction chamber with a suction valve, and a discharge chamber with a discharge valve, the compressor comprising: at least one piezoelectric element; a primary displacement component connected to said at least one piezoelectric element; a slave displacement member connected to said piston; and an incompressible fluid filled within fixed predetermined volumes of said primary displacement member and said secondary displacement member; wherein the electric drive on the at least one piezoelectric element controllably causes the primary displacement member to displace a predetermined distance, and the primary displacement member, through an incompressible fluid, causes the slave displacement member to generate a displacement depending on the Fixed the displacement of the magnification distance for the predetermined volume. 2. The compressor of claim 1, wherein said at least one piezoelectric element is adapted to receive an electrical signal for electrical actuation. 3. The compressor of claim 2, wherein said electrical signal comprises a series of voltage pulses. 4. The compressor of claim 2, wherein said electrical signal comprises a series of current pulses. 5. The compressor of claim 1, further comprising a damper and a piston spring installed between the damper and the secondary displacement member. 6. The compressor of claim 1, wherein said incompressible fluid comprises hydraulic oil or compressor lubricating oil. 7. The compressor of claim 1, wherein a contact area of the primary displacement member with the incompressible fluid is larger than a contact area of the slave displacement member with the incompressible fluid. 8. A compressor having a piston-cylinder assembly capable of continuously sucking in and expelling a compressible fluid, thereby increasing the fluid pressure of said compressible fluid in a substantially sealed cavity, wherein said piston-cylinder assembly comprises a piston, a cylinder . A suction chamber with a suction valve and a discharge chamber with a discharge valve, the compressor comprising: at least one piezoelectric element; a primary displacement component connected to said at least one piezoelectric element; a slave displacement member connected to said piston; and an incompressible fluid filled within fixed predetermined volumes of said primary displacement member and said secondary displacement member; Wherein, in response to the electric drive on the at least one piezoelectric element, the displacement of the slave displacement member is amplified according to the displacement of the master displacement member, the amplified displacement depends on the fixed predetermined volume and the Contact areas of the primary displacement member and the secondary displacement member with the incompressible fluid. 9. The compressor of claim 8, wherein the at least one piezoelectric element is adapted to receive an electrical signal for electrical actuation. 10. The compressor of claim 9, wherein said electrical signal comprises a series of voltage pulses. 11. The compressor of claim 9, wherein said electrical signal comprises a series of current pulses. 12. The compressor of claim 8, further comprising a damper and a piston spring installed between the damper and the secondary displacement member. 13. The compressor of claim 8, wherein said incompressible fluid comprises hydraulic oil or compressor lubricating oil. 14. The compressor of claim 8, wherein a contact area of the primary displacement member with the incompressible fluid is larger than a contact area of the slave displacement member with the incompressible fluid. 15. A fluid delivery device having a piston-cylinder assembly capable of continuously sucking and discharging fluid, wherein the piston-cylinder assembly includes a piston, a cylinder, a suction chamber with a suction valve, and a discharge chamber with a discharge valve, the fluid delivery Devices include: at least one piezoelectric element; a primary displacement component connected to said at least one piezoelectric element; a slave displacement member connected to said piston; and an incompressible fluid filled within fixed predetermined volumes of said primary displacement member and said secondary displacement member; Wherein, in response to the electric drive on the at least one piezoelectric element, the displacement of the slave displacement member is amplified according to the displacement of the master displacement member, the amplified displacement depends on the fixed predetermined volume and the The contact area between the master displacement member and the slave displacement member with the incompressible fluid. 16. The fluid delivery device of claim 15, wherein the at least one piezoelectric element is adapted to receive an electrical signal for electrical actuation. 17. The fluid delivery device of claim 16, wherein the electrical signal comprises a series of voltage pulses. 18. The fluid delivery device of claim 16, wherein the electrical signal comprises a series of current pulses. 19. The fluid delivery device of claim 15, further comprising a baffle and a piston spring mounted between the baffle and the secondary displacement member. 20. The fluid delivery device of claim 15, wherein the incompressible fluid comprises hydraulic oil or compressor oil. 21. The fluid delivery device of claim 15, wherein the contact area of the primary displacement member with the incompressible fluid is greater than the contact area of the slave displacement member with the incompressible fluid.

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