Cooling device for internal combustion engines

Abstract: A cooling device for an internal combustion engine includes a brushless DC motor having a housing, an output shaft, a magnet rotor fixedly mounted on the output shaft, and a stator positioned in the housing and having three phase windings which are arranged in the circumefrential direction around the magnet rotor; an impeller connected at an outside of the housing to one end of the output shaft of the motor and circulating a cooling liquid through the engine and a radiator while the output shaft is being rotated; and a device for generating a heat at the phase windings for warming-up the cooling liquid if a temperature of thereof is below a set value. A cooling device for an internal combustion engine includes an electrically operated motor having an output shaft and rotating the output shaft upon energization of the motor, an impeller connected to one end of the output shaft for circulating a cooling liquid through the engine and a radiator while the output shaft of the motor is being rotated, and a device for stopping the rotation of the output shaft of the motor without interrupting the energization of the motor when a temperature of the cooling liquid is below a set value.

Description: The present invention is directed to a cooling device for internal combustion engines wherein a cooling water is circulated through a radiator and the internal combustion engine. More particularly, the present invention is directed to a cooling device of the type in which a shorter time period of engine warm-up mode can be established. It has been requested to shorten a time period of engine warm-up mode. To comply with such a request, the United States Patent No. 5,435,277 provides a device wherein an amount of high temperature water is injected into an engine whenever the engine is started, thereby accelerating the warming-up operation of the engine. Thus, the time period for engine warm-up mode can become shorter. However, for establishing such an injection of high tempered water, a tank for storing therein has to be prepared. In addition, an additional water passage has to be connected to the existing water circulation line, and the resultant complexity thereof in structure makes it cumbersome to assemble. In light of the foregoing circumstances, a cooling device for internal combustion engines is desired which is free from the foregoing drawbacks. In order to attain the foregoing objects, the present invention provides a cooling device for an internal combustion engine as set out in the claim 1, claim 10 or claim 17. Further advantageous developments are set out in the dependent claims. The above and other objects, features and advantages of the present invention will be more apparent and more readily appreciated from the following detailed description of preferred exemplary embodiments of the present invention, taken in connection with the accompanying drawings, in which: FIG.1 is a schematic illustration of a first embodiment of a cooling device in accordance with the present invention; FIG.2 is a cross-sectional view of the liquid pump shown in FIG.1; FIG.3 is a cross-sectional view taken along line A-A in FIG.2; FIG. 4 is a cross-sectional view of another liquid pump as a modification of the liquid pump shown in FIG.2; FIG.5 is a schematic illustration of a second embodiment of a cooling device in accordance with the present invention; and FIG. 6 is a chart showing a relationship between current supply to phase winding and an angular position of an output shaft of a motor. Preferred embodiments of the present invention will be described hereinafter in detail with reference to the accompanying drawings. Referring first to FIG.1, there is illustrated a cooling device which has, as a major element, a liquid or water pump 1 fixedly mounted to an internal combustion engine 3. The engine 3 is supplied with a cooling water from a radiator 12 and the resultant cooling water passes through a passage 17 in the engine 3. The cooling water which is warmed up to a hot temperature during movement through the engine 3 due to a heat transfer from the engine 3 at a high temperature to the cooling water at a lower temperature is returned to the radiator 12. While the cooling water passes through the radiator 12, a heat transfer is established from the cooling water to an ambient air by close contact therebetween in the radiator 13, whereby the cooling water is re-cooled and such a cooling water is used