Abstract:
A power assist system for a motor vehicle subsystem having a component support structure is described. The power assist system comprises a fluid reservoir, a pump having an inlet for receiving a fluid from the reservoir and a pump securing structure including at least one aperture. The system additionally includes at least one fastener. The reservoir fluid outlet is directly coupled to the pump inlet and the at least one fastener secures the reservoir mounting structure by passing directly through the pump mounting structure and attaching to the motor vehicle component support structure.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a fluid power assist system for a motor vehicle. More specifically, this invention relates to a fluid power assist system having a fluid reservoir in cooperation with a pump for a motor vehicle. 
   2. Prior Art 
   Conventional vehicles employ power assistance systems in many ways. Power assisted brakes and power assisted steering are just two of such applications. Power assisted steering systems are systems in which the steering force is produced by the driver&#39;s muscular energy and by an energy source within the vehicle. For this purpose, a hydraulic oil, which is pressurized by means of a pump and serves to generate or increase the steering power, is provided in a closed system. Power assisted brakes work in a similar manner. The energy source may comprise a vacuum booster for a brake system or a pump driven by flywheel for a steering system. These systems typically include an oil reservoir and the corresponding hoses and pipes which transfer the fluid through the system. 
   Conventional vehicle power steering systems may mount the oil reservoir on the body structure underneath the hood. In these systems, the power steering oil or fluid is typically collected in the power steering oil reservoir after its use by the steering gear and then supplied to the pump through a large diameter suction hose. The design of this system has its drawbacks. First, the suction hose offers poor under hood appearance. Competition between Original Equipment Manufacturers (OEMs) is fierce in today&#39;s marketplace. Under-hood craftsmanship is another area in which OEMs can attempt to differentiate their brand. Second, the suction hose is a costly item. The under-hood hose material is often required to have increased durability and performance requirements. These hoses are often long and must be formed in order to effectively negotiate other components located in the engine compartment. The forming also increases its piece cost. The size of the suction hose requires additional fluid in the system in order to operate the steering system. The assembly costs are increased because of the size of the hoses and overall system, more evacuation and field time is required in the assembly plant. Third, power steering hoses also provide opportunities for leakage which can be a nagging warranty item. Finally, the more fluid required to be pushed through the system requires more energy and adds to fluid consumption. Therefore, what is needed is a power assist system which is better designed for assembly and reduces labor time, eliminates unnecessary parts, reduces warranty, improves under hood appearance, and offers a more efficient and cost saving system. 
   SUMMARY OF THE INVENTION 
   According to the present invention, a power assist system for a motor vehicle subsystem, the motor vehicle having a component support structure comprises a fluid reservoir having a reservoir fluid outlet, a return fluid inlet for receiving fluid, and a reservoir mounting structure. The power assist system further comprises a pump having an inlet for receiving the fluid from the reservoir, a pump outlet for providing the fluid, and a pump securing structure including at least one aperture. Additionally, the system includes at least one fastener for securing the reservoir mounting structure to the motor vehicle component support structure. The fastener secures the reservoir mounting structure by passing directly through the pump securing structure aperture and attaching to the component support structure. 
   The invention has the advantage of removing costs from a vehicle&#39;s power assist system. The elimination of the main suction hose, the hose&#39;s associated clamps, as well as a reservoir mounting bracket, result in a smaller and more efficient system. In contrast, the conventional system results in a suction hose full of fluid. In the preferred embodiment, the amount of fluid required in the overall system is reduced as well. 
