Engine cooling system

Abstract

 An engine cooling system includes a cooling fan (57) for cooling a radiator (51), a hot coolant pump (58) for circulating a hot coolant, which is held in a heat accumulator (64), along a predetermined route, and a motor (55) that rotates in a predetermined direction and in a direction opposite to the predetermined direction for driving the cooling fan (57) and the hot coolant pump (58). A power transmission member (70) connects the cooling fan (57) to the motor (55) and transmits rotation of the motor (55) only in one direction to the cooling fan (57).

Description

[0001] The present invention relates to an engine cooling system, and, more particularly, to a structure for driving a motor that drives a cooling fan of a radiator.

[0002] Engine cooling systems that include a hot coolant pump have been proposed. The hot coolant pump is driven by a fan motor, which drives a cooling fan of a radiator, to cause a coolant heated by a heat accumulator to circulate through an engine and a heater. For example, in a cold environment, an engine and a passenger compartment are cold when the engine is first started. To heat the engine and the passenger compartment, the hot coolant pump is driven by the fan motor thereby circulating the hot coolant through the engine and the heater. When the engine and the passenger compartment are sufficiently warm, the fan motor drives the cooling fan, which cools the coolant for cooling the engine. This engine cooling system uses a single motor in order to drive the cooling fan and the pump that circulates the hot coolant.

[0003] Fig. 2 is a diagrammatic view showing an example of one of the prior art engine cooling systems. A radiator 51 includes an inlet 51a and an outlet 51b. The inlet 51a is connected to an outlet 52a of an engine 52. The outlet 51b of the radiator 51 is connected, via a thermovalve 53 and a cold coolant pump 54, to an inlet 52b of the engine 52. A coolant heated by the engine 52 flows from the outlet 52a of the engine 52 to the inlet 51a of the radiator 51 and further flows from the outlet 51b of the radiator 51. The right side and the left side of Fig. 2 respectively correspond to the directions of the front and the back of a car.

[0004] A motor 55 is fixed relative to the back of the radiator 51 with a predetermined distance between the motor 55 and the radiator 51. A front end 56a of a rotary shaft 56 of the motor 55 extends toward the radiator 51. A cooling fan 57 is connected to the front end 56a. When the motor 55 rotates in a predetermined direction, the cooling fan 57 rotates in the predetermined direction to blow a current of air toward the radiator 51. When the motor 55 rotates in an opposite direction to the predetermined direction, the cooling fan rotates in the opposite direction, and the cooling fan 57 does not blow a current of air toward the radiator 51.

[0005] The motor 55, when rotating in the predetermined direction, drives the cold coolant pump 54, which circulates the coolant from the engine 52, through the radiator 51, the thermovalve 53, and the cold coolant pump 54, and back to the engine 52. When the coolant passes through the radiator 51, the coolant is cooled by heat transfer.

[0006] A hot coolant pump 58 is fixed to the back of the motor 55. A housing 58a of the hot coolant pump 58 includes an inlet 59 and an outlet 60. The rear end 56b of the rotary shaft 56 of the motor 55 is located in the housing 58a. An impeller 61 of the hot coolant pump 58 is connected to the rear end 56b. In other words, the impeller 61 is integrally connected to the cooling fan 57 by the rotary shaft 56. The impeller 61 and the cooling fan 57, therefore, integrally rotate as the motor 55 rotates.

[0007] When the motor 55 rotates in the opposite direction, that is, when the cooling fan 57 does not blow a current of air toward the radiator 51, the impeller 61 rotates in the opposite direction and causes the hot coolant pump 58 to draw the hot coolant from the inlet 59 and to discharge the hot coolant from the outlet 60. When the motor 55 rotates in the predetermined direction, that is, when the cooling fan 57 blows a current of air toward the radiator 51, the impeller 61 also rotates in the predetermined direction. However, in this case, the hot coolant pump 58 neither draws the hot coolant from the inlet 59 nor discharges the hot coolant from the outlet 60.

[0008] The inlet 59 of the hot coolant pump 58 is connected to a heater 62, which heats a passenger compartment. The heater 62 is connected to a hot coolant heat accumulator 64 via a valve 63. The heat accumulator 64 stores hot coolant. The outlet 60 of the hot coolant pump 58 is connected to the heat accumulator 64. When the motor 55 rotates in the opposite direction, the hot coolant pump 58 causes hot coolant to circulate from the heat accumulator 64 through the valve 63, the heater 62, and the hot coolant pump 58, and back to the heat accumulator 64. During the passage of the hot coolant through the heater 62, heat is transferred from the coolant to heat the passenger compartment.

