Abstract:
A vehicle coolant pump with heat protection for the internal electronics and circuit boards for operation of the coolant pump. Gap fillers positioned adjacent said electronics and circuit boards transfer heat to the coolant fluid in the engine.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims benefit of U.S. Patent Application 62/024,492 filed on Jul. 15, 2014. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention is related to vehicle coolant pumps, and more particularly to improved coolant pumps with heat protection. 
       BACKGROUND 
       [0003]    Coolant pumps for circulating cooling fluids in vehicles and other cooling systems are in constant use today. There are various types of coolant pumps, most of which work to various degrees of satisfaction. 
         [0004]    Some coolant pumps contain electrical systems and/or electromagnetic components and systems, and thus contain heat sensitive electronic components, such as circuit boards. This is particularly true with dual mode coolant pumps that may contain both electric motors and electromagnetic mechanisms. If the electrical and electronic components and systems are not maintained within conventional operating temperatures, the coolant pumps could be ineffective or fail. 
         [0005]    There is thus a need to provide coolant pumps with improved methods of protecting electric or electronic components and systems from excessive heat. 
       SUMMARY OF THE INVENTION 
       [0006]    It is an objective of the present invention to provide an improved coolant pump that meets these needs and provides benefits and advantages over known coolant pumps. 
         [0007]    In a preferred embodiment of the invention, a dual mode coolant pump is provided which selectively rotates an impeller in a coolant fluid housing. The dual mode coolant pump includes housings in which an electric motor drive mechanism and a mechanical drive mechanism for rotating the impeller are positioned. The coolant fluid housing is attached to the vehicle engine and has an inlet port for receipt of coolant fluid and an outlet port for transfer of the coolant fluid into the engine block. 
         [0008]    The electric motor, which preferably is a brushless DC motor, and the electromagnetic clutch mechanism for the mechanical drive mechanism are both operated electrically. A circuit board (CB) is located in the coolant pump housing adjacent the coolant fluid housing, and contains electronic components for operating the electric motor and electromagnetic clutch mechanism. Power is supplied from the vehicle electrical systems, including an electronic control unit (ECU). If electrical power is absent, the electric motor can be powered by the vehicle battery. 
         [0009]    A gap filler is positioned in the pump housing adjacent to, and in contact with, the circuit board. The gap filler acts as a heat sink and transfers heat from the circuit board and its components through the pump housing and into the coolant fluid. Since typically the coolant fluid is at a temperature lower than the temperatures of the circuit board components, this embodiment of the invention protects the heat sensitive electronic components by maintaining them within their acceptable temperature limits. 
         [0010]    Further embodiments of the invention as well as additional features and benefits of the invention will be disclosed below in the following written description and accompanying drawings, together with the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  depicts an embodiment of the invention. 
           [0012]      FIG. 2  is an exploded view of the embodiment of  FIG. 1 . 
           [0013]      FIG. 3  is a cross-sectional view of the coolant pump depicted in  FIG. 1 . 
           [0014]      FIG. 4  schematically depicts a cooling system and an associated control system relative to an embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    A perspective view of an embodiment of the present invention  10  is shown in  FIG. 1 , and an exploded view is depicted in  FIG. 2 . The embodiment includes a dual mode coolant pump  20  and an impeller housing  30 . The impeller housing  30  is adapted to be connected to, or at least be in fluid communication with, a vehicle engine block  40 . 
         [0016]    The coolant pump  20  includes a motor housing  22 , an electric motor  24 , a solenoid housing  26 , a friction clutch mechanism  33  (as better shown in  FIG. 3 ) and a pulley member  29 . The pulley member  29  is adapted to be rotated by an engine belt. An engine belt for this purpose is shown in  FIG. 4  and designated by reference number  31 . The engine belt is also attached to a pulley member  32  positioned on the vehicle engine block  40 . The pulley member  29  is rotated by the engine at a speed (“input speed”) determined by a pulley ratio. 
