Abstract:
A hydraulic engine which may generate rotational power by using environmentally friendly electric energy and have improved performance and a long life span, and more particularly, environmentally friendly hydraulic power units that that may extrude a working fluid to realize an engine and has a long life span. The hydraulic engine includes: a housing; a rotor that is rotatably supported in the housing and allows rotor blades to be disposed therearound; a plurality of hydraulic power units that are disposed around the rotor to be spaced apart from one another; and an output shaft that rotates as the rotor rotates and the output shaft protrudes beyond the housing, wherein a fluid extruded from hydraulic power units pressurizes the rotor blades and generates a rotational force of the output shaft.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a hydraulic power unit and a hydraulic engine including the same, and more particularly, to a hydraulic power unit that includes a ceramic oscillator and may introduce or extrude a fluid due to an operation of the ceramic oscillator, and a hydraulic engine that includes the hydraulic power unit and generates a rotational force. 
         [0003]    2. Description of the Related Art 
         [0004]    Power, which is used for driving vehicles, various machines, or mechanisms, is usually obtained by burning fossil fuel. When fossil fuel is burnt, a lot of carbon dioxide is generated and various other harmful materials are produced, thereby polluting the environment. Also, since there is a limited amount of fossil fuel such as crude oil or coal on the earth, there is a limitation to depending on such fossil fuel. Accordingly, attempts to find new energy sources and develop methods of efficiently using existing energy sources have been conducted. 
         [0005]    Results of the attempts made so far include a method of generating electric energy by charging batteries to power vehicles or other machines and a hybrid method using both combustion of fossil fuel and energy from batteries. However, there is a performance limitation with respect to conventional power systems (engines) using electric energy. Accordingly, there is a demand for a power system which does not generate carbon dioxide, generates environmentally friendly electric energy, and has improved performance and a long life span. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides an engine which may generate rotational power by using environmentally friendly electric energy and may have improved performance and a long life span. 
         [0007]    The present invention also provides an environmentally friendly hydraulic power unit that may extrude a working fluid to realize an engine and may have a long life span. 
         [0008]    According to an aspect of the present invention, there is provided a hydraulic engine including: a housing; a rotor that is rotatably supported in the housing and allows rotor blades to be disposed therearound; a plurality of hydraulic power units that are disposed around the rotor to be spaced apart from one another; and an output shaft that rotates as the rotor rotates and the output shaft protrudes beyond the housing, wherein each of the plurality of hydraulic power units includes: a hydraulic tube that has a cavity therein, allows a fluid inlet through which a fluid may be introduced and a fluid outlet through which a fluid may be extruded to be formed in a surface thereof, and has a front end portion closed, wherein the fluid inlet and the fluid outlet are formed as V-shaped grooves, an outer check ring that is formed of an elastic material and is disposed to be attached to the outer V-shaped groove of the hydraulic tube to close the fluid outlet; an inner check ring that is formed of an elastic material and is disposed to be attached to the inner V-shaped groove of the hydraulic tube to close the fluid inlet in the cavity of the hydraulic tube; an oscillation tube that includes an insulating oil chamber that includes an elastic tube layer in which a cavity is formed and a metal tube layer disposed around an outer circumferential surface of the elastic tube layer, and a transmission holder that is disposed on a rear end portion of the insulating oil chamber and receives a force applied from an oscillator; an amplitude amplification device that includes a casing that is disposed under the oscillation tube and has a cavity therein, a swell tube that is disposed in the casing, has a cylindrical shape with a cavity therein, and has a plurality of slits formed in a longitudinal direction in a surface thereof; and an elastic chip that is disposed in the swell tube to cross the cavity of the swell tube; the oscillator that is disposed under the amplitude amplification device to be deformed toward or away from the hydraulic tube, and increases or reduces a pressure of a fluid in the hydraulic tube and the oscillation tube; and an oscillation front end portion that is partially inserted into the swell tube and is connected to the oscillator. 
         [0009]    When electric energy is applied to the oscillator, the oscillator may be deformed due to a converse piezoelectric effect toward or away from the cavity of the hydraulic tube. 
         [0010]    The amplitude amplification device may be configured such that a portion of the transmission holder and a portion of the oscillator front end portion are inserted into the cavity of the swell tube, and the elastic chip is disposed between the transmission holder and the oscillator front end portion, wherein the elastic chip is formed of an elastic material and has a restoring force to return to its original shape after being deformed, has a circular plate shape having a curvature and a protruding central portion, and has a plurality of holes formed in a circumferential direction thereof. 
