Abstract:
A unitized hydraulic system comprises a tank for holding hydraulic fluid, a hydraulic pump powered by a pump motor for receiving hydraulic fluid from the tank and creating a high pressure stream of fluid, a control valve for receiving hydraulic fluid from the hydraulic pump and regulating movement of the hydraulic fluid within the system, an actuator for receiving hydraulic fluid from the control valve to drive a shaft coupled to the actuator, and a controller in communication with the pump motor and configured to provide controlled actuation of the pump motor, wherein all components are coupled together to form a single unit which is capable of being easily installed and interchanged.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/736,218, filed Nov. 14, 2005, the entirety of which is incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     Generally speaking, the present invention relates to hydraulic systems. More specifically, the present invention relates to a unitized hydraulic system which can be used as a single component of another device or system.  
         [0003]     Hydraulic systems are widely used for a number of applications in today&#39;s society. Most of these hydraulic systems are utilized in different mechanical devices, which are used for many different applications. For example, manufacturing equipment typically uses hydraulic systems to operate certain manufacturing processes. Further, construction and earth moving equipment (bulldozers, front end loaders, graders, etc.) all utilize hydraulic systems to actuate and move various components. As another example, snowplows typically utilize hydraulic cylinders to move and position plowing blades. Similarly, lawn care devices, especially more complex mowers and turf care equipment, also utilize hydraulic devices for various purposes. Naturally, this is a short list of examples, and several other applications exist.  
         [0004]     As can be appreciated, hydraulic systems range in complexity from very straightforward simple systems, to very complex. On the more simple side, a single hydraulic cylinder or hydraulic actuator of some type may be used. Conversely, more complex systems such as the above-mentioned earth moving equipment involves multiple cylinders and multiple control components, all cooperating with one another to allow multiple components to be moved and positioned in desired ways. In each of these systems, hydraulic components, mechanical components, and electrical components are all combined to create a system which achieves the desired results.  
         [0005]     As mentioned above, a typical hydraulic system will include multiple components. For example, a typical hydraulic system will likely contain a reservoir for maintaining fluid utilized in the system. Naturally, hydraulic actuators are required to achieve the desired movements and positioning. In order to move fluid and create pressures necessary within the hydraulic cylinders, pumps are required, along with fluid handling components such as hoses and related couplings. To direct fluid movement, a valve system must be incorporated which allows fluid to be moved in appropriate directions and at appropriate pressures. Naturally, electrical components are typically coupled with many of these different devices to control overall operation. These electrical components may include actuator switches and control devices utilized by the operator, and may also include multiple sensors and control devices (e.g. controllers) to achieve desired operation.  
         [0006]     As suggested above, necessary coupling and attachment devices are often utilized in hydraulic system applications. For example, hoses will typically carry hydraulic fluid from the reservoir tank to an actuator or switching mechanism of some type. When the switches or actuators are actually utilized, additional hoses are required to carry the necessary fluid from the actuator to the actual hydraulic cylinder. Additionally, return hoses or reversing hoses are often required to achieve desired operations. As can be imagined, the use of these multiple hoses, along with all related fittings and coupling components, is not entirely desirable and increases the complexity of the system.  
         [0007]     In addition to the hydraulic components mentioned above, corresponding electrical couplings and controls are often included, thus increasing the complexity of the system.  
         [0008]     In each application, it is desirable to reduce the complexity of a system as much as possible. Due to the various concerns, however, this is often not possible or realistic.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009]     The present invention solves the foregoing problems by providing a unitized hydraulic system including a tank for holding hydraulic fluid, a hydraulic pump powered by a pump motor for receiving hydraulic fluid from the tank and creating a high pressure stream of fluid, a control valve for receiving hydraulic fluid from the hydraulic pump and regulating movement of the hydraulic fluid within the system, an actuator for receiving hydraulic fluid from the control valve to drive a shaft coupled to the actuator, and a controller in communication with the pump motor and configured to provide controlled actuation of the pump motor. Each of these components is coupled to one another to create a single component.  