   The invention has the further advantage of providing a more efficient and flexible power assist system without realizing the high costs of development that accompany the redesign of a conventional variable displacement pump integral to power assist systems. The power assist system described here takes advantage of an existing pump design and mounts the reservoir mounting structure by passing directly through the pump securing structure aperture and attaching to the component support structure. Although many of the pumps having reservoirs directly integrated into their housing exist today to provide space savings, the savings come with disadvantages of a high cost and a loss of flexibility. The cost associated with retooling and redesigning the molds for a pump to make the reservoir an integral part of a pump is a significant amount. Additionally, in the undesired circumstance that the reservoir portion fails, there is no way to “limp home” since removing the reservoir renders the pump useless. In contrast, the system described herein allows for the old reservoir to be removed and a temporary reservoir to be substituted into the system with hoses and clamps, etc. For work vehicles such as trucks and farm equipment used in remote locations, the flexibility of a vehicle subsystem is often beneficial. 
   According to a further object of the present invention, a method of providing a reservoir for a fluid power assist system in a motor vehicle having a component support structure is attained. The fluid power assist system has a pump and at least one reservoir fastener. The reservoir has a chamber, a reservoir fluid supply outlet, a fluid return inlet, and a reservoir mounting including a securing aperture. The pump includes a pump securing structure containing an aperture, a pump inlet. The method comprises the steps of directly coupling the reservoir fluid supply outlet port to the pump inlet, aligning axially the reservoir mounting securing aperture and the pump mounting aperture, inserting one end of the reservoir fastener through both the reservoir mounting securing aperture and the pump mounting aperture to the motor vehicle component support structure, and securing the reservoir fastener into the motor vehicle component support structure. 
   According to a further object of the present invention, a reservoir for a pump having a fluid inlet and a pump mounting structure containing at least one securing aperture comprises an internal fluid chamber, a fluid outlet, and a reservoir mounting structure having a securing aperture. The reservoir fluid outlet connects directly to the pump fluid inlet and the reservoir securing aperture aligns with one of the at least pump securing apertures. 
   The invention has the further advantage of reducing plant labor time. The elimination of the reservoir mounting bracket and the suction hose and its corresponding clamps, results in fewer parts to assemble. Furthermore, since one reservoir fluid outlet connects directly to the pump fluid inlet and the reservoir surface is in close proximity to the a pump surface, the two components tend to orient themselves into position during loose assembly allowing the reservoir and the pump to be assembled into final position without additional clamping. 
   The invention has the further advantage of improving the under hood appearance of the power assist system. The removal of the formed suction hose provides a simple, compact system with improved underhood craftsmanship. 
   The invention has the further advantage of providing improving the power assist system while maintaining the flexibility to end user of the motor vehicle in the event of a reservoir failure of the power assist system in the field. Because the reservoir is not integrated into the housing of the pump, the power assist system will still function if supplied with fluid. In the event the reservoir fails in the field, it can be temporarily replaced by a conventional reservoir that can receive and supply fluid to the system using conventional pipes and suction hoses. For commercial vehicles operating in remote locations, the ability to reduce the time and expense to recover a stranded vehicle is of value. 
   The above and other objects, features, and advantages of the present invention will become more apparent for the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of the illustrative examples. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Presently preferred embodiments of the invention are disclosed in the following description and in the accompanying drawings, wherein: 
       FIG. 1  is a schematic diagram of a prior art power assist system; 
       FIG. 2  is a schematic diagram of one embodiment of a power assist system according to the invention; 
       FIG. 3  is a side view of a fluid reservoir according to the invention; 
       FIG. 4  is an exploded view of a portion of a power assist system according to the invention; 
       FIG. 5  is a perspective view of a portion of a power assist system according to the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , a prior art power assist system  10  is schematically shown comprising a pump  12  for supplying a motor vehicle subsystem  14  with fluid  15  using a high pressure line  16 . Pump  12  may be a variable displacement or a positive fixed hydraulic pump such as a power steering pump, oil pump, transmission pump, etc. A return line  20  transfers fluid  15  between the motor vehicle subsystem  14  and a reservoir  22 . An optional cooler  18  is often found in such systems to reduce the temperature of the fluid  15  exiting the motor vehicle subsystem  14  and prior to returning to the reservoir  22 . The reservoir  22  is typically secured to a first vehicle component support structure  24  such as a vehicle body, frame or a portion of an engine using reservoir fasteners  25 . The reservoir fasteners  25  may be bolts, such as hex head carriage bolts, screws, or any other conventional fastener. Supply line  26  provides fluid  15  returned or stored in the reservoir  22  to pump  12 . The supply line  26  may be a suction hose in conventional vehicles. The pump  12  is secured to a second vehicle component support structure  13  using pump fasteners  17 . In a conventional motor vehicle, the first vehicle component support structure  24  and the second vehicle component support structure  13  are typically located in the engine compartment in distinctly separate locations. The pump  12  is typically powered thru a pulley connected to the engine  28 . In the alternative, an electric motor may be used to supply power to the pump  12 . Similar to the first vehicle support structure  24 , the second vehicle support structure  13  may be a bracket formed by body or frame structure, or some other vehicle component, such as engine  28 . The motor vehicle subsystem  14  may be a steering gear of a power steering system, a power brake system, or other such type of system. 