         [0011]    The plurality of holes may have fan shapes each having a portion of a circumferential surface of the elastic chip as an arc. 
         [0012]    A plurality of slits which extend in a longitudinal direction may be formed in the metal tube layer. 
         [0013]    A protrusion that helps the hydraulic tube to be kept deformed inward may be formed on a rear end of the oscillation tube. 
         [0014]    A plurality of the fluid inlets may be formed around the hydraulic tube, and a plurality of the inner check rings may be disposed to contact V-shaped grooves of the plurality of fluid inlets and close the plurality of fluid inlets. 
         [0015]    A plurality of the fluid outlets may be formed around the hydraulic tube, and a plurality of the outer check rings may have ring shapes, may be disposed to contact V-shaped grooves of the plurality of fluid outlets, and may close the plurality of fluid outlets. 
         [0016]    The hydraulic engine may further include a front end accumulation unit that is disposed on a closed front end of the hydraulic tube, wherein the front end accumulation unit includes an accumulation plate, a front end cap, a spring guide tube, and a spring, wherein the spring is disposed between the front end cap and the accumulation plate and applies an elastic force between the front end cap and the accumulation plate. 
         [0017]    The hydraulic engine may further include an insulating oil circulation cooling device, wherein the insulating oil circulation cooling device is disposed to connect at least two hydraulic power units, and includes: a first pipeline and a second pipeline that connect the hydraulic power units; a valve unit that connects the first pipeline and the second pipeline; a third pipeline that is connected to the first pipeline and the second pipeline and is provided with cooling effect of a cooler; a first check ball receiving portion that is disposed in the first pipeline; a first check ball that is inserted into the first check ball receiving portion and is elastically deformable; and a second check ball that is disposed between the hydraulic power units and the first pipeline and is elastically deformable. 
         [0018]    The hydraulic engine may further include a sleeve flange on which the rotor and the hydraulic power units may be disposed, wherein the sleeve flange includes: a cavity in which the rotor is disposed; a plurality of arrangement holes that are disposed outside the cavity and allow the hydraulic power units to be disposed therein; a plurality of extrusion slots that are formed in a front portion of a side surface of the sleeve flange with the cavity and extend in a longitudinal direction; and 
         [0019]    a plurality of introduction slots that are formed in a rear portion of the side surface of the sleeve flange with the cavity and extend in the longitudinal direction, wherein the rotor includes double helical blades, and is inserted into the cavity of the sleeve flange. 
         [0020]    The hydraulic engine may further include a driving module that drives the hydraulic power units, adjusts the number of rotations and torque of the rotor, and includes a secondary battery as a driving power source. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
           [0022]      FIG. 1  is a perspective view illustrating a hydraulic engine according to an embodiment of the present invention; 
           [0023]      FIG. 2  is a cross-sectional view illustrating the hydraulic engine of  FIG. 1 ; 
           [0024]      FIG. 3  is a perspective view illustrating a sleeve flange of the hydraulic engine of  FIG. 1 ; 
           [0025]      FIG. 4  is a cross-sectional view illustrating the sleeve flange of  FIG. 3 ; 
           [0026]      FIG. 5  is a cross-sectional view illustrating one of hydraulic power units; 
           [0027]      FIG. 6  is a cross-sectional view illustrating an oscillation tube; 
           [0028]      FIG. 7  is a cross-sectional view illustrating an amplitude amplification device; 
           [0029]      FIG. 8  is a cross-sectional view illustrating the amplitude amplification device; 
           [0030]      FIGS. 9 and 10  are cross-sectional views for explaining an operation of the amplitude amplification device of  FIG. 8 ; 
           [0031]      FIG. 11  is a cross-sectional view illustrating the amplitude amplification device of  FIG. 8 ; 
           [0032]      FIG. 12  is a view illustrating an insulating oil circulation cooling device in the hydraulic engine of  FIG. 1 ; and 
           [0033]      FIG. 13  is a circuit diagram for explaining an operation of the insulating oil circulation cooling device of  FIG. 12 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. 
