Patent Publication Number: US-9845802-B2

Title: Intake charged pump for delivering a liquid

Description:
This application claims priority from German patent application serial no. 10 2011 084 405.8 filed Oct. 13, 2011. 
     FIELD OF THE INVENTION 
     The invention concerns an intake charged pump for delivering a liquid. 
     BACKGROUND OF THE INVENTION 
     Such pumps can be, for instance, part of power steering assist systems in motor vehicles in which they generate the hydraulic pressure of a servo liquid for a piston-cylinder configuration which supports the required steering forces at the steering wheel of a motor vehicle. In another example, they can also be part of the vehicle transmission were they provide the hydraulic pressure of a transmission oil to lubricate and/or activate (changing of a gear ratio, engaging/disengaging of transmission shafts) in the motor vehicle transmission. Preferably, this is a vane type pump as described in DE 39 28 029 A1 and in DE 41 38 516 A1, and where the content is in here fully disclosed. Such vane type pumps draw the oil out of a supply container, which is external to the pump, and are usually equipped with a flow controlling valve through which the oil is conveyed from the high-pressure area to the intake of the pump. Starting at a certain pump rotational speed or rather a certain flow rate, the flow control valve opens so that the oil, which is at high-pressure, can exit in to a pressure duct through which it passes into the suction area of the pump. 
     Known from DE 41 38 516 A1 is an intake charged pump which, to guarantee highly reliable and low noise operation and while preventing the creation of cavities and sound from drawn in air bubbles, is equipped with an additional injector at high oil pressure, and through which the oil can be channeled from the intake channel into the intake of the pump. Hereby, adequate filling of the intake of the pump shall be achieved under all operating conditions and, due to the adequate supply of oil to the intake, damages which are caused by cavities can be avoided. The embodiment example which is presented and described therein refers to the fact that the center axis of the injector matches the center axis of a channel section which leads into the intake of the pump, and also matches a center axis of an output bore of the flow control valve. It is also mentioned and noted that it is possible to pivot the center axis of the injector with respect to the other two axes, for instance to the right, so that the fluid which is under high-pressure and flowing through the injector, as well as its entrained oil, and that the intake of the pump, even with a different configuration of the parts, can be filled at an optimum with fluid to be transported. 
     In addition to DE 41 38 516 A1, the document DE 198 36 628 A1 mentions that the injector device is effective just at one side of the housing with a jet nozzle and from there on needs to direct the fluid from a tank to both sides of the enclosure to the respective intake, to provide the fluid for the suction pockets which are positioned on both sides of the transport device or the rotational group, respectively, in an adequate level. Due to the different lengths of the flow paths to the suction pockets on both sides, different pressure conditions occur in the fluid, which causes different load levels at the suction pockets on both sides. This causes, especially at large transport outputs of the pump, the cavities or rather damage due to cavities. In addition, an equal filling of the suction areas on both sides is doubtful. 
     To avoid these problems, DE 198 36 628 A1 proposes that the feed duct on both sides of the transport device each leads with one partial duct into a jet chamber, and that the injector device emits the oil on both sides so that at least one jet nozzle is aiming into each of the two jet chambers of the injector device. From that point, the fluid flows, via branching intake ducts, to diametrically opposed suction pockets of a dual-chamber vane type pump, which are mainly designed as having equal lengths so that the same pressure conditions in the suction area and the same fluid volume is provided at both sides. However, the fluid which is ejected from the jet nozzles hits a perpendicular wall of the jet chambers which results in a loss of kinetic energy and prevents an even pressure reduction in the direction of the suction pockets. 
     Although DE 102 16 549 A1 mentions that a pump of a similar type includes flow separators for the oil return flow which divide the oil return flow in a way such that the partial flows have the same energy content and load pressure at all suction pockets so that in particular the same energy content of the flow, as well as the same load pressure can be provided to all four suction pockets. This arrangement also requires sharp redirecting edges and impact surfaces which create losses of kinetic energy of the stream. 