         [0010]     As mentioned above, the present invention combines the necessary components to create a unitized system which has several advantages. Specifically, a single utilized system can be installed and utilized within a piece of equipment, as a single component. Further, the single hydraulic actuator, for performing some defined movement, can be designed into a system, without the overall need for coordinating components typically utilized. As a result, individual unitized hydraulic systems can easily be replaced and swapped, by simply removing the entire component and replacing as necessary.  
         [0011]     One approach to creating the unitized system is through the use of a single housing which is designed to contain the necessary components. Specifically, a fluid holding tank is designed within the housing, along with appropriate fluid flow pathways. Additionally, the housing is designed to contain a hydraulic pump, powered by an appropriate motor, which is also in fluid communication with the tank and necessary fluid pathways. Also, the necessary valves are incorporated within the housing to move fluid in a predetermined manner. The hydraulic cylinder of the present invention includes an actuator and a related shaft which is designed to move consistent with a typical hydraulic cylinder. In this case, the hydraulic cylinder, actuator and related shaft are all designed to be an integral components of the overall system.  
         [0012]     In its anticipated application, the unitized hydraulic system will simply include necessary physical connections to allow for attachment to the physical devices contemplated, along with appropriate electrical connections to provide power and control signals. The power supply will be attached to the appropriate connector to provide power to drive the pump motor, thus generating the necessary hydraulic pressure utilized by the system. Additionally, electrical control signals are also provided to the system to control actual movement of the actuator itself.  
         [0013]     Again, the contemplated application includes attachment of the unitized hydraulic system to a framework of some type, and to an actuated component. Consequently, when the actuator is moved through its typical stroke, the related component is likewise moved. Due to the unitized nature of the system of the present invention, the entire system is capable of easy replacement where necessary. Consequently, should replacement be necessary, the unitized system can simply be disconnected from its physical connections, and electrical connections, and simply replaced with an identical system.  
         [0014]     In addition to the replacement advantages outlined above, system designers are also provided with a simplified tool to achieve the functions necessary. Rather than concern themselves with placement of hoses and fluid lines, along with appropriate electrical couplings, system designers can simply purchase the unitized system of the present invention for incorporation into their equipment. Consequently, the only design criteria for the equipment designer are the physical attachment mechanisms, and electrical control connections (in addition to providing enough space and clearance). All other concerns related to fluid handling pumps, and other components (e.g., valves and sensing components) are simply included in the design of the unitized hydraulic system.  
         [0015]     As generally outlined above, it is an object of the present invention to provide a single hydraulic system which is virtually self-contained and capable of using incorporation into related equipment. Consequently, the equipment designer and maintenance personal have greatly simplified responsibilities and tasks and can concern themselves with other aspects of the equipment design.  
         [0016]     It is a further object of the present invention to provide a hydraulic actuator system which is easily incorporated into an equipment design, and likewise easily repaired should any conditions exist.  
         [0017]     Further objects and advantages of the present invention can be seen by reading the following detailed description in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is a perspective view of one embodiment of a unitized hydraulic system according to the present invention  
         [0019]      FIG. 2A  is a side view of the unitized hydraulic system of  FIG. 1  with a shaft in a retracted position.  
         [0020]      FIG. 2B  is a side view of the unitized hydraulic system of  FIG. 1  with the shaft in an extended position.  
         [0021]      FIG. 3  is a diagram illustrating a hydraulic system having a first unitized hydraulic system, a second unitized hydraulic system, a third unitized hydraulic system, and multiplexing means for delivering signals to the hydraulic systems.  
         [0022]      FIG. 4A  is a diagram illustrating a pair of unitized hydraulic systems according to the present invention coupled to and configured to control position of a snowplow blade.  
         [0023]      FIG. 4B  is a diagram illustrating the snowplow blade in a V-shaped configuration.  
         [0024]      FIG. 5  is a perspective view of a second embodiment of the unitized hydraulic system.  
         [0025]      FIG. 6  is a front view of the unitized hydraulic system shown in  FIG. 5 .  
         [0026]      FIG. 7  is a cross sectional view of the unitized hydraulic system shown in  FIG. 6  with the cross section taken along E-E.  
         [0027]      FIG. 8  is a side view of the unitized hydraulic system shown in  FIG. 5 .  