         [0035]      FIG. 1  is a perspective view illustrating a hydraulic engine  100  according to an embodiment of the present invention.  FIG. 2  is a cross-sectional view illustrating the hydraulic engine  100  of  FIG. 1 .  FIG. 3  is a perspective view illustrating a sleeve flange  140  of the hydraulic engine  100  of  FIG. 1 .  FIG. 4  is a cross-sectional view illustrating the sleeve flange  140  of  FIG. 3 .  FIG. 5  is a cross-sectional view illustrating one of hydraulic power units  200 .  FIG. 6  is a cross-sectional view illustrating an oscillation tube  300 .  FIG. 7  is a cross-sectional view illustrating an amplitude amplification device  400 .  FIG. 8  is a cross-sectional view illustrating the amplitude amplification device  400 .  FIGS. 9 and 10  are cross-sectional views for explaining an operation of the amplitude amplification device  400  of  FIG. 8 .  FIG. 11  is a cross-sectional view illustrating the amplitude amplification device  400  of  FIG. 8 .  FIG. 12  is a view illustrating an insulating oil circulation cooling device  500  in the hydraulic engine  100  of  FIG. 1 .  FIG. 13  is a circuit diagram for explaining an operation of the insulating oil circulation cooling device  500  of  FIG. 12 . 
         [0036]      FIG. 2  is a cross-sectional view taken along line A-A′ of  FIG. 1  and  FIG. 12  is a cross-sectional view taken along line E-E′ of  FIG. 1 . 
         [0037]    Referring to  FIGS. 1 through 13 , the hydraulic engine  100  includes a housing  110 , a rotor  130 , an output shaft  120 , and a plurality of hydraulic power units  200 . 
         [0038]    The housing  110  defines an outer shape of the hydraulic engine  100 . The rotor  130  and the plurality of hydraulic power units  200  may be disposed in the housing  110 . 
         [0039]    The rotor  130  which is rotatably disposed in the housing  110  includes a plurality of rotor blades  132  that protrude in a radial direction of the rotor  130  about a rotational shaft of the rotor  130 . The rotor  130  may have a structure similar to that of a double helical gear. 
         [0040]    The output shaft  120 , which is formed by extending the rotational shaft of the rotor  130  disposed in the sleeve flange  140  or is integrally formed with the rotational shaft of the rotor  130 , protrudes beyond the housing  110 . 
         [0041]    A hydraulic oil cooling pump chamber  150  may be provided beside the output shaft  120 . 
         [0042]    An even number of, for example, four, hydraulic power units  200  which enable a fluid to be extruded or introduced in a tangential direction of the rotor  130  from or into the plurality of rotor blades  132  disposed on the rotor  130  may be provided around the rotor  130 . However, the number of the hydraulic power units  200  included in the hydraulic engine  100  is not limited to four, and two or more hydraulic power units  200  may be provided as long as every two hydraulic power units may operate as a pair. If the hydraulic power units  200  are grouped into sets, each set may include two hydraulic power units  200 , one common accumulator which will be explained below may be provided outside the housing  110  of the hydraulic engine  100 , and the hydraulic power units  200  may communicate with a common introduction chamber  233  and a common extrusion chamber  223 . 
         [0043]    In the hydraulic engine  100  of  FIG. 1 , from among the four hydraulic power units  200  disposed around the rotor  130 , every two hydraulic power units  200  operate as a pair and enable a fluid to flow. 
         [0044]    That is, when the hydraulic power units  200  disposed around the rotor  130  are referred to as first through fourth hydraulic power units  200   a ,  200   b ,  200   c , and  200   d  clockwise, an extrusion operation of the first and third hydraulic power units  200   a  and  200   c  and an introduction operation of the second and fourth hydraulic power units  200   b  and  200   d  may be simultaneously performed. In this case, a fluid extruded from the first and third hydraulic power units  200   a  and  200   c  may pass through the common extrusion chamber  223  in front of the sleeve flange  140 , pass through extrusion slots  146  formed in a front portion of the sleeve flange  140 , and pressurize the rotor blades  132  of the rotor  130  disposed in a cavity  141  of the sleeve flange  140  to rotate the rotor  130 . The fluid may pass through a plurality of introduction slots  144  formed in a rear portion of the sleeve flange  140 , pass through the common introduction chamber  233 , and may be introduced into inlets of the second and fourth hydraulic power units  200   b  and  200   d . The common extrusion chamber  223  and the common introduction chamber  233  may be separated from each other by the sleeve flange  140 . When the hydraulic engine  100  is driven by using the hydraulic power units  200 , every two hydraulic power units  200  may constitute one set and may communicate with the common introduction chamber  233  and the common extrusion chamber  223 . 
         [0045]    When each of the hydraulic power units  200  operates in reverse order by making a fluid flow in the same direction, rotational power may be applied to the rotor  130 . 