     The previously mentioned vane type pumps or roller cell pumps, however, are designed in a compact manner, but have the previously mentioned disadvantages due to their compactness. 
     SUMMARY OF THE INVENTION 
     Based on that background, the object of this invention is to propose an intake charged pump for delivering a liquid, especially for a motor vehicle, which is constructed in a simple way and which brings a jet stream of a liquid under pressure from the pressure area to the intake area of the pump, whereby assisting the suction of the liquid through the pump takes place by means of a storage container with high efficiency. 
     The invention relates to an intake charged pump for conveying a liquid, especially of a motor vehicle, and having an inner space in a housing, an intake duct for the liquid which extends to the intake area of the pump, a pressured duct which is connected with a pressure area of the pump through which a jet stream can be conveyed from the pressure area to the intake area of the pump, and a nozzle arrangement in the intake duct for accelerating the liquid which recirculates with the jet stream, and for supporting the suction of an intake stream of the liquid from a storage container. The liquid which has to be conveyed can be in particular, based on the application of the pump, oil, hydraulic liquid, brake fluid, water, or gasoline. The pump is mainly designed as a vane cell, or gear wheel pump, or roller cell pump. 
     To achieve the stated objective, the pump is provided with an intake duct that is positioned in front of the housing of the pump and designed in particular as a cylindrical mixing chamber, the suction stream can be fed into the mixing chamber and a nozzle of the nozzle configuration is directed at an acute angle into the mixing chamber, such that the jet stream discharged from the nozzle creates a common mixing stream with the intake suction stream from a supply container, through which portions of the flow having the same pressure are directed at least to a front suction pocket and a back suction pocket of the dual-flow pump. Preferably, the nozzle of the nozzle configuration is aimed and directed in such a way that the injected partial flows for the suction pockets also have substantially the same energy content. 
     The term “front” and “back” is herein to be understood in reference to the length of the distance which the partial stream travels to the respective suction pocket. That means that the suction pockets in the back is the suction pocket to which the respective partial stream travels a longer way, while the front section pocket is the suction pocket to which the respective partial stream, here as reference, travels a shorter way. 
     Contrary to the previously discussed state of the art, the inventive pump does not need any special, constructive design for guiding fluid to the areas of the rotor with abrupt changes of the direction and sharp redirecting edges. The separation of the partial flows to the opposing suction pockets arises from the mentioned, special nozzle configuration which creates, in the mixing chamber, a common stream including a jet stream and suction stream through which partial streams, having substantially the same pressure, and if necessary the same energy content, arrives at the front and back suction area of the dual-flow pump. This creates a very steady run of the pump with a low possibility of creating cavities, which allows the pump to operate with low noise and low wear. 
     It is provided, in accordance with a further embodiment of the invention that, beginning at the mixing chamber, the housing of the pump has in a front intake area at least a front suction pocket and in the intake area in the back at least one suction pocket, wherein the front and the back suction pockets are positioned diametrically opposite each other, and the back suction pocket is connected with the output side end of the mixing chamber via a ring duct. 
     A further embodiment of the invention provides that the nozzle opens into the mixing chamber at such an angle α, that a first partial stream leads to the front suction pocket, which is created by mixing the jet stream with the sucked in suction stream, and that a second partial stream, which leads to the back suction pocket, is mainly directed at the inner wall of the mixing chamber to the ring duct and from there to the back suction pocket. 
     Through the ring duct, which is preferably designed as an inner shell surface of the pump housing, the liquid is conducted directly to the back suction pump by radially streaming around the rotor of the pump in the ring duct. The dimensions of the ring duct are set such that, considering the fluid pressure at the input of the ring duct and the friction losses at the walls of the ring duct at the input to the back suction pocket, a second partial stream arrives which has substantially the same pressure and energy content as the first partial stream at the input of the front suction pocket. 
     In accordance with another further embodiment, to provide a sufficiently large inflow cross section into the pump, the suction pockets are designed in pairs with one on each side of the housing and both housing lids. Thus, the pump has at least a pair of front and back suction pockets at the sides of the housing lids. 