         [0028]      FIG. 9  is a side view of an additional embodiment of the present invention incorporating an auxiliary fluid tank. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]     The present invention involves a unitized hydraulic system for use in multiple applications. As will be further described below, by combining multiple unitized hydraulic systems, many different device applications could be achieved. Each unitized hydraulic system may be entirely self-contained and may include, among other components, a motor, control electronics, a hydraulic pump, a hydraulic control valve, and a hydraulic cylinder. Furthermore, all fluid flow paths may be entirely self-contained within the unitized system, thus eliminating the need for hoses and complex valve bodies. Generally speaking, control of the unitized system may be achieved via electrical controls which actuate the motor in an appropriate way.  
         [0030]      FIG. 1  is a perspective view of one embodiment of a unitized hydraulic system  10  according to the present invention, which includes tank  12 , hydraulic pump  14 , pump motor  16 , control valve  18 , and an actuator including hydraulic cylinder  20 . In  FIG. 1 , the outer walls of tank  12  and cylinder  20  are transparent to provide a view into cylinder  20 , and to illustrate cooperating components. In the preferred embodiments, these components are typically not transparent. Hydraulic cylinder  20  includes piston  22  disposed within the cylinder. Coupled to piston  22  is shaft  24  which, as will be described in more detail to follow, moves axially with piston  22  as the volume of high pressure hydraulic fluid within hydraulic cylinder  20  is varied.  
         [0031]     As can be seen in  FIG. 1 , all components of unitized hydraulic system  10  are integrated into a self-contained unit. Specifically, shown in the upper portion of  FIG. 1  is fluid tank  12 . Fluid tank  12  is designed to hold fluid, such as hydraulic fluid or oil that is circulated throughout unitized hydraulic system  10 . Fluid tank includes removable cap  13 , which allows a user to either add or remove hydraulic fluid from tank  12  as necessary. Although not visible in  FIG. 1 , appropriate fluid handling passages are incorporated into the design of fluid tank  12  so as to allow appropriate fluid movement throughout unitized hydraulic system  10 . In the embodiment of  FIG. 1 , fluid tank  12  is shown surrounding cylinder  20 . It will be understood that fluid tanks which do not surround a cylinder, and are located at various other locations, are also contemplated. In addition, a reserve fluid tank may also be incorporated into unitized hydraulic system  10  to ensure a sufficient amount of hydraulic fluid is always available.  
         [0032]     Hydraulic pump  14  is coupled to fluid tank  12  in such a way to allow hydraulic fluid to be received from fluid tank  12 . Within hydraulic pump  14 , all necessary components are included to create a necessary stream of high pressure hydraulic fluid. The stream of high pressure hydraulic fluid may then be distributed to cylinder  20  to control axial movement of piston  22 . Many different types of hydraulic pumps may be incorporated into unitized hydraulic system  10  including, but not limited to, gear pumps, vane pumps, or axial pumps.  
         [0033]     As can be appreciated, care must be taken to insure that fluid can flow to pump  14  in a controlled manner. Naturally, tank  12  will have an outlet, which is designed to allow fluid to flow to pump  12 . In the tank design of the present invention, the outlet of the tank is specifically design to take into consideration any operating peculiarities that may be encountered. For example, when the hydraulic cylinder is to be operated in a horizontal orientation, tank  12  is designed to have its fluid outlet in a portion of the tank that will be positioned on a “bottom” side thereof. Thus, gravity flow of fluid will ensure that pump  14  will draw fluid when needed, and not be pulling air into the hydraulic system. Similar care must be taken when tank  12  will be operated in a vertical orientation. In some instances, it is possible for a single inlet location to meet both of these needs. In other cases, the system must be modified slightly to meet the particular operating conditions.  
         [0034]     It is further contemplated that the unitized hydraulic system of the present invention may include a unique inlet design that is configured to move as needed. For example, where tank  12  and cylinder  20  are required to move through a particular travel path which causes fluid within the tank to be shifted, the tank may include a slidable inlet which moves as needed to insure fluid is provided to pump  14 . In this manner, the unitized hydraulic system will be capable of operation regardless of its orientation. Such a movable inlet may be attached to an internal hose, or may include a slidable coupling that is attached to the housing.  