         [0046]    The hydraulic engine  100  may be used by connecting the output shaft  120  of the hydraulic engine  100  to vehicles or mechanical devices requiring a rotational force by means of power transmission elements such as pulleys, belts, or gears. That is, a member such as a pulley  111  may be coupled to the output shaft  120 . 
         [0047]    Referring to  FIG. 2 , the first and second hydraulic power units  200   a  and  200   b  are disposed at both sides of the rotor  130 . 
         [0048]    For easy attachment and detachment, the housing  110  may include a cover  112  and a main body housing  114 , and a seal member  116  may be disposed between the cover  112  and the main body housing  114  to prevent fluid leakage. 
         [0049]      FIG. 3  illustrates the sleeve flange  140 . Referring to  FIG. 3 , the sleeve flange  140  may act as a framework of the hydraulic engine  100 , and arrangement holes  142  that allow the hydraulic power units  200  to be disposed at right positions may be formed in the sleeve flange  140 . Also, the sleeve flange  140  may have a cylindrical shape having the cavity  141  in which the rotor  130  is disposed, and the introduction slots  144  and the extrusion slots  146  may be formed in the sleeve flange  140  such that a fluid may flow between the hydraulic power units  200  and the rotor  130 . The introduction slots  144  may be formed in the rear portion of the sleeve flange  140 , and the extrusion slots  146  may be formed in the front portion of the sleeve flange  140 . The introduction slots  144  and the extrusion slots  146  may extend in a longitudinal direction of the sleeve flange  140 . As shown in  FIG. 3 , the introduction slots  144  and the extrusion slots  146  may be inclined in a tangential direction of the rotor  130  instead of a radial direction of the rotor  130  such that a fluid introduced or extruded into or from the hydraulic power units  200  may easily rotate the rotor  130  through the rotor blades  132 . 
         [0050]    Each of the hydraulic power units  200  includes a front end accumulation unit  260 , a hydraulic tube  210 , the oscillation tube  300 , the amplitude amplification device  400 , and an oscillator  240 . 
         [0051]    The front end accumulation unit  260  is provided on a front end portion of each of the first and second hydraulic power units  200   a  and  200   b . The front end accumulation unit  260  does not need to be provided on all hydraulic power units  200 , and may be provided on only one, from among the plurality of hydraulic power units  200  which operate in pairs, which extrudes a fluid by using a first driving signal. 
         [0052]    The front end accumulation unit  260  which absorbs a fluid first extruded in the hydraulic tube  210  includes a front end cap  268 , a spring  262 , a spring guide tube  264 , and an accumulation plate  266 . The front end cap  268  is coupled to the hydraulic tube  210 , and both ends of the spring  262  are coupled to the front end cap  268  and the accumulation plate  266 . 
         [0053]    After a plurality of seal grooves  148  are formed in an outer surface of a rear end portion of the hydraulic tube  210 , the hydraulic tube  210  and the oscillation tube  300  may be coupled to each other by disposing a seal member in the seal grooves  148 . 
         [0054]    The hydraulic tube  210  contains a working fluid. A front end portion of the hydraulic tube  210  is coupled, sealed, and tightly shut, and at least one fluid outlet  222  and at least one fluid inlet  232  are formed in the hydraulic tube  210 . 
         [0055]    An inner check ring  230  is mounted in the fluid inlet  232  formed in the hydraulic tube  210 , and the inner check ring  230  opens or closes the fluid inlet  232 . Preferably, a V-shaped groove may be formed along an inner wall of the hydraulic tube  210  in a portion of the hydraulic tube  210  in which the fluid inlet  232  is formed, and the inner check ring  230  may be mounted in the V-shaped groove. 
         [0056]    An outer check ring  220  is mounted in the fluid outlet  222  formed in the hydraulic tube  210 , and the outer check ring  220  opens or closes the fluid outlet  222 . Preferably, a V-shaped groove is formed along an outer wall of the hydraulic tube  210  in a portion of the hydraulic tube  210  in which the fluid outlet  222  is formed, and the outer check ring  220  is mounted in the V-shaped groove. 
         [0057]    The inner check ring  230  and the outer check ring  220  may be formed of an elastic material to be deformed. Accordingly, as the inner check ring  230  and the outer check ring  220  are deformed, a fluid may be introduced into the hydraulic tube  210  through the fluid inlet  232 , or may be extruded from the hydraulic tube  210  through the fluid outlet  222 . 