     Regarding the nozzle, an advantageous nozzle configuration comprises of a carrier plate with a nozzle that is directed into it or is inserted into it. The carrier plate can hereby be part of a suction filter housing which is connected with the pump or a single part which is clipped to the output of the pressure duct into an accommodating groove of the suction filter housing. The carrier plate can also be fixed in the holding groove by other means, for instance through adhesives or clamping. 
     In a specific design with respect to the arrangement and orientation of the nozzle, to produce the desired two partial flows it is considered advantageous, to set the longitudinal axis of the nozzle at an angle α of approximately 15° to 45° in reference to the longitudinal axis of the mixing chamber. As such, the longitudinal axis of the nozzle is essentially the axis along which the liquid from the nozzle flows, but it can also be a geometric center axis of an inner chamber in which the liquid from the nozzle passes through. The longitudinal axis of the mixing chamber, is in particular, the axis along which the liquid flows in the mixing chamber, but it can also be a geometric center axis of an inner chamber in which the liquid passes through. 
     It is preferred that the longitudinal axis of the nozzle, as viewed in a vertical longitudinal section, has an offset of an angle α of approximately 15° to 45° in relation to the longitudinal axis of the mixing chamber. It can also be provided as an alternative that the longitudinal axis of the nozzle, as viewed in a horizontal longitudinal section plane, runs at an angle of approximately 15° to 45° in relation to the longitudinal axis of the mixing chamber. Hereby, a favorable separation of the partial streams to the suction pockets is achieved and which have the same pressures. The nozzle input in this embodiment can also be positioned, as viewed in the vertical longitudinal section plane and in reference to the longitudinal axis of the mixing chamber, at an axis deviation of approximately 10% to 25% of the diameter of the mixing chamber. 
     The vertical longitudinal section runs, in particular, vertically to a rotational axis of the pump rotor of the pump, along the longitudinal axis of the mixing chamber. The horizontal longitudinal section plane runs hereby preferably parallel to the rotational axis of the common rotor of the pump along the longitudinal axis of the mixing chamber. The rotational axis is hereby the axis around which the pump rotor in the pump is rotatable positioned. By rotating around the rotational axis when the pump is operated, the pump rotor creates the desired transportion of the liquid. The pump rotor can hereby be for instance a transport gear wheel, if the pump is a gear wheel pump, or a rotary piston if the pump is a rotary piston pump, or a vane, if the pump is a vane cell pump. 
     It is provided in accordance with an even more concrete embodiment that the longitudinal axis of the nozzle in the vertical longitudinal section plane is tilted at an angle α of approximately 15° to 20° with respect to the longitudinal axis of the mixing chamber. The longitudinal axis of the nozzle runs hereby, or as an alternative to it, in the horizontal longitudinal section plane at an angle of 30° to 35° with respect to the longitudinal axis of the mixing chamber. Hereby, an especially favorable separation of the partial streams to the suction pockets is achieved, each having almost the same pressures. The inlet of the nozzle is positioned, preferably in the vertical longitudinal section plane and with respect to the longitudinal axis of the mixing chamber, at an axis deviation of approximately 15% to 20% of the diameter of the mixing chamber. 
     Finally, it can be advantageous for additional optimization if the nozzle has inside, with respect to its longitudinal axis, a nonsymmetrical inner shell surface. It is preferably designed so that the jet stream which leaves a nozzle has a twist overlay. This twist guarantees, on one hand, acceptable mixing with the drawn in liquid, and still favors the creation of a partial stream which flows to the back suction pockets of the pump. 