         [0035]     Pump motor  16  is coupled to hydraulic pump  14  to operate and drive the pump in a desired manner. In particular, pump motor  16  provides power to hydraulic pump  14 , which then uses that energy to create the stream of high pressure hydraulic fluid. Pump motor  16  is typically an electric motor or engine and may be connected to hydraulic pump  14  through, for example, gears, belts, or a flexible elastomeric coupling.  
         [0036]     Control valve  18  is functionally disposed between hydraulic pump  14  and hydraulic cylinder  20 . In particular, control valve  18  is in fluid connection with hydraulic pump  14  and routes hydraulic fluid to the desired location within unitized hydraulic system  10 . In one embodiment, control valve  18  may consist of a spool inside a housing, wherein the spool slides to different positions within the housing. Hydraulic fluid is then routed to the desired location based upon the position of the spool within the housing. Naturally, other valve configurations are possible.  
         [0037]     Hydraulic cylinder  20  is located in the upper portion of unitized hydraulic system  10  and is in fluid connection with control valve  18 . Hydraulic cylinder  20  is configured to receive controlled amounts of fluid from control valve  18  to control the axial position of piston  22  within the cylinder. In particular, hydraulic cylinder  20  includes a fluid port on each end of the cylinder to admit or return hydraulic fluid. Because shaft  24  is coupled to piston  22 , movement of piston  22  drives axial movement of shaft  24 . For instance, control valve  18  may route the high pressure stream of hydraulic fluid to a first portion of hydraulic cylinder  20 , thereby causing shaft  24  to extend. On the other hand, control valve  18  may route the high pressure stream of hydraulic fluid to a second portion of hydraulic cylinder  20 , thereby causing shaft  24  to retract.  
         [0038]     Shaft  24  is designed such that it may be coupled to a component to control (at least in part) movement of that component. For example, as shown in  FIG. 1 , shaft  24  includes through-hole  25  which is configured to receive a pin or similar element to secure shaft  24  to another component. In one embodiment of shaft  24 , the shaft may have a 2 inch diameter and a 10 inch stroke. However, one skilled in the art would appreciate that the shaft diameter and stroke required will depend upon the particular application of unitized hydraulic system  10 , and that shafts having any diameter or stroke are contemplated and within the scope of the present invention.  
         [0039]     Although a specific attachment coupling is not shown, it is understood that the cylinder, or some portion of the cylinder, would also be attached to other components. For example, in many equipment applications, the cylinder is attached to a framework of some type, while the shaft  15  attached to a movable component. As one example, in a snowplow application, the cylinder may be attached to a vehicle while the shaft would be attached to the plow blade to achieve the lifting function.  
         [0040]     As can be seen in  FIG. 1 , unitized hydraulic system  10  may also include controller  26 . Controller  26  may be configured to receive and send signals to operate one or more of the components within unitized hydraulic system  10 . For instance, in reference to pump motor  16 , controller  26  may send a signal to pump motor  16  indicating the timing and the magnitude of the power the pump motor should supply to hydraulic pump  14 . In reference to control valve  18 , controller  26  may send a signal to control valve  18  indicating the desired route of hydraulic fluid through the control valve.  
         [0041]     Unitized hydraulic system  10  may include an electrical connection means such as electrical connector  28  on controller  26 . Electrical connector  28  may be designed to provide power to any component of unitized hydraulic system  10  requiring power to operate. For example, electrical connector  28  may serve as the means to connect electrical power to pump motor  16 . Although electrical connector  28  is shown as a standard two-prong plug, other types and configurations of electrical connectors are contemplated.  
         [0042]      FIGS. 2A and 2B  illustrate the axial range of motion of shaft  24 , which is driven by hydraulic cylinder  20  as described above in reference to  FIG. 1 . In particular,  FIG. 2A  is a side view of unitized hydraulic system  10  with shaft  24  in a retracted position. As shown in  FIG. 2A , hydraulic cylinder  20  has first side  30  and second side  32 . Similarly, piston  22  has first side  34  and second side  36 . When the hydraulic fluid within hydraulic cylinder  20  is controlled such that first side  34  of piston  22  contacts first side  30  of hydraulic cylinder  20 , shaft  24  is in the fully retracted position. In the retracted position, end portion  38  of shaft  24  extends to a location X 1  outside of hydraulic cylinder  20 .  