         [0017]    The coolant pump  20  is depicted in cross-section in  FIG. 3 . A preferred dual mode coolant pump that can be utilized with the present invention is disclosed and discussed in detail in U.S. patent application Ser. No. 14/149,683, filed on Jan. 7, 2014, and entitled “Accessory Drive With Friction Clutch and Electric Motor”, the disclosure of which is hereby incorporated herein by reference. 
         [0018]    An electric motor  24  is positioned in the motor housing  22 . The motor housing is preferably made of a metal material with good thermal conductivity, such as aluminum. The electric motor is preferably a brushless DC motor, and includes a coil-type stator member  25  and a rotor member  27 . The rotor member is fixedly attached to central pump shaft member  28 . 
         [0019]    A solenoid member  34  is positioned in the solenoid housing  26 . The solenoid housing is preferably made of a metal material, such as low carbon steel. 
         [0020]    The electronics for electric motor  24  and solenoid member  34  are contained in the circuit board (“CB”)  50 . The circuit board contains the electronic components which electrically control the operation of the electric motor and the solenoid member, including turning them on and off. Power from the circuit board  50  is supplied to the electric motor  24  through lead frame  52 , and to the solenoid member  34  through lead frame  57 . 
         [0021]    Electric power to the circuit board  50  is supplied through connector member  60  (shown in  FIGS. 1 and 2 ). The connector member  60  has a plurality of lead wires that are connected to the circuit board. The lead wires include two wires which provide power to the circuit board and a plurality of other wires which are signal wires to provide signals to operate the electric motor and solenoid member. The circuit board  50  is connected to the motor housing  22  by a plurality of fasteners, such as screw members  53 . 
         [0022]    Positioned between the circuit board  50  and the inside wall of the motor housing is a gap filler member  55 . The filler member conducts heat from the circuit board into the aluminum motor housing  22  where the heat in turn is distributed to the coolant fluid which is being circulated in the impeller housing  30 . 
         [0023]    The gap filler member  55  can be any conventional type for providing heat transfer between a CB heat source and a heat sink surface. Gap fillers typically are soft materials with low durometers and which have good thermal conductivity. Gap fillers can be used to fill gaps between hot components. The materials can be flexible with an elastic nature and can blanket uneven surfaces, either individually or in layers or groups. In the present invention, heat is conducted away from the circuit board  50  by the gap filler  55  and into the aluminum motor housing  22  where the heat is conducted to the cooler coolant fluid. Typically in vehicle cooling systems, the coolant fluid has a maximum temperature of about 129° C., while most circuit board components have a rated temperature of 150° C. or higher. 
         [0024]    The wall  72  of the motor housing  22  faces and is in contact with the coolant fluid. The wall  72  has a plurality of fluid recesses or pockets  70 , and can be individual recesses or annular grooves. Some of the recesses  70  are shown in  FIG. 3 . Any number of recesses, pockets or grooves can be provided. These items  70  make the motor housing wall  72  thinner in spots, places or areas, which assists in transferring or conducting heat from the circuit board  50  and gap filler  55  into the coolant fluid. Preferably the thickness of the motor housing wall in the bottoms of the recesses is about five to twenty millimeters (5-20 mm) This is represented by distance D in  FIG. 3 . The surfaces at the ends of the recesses, pockets, grooves, etc. should be as thin as possible in order to aid in transferring heat from the circuit board, but without sacrificing the integrity and durability of the motor housing wall  72  or the motor housing itself. 
         [0025]    The coolant pump shaft  28  is positioned centrally in the housings  22  and  26 , with the electric motor  24  and friction clutch mechanism  33  being positioned in axial alignment around the shaft  28 . An impeller member  80  is connected to impeller shaft  29  which is connected at one end  28 A of the coolant pump shaft  28 . The impeller member  80  and impeller shaft  29  protrude from the motor housing and extend into the interior of the impeller housing  30 . 
         [0026]    The impeller housing  30  is made of a metal material, such as aluminum, and has a central cavity  90 , an inlet port  92  for inlet of coolant fluid, and an outlet port (not shown) for passage of the coolant fluid into the engine block  40 . When the impeller  80  is rotated by the dual mode coolant pump  20 , the coolant liquid is pumped through the outlet into and through the engine and the rest of the engine cooling system, and then returned to the coolant pump inlet port  92 . 