         [0058]    The outer check ring  220  may have a ball shape, instead of a ring shape, and may perform the same function. For example, after a ball sheet on which a check ball is mounted is formed on the fluid outlet  222 , an outer housing may be provided to attach the check ball to the fluid outlet  222 . In this case, the check ball may be kept slightly pressurized between the fluid outlet and the outer housing. When a pressure in the hydraulic tube  210  is increased, the check ball may be deformed to open the fluid outlet. Also, when a pressure in the hydraulic tube  210  is reduced, the check ball may be attached to the fluid outlet to close the fluid outlet. 
         [0059]    The hydraulic tube  210  may be connected to a pipe hole  118 , and the pipe hole  118  may be connected to an accumulator  119 . 
         [0060]    The oscillation tube  300  may be deformed to reduce a volume in the hydraulic tube  210  and the oscillation tube  300  as the oscillator  240  operates. Accordingly, the oscillation tube  300  is used to overcome the fact that an oscillation amplitude of the oscillator  240  is limited and to increase the amount of a fluid flowing as the oscillator  240  moves. The oscillation tube  300  has a two-layer structure including a metal tube layer  320  and an elastic tube layer  310 , and includes an insulating oil chamber  330  disposed outside the metal tube layer  320 . A plurality of slits  322  are formed in a longitudinal direction in the metal tube layer  320 . 
         [0061]      FIG. 6  is a cross-sectional view illustrating the oscillation tube  300 . 
         [0062]    Referring to  FIG. 6 , the oscillation tube  300  includes two layers. The elastic tube layer  310  which is an inner layer of the two layers and is easily elastically deformed and restored may be formed of, for example, urethane or rubber. The metal tube layer  320  which is an outer layer of the two layers is formed of a metal material. The plurality of slits  322  are formed in the longitudinal direction at predetermined intervals in a circumferential direction of the metal tube layer  320  in the metal tube layer  320 . 
         [0063]    Since the metal tube layer  320  is formed of a material having an elastic modulus lower than that of the elastic tube layer  310  but the slits  322  are formed in the metal tube layer  320 , the metal tube layer  320  may be deformed toward the hydraulic tube  210  and restored. 
         [0064]    Since a protrusion  312  is formed on an end portion of the elastic tube layer  310  and a groove for receiving the protrusion  312  is formed in an end of the hydraulic tube  210 , the elastic tube layer  310  is firmly fixed to the hydraulic tube  210 . 
         [0065]    The insulating oil chamber  330  in which insulating oil may be filled may be formed around the metal tube layer  320  to have a predetermined gap from the main body housing  114 , and may have a cylindrical shape disposed between the main body housing  114  and the metal tube layer  320 . 
         [0066]    A cooling pipe  340  may be formed at a side of the oscillation tube  300  to be connected to an insulating oil circulation cooling device which will be explained below. A transmission holder  350  for transmitting a force by deforming the oscillator  240  is disposed at a lower end of the oscillation tube  300 . 
         [0067]    The oscillator  240  is disposed on a rear end portion of each of the hydraulic power units  220 , and may be deformed in a longitudinal direction of the hydraulic power units  200 . The oscillator  240  includes piezoelectric elements, and preferably, may have a structure in which the piezoelectric elements are stacked. An oscillator front end portion  242  for transmitting a force by deforming the oscillator  240  may be disposed on a front end of the oscillator  240 . Also, a connection device  250  may be disposed on a driving module (not shown) for driving the oscillator  240 . 
         [0068]    The driving module may drive the hydraulic power units  200  by applying an operation signal to the oscillator  240 , adjust the number of rotations and torque of the rotor  130 , and include a secondary battery as a driving power source. 
         [0069]    An oscillator housing  160  that surrounds the oscillator  240  may be disposed under the main body housing  114 . Insulating oil may be filled in the oscillator housing  160  to dissipate heat generated when the oscillator  240  operates. A pipe  161  in which the insulating oil flows may communicate with the insulating oil circulation cooling device  500  as will be described below. 
         [0070]    The amplitude amplification device  400  is disposed between the oscillator  240  and the oscillation tube  300 . Although the oscillator  240  is deformed to a limited extent, the amplitude amplification device  400  further increases a hydraulic force by increasing the amount of a fluid flowing in the hydraulic tube  210 , and increases outputs of the hydraulic power units  200 . 
         [0071]    The amplitude amplification device  400  includes a casing  430 , a swell tube  410 , and an elastic chip  420 . 