     FIG. 2  is a schematic diagram of a power assist system according to the present invention. A power assist system  100  comprises a pump  102  providing a volume of high pressure fluid  103  to a motor vehicle subsystem  104  by means of a high pressure line  106 . The high pressure line is a conventional pressure line and may be a pipe made of a metal material. Pump  102  may be powered by an engine  114  thru a pulley (not shown). In the alternative, the motor vehicle subsystem  104  may be a steering gear of a steering system, a brake system, or other motor vehicle subsystem  104  requiring power assistance. Fluid  103  is returned through a return line  110  to a reservoir  112 . The return line  115  may be a pipe fabricated out of a metal material. An optional cooler  108  may exist in between the motor vehicle subsystem  104  and the reservoir  112  to serve as a conventional heat exchanger in order to reduce the temperature of the fluid  103  prior to entry into the reservoir  112 . The reservoir  112  has an exterior surface  113  in close proximity with a surface  115  of the pump such that both surfaces abut against each other. An interface connection  111  between the pump  102  and the reservoir  112  allows the fluid  103  to transfer directly from inside the reservoir  112  to inside the pump  102  without need for a suction hose. Reservoir  112  is secured in place by one or more fasteners  146  passing through a portion of the reservoir  112 , a portion of the pump  102 , and received by a vehicle component support structure  150 . 
   Referring now to  FIGS. 3-5 ,  FIG. 3  is a side view of reservoir  112  according to one embodiment of the present invention. An upper portion  131  of the reservoir is formed in a rectangular shape and comprises an internal chamber  140  for containing the bulk of the fluid. Inside the reservoir  112 , a strainer  121  is located for filtering fluid. A filler neck  124  is located on a top surface  126  to allow additional fluid needed by the system to be poured from above the reservoir  112  into the chamber  140 . The reservoir  112  may be sealed by a cap  128  or similar functional component. Optionally, one surface of the chamber  120  may comprise a fill max and min indicator  142  to aid in adding additional fluid  103 . Alternatively, a fill indicator may be included as a portion of cap  128 . 
   Reservoir  112  is constructed of man-made materials such as a glass-filled nylon. The exterior of the upper and lower portions  131 ,  132  may be injection molded. In the alternative other molding methods such as cold molding processes may be used. 
   A lower portion of the reservoir  132  comprises a reservoir fluid outlet port  134  and a return inlet  136 . The lower portion  132  is smaller in size compared to the upper portion  131  and formed toward one end of the reservoir  112 . The relationship between lower portion  132  and upper portion  131  aids in allowing the fluid outlet port  134  to have clearance to a pump connection. The reservoir fluid outlet port  134  extends away from the lower portion  132  to allow for an interface with a pump (not shown). The outlet port  134  may be formed with a circular end and comprise a seat  135  for use in combination with an o-ring. The reservoir fluid outlet  134  is formed to allow for a flush mating connection with a pump inlet port (not shown) to provide for the discharge of fluid to the pump. A reservoir return inlet  136  extends from a bottom surface  139  for receiving pressurized fluid from a return line from a motor vehicle system. 
