Patent Publication Number: US-2019186339-A1

Title: Water pump for vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The-present application claims priority to and the benefit of Korean Patent Application No. 10-2017-0174098 filed on Dec. 18, 2017, which is incorporated herein by reference in its entirety. 
     FIELD 
     The present disclosure relates to a water pump for a vehicle, and more particularly, a water pump for a vehicle capable of controlling a discharge flow rate in multiple stages. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     Generally, a water pump used in a vehicle is a device for improving the cooling efficiency of the engine by forcibly circulating the coolant of the engine. It may be divided into a mechanical water pump which directly receives rotational drive power from the engine to be driven in proportion to the number of revolutions of the engine and a variable or electric water pump which is operated through a separate drive source such as a motor without directly receiving rotational power from the engine. 
     Since the mechanical water pump is disadvantageous in terms of energy efficiency and fuel efficiency because it cannot control variously the driving mode of the water pump in accordance with the driving state of the engine and the vehicle, the variable water pumps have been recently applied to improve fuel efficiency, and so on, even at the expense of rising costs. 
     Various methods have been used to control the discharge flow rate of variable water pump to various discharge modes. 
     For example, a vacuum type water pump is a structure that adjusts the impeller outlet by operating the slide with a negative pressure. It is advantageous in terms of layout and has a simple control structure. 
     The water pump of the intermediate wheel type is a structure that controls the rotation of the pulley by moving the position of the intermediate wheel through a built-in actuator, which is disadvantageous to durability due to slip and abrasion, and or the like. 
     Furthermore, an electronic clutch type water pump, which controls the rotation of the impeller through an incorporated clutch, is advantageous in terms of layout but has a complicated drawback, and a variable water pump, which controls the speed of the pump by controlling the connection or disconnection of a pulley and a drive shaft through permanent magnet, has been usually applied to commercial vehicle, but it is difficult to precisely control the intensity of permanent magnet and since the slip in the magnetic field requires radiating fins, which makes the structure thereof complicate and disadvantage in terms of cost. 
     SUMMARY 
     The present disclosure provides a water pump for a vehicle capable of reducing the weight and cost by simple structure and precisely controlling the flow rate discharged from the water pump in multiple steps. 
     A water pump for a vehicle in one form of the present disclosure may include, an impeller with an impeller discharging port pumping and discharging coolant, a shroud movably installed to open and close the impeller discharging port, a first pushing unit configured to push the shroud in a direction of opening the impeller discharging port, and a second pushing unit configured to push the shroud in a direction of closing the impeller discharging port. 
     A drive shaft may be installed at the impeller and a pulley may be connected with the drive shaft. 
     The shroud may be movably installed in the axial direction along the drive shaft. 
     The first pushing means may include a spring disposed between the impeller and the shroud. 
     The second pushing unit may include a wax being connected with the shroud through a pushrod and volume-expanding or contracting depending on the supplied heat amount, and a heater selectively supplying heat to a wax. 
     The heater may be connected to the engine control unit to be controlled by the operating signal of the engine control unit. 
     The engine control unit may be to apply an operating signal to the heater so that the heater heats up to the wax when the engine warms up. 
     The engine control unit may apply an operating signal to the heater corresponding to the rotation speed of the engine, the load, and the ambient temperature. 
     In accordance with a water pump for a vehicle in another form of the present disclosure, the heater is operated according to the control signal of the engine control unit to control the amount of heat supplied to the wax, so that the opening of the impeller outlet through the shroud supported by the spring and the discharge flow rate of the water pump can be precisely controlled in a stepwise manner. 
     By controlling the shroud to adjust the impeller outlet through only the wax and heater, the control structure can be simplified and weight and cost can be saved, and durability can be improved because there is no friction element. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
         FIG. 1  is an example of a coolant circulation system for a vehicle to which a water pump is applied; 
         FIG. 2  is an operating cross-sectional view when the water pump for the vehicle does not discharge the flow rate; 
         FIG. 3  is an operating cross-sectional view when the water pump for the vehicle discharges the flow rate; and 
         FIG. 4  is an operating cross-sectional view when the water pump for the vehicle discharges the maximum flow rate. 
     
    
    