again to cool the engine 3. Thus, circulating the cooling water through the radiator 13 and the engine 3 makes a continual cooling the engine 3. Referring next to FIG.2, there is illustrated the detailed structure of the water pump 1 which is used to circulate the cooling water through the radiator 12 and the engine 3. For driving or running the water pump 1, an electric motor 2 is used for converting an electrical input from a battery (not shown) into a mechanical output. A control division 14 is provided to the motor 8 for activating and deactivating each phase winding or coil 8 of the motor 2. The control division 14 is a portion of a control device 13 which processes various input and output signals regarding vehicle cruise control. The electric motor 2, which is in the form of a brushless DC motor, includes an output shaft 7 fixedly mounted thereon a rotor 6 and provided at a distal end thereof with a metal-made impeller 5 for circulating the cooling water, a core 15 positioned outside the rotor 6 such that a space is defined therebetween, a stator 9 constituted by the core 15 and a plurality of equi-pitched angularly spaced coils 8 which are arranged inside the core 15, and a housing 10 accommodating therein the stator 9 and fixed to the engine 3. At an inside portion of the stator 9, there is fixed a partition wall 16 having the illustrated shape, thereby defining a chamber 11 therebetween into which the cooling water flows. It is to be noted that the partition wall 11 acts as a seal member so as to prevent a flow of the cooling water toward the stator 9 from the chamber 16. The distal end of the shaft 7 mounting thereon the impeller 5 is extended into a midway portion 17 of the passage formed in a housing 18. The midway portion 17 is positioned in the passage through which the cooling water passes. An base end of the shaft 9 is supported on flat bearing 19 fitted in the partition wall 16 secured to the housing 18. The shaft 7 is also supported on a flat bearing 20 fitted in the housing 18 so as to be located between the chamber 11 and the midway portion 17 in the passage. The flat bearing 20 is provided therein with a plurality of axially extending passages (not shown) for continual fluid communication between the chamber 11 and the midway portion 17 of the passage. In the chamber 11, there is installed a temperature sensor 21 for determining a temperature of the cooling water. The cooling water temperature determined at the temperature sensor 21 is fed, as an electric signal, to the control division 14 and is used for controlling the coils 8. The rotor 6 which is in the form of a circular magnet is pressed onto the shaft 7 and is fixed thereto by bonding. An outer surface of the circular magnet 6 has two pairs of N poles and S poles alternatingly formed by magnetizing as shown in FIG.3. Of course, it is possible to employ separate magnets already or previously magnetized instead of the circular magnet 6, and the pole numbers are not limited as shown in FIG.3. The stator 9 is formed by providing three-phase coil portions 8 which are positioned diagonally inside the core 15. Each coil portion 8 is made by winding a cooper wire which is of an excellent conductivity. The stator 9 is fitted in the housing 10. When three-phase coil portions 8 are turned on electrically (alternately) by the battery, the coil portions 8 generate electromagnetic force, whereby the water pump 1 is driven. That is to say, a magnetic field is formed between the core 15 and the magnet 6. Turning on the coil portions 8 controls the changing of N poles and S poles generated in the core 15, and the shaft 7 rotates by attracting the magnetic flux from the magnet 6 to the coil portion 8. For stopping the rotation of the shaft 7 of the motor 2, all of the three-phased coil portions 8 are activated by order of the control division 14 instead of in-turn or sequential activation of one-phased coil portions 8. Under such a state or the concurrent activated condition of the three-phased coil portions 8, the magnetic flux is formed from the magnet 6 to each the coil portion 8, whereby the magnet 6 fixed on the shaft 7 fails to be rotated. In addition, each coil portions 8 is supplied with a current, and the resultant heat warms quickly the cooling water in the chamber, thereby accelerating warming-up operation of the engine 3. It is to be noted the two adjacent coil portions 8 can be supplied with either currents of different direction or currents of same direction. Instead