[0009] The rotation of the motor 55 in the predetermined direction and that in the opposite direction are controlled by an electronic control unit (ECU) provided for the car (not shown). Specifically, the ECU controls the motor to rotate in the predetermined direction or in the opposite direction or to stop in accordance with the temperature of the coolant in the engine, the temperature of outside air, the temperature in the passenger compartment, and the driving state of the car.

[0010] The impeller 61 and the cooling fan 57 integrally rotate with the motor 55. That is, the coolinq fan 57 and the hot coolant pump 58 are driven in synchronism with the motor 55. In other words, when the engine is first started (when the cooling fan 57 is not required to rotate), the cooling fan 57 is rotated if the motor 55 is driven. When the engine is cooled (when the hot coolant pump 58 is not required to be driven), the hot coolant pump 58 is driven if the motor 55 is driven. As a result, the efficiency of the motor 55 decreases. Additionally, driving the cooling fan 57 when the engine is first started (when the cooling fan 57 is not required to rotate) produces noise.

[0011] An object of the present invention is to provide an engine cooling system that improves drive efficiency of a motor and reduces noise produced by unnecessary rotation of a cooling fan.

[0012] To solve the above problems, the present invention provides an engine cooling system. The engine cooling system includes a cooling fan for cooling a radiator and a hot coolant pump for circulating a hot coolant, which is stored in a heat accumulator, along a predetermined route. The engine cooling system further includes a motor connected to the cooling fan and the hot coolant pump. The motor rotates in a predetermined direction and in a direction opposite to the predetermined direction to drive the cooling fan and the hot coolant pump, respectively. The engine cooling system is characterized by a power transmission member for transmitting rotation of the motor to the cooling fan only in one direction. The cooling fan is connected to the motor via the power transmission member.

[0013] Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

[0014] The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

Fig. 1 is a cross-sectional view showing an engine cooling system according to the present invention; and

Fig. 2 is a diagrammatic view showing a prior art engine cooling system.

[0015] A first embodiment in which present invention is adapted to an engine cooling system will be described below with reference to Fig. 1. The engine cooling system according to the present invention is identical to the prior art engine cooling system except for the structure for driving a motor. To avoid redundancy, like or same reference numerals are given to those components that are the same as the corresponding components of the prior art engine cooling system. Only different features will now be discussed.

[0016] Fig. 1 is a diagrammatic view showing an engine cooling system according to the present embodiment. The engine cooling system includes a radiator 51, a cooling fan 57 for cooling the radiator 51, a hot coolant pump 58 for heating a passenger compartment, and a motor 55 for driving the cooling fan 57 and the hot coolant pump 58.

[0017] The cooling fan 57 is connected to the front end 56a of a rotary shaft 56 of the motor 55 via a one-way clutch, which serves as a power transmission member.

[0018] The one-way clutch 70 transmits rotation of the motor 55 to the cooling fan 57 only in one direction. In the present embodiment, the one-way clutch 70 transmits the rotation of the motor 55 in the predetermined direction to the cooling fan 57. The one-way clutch 70 does not transmit the rotation of the motor 55 in the direction opposite to the predetermined direction to the cooling fan 57. In other words, the one-way clutch 70 disconnects the motor 55 from the cooling fan 57.

[0019] An impeller 61 of the hot coolant pump 58 is fixed to the rear end 56b of the rotary shaft 56 of the motor 55. The impeller 61 is inclined with respect to the rotary shaft 56 of the motor 55 at a predetermined angle. When the motor 55 rotates in the predetermined direction, the impeller 61 does not pump the coolant. Conversely when the motor 55 rotates in the opposite direction to the predetermined direction, the impeller 61 pumps the coolant.

[0020] To cool the engine, the motor 55 rotates in the predetermined direction and the cold coolant pump 54 is driven. In this condition, the cold coolant pump 54 causes the coolant to circulate from the engine 52, through the radiator 51, a thermovalve 53, and the cold coolant pump 54, and back to the engine 52, (see Fig. 2). The rotation of the motor 55 in the predetermined direction is transmitted to the cooling fan 57 by the one-way clutch 70. Consequently, the cooling fan 57 rotates in the predetermined direction to blow a current of air toward the radiator 51. The current of air cools the coolant passing through the radiator 51. The impeller 61, on the other hand, rotates in the predetermined direction together with the motor 55, but the impeller 61 does not pump the hot coolant.

[0021] Conversely, when the motor 55 is rotated in the opposite direction in order to heat the passenger compartment with a heater 62, the impeller 61 of the hot coolant pump 58 also rotates in the opposite direction and causes the hot coolant in a heat accumulator 64 to circulate from the heat accumulator 64, through a valve 63, the heater 62, and the hot coolant pump 58, and back into the heat accumulator 64 (see Fig. 2). At this time, the rotation of the motor 55 is not transmitted to the cooling fan 57 by the one-way clutch 70. The cooling fan 57 therefore does not rotate.