     The inventive pump is in particular a motor vehicle pump, preferably of a motor vehicle transmission for the transfer of the transmission oil or a power steering assist system for the transfer of a servo liquid of the power steering assist system, because low noise pumps are desired here which are not or only slightly noticeable by the passengers, and which is achieved by the inventive pump. The inventive pump can also be applied in other suitable application needs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following, the invention is further explained based on the embodiment example presented in the drawing. The drawing shows in 
         FIG. 1  a schematic side sectional view of an intake charged dual-flow pump illustrating a jet stream injected to the pump, the intake suction stream, a mixing stream and the partial streams directed to the front and back suction pockets, 
         FIG. 2  an enlarged vertical longitudinal sectional view of a mixing chamber and a nozzle arrangement in the same, and 
         FIG. 3  a sectional view through the upstream end of the mixing chamber and the nozzle of the nozzle arrangement facing in the direction of the mixing chamber. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Of a dual flow, intake charged vane cell pump  1  for transporting liquid, in  FIG. 1 , only a housing  2  with an inner space  3  is presented in a longitudinal sectional view. The presented pump can be in particular an oil pump of a motor vehicle transmission, preferably an automatic transmission, for the lubrication and/or actuation (execution of shift operations or the engaging/disengaging of transmission shafts) of the transmission. The vane cell pump  1  has front and back intake areas  18 ,  19  that are arranged in pairs with the front suction pockets  4  and the rear suction pockets  5 , which are both arranged diametrically opposed to each other at the housing lids  21  of the housing  2 . The suction pockets  4 ,  5  lead into the inner space  3  of the pump. Arranged inside the inner space  3  is a pump rotor, which is not shown for the purpose of clarity, that rotates around a central rotational axis  29 . Wherein, because the pump is designed as a vane cell pump, the pump rotor is a vane rotor. In another design of the pump, for instance as a gear wheel pump, a respective other design of the pump rotor will be applied for instance a transportation gearwheel. Depending on the pump design, several pump rotors can be positioned in the inner space  3 . 
     In addition, first and second pressure areas  11 ,  12  lead into the inner space  3 . During the operation of the pump, rotation of the pump rotor around the rotational axis  29  transports the liquid from the suction pockets  4 ,  5  through the inner space  3  to the pressure areas  11 ,  12  and beyond. 
     At the housing  2 , a mainly tangentially directed, cylindrical intake duct is positioned, for the liquid which needs to be transported by the pump  1 , and which is, in accordance with the invention, mainly designed as a cylindrical mixing chamber  6 . The input side of the mixing chamber  6  is connected with a cover of a suction filter housing  7  or directly designed at it. Through an opening  28  in the cover of the suction filter housing  7 , the liquid is sucked in from a not shown storage container. In the connecting area of the mixing chamber  6  and the suction filter housings  7 , the cover of the suction filter housing  7  is provided with a nozzle configuration which has a carrier plate  14  for a nozzle  13 . The carrier plate  14  is, in this embodiment example, fixed into a holding groove  26  of the cover of the suction filter housing  7 , especially clipped to it. The nozzle  13  is preferably designed as one piece with the carrier plate  14 . 
     In addition, at the cover of the suction filter housing  7  is a pressure duct  9  through which, when the pump  1  is operated, a jet stream  10 , branched off from its pressure area  11 ,  12 , is transported to the nozzle  13  which injects it into the mixing chamber  6 . The connecting ducts between the pressure areas  11 ,  12  and the pressure duct  9  are not shown here for the reason of clarity. This liquid return operation is to be known in vane cell pumps, for instance in power steering assist systems as described for instance in DE 41 38 516 A1. Such pumps are equipped with a not shown flow control valve through which the transported liquid is brought in a controlled way from the high-pressure area of the pump to its intake area. 
     The exiting jet stream  10  from the nozzle  13  supports the suction of a hydraulic suction stream  8  which flows, through an opening  28  in the cover of the suction filter housings  7  and via a filter  25 , to the mixing chamber  6 . After combining of the jet stream  10  and the suction stream  8 , a mixed stream  15  is created, preferably with a twist overlay in the mixing chamber  6  from which a first partial stream  16  reaches, via a first, front intake area  18 , the front suction pockets  4 , and a second partial stream  17  reaches, via a second intake area  19 , the back suction pockets  5  in the back. 