     The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     While the disclosure will be described in conjunction with exemplary forms, it will be understood that present description is not intended to limit the disclosure to those exemplary forms. On the contrary, the disclosure is intended to cover not only the exemplary forms, but also various alternatives, modifications, equivalents and other exemplary forms, which may be included within the spirit and scope of the disclosure as defined by the appended claims. The terminology used herein is for the purpose of describing particular forms only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. For example, in order to make the description of the present disclosure clear, unrelated parts are not shown and, the thicknesses of layers and regions are exaggerated for clarity. Further, when it is stated that a layer is “on” another layer or substrate, the layer may be directly on another layer or substrate or a third layer may be disposed there between. It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicle in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats, ships, aircraft, and the like and includes hybrid vehicles, electric vehicles, combustion, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). Some forms of the present disclosure will now be described in detail with reference to the accompanying drawing. Referring to  FIG. 1 , an engine coolant circulation system for a vehicle to which a water pump for a vehicle in some forms of the present disclosure is applied may be configured as follows. 
     A water pump for a vehicle  1  in some forms of the present disclosure pressurizes and pumps coolant to supply it to a cylinder block  2  of an engine; the coolant cools a cylinder block  2  and a cylinder head  3  and then, discharged from the cylinder head  3  to be flowed into a direction adjusting valve  4 . 
     Some coolant flowed into the direction adjusting valve  4  is heated by a heater  6  via a low pressure EGR (Exhaust Gas Recirculation) cooler  5 , and then flows into the water pump  1  and some coolant flowed back to the water pump  1  via an EGR valve  7 . 
     Some coolant flowed into the direction adjusting valve  4  is injected into a reservoir tank  8  and stored in the reservoir tank  8  or supplied to a radiator  9  to be cooled and then flows into a thermostat valve  10 , and the coolant passing through the thermostat valve  10  is again flowed into the water pump  1 . 
     Furthermore, some coolant flowed into the direction adjusting valve  4  is flowed into the water pump  1  via an ATF warmer  11 , an oil cooler  12  and a high pressure EGR cooler  13 , and the coolant discharged from the reservoir tank  8  flows into the thermostat valve  10 . 
     The water pump  1  in some forms of the present disclosure applied to the coolant circulation system as described above may include, as shown in  FIG. 3 , an impeller  32  for pressurizing and pumping the coolant and discharging through an impeller discharging port  31 , a drive shaft  33  thereof, and a pulley  34  for supplying rotational power to the impeller drive shaft  33 . 
     A bearing  35  may be mounted at the outer circumference of the impeller drive shaft  33  to support the impeller drive shaft  33  to be rotatable. 
     The impeller discharge port  31  may be closed or partially open or fully open by a shroud  36  which may be movably mounted along the impeller drive shaft  33 . 
     A spring  37  may be installed as a first pushing means between the impeller  32  and the shroud  36  to elastically push the shroud  36  in a direction to open the impeller discharging port  31 . The spring  37  may be seated on and supported by a spring seat  38 . 
     A second pushing means may be provided opposite the spring  37  to push the shroud  36  in a direction closing the impeller discharging port  31 . 
     The second pushing means may include a wax  40  that volumetrically expands or contracts according to the calorie supplied with the shroud  36  via a pushrod  39  and a heater  41  that does not supply or supply heat to the wax  40 . 
     The heater  41  may be connected to an engine control unit ECU, and its operation may be controlled according to the control signal of the engine control unit ECU. 
     The heater  41  and the wax  34  may be connected to a heat conducting wire  42  or a heat conducting rod. 
     The engine control unit The ECU can judge the driving state of the engine and also judge the driving state of the vehicle through various sensors. 
     The operation state of  FIG. 2  shows the state that the engine control unit ECU applies an operation signal to the heater  41 , and the heat generated in the heater  41  is supplied to the wax  34  through the heat conducting wire  42 , so that the wax  34  is expanded to the maximum, the spring  37  is compressed by the shroud  36 . 
     The pushrod  39  pushes the shroud  36  according to the volume expansion of the wax  34 , as shown by the arrows, so that the shroud  36  closes the impeller discharging port  31  to prevent the circulation of the coolant through the water pump  1  and the coolant temperature rises quickly, thereby shortening the warm-up time of the engine and improving fuel efficiency. 
     When the coolant temperature rises appropriately after the warm-up of the engine, the engine control unit ECU controls the operating signal of the heater  41  to control the amount of heat generated by the heater. 
     Then, as shown in  FIG. 3 , the position of the shroud  36  is adjusted at the point where the elastic restoring force of the spring  37  and the expansion force of the wax  40  are in equilibrium, the impeller discharging port  31  is opened to the partial by the shroud  36 , and the coolant circulation is performed while the water pump  1  pressurizes and discharges the coolant. 
     The engine control unit ECU can control the heat amount generated by the heater  41  by controlling the operation signal applied to the heater  41  according to the predetermined map or the program in consideration of the factors such as the rotation speed of the engine, the load and the outside temperature. For example, in the high load operating range of the engine, the coolant discharge flow rate is increased and in the low load operating range of the engine, the discharge flow rate is reduced to improve the fuel efficiency. 
     On the other hand, when the coolant temperature of the engine rises to become hot, the engine control unit ECU interrupts the operating signal applied to the heater  41 , and accordingly the shroud  36  is pushed in the direction of opening the impeller discharging port  31  to fully open the impeller discharging port  31 , so that the coolant circulates rapidly along the circulating system. 
     In some forms of the present disclosure, although the spring are exemplified as the first pushing means and the wax and the heater as the second pushing means, a solenoid valve, a clutch or the like can be replaced. 
     The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure. 
     DESCRIPTION OF SYMBOLS 
     
         
           1 : water pump 
           2 : cylinder block 
           3 : cylinder head 
           4 : direction adjusting valve 
           5 : low pressure EGR cooler 
           6 : heater 
           7 : EGR valve 
           8 : reservoir tank 
           9 : radiator 
           10 : thermostat valve 
           11 : ATF warmer 
           12 : oil cooler 
           13 : high pressure EGR cooler 
           31 : impeller discharging outlet 
           32 : impeller 
           33 : drive shaft 
           34 : pulley 
           35 : bearing 
           36 : shroud 
           37 : spring 
           38 : spring seat 
           39 : pushrod 
           40 : wax 
           41 : heater