         [0043]      FIG. 2B  is a side view of unitized hydraulic system  10  with shaft  24  in an extended position. When the hydraulic fluid within hydraulic cylinder  20  is controlled such that second side  36  of piston  22  contacts second side  32  of hydraulic cylinder  20 , shaft  24  is in the fully extended position. In the extended position, end portion  38  of shaft  24  extends to a location X 2  outside of hydraulic cylinder  22 . Thus, as indicated in  FIG. 2B , the axial range of motion of shaft  24  may be represented by ΔX. One skilled in the art would understand that although only the fully retracted and fully extended shaft positions are illustrated in  FIGS. 2A and 2B , pump  14  and control valve  18  may control the hydraulic fluid within hydraulic cylinder  20  such that end portion  38  of shaft  24  may be positioned anywhere between locations X 1  and X 2 .  
         [0044]     As can be seen in  FIGS. 2A and 2B , unitized hydraulic system  10  may also include a sensor S coupled to hydraulic cylinder  20 . In particular, sensor S may be designed to sense speed of piston  22  as it moves through hydraulic cylinder  20 , axial position of piston  22  within hydraulic cylinder  20 , or both. In some applications of the present invention, the speed at which piston  22  (and thus, shaft  24 ) moves may be important. For example, extending or retracting shaft  24  at a rapid rate may create safety concerns for users or the potential of damaging the device to which the hydraulic system is attached. In addition, in some applications of the present invention, it may be helpful to monitor the position of piston  22  within hydraulic cylinder  20 . Because shaft  24  is attached to piston  22 , there is a known relationship between the location of end portion  38  of shaft  24  and piston  22 . Therefore, by determining the position of piston  22  with respect to hydraulic cylinder  20 , the position of end portion  28  of shaft  24  may also be determined. The position sensor may be useful to sense when piston  22  reaches a position within cylinder  20  that corresponds with the desired position of end portion  38  of shaft  24 .  
         [0045]     Controller  26  may be coupled to sensor  80  to allow the controller to receive signals related to the speed and/or position of piston  22  to control operation of cylinder  20 . Thus, sensor  80  may be useful for providing “real-time” feedback to control the operation of shaft  24 . In addition, controlled, accurate presets for position and/or speed may be pre-programmed into controller  26  to enable automated positioning of shaft  24 .  
         [0046]     Although unitized hydraulic system  10  is described as having an actuator comprising a hydraulic cylinder, other types or actuators including but not limited to rotary actuators and motors may be used without departing from the intended scope of the present invention. Furthermore, although the components of unitized hydraulic system  10  are shown and described in reference to particular locations with the system, one skilled in the art would understand that the location of one or more of the components within the self-contained system may be varied without departing from the intended scope of the present invention.  
         [0047]     In a first alternative embodiment of the unitized hydraulic system shown in  FIG. 1 , hydraulic pump  14  may be a bi-directional hydraulic pump, thereby eliminating the need for control valve  18  to control the axial position of piston  22  within cylinder  20 . A typical bi-directional hydraulic pump could include two outlet ports, with one of the outlet ports feeding the first portion of hydraulic cylinder  20 , and the other outlet port feeding the second portion of hydraulic cylinder  20 . A switching means internal to the pump would allow control of the outlet ports such that only one outlet port may distribute hydraulic fluid at any point in time. In effect, when the hydraulic pump feeds the first portion of hydraulic cylinder  20 , shaft  24  may move to the extended position. Similarly, when the hydraulic pump feeds the second portion of hydraulic cylinder  20 , shaft  24  may move to the retracted position. Thus, as would be appreciated by one skilled in the art, a bidirectional pump may eliminate the need for control valve  18  to route hydraulic fluid to the desired portion of hydraulic cylinder  20 .  