of the forgoing method for preventing the rotation of the rotor 6 which is established in such a manner that all the coil portions 8 are supplied with the currents, flowing a current through a specific one-phase coil portions 8 which are diagonally positioned can be employed subject to remaining the inactivated conditions of other tow-phase coil portions 8. The reason is that such an electric control of the coil portions 8 by the control division 14 remains the position of the rotor 6 unchanged which causes the shaft 6 not to rotate. However, the heat amount generated at the activated coil portions 8 becomes one third relative to the foregoing condition. Thus, if desired, more rapid warming-up of the engine 3 requires activating all or three-phased coil portions 8. The water pump 1 is brought into operation when the motor 2 is turned on in concurrency with the engine 3 is started, whereby the rotation of the rotor 6 causes a rotation of the rotor or impeller 5 which circulates the cooling fluid through the radiator 12 and the engine 1. In normal, about four amperes (4A) of current flows through each the coil portion 8. If the temperature sensor 21 indicates that the engine temperature is below a set value of 60 degrees in centigrade, the control division 14 begins to flow currents through all the coil portions 8 for stopping the rotation of the shaft 5. Under the resultant condition, while the current continues to flow through each the coil portion8, the rotor 6 is held against rotation which fails to generate a counter electromotive force in each the coil portion 8, the current flowing through the coil portion 8 is at its maximum degree (permissible current), thereby heating the cooling water in rapid. The maximum working ampere of the motor 2 is set to be 50A. When the heat is generated at each the coil portion 8, the current of 50A flows therethrough, a heat amount of 600W (12V x 50A) or 140 cal/sec is developed. Assuming that the chamber 11 is 70cc in volume and the water is warmed by the engine 3 per se, a temperature increase of at least 2 degrees per second is attained in the water in the chamber 11. If the temperature of the water becomes above 60 degrees in centigrade during such a warming of the circulating water in the chamber 11, the control division changes the activation mode to rotate the shaft 5 again, thereby re-starting the circulation of the cooling water through the radiator 12 and the engine 3. Whenever the water in the chamber 11 indicative of below 60 degrees in centigrade, the control division stops rotating the rotor 6 for warming the water in the chamber before its circulation. The resultant or stopped condition of the rotor 6 is continued until the temperature sensor indicates above 60 degrees. As explained above, flowing current continually in each the coil portion 8 increases a developed heat in each the coil portion 8, thereby warming up the cooling water quickly. Thus, even though the engine 3 is started at its cold condition, a rapid warming-up of the engine 3 can be established. As can be seen from FIG.1, in addition to the water pump 1 driven by the electric motor 2, a second water pump 24 is provided to the engine 3 via a cam shaft 23 and while the engine 3 is running and the temperature of the cooling water is below 60 degrees in centigrade, the second pump 24 continues to operate to assist or prompt the circulation of the cooling water which is established by the water pump 1. After the temperature of the cooling water becomes above 60 degrees in centigrade, at least the minimum or suitable flow rate of the cooling water is ensured by driving the water pump 1. Due to the resultant cooling water, each the coil portions 8, the rotor 6, the shaft 7 and other elements can be cooled down. In addition, setting the control division 14 to control the three-phase coil portions 8 based on the signal from the temperature sensor 21 which is indicative of the cooling water temperature and the engine rotational speed enables that for ensuring the minimum or suitable quantity of the cooling water driving the water pump 1 has to be established only whenever it is requested to operate. Referring to FIG.4, there is illustrated a modification of the water pump 1. This modified water pump 1 is designed to be stopped by an electromagnetic clutch 4. Employing such an electromagnetic clutch 4 as a rotation stopping means differentiates the modified mode from the original mode. Elements other than the clutch 22 in FIGs. 4 and 