COOLANT PUMP WITH HEAT SINKING TO COOLANT

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

TECHNICAL FIELD

The present invention is related to vehicle coolant pumps, and more particularly to improved coolant pumps with heat protection.

BACKGROUND

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.

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.

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

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.

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.

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.

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.

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

FIG. 1 depicts an embodiment of the invention.

FIG. 2 is an exploded view of the embodiment of FIG. 1.

FIG. 3 is a cross-sectional view of the coolant pump depicted in FIG. 1.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 28A 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Claims

1. A cooling system for a vehicle engine, comprising: (a) a coolant pump, said coolant pump comprising a drive mechanism and a driven mechanism with said drive mechanism comprising a mechanical drive mechanism, and said driven mechanism comprising an electric motor, said electric motor positioned in a motor housing;(b) a control system for operating said coolant pump, said control system comprising at least one temperature sensor, an ECU, and a circuit board; and(c) a gap filler positioned in said motor housing and in contact with said circuit board;wherein heat from said circuit board is transferred through said gap filler and said motor housing, and into a coolant fluid.

2. The cooling system as described in claim 1 wherein said coolant pump is a dual mode coolant pump.

3. The cooling system as described in claim 1 wherein said electric motor is a brushless DC motor.

4. The cooling system as described in claim 1 wherein said motor housing has at least one wall member which is positioned between said circuit board and the coolant fluid, and wherein said gap filler is positioned between said at least one wall member and said circuit board.

5. The cooling system as described in claim 1 wherein a plurality of recesses are provided in a first side of said at least one wall member which is in contact with a coolant fluid, and wherein said gap filler is positioned on the opposite side of said first side of at least one wall member.

6. The cooling system as described in claim 5 wherein the wall thickness in bottoms of said recesses is about 5 to 20 millimeters.

7. The cooling system as described in claim 1 further comprising a shaft member and an impeller member, said shaft member being selectively driven by said drive mechanism and said driven mechanism.

8. The cooling system as described in claim 7 wherein said shaft member is supported in said coolant pump by a pair of bearing members, and said electric motor is positioned between said bearing members.

9. The cooling system as described in claim 1 wherein operation of said coolant pump is controlled at least in part by control logic.

10. The cooling system as described in claim 1 wherein said mechanical drive mechanism includes a solenoid member and a friction clutch member.

11. The cooling system as described in claim 10 wherein activation of said solenoid member prevents said mechanical drive member from rotating said shaft member.

12. The cooling system as described in claim 10 wherein activation of said solenoid members allows said mechanical drive member to rotate said shaft member.