         [0072]    The casing  430  may act as a housing of the amplitude amplification device  400  and may have a cylindrical shape in which a cavity is formed. A holder such as a predetermined protrusion may be provided on an end portion or on both end portions of the casing  430  to firmly fix the amplitude amplification device  400 , like in the oscillation tube  300 . A screw portion may be formed on an outer surface of the casing  430  to firmly couple the casing  430  to the main body housing  114 . 
         [0073]    The swell tube  410  may be disposed in the casing  430  and may have a cylindrical shape in which a cavity is formed like that of the casing  430 . A plurality of slits  412  may be formed in a longitudinal direction on a surface of the swell tube  410 , like in the metal tube layer  320 . 
         [0074]    Referring to  FIG. 8 , the elastic chip  420  is disposed in the swell tube  410  and has a circular plate shape crossing the cavity of the swell tube  410  before being deformed. The elastic chip  420  is disposed between the oscillator front end portion  242  and the transmission holder  350  in the swell tube  410 . A plurality of holes  422  are formed in the elastic chip  420  in a circumferential direction of the elastic chip  420 . The holes  422  may be arranged in a radial direction and each may have a fan shape having an inner surface of the cavity as an arc as shown in  FIG. 8 . 
         [0075]    The elastic chip  420  may be formed of an elastic material to return to its original shape, for example, a thin film formed of a metal. The elastic chip  420  may have a curved shape which has a curvature and thus a protruding central portion like a portion of a lens or a spherical surface. Accordingly, the elastic chip  420  may be flattened or curved according to whether an external force applied to the elastic chip  420  is increased or reduced or whether there exists an external force. In this case, the elastic chip  420  which is formed of an elastic material has a restoring force to return to its original shape after being deformed. 
         [0076]    Since the elastic chip  420  is disposed between the oscillator front end portion  242  and the transmission holder  350  to receive a force applied by the oscillator front end portion  242  and the transmission holder  350 , when there is no external force, the elastic chip  420  remains flattened. Next, when an external force is applied due to the oscillator  240 , the elastic chip  420  is deformed to be curved due to its restoring force. 
         [0077]    An operation of the amplitude amplification device  400  will be explained as follows. 
         [0078]    Referring to  FIG. 9 , when an external force is applied due to the oscillator  242 , the elastic chip  420  may be curved to have a protruding central portion. The elastic chip  420  may be repeatedly deformed and restored as an external force is applied due to the oscillator  240  disposed on a lower end portion of each of the hydraulic power units  200 . 
         [0079]    For example, when the oscillator  240  is deformed in a forward direction to increase a pressure in the hydraulic tube  210 , the swell tube  410  is deformed inward through the oscillator front end portion  242  and the elastic chip  420  is pressurized to be flattened. Since the elastic chip  420  is formed of an elastic material and has a restoring force as described above, the elastic chip  420  returns to its original shape and a force generated due to the oscillator  242  pushes the transmission holder  350  and is applied to the oscillation tube  300 . The force generated due to the deformed oscillator  240  pressurizes a fluid in the hydraulic tube  210 , and thus the inner check ring  230  is attached to the fluid inlet  232  to continuously close the fluid inlet  232  and the outer check ring  220 , whose stiffness is less than that of a wall surface of the hydraulic tube  210 , is deformed to make the fluid be extruded through the fluid outlet  222 . 
         [0080]    Since the elastic chip  420  is disposed between the oscillator front end portion  242  and the transmission holder  350  to receive a force applied by the oscillator front end portion  242  and the transmission holder  350 , when there is no external force due to the oscillator  240 , the elastic chip  420  remains flattened as shown in  FIG. 10 . 
         [0081]    Referring to  FIG. 11 , a plurality of the elastic chips  420  may be provided. For example, a first elastic chip  424  and a second elastic chip  428  may be provided. A support plate  426  that fixedly supports the first and second elastic chips  424  and  428  and enables a force to be applied in a longitudinal direction of the hydraulic power units  200  may be disposed between the elastic chips  420 . 
         [0082]    An operation of each of the hydraulic power units  200  used in the hydraulic engine  100  will be explained below. 
         [0083]    When the oscillator  240  is deformed to reduce a volume in the hydraulic tube  210 , the oscillation tube  300  is deformed inward and a pressure in the hydraulic tube  210  is increased. Accordingly, the fluid inlet  232  is closed by the inner check ring  230 , and the outer check ring  220  is deformed to extrude a working fluid through the fluid outlet  222 . Also, the fluid passing through the fluid outlet  222  is extruded through the extrusion slots  146  of the common extrusion chamber  223  toward the rotor blades  132 . 