5 are identical to those in FIGs.1 through 3 and therefore are denoted by the same reference numerals. The clutch 4 is brought into its engaged condition upon activation thereof and activating and deactivating control of the clutch 4 is made by the control division 14. Elements other than the clutch 22 in FIGs. 4 and 5 are identical to those in FIGs.1 through 3 and therefore are denoted by the same reference numerals. The electromagnetic clutch 4 is secured to the housing in which the cooling water passage 17 is defined and is under control of the control division 14. In order prevent a re-rotation of the rotor or impeller 5 after an establishment of the engagement of the clutch 4, the electromagnetic force issued from the coil 22 is so set as to be larger than the starting torque of the electric motor 2, and while each of the coil portions 8 is being activated in turn upon activation of the clutch 22 the metal-made impeller 5 is prevented to rotate. The operation of the second mode water pump 1 is similar to that of the first mode water pump except for the method for stopping the rotation of the impeller 5. In detail, when the coil 22 is activated by the control division 14, the resultant electromagnetic force attracts the impeller 5, resulting in stopping the impeller 5. Under the resultant condition, the rotor or magnet 4 is at rest, no counter electromotive force is generated in the motor 2 while the continual activation of each coil portion 8 is being established in turn, the maximum current continues to flow through each coil portion 8. As shown in FIG.5, the second mode water pump 1 is fixed to a lower portion of the engine 3. Such an arrangement brings that the cooling water heated by each coil portion 8 circulates through the radiator 12 and the engine 3 by convection, which results in that no additional water pump is required. This leads to decreases in the number of parts and the manufacturing cost. In addition, it is to be noted that in brushless DC motors if a phase shift of a current which is to be supplied to one of three phase windings is established relative to an angular position of an output shaft of a motor, this phase winding generates a heat. In detail, referring to FIG.6, as indicated in real line, when the phase windings 8A, 8B, and 8C are supplied with currents in such a manner that two adjacent current supplies are out of 120 degrees in phase. Each of such a current supply is used only to rotate the output shaft of the motor. However, if a phase shift of each of the current supplies as indicated in phantom line with respect to an angular position of the output shaft of the motor, some of the current makes this phase winding generate a heat as well known.Such a current supply mode, unlike the foregoing current supply modes, fails to stop the rotation of the output shaft. Thus, transferring such a heat to the circulating cooling liquid when the temperature is below 60 degrees in centigrade, thereby shorting time period for engine warming-up. The invention has thus been shown and description with reference to specific embodiments, however, it should be understood that the invention is in no way limited to the details of the illustrates structures but changes and modifications may be made without departing from the scope of the appended claims. A cooling device for an internal combustion engine includes a brushless DC motor having a housing, an output shaft, a magnet rotor fixedly mounted on the output shaft, and a stator positioned in the housing and having three phase windings which are arranged in the circumefrential direction around the magnet rotor; an impeller connected at an outside of the housing to one end of the output shaft of the motor and circulating a cooling liquid through the engine and a radiator while the output shaft is being rotated; and a device for generating a heat at the phase windings for warming-up the cooling liquid if a temperature of thereof is below a set value. A cooling device for an internal combustion engine includes an electrically operated motor having an output shaft and rotating the output shaft upon energization of the motor, an impeller connected to one end of the output shaft for circulating a cooling liquid through the engine and a radiator while the output shaft of the motor is being rotated, and a device for stopping the rotation of the output shaft of the motor without interrupting the energization of the motor when a temperature of the cooling liquid is below a set value.