         [0048]     In addition to controlling the axial range of motion of shaft  24 , pump motor  16  may also help control the speed that shaft  24  moves within hydraulic cylinder  20 . For example, in reference to the first alternative embodiment described above having a bi-directional hydraulic pump, pump motor  16  may be a switched reluctance motor configured to provide power to the bidirectional hydraulic pump. In general, a switched reluctance motor is a rotating electric machine having a stator and rotor with salient poles. The motor is excited by applying a sequence of current pulses at each phase, such as by pulse width modulation. One advantage of a switched reluctance motor, as compared to a permanent magnet motor, is its ability to operate over a wide speed range at constant power. Controlling the speed of pump motor  16  enables control over the pressurization of hydraulic fluid within the hydraulic pump. As a result, the speed of piston  22  (and thus, shaft  24 ) within hydraulic cylinder  20  may be controlled.  
         [0049]      FIG. 3  is a diagram illustrating a hydraulic system  40  having a first unitized hydraulic system  110 , a second unitized hydraulic system  210 , and a third unitized hydraulic system  310 . Although  FIG. 3  depicts three unitized hydraulic systems, a hydraulic system incorporating any number of unitized hydraulic systems is possible and within the intended scope of the present invention.  
         [0050]     When multiple unitized hydraulic systems are coupled to form a larger hydraulic system, coordinated control of the various hydraulic systems is required. This coordinated control may be achieved by using well understood multiplexing and sensing concepts to control each hydraulic system.  
         [0051]     In general, multiplexing involves sending multiple signals or streams of information on a carrier at the same time in the form of a single, complex signal and then recovering the separate signals at the receiving end. In reference to  FIG. 3 , hydraulic system  40  further comprises multiplexing means  42  for providing coordinated control of unitized hydraulic systems  110 ,  210 , and  310 . Multiplexing means  42  includes signal input device  44 , carrier line  46 , first multiplexed node  48 , second multiplexed node  50 , and third multiplexed node  52 .  
         [0052]     Signal input device  44  of multiplexing means  42  is configured to control and provide instructions (signals) to unitized hydraulic systems  110 ,  210 , and  310 . In one embodiment, a user manually inputs instructions into signal input device  44  as necessary to achieve the desired function of hydraulic system  40 . In another embodiment, signal input device  44  may receive signals from sensors (such as those described above in reference to  FIGS. 2A and 2B ) and provide instructions to unitized hydraulic systems  110 ,  210 , and  310  based upon those signals. In yet another embodiment, instructions may be pre-programmed into signal input device  44 , which may then be delivered to unitized hydraulic systems  110 ,  210 , and  310  at specified times or upon the occurrence of specified events.  
         [0053]     Signal input device  44  provides a signal to unitized hydraulic systems  110 ,  210 , and  310  over carrier line  46 . First multiplexed node  48 , second multiplexed node  50 , and third multiplexed node  52  then extract any portion of the multiplexed signal pertaining to their associated unitized hydraulic system. Thus, signal input device  44  combines multiple signals into a single data stream, while multiplexed nodes  48 ,  50 , and  52  split the single data stream into the original, multiple signals for use by the unitized systems.  
         [0054]     Similar to the discussion above, speed and position of the shafts within the unitized hydraulic systems may be controlled by using speed sensors and position sensors, as well as by pulse width modulation. Also, to differentiate the various hydraulic systems making up an overall system, it is contemplated that electrical control may key the various systems to their position and function within the overall system. Consequently, ease of interchangeability is achieved. Furthermore, frequency hopping could be used in conjunction with multiplexing means to assure system reliability.  
         [0055]     In one application of the present invention, one or more unitized hydraulic systems may be utilized for operation of snowplows, which are traditionally attached to plowing vehicles. As is well understood by those skilled in the art, several hydraulic systems may be utilized to move and position a snowplow blade during operations. These movements include lifting, lowering, angling, and applications providing splits in the blade itself. As will be appreciated from the above discussion regarding the unitized hydraulic system, multiple systems could be coupled to a single snowplow blade to provide appropriate movement and actuation of the blade. Utilizing a number of unitized hydraulic systems provides several advantages, most significantly the interchangeability of hydraulic systems. Utilizing unitized hydraulic systems in applications such as plowing vehicles provides significant advantages including, but not limited to, greatly easing repair costs and allowing operators to make on-the-fly repairs while in the middle of plowing jobs.  