     While the first partial stream  16  for the front suction pockets  4  mostly directly reaches the front intake area  18 , the second partial stream  17  for the back suction pockets  5  is brought through a ring duct  20  into the housing  2  to the intake area  19  at the back and enters through the suction pockets  5  into the inner space  3  at back of the pump housing  2 . Within the ring duct  20 , the flow velocity of the second partial stream  17  diminishes up to the intake area  19  in the back, wherein its kinetic energy is almost completely converted in to pressure energy (ram pressure), in so far that the pressure of the second partial stream  17  present at the back suction pockets  5  essentially matches the pressure of the first partial stream  16  present at the front suction pockets  4 . 
     As it can be seen in the  FIGS. 2 and 3 , the longitudinal axis  22  of the nozzle  13  extends, in a vertical longitudinal sectional plane A (here the drawing plane of  FIG. 2 , which is perpendicular to the rotational axis  29  and along which the longitudinal axis  22  extends) at an angle α of approximately 15° to 45°, preferably 15° to 20°, with respect to the longitudinal axis  23  of the mixing chamber  6 . Also, the longitudinal axis  22  of the nozzle  13  extends in a horizontal longitudinal sectional plane B (here a plane which is perpendicular to the drawing plane of  FIG. 2 , which runs parallel to the rotational axis  29  along the longitudinal axis  22 ) at an angle of approximately 15° to 45°, preferably 30° to 35° with respect to the longitudinal axis  23  of the mixing chamber  6 . It can also be seen that the inlet of the nozzle  13 , in the vertical sectional plane with respect to the longitudinal axis  23  of the mixing chamber  6 , is positioned at an axis deviation of approximately 19% to 25%, preferably 15% to 20%, of the diameter of the mixing chamber  6 . 
     Through this positioning of the nozzle  13  with respect to the input side end of the mixing chamber  6 , the desired suction of the suction stream  8  and the creation of a mixed stream  15  is achieved, which causes the front suction pockets  4  and the back suction pockets  5  of the dual flow pump  1  to receive the partial streams  16 ,  17  with the same pressure and energy content. It can be achieved without a complicated construction effort and without significant energy losses at impact walls, so that practically all the energy content of the jet stream  10 , which is under high pressure, is available for the intake charging of the vane cell pump  1 . 
     Finally, it can particularly be seen in  FIG. 2 , that the nozzle  13  has, with respect to its longitudinal axis  22 , an asymmetrical inner shell surface  27  which additionally favors the above described creation of flow. Thus, the inner shell surface  27  can be designed in a way that it favors the creation and presence of a very stable partial stream  17  at the outside at the inner wall of the mixing chamber  6 , which flows mainly to the back suction pockets  5 , while the suction stream  8 , which is drawn by the jet stream  10 , delivers the front suction pockets  4  with liquid. 
     REFERENCE CHARACTERS 
     
         
           1  Vane Cell Pump 
           2  Housing 
           3  Inner Space 
           4  Front Suction Pocket 
           5  Back Suction Pocket 
           6  Mixing Chamber, Feeding Channel 
           7  Suction Filter housing, Cover of the Suction Filter housing 
           8  Suction Flow 
           9  Pressure Duct 
           10  Jet Stream 
           11  Back Pressure Area 
           12  Front Pressure Area 
           13  Nozzle 
           14  Carrier Plate 
           15  Mixed Stream 
           16  Partial Stream to the Front Suction Pockets 
           17  Partial Stream to the Back Suction Pockets 
           18  Front Intake area 
           19  Back Intake area 
           20  Ring Duct 
           21  Housing Cover 
           22  Longitudinal Axis of the Nozzle 
           23  Longitudinal Axis of the Mixing Chamber 
           24  Axis Deviation 
           25  Filter 
           26  Holding Groove for the Carrier Plate or Nozzle, respectively 
           27  Inner Surface Part of the Nozzle 
           28  Opening in the Cover of the Suction Filter Housing 
         A Vertical Longitudinal Cut Plane 
         B Horizontal Longitudinal Cut Plane