[0022] The advantages of the engine cooling system according to the present invention will now be discussed.

[0023] The cooling fan 57 is connected to the front end 56a of the rotary shaft 56 of the motor 55 through the one-way clutch 70. When the engine is cooled (when the motor 55 rotates in the predetermined direction), the rotation of the motor 55 is transmitted to the cooling fan 57 by the one-way clutch 70 thereby rotating the cooling fan 57. In other words, when the passenger compartment is heated by the heater 62 (when the motor 55 rotates in the opposite direction), rotation of the cooling fan 57 is prevented by the one-way clutch 70, which interrupts power transmission between the motor 55 and the cooling fan 57 such that the rotation of the motor 55 is not transmitted to the cooling fan 57.

[0024] Therefore, the driving force of the motor 55 is used more effectively in comparison to the prior art, in which the cooling fan 57 rotates with the motor 55 in the opposite direction when the passenger compartment is heated by the heater 62. Additionally, when the hot coolant pump 58 is driven to heat the passenger compartment with the heater 62 (when the cooling fan 57 is not required to rotate), the cooling fan 57 does not rotate and does not produce noise. Accordingly, the efficiency of the motor 55 improves, arid noise, which is caused by rotation of the cooling fan 57 during heating of the passenger compartment, decreases.

[0025] The present embodiment is to be considered as illustrative and not restrictive, and the present invention may be embodied in the following forms.

[0026] In the above-described embodiment, the cooling fan 57 may be connected to the rotary shaft 56 of the motor 55 through a power transmission member other than the one-way clutch 70.

[0027] The impeller 61 of the hot coolant pump 58 may be connected to the rear end 56b of the rotary shaft 56 of the motor 55 through the one-way clutch such that the impeller 61 is driven by the motor 55 only when the motor 55 rotates in the opposite direction to heat the passenger compartment. In addition to the advantages described above, this prevents the driving force of the motor 55 from being wasted by rotation of the impeller 61 when the engine is cooled (when the impeller 61 is not required to rotate). Accordingly, the drive efficiency of the motor 55 further improves.

[0028] In the present embodiment, the cooling fan 57 is connected to the rotary shaft 56 of the motor 55 through the one-way clutch 70, and the impeller 61 of the hot coolant pump 58 is connected to the roLary shaft 56 of the motor 55. However, the motor 55 used in the present embodiment may be replaced by a motor provided with a speed reducer, and the cooling fan 57 and the hot coolant pump 58 may be coupled to an output shaft of the speed reducer.

[0029] The present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.

[0030] An engine cooling system includes a cooling fan (57) for cooling a radiator (51), a hot coolant pump (58) for circulating a hot coolant, which is held in a heat accumulator (64), along a predetermined route, and a motor (55) that rotates in a predetermined direction and in a direction opposite to the predetermined direction for driving the cooling fan (57) and the hot coolant pump (58). A power transmission member (70) connects the cooling fan (57) to the motor (55) and transmits rotation of the motor (55) only in one direction to the cooling fan (57).

Claims

1. An engine cooling system including a cooling fan (57) for cooling a radiator (51), a hot coolant pump (58) for circulating a hot coolant, which is stored in a heat accumulator (64), along a predetermined route, and a motor (55) connected to the cooling fan (57) and the hot coolant pump (58), wherein the motor (55) rotates in a predetermined direction and in a direction opposite to the predetermined direction to drive the cooling fan and the hot coolant pump, the engine cooling system being characterized by:

a power transmission member (70) for transmitting rotation of the motor (55) only in one direction to the cooling fan (57), wherein the cooling fan (57) is connected to the motor (55) through the power transmission member.

2. The engine cooling system according to claim 1, characterized in that the cooling fan (57) and the hot coolant pump (58) are connected to a rotary shaft of the motor, wherein the power transmission member is located between the rotary shaft of the motor and the cooling fan.

3. The engine cooling system according to claim 1 or 2, characterized in that the power transmission member is a one-way clutch (70).

4. The engine cooling system according to claim 1 or 2, characterized in that the hot coolant pump (58) includes an impeller (61), which is fixed to the rotary shaft of the motor.

5. The engine cooling system according to claim 4, characterized in that when the motor (55) rotates in the predetermined direction, the rotation is transmitted to the cooling fan (57) by the one-way clutch (70) and the impeller (61) is ineffective for pumping, and when the motor (55) rotates in the opposite direction, the rotation is not transmitted to the cooling fan (57) by the one-way clutch (70) and the impeller (61) is effective for pumping.

Drawing