   The upper and lower portion  131 ,  132  respectively are formed and adapted to aid in the mounting and securing of the reservoir in close proximity to a pump. An exterior surface of the reservoir  122  is formed by the upper portion  131  and the lower portion  132  to allow the reservoir to align itself with relevant portions of the pump. The reservoir  112  has a mounting structure  130  adapted for securing the reservoir in close proximity to the pump. The mounting structure  130  comprises a two vertical elements extending from upper portion  131 . A reservoir mounting aperture  129  is present in each vertical element to aid in securing the reservoir  112 . Apertures  129  allow fasteners  146  to pass through and secure the reservoir  112  in place. Surface  122  extends horizontally along the lower portion  132  to forms a clearance for one of the fasteners  146  to one of the apertures  129  located in the mounting structure  130 . A surface  125  is similarly formed to provide clearance for one of the fasteners  146  which extends horizontally along the lower portion  132  in a lower vertical plane arranged parallel to surface  122 . 
   Referring to  FIG. 4 , an exploded view of an embodiment of a pump  102  and reservoir  112  according to the invention is described. Pump  102  is cylinder-shaped body shown powered by a belt  152  connected to a motor vehicle engine (not shown) thru a pulley  116 . The pump is supported by a vehicle component support structure  150  in the form of a body support panel. In an alternative embodiment, the vehicle component support structure  150  may be a firewall or body-in-white framing made from sheet metal. Pump inlet port  138  is a circular-shaped female connector extending horizontally from the pump  102 . Pump securing structures  148  extend horizontally along an upper surface  154  of the pump  102 . The pump securing structures  148  are each defined by an aperture  144  and a cylindrical passage  156  extending throughout its length. 
   When reservoir  112  is in its ideal final position, the mounting apertures  129  of the reservoir mounting structure  130  are aligned with pump securing apertures  144 . Reservoir exterior surface  122  is in close proximity with the securing structure  148  of the pump  102 . The exterior surface  122  is formed to allow it to lie beside the pump securing structures  148 . The fluid outlet port  134  engages pump inlet port  138 . The connection allows fluid to transfer directly from the reservoir  112  to inside the pump  102  without need for a suction hose. An o-ring or similar may be used in combination with the fluid outlet  134  to provide a seal for the press or slip-fit connection. Reservoir  112  is secured in place by one or more fasteners  146  passing through a reservoir through reservoir mounting apertures  129  and through the pump securing apertures  144 . Each of the fasteners  146  is received by the vehicle component support structure  150 , thereby securing the reservoir  112 . 
     FIG. 5  is a perspective view of a fluid reservoir of a power assist system according to the invention. The reservoir  112  is shown in an operable position located behind the pulley  116  of a pump  102 . Reservoir  112  is adapted to lie beside or abut against an external surface of the pump (not shown). By aligning the reservoir  112  to lie beside a surface of the pump, reservoir fluid outlet and the pump fluid inlet are brought into close proximity to each other and the need for a long suction hose between the reservoir and the pump is further eliminated. The return line  110  returns fluid  103  to the reservoir through a return inlet  136  located on a lower portion  132  of the reservoir  112 . 
   A method of providing fluid for a power assist system in a motor vehicle will now be further described. First the reservoir fluid supply outlet port is coupled directly to the pump inlet port. Next, the reservoir mounting structure aperture is aligned with the pump securing structure aperture in order to receive the reservoir fasteners. Third, one end of the reservoir fastener is inserted through both the aligned portions of the reservoir mounting structure aperture and the pump securing structure aperture. Fourth, the reservoir fastener is secured to the motor vehicle component support structure. 
   Although there have been described what are at present considered to be the preferred embodiments of the invention, it will be understood that the invention may be embodied in other specific forms without departing from the essential characteristics disclosed. The present embodiment is to be considered in all respects as illustrative, and not restrictive. The scope of the invention is indicated by the claims which follow rather than by the foregoing description.