Claims: A cooling device for an internal combustion engine comprising; an electrically operated DC motor ( 2 ) having a housing ( 18 ), an output shaft ( 7 ), a magnet rotor ( 6 ) fixedly mounted on the output shaft, and a stator ( 9 ) having phase windings ( 8 ) positioned in the housing; an impeller ( 5 ) connected at an outside of the housing to one end of the output shaft of the motor and circulating a cooling liquid through the engine and a radiator ( 12 ) while the output shaft is being rotated; and means ( 14 ) for generating a heat at the phase windings for warming-up the cooling liquid if a temperature thereof is below a set value. A cooling device as set forth in Claim 1, wherein the means stops the rotation of the output shaft of the motor without interrupting an energization to the motor by controlling the energization to the motor. A cooling device as set forth in Claim 2, wherein the stator has three phase windings ( 8A, 8B, 8C ) arranged in the circumferential direction around the magnet rotor, the means supplies currents concurrently to all of the phase windings. A cooling device as set forth in Claim 2, wherein the means supplies currents to the phase windings in cyclic of 120 degree phase and each supply is made with a phase difference relative to an angular position of the output shaft. A cooling device as set forth in Claim 2, wherein the impeller ( 5 ) is made of a metal, the means is in the form of an electromagnetic clutch ( 4 ) constituted by the metal-made impeller and an electromagnetic coil provided to the housing so as to oppose to the metal-made impeller. A cooling device as set forth in Claim 1, wherein a chamber ( 11 ) for receiving therein the cooling liquid between the stator and the magnetic rotor in the housing. A cooling device as set forth in Claim 1, comprising a liquid pump ( 1 ) positioned at a lower side of the engine. A cooling device as set forth in Claim 6, wherein a temperature sensor ( 21 ) is installed in the chamber to determine the temperature of the cooling liquid. A cooling device as set forth in Claim 1, wherein the electrically operated motor is in the form of a brushless DC motor. A cooling device for an internal combustion engine comprising: an electrically operated motor ( 2 ) having an output shaft ( 7 ) and rotating the output shaft upon energization of the motor; an impeller ( 5 ) connected to one end of the output shaft and circulating a cooling liquid through the engine ( 3 ) and a radiator while the output shaft of the motor is being rotated; and means ( 14 ) for stopping the rotation of the output shaft of the motor without interrupting the energization of the motor when a temperature of the cooling liquid is below a set value. A cooling device as set forth in Claim 10 ,wherein the electric motor ( 2 ) is in the form of a brushless DC motor and includes a magnet rotor ( 6 ) fixedly mounted on the output shaft, a stator ( 9 ) having three phase windings ( 8A, 8B, 8C ) which are arranged in the circumferential direction around the output shaft, the magnetic rotor and the stator are accommodated in a housing, the means continues to energize at least one of the phase windings for stopping the rotation of the output shaft when the temperature of the cooling liquid is below the set value. A cooling device as set forth in Claim 11, wherein the means is a device which establishes concurrent energizing all of the phase windings. A cooling device as set forth in Claim 10, wherein the electric motor ( 2 ) is in the form of a brushless DC motor and includes a magnet rotor ( 6 ) fixedly mounted on the output shaft, a stator ( 9 ) having three phase windings ( 8A, 8B, 8C ) which are arranged in the circumferential direction around the output shaft, the magnet rotor and the stator are accommodated in a housing, the impeller is made of a metal, the means is in the form of an electromagnetic clutch provided to the housing so as to be brought into electromagnetic coupling with the impeller despite of the energization of the motor when the temperature of the cooling liquid is below the set value. A cooling device as set forth in Claims 11, wherein the housing is provided therein with a chamber ( 11 ) for receiving therein the cooling liquid under circulation, the chamber is defined between the magnet rotor and the stator. A cooling device as set forth in Claims 13, wherein the housing is provided therein with a chamber ( 11 ) for receiving therein the cooling liquid under circulation, the chamber is defined between the magnet rotor and the stator. A cooling device as set forth in Claim 10, comprising a liquid pump ( 1 ) positioned at a lower portion of the engine. A cooling device for an internal combustion engine comprising: a brushless DC motor ( 2 ) having an output shaft ( 7 ), a magnet rotor ( 6 ) fixedly mounted on the output shaft, and a stator ( 9 ) having three phase windings ( 8A, 8B, 8C ) which are arranged in the circumferential direction around the output shaft; an impeller ( 5 ) connected to one end of the output shaft for circulating a cooling liquid through the engine and a radiator while the output shaft of the motor is being rotated; and means for energizing the stator in such manner that a current to be supplied to each of the phase windings is established in view of an angular position of the output shaft so as to generate heat if a temperature of the cooling liquid is below a set value.

Inventors: HOTTO TAKAYUKI, OZAWA YASUO, HOTTO, TAKAYUKI, OZAWA, YASUO
Applicants: AISIN SEIKI, AISIN SEIKI KABUSHIKI KAISHA
Application year: 1999
Main classification: F01P5
IPC codes: F01P7, F01P5