         [0056]      FIGS. 4A and 4B  illustrate a top view of a simplified snowplow system  60 . In particular, and as illustrated in  FIG. 4A , snowplow system  60  includes frame  64 , snowplow blade  66  having first blade portion  68 , second blade portion  70 , and hinge means  72 , and a pair of unitized hydraulic systems  10 A and  10 B attached to frame  64 . End portion  38 A of shaft  24 A is coupled to first blade portion  68 , while end portion  38 B of shaft  24 B is coupled to second blade portion  70 . It should be understood that snowplow system  60  is merely one example of a snowplow system, which has been simplified to illustrate how one or more unitized hydraulic systems according to the present invention may be used in such a system.  
         [0057]     Snowplow blade  66  of snowplow system  60  is movable between a straight configuration, as shown in  FIG. 4A , and a V-shaped configuration, as shown in  FIG. 4B . In the straight configuration shown in  FIG. 4A , shafts  24 A and  24 B of unitized hydraulic systems  10 A and  10 B are both in the extended position. As a result, a substantially straight plow blade is formed.  
         [0058]      FIG. 4B  is a diagram illustrating snowplow blade  66  in the V-shaped configuration. In the V-shaped configuration, shafts  24 A and  24 B of unitized hydraulic systems  10 A and  10 B are both in the retracted position. When shafts  24 A and  24 B are actuated from the extended to retracted position, first blade portion  68  and second blade portion  70  pivot about hinge means  72  as indicated by angles A and B, respectively. In general, angles A and B are substantially equivalent, although the position of shafts  24 A and  24 B may be controlled such that angles A and B are not substantially equivalent without departing from the intended scope of the present invention.  
         [0059]     It is further contemplated that snowplow system  60  may include a plow headlight, which could house an “on/off” plow coupling switch. In addition, snowplow system  60  may also incorporate and utilize a solid state security system, along with multiplexing, to activate plow coupling.  
         [0060]     It should be understood that a snowplow system incorporating unitized hydraulic systems is discussed merely for purposes for example and not limitation. Furthermore, one skilled in the art would appreciate that one or more unitized hydraulic systems according to the present invention may be incorporated into many other types of equipment or systems, including but not limited to construction equipment, earth moving equipment, and lawn care equipment.  
         [0061]     To provide further perspective regarding the unitized hydraulic system of the present invention,  FIGS. 5-8  illustrate an alternative embodiment of the present invention. As can be seen, unitized hydraulic system  100  has a slighty modified configuration. For example, a set of electrical connecting wires  102  are shown attached to an opposite side of motor  16 . Further, a different housing  104  is utilized to connect many components. Again,  FIGS. 5 &amp; 8  are shown to be somewhat transparent to illustrate some of the internal components. Most illustrative however is  FIG. 7  which shows a cross sectional diagram along sections lines E-E (as labeled on  FIG. 6 ).  FIG. 7  more clearly shows one embodiment of the invention using an integrated tank  12  surrounding the hydraulic cylinder. The interior  13  of tank  12  can also be more completely shown. Additionally, one exemplary internal fluid passageway  120  can be seen in this cross sectional view.  
         [0062]     Lastly,  FIG. 9  illustrates one additional embodiment of the present invention. Here, a third embodiment of a unitized hydraulic system  200  is shown, which incorporates an additional auxiliary fluid tank  202 . In this case, the same type of fluid tank  12  is utilized to surround the hydraulic cylinder (not shown). Again, the same type of motor  16  is utilized. In order to accommodate additional fluid however, auxiliary tank  202  is configured to surround a revised pump  204 . Auxiliary tank  202  is in fluid communication with tank  12  to provide additional fluid capacity. A fluid fill cap  206  allows for fluid to be filled into the auxiliary tank  202 .  
         [0063]     As will be appreciated by one skilled in the art, the unitized hydraulic system of the present invention is very versatile and efficient. Obviously, only a few alternative embodiments of this invention have been illustrated in the drawings and discussed in detail. Naturally, numerous variations could be made to the configuration and arrangement of components within the hydraulic systems while continuing to utilize the overall concept described above.  
         [0064]     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.