         [0084]    On the contrary, when the oscillator  240  is deformed to restore the volume in the hydraulic tube  210 , the oscillation tube  300  returns to its original position and the pressure in the hydraulic tube  210  is reduced. Accordingly, the fluid inlet  232  is opened, a working fluid is introduced into the hydraulic tube  210  through the introduction slots  144  of the common introduction chamber  233 , and the oscillation tube  300  returns to its original position. 
         [0085]    The front end accumulation unit  260  for uniformly maintaining a slight difference between the amount of a driving fluid extruded and the amount of a fluid introduced between one pair of hydraulic power units  200  is disposed on a front end portion of at least one hydraulic power unit  200 . 
         [0086]    The front end accumulator  260  helps a fluid which initially stands still in the hydraulic tube  210  so as to flow fast when the hydraulic engine  100  starts up. That is, when the oscillator  240  moves to apply a pressure for start-up, the spring  262  of the front end accumulator  260  is compressed to absorb a fluid, store power, and enable fast start-up. A fluid is accumulated, due to the movement of the oscillator  240 , on the front end portion of each of the hydraulic power units  200 . When the hydraulic engine  100  stops, the accumulated fluid is extruded and the spring  262  returns to its original state due to its restoring force, thereby enabling the hydraulic engine  100  to start up easily. 
         [0087]    To this end, it is preferable that the driving module for controlling a driving signal to be applied to the oscillator  240  of each of the hydraulic power units  200  is additionally used in addition to the hydraulic power units  200 . 
         [0088]    When the driving module controls the hydraulic power units  200 , the hydraulic engine  100  may be configured as follows. 
         [0089]    In this case, driving signals are simultaneously applied to two hydraulic power units  200 . 
         [0090]    When an initial driving signal of the driving module is applied, the oscillator  240  disposed on one of the hydraulic power units  240  is deformed forward to increase a pressure in the hydraulic tube  210 , the oscillation tube  300  is deformed, and a force is applied to a fluid in the hydraulic tube  210 . The force which is very large due to the oscillator  240  is applied to the fluid in the hydraulic tube  210 . Due to the force, the inner check ring  230  is attached to the fluid inlet  232  to continuously close the fluid inlet  232 , and the outer check ring  220  whose stiffness is less than that of the wall surface of the hydraulic tube  210  is deformed to make the fluid be extruded through the fluid outlet  222 . 
         [0091]    The initial driving signal of the driving module is also applied to the oscillator  240  of the other hydraulic power unit  200 , the oscillator  240  is deformed backward to reduce a pressure in the hydraulic tube  210 , and the oscillation tube  300  is deformed. As the pressure in the hydraulic tube  210  is reduced, the outer check ring  220  is continuously attached to the fluid outlet  222  and the inner check ring  230  opens the fluid inlet  232  to make the fluid be introduced through the fluid inlet  232  in which the inner check ring  230  is mounted. 
         [0092]    When the hydraulic power units  200  and all members connected to the hydraulic power units  200  are filled with a fluid and sealed to form a sealed space, cavitation may be prevented from occurring in the fluid by circulating the fluid in a desired direction in the sealed space. 
         [0093]    In order to increase the amount of a fluid extruded through the fluid outlet  222 , it is necessary to increase the amount of deformation of the oscillator  240 , that is, a stroke. In order to increase a stroke, a voltage of electric energy applied to the oscillator  240  may be increased or a plurality of piezoelectric elements included in the oscillator  240  may be stacked. 
         [0094]    Also, since the amplitude amplification device  400  is disposed between the oscillator  240  and the oscillation tube  300  as described above and thus the amount of a fluid extruded through the fluid outlet  222  and the amount of a fluid introduced through the fluid inlet  232  may be increased, outputs of the hydraulic power units  200  and the hydraulic engine  100  may be further increased. 
         [0095]      FIG. 12  is a view illustrating the insulating oil circulation cooling device  500  and  FIG. 13  is a circuit diagram for explaining an operation of the insulating oil circulation dissipation heating device  500 . 
         [0096]    Referring to  FIGS. 13 and 14 , the hydraulic engine  100  may include the insulating oil circulation cooling device  500 . 
         [0097]    The circulation cooling device  500  for dissipating heat generated when the oscillator  240  is driven may be filled with insulating oil that may flow during an operation of the hydraulic power units  200 . The insulating oil may flow through a pipeline and dissipate heat through a dissipater, thereby making it possible to maintain a driving temperature of the oscillator  240 . 