         [0027]    In an alternate embodiment of the invention, a coolant control valve (CCV) can also be provided. Coolant control valves control the direction and amount of flow of the coolant as it enters the engine block. 
         [0028]    As indicated above, the rotor  27  of the electric motor  24  is fixedly attached to the coolant pump shaft  28  and rotates with it. When the motor is activated, the shafts  28  and  29 , as well as the impeller member  80 , rotate. The rotation of the impeller member causes the coolant fluid to flow through the impeller housing and the rest of the coolant system. 
         [0029]    Preferably, the coolant pump shaft  28  is rotated by the electric motor for most of the period in which a coolant pump is needed. When additional coolant flow is required, such as when the vehicle pulls a heavy load and more cooling is required, the pump shaft  28  is rotated mechanically at input speed. For this purpose, the solenoid member  34  is deenergized which allows armature member  110  to shift axially away from the solenoid. This allows the friction lining member  112  on the spring biased friction plate  114  to contact the cover member  116 . Since the cover member  116  is attached to the pulley member  29  and rotates with it, this provides rotation of the coolant pump shaft at input speed. The components, including the solenoid member, armature member, friction plate, friction linings and biasing spring members are collectively called a friction clutch mechanism  33 . 
         [0030]    Under normal operation when the coolant pump shaft and impeller are being rotated by the electric motor, the solenoid member  34  is electrically activated. This attracts the armature member  110 , which is made of a magnetic metal material and prevents the friction plate  114  from being biased against the cover where the friction linings  112  on the friction plate  114  can contact the inside surface of the cover member and cause mechanical rotation of the shafts  28  and  29  and the impeller  80 . 
         [0031]    The coolant pump shaft  28  is mounted in the housing and allowed to rotate by a pair of bearing members  120  and  122 . The electric rotor  27  is positioned on the shaft  28  between the two bearing members  120 ,  122 . 
         [0032]    The pulley member  29  is mounted in the coolant pump by bearing member  124  and allowed to rotate freely around the friction clutch mechanism. The armature member  110  is biased in the coolant pump by a plurality of coil spring members  130 . Additional details of the structure of the dual mode coolant pump and its operation are contained in U.S. patent application Ser. No. 14/149,683, the disclosure of which is incorporated herein by reference. 
         [0033]      FIG. 4  depicts a preferred system and process for operating the coolant pump  20  and a vehicle cooling system  130  in accordance with the present invention. The coolant pump  20  is a dual mode coolant pump and includes an electric motor  24 , and a friction clutch mechanism  33 . The mechanism  33  in combination with a pulley member  29  comprise a mechanical drive “M”. The dual mode coolant pump  20  rotates an impeller member  80  in the impeller housing  30 . 
         [0034]    The operation of the coolant pump  20  is operated by control logic  140  which receives appropriate data and information from an engine electronic control unit (“ECU”)  142 . The engine ECU  142  receives data and information from one or more temperature sensors  150 , other engine and vehicle sensors  152 , as well as control instructions and signals from a vehicle ECU  160 . The ECUs and control logic operate the coolant pump  20  and impeller rotation to maintain the temperature of the coolant fluid within acceptable limits. 
         [0035]    Coolant fluid from the coolant pump  20  flows into and through the engine  40 . The coolant fluid then exits the engine and flows through a heat exchanger  184  such as a radiator, where it is cooled. The temperature of the coolant can be read by a thermostat  190 . Following flow through the heat exchanger, the cooler coolant fluid is then returned  186  to the coolant pump  20 . 
         [0036]    The present invention provides an improved coolant pump and engine cooling system that not only maintains the coolant fluid within appropriate temperature limits, but also maintains the temperature of the coolant pump electronics and circuit board within their appropriate temperature limits. This provides a coolant pump and cooling system which is efficient, durable, and long-lasting. 
         [0037]    Although the invention has been described with respect to preferred embodiments, it is to be also understood that it is not to be so limited since changes and modifications can be made therein which are within the full scope of this invention as detailed by the following claims.