         [0098]    As described above, the cooling pipe  340  may be connected to the oscillation tube  300 , and the circulation cooling device  500  may be connected to the cooling pipe  340 . 
         [0099]    The circulation cooling device  500  may be disposed to connect at least two hydraulic power units  200 , and may include, for example, a first pipeline  510  and a second pipeline  512  that connect the first hydraulic power unit  200   a  and the second hydraulic power unit  200   b , a valve unit  514  that connects the first pipeline  510  and the second pipeline  512 , and a third pipeline  522  that is connected to the first pipeline  510  and the second pipeline  512  and is provided with a cooling effect of a cooler FAN. A first check ball receiving portion  516  is provided on a central portion of the first pipeline  510 , and a first check ball  518  which may be elastically deformed is inserted into the first check ball receiving portion  516 . Also, a second check ball  520  which may be elastically deformed may be disposed between the second hydraulic power units  200  and the first pipeline  510 . Also, each pipeline of the circulation cooling device  500  may be filled with insulating oil. As the insulating oil flows, heat exchange occurs and the oscillator  240  may be cooled. 
         [0100]    An accumulator (not shown) may be connected to deal with a change in the insulating oil as temperature changes and prevent the insulating oil from being lost as time elapses. The valve unit  514  may be provided to control insulating oil supply through the second pipeline  512 . The valve unit  514  may be a throttle valve. 
         [0101]    An operation of the circulation cooling device  500  will be explained below. 
         [0102]    For example, when the oscillator  240  in the first hydraulic power unit  200   a  is deformed to introduce a fluid in the hydraulic tube  210 , the oscillation tube  300  may be deformed outward, and thus the insulating oil may be extruded along the first pipeline  510  from the insulating oil chamber  330  of the oscillation tube  300 . 
         [0103]    In this case, the first check ball  518  may be deformed due to the insulating oil, the insulating oil flows to the second hydraulic power unit  200   b  through the first pipeline  510 , and part of the insulating oil may flow to the second hydraulic power unit  200   b  through the valve unit  514 . Accordingly, the insulating oil flows through the first pipeline  510  and the second pipeline  512 . 
         [0104]    Next, when the oscillator  240  in the second hydraulic power unit  200   b  is deformed to introduce a fluid in the hydraulic tube  210 , the oscillation tube  300  is deformed outward, the insulating oil is extruded from the insulating oil chamber  330  of the oscillation tube  300 , and the second check ball  520  is deformed to close the first pipeline  510  communicating with the first hydraulic power unit  200   a . Accordingly, the insulating oil may flow through the third pipeline  522 , and in this case, the insulating oil may be cooled by the cooler FAN disposed in the third pipeline  522 . 
         [0105]    Since the insulating oil circulation cooling device  500  is provided, the oscillator  240  of the hydraulic engine  100  may be efficiently cooled, and thus operational efficiency of the hydraulic engine  100  may be prevented from being reduced. 
         [0106]    According to the present invention, a hydraulic engine mainly uses a converse piezoelectric effect in a ceramic oscillator included in each of hydraulic power units constituting the hydraulic engine. Due to the converse piezoelectric effect, a displacement and a large force are generated in the ceramic oscillator according to a driving voltage, a driving frequency, and a rigidity of the ceramic oscillator. Due to the displacement and the large force, since a working fluid strongly impinges on rotor blades, when extruded, the torque of a rotor may be greatly increased. In particular, a flow rate may be arbitrarily changed by adjusting a time when a driving signal is applied. 
         [0107]    The hydraulic engine does not require additional power or fuel other than power of a secondary battery included in a driving module that is used to generate a signal applied to the ceramic oscillator included in each of the hydraulic power units. Accordingly, without supplying additional power or fuel, the hydraulic engine may be continuously driven within life spans of the ceramic oscillator and the secondary battery that supplies power needed to apply a driving signal to the ceramic oscillator. 
         [0108]    Also, since the hydraulic engine includes an amplitude amplification device and thus an oscillation amplitude of the ceramic oscillator may be further increased, more outputs may be provided. 
         [0109]    In addition, since the hydraulic engine includes an insulating oil circulation cooling device formed of ceramic, heat generated during operation may be efficiently dissipated. 
         [0110]    While the present invention has been particularly shown and described with reference to exemplary embodiments thereof by using specific terms, the embodiments and terms have been used to explain the present invention and should not be construed as limiting the scope of the present invention defined by the claims. The exemplary embodiments should be considered in a descriptive sense only and not for purposes of limitation. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.