JP3823481B2 - Automotive cooling system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a cooling fan used in an automotive cooling device.
[0002]
[Prior art]
Conventionally, as a cooling device for an automobile, a cooling fan that is driven by an electric motor toward a radiator that cools engine cooling water or a condenser that is a condenser for air conditioning of a vehicle is known. is there. In such a cooling fan, for example, the rotational speed is variably controlled by the temperature of engine coolant or the high pressure of the refrigerant.
[0003]
[Problems to be solved by the invention]
In recent years, various improvements in the internal combustion engine (engine) have led to a reduction in the vibration generated in the explosion process of the engine. There is a problem that the vibration caused by the rotation of the fan is conspicuous and gives the passenger discomfort.
[0004]
[Means for Solving the Problems]
Therefore, the present inventors have studied to reduce the vibration of the cooling fan, and are the explosion vibration frequency that is the number of explosions per unit time of the internal combustion engine and the rotation number of the cooling fan per unit time. We found a phenomenon in which the vibration of the cooling fan was increased by resonating with the rotational vibration frequency.
[0005]
The present invention has been conceived by finding such a phenomenon. In the inventions according to claims 1 to 6, an explosion vibration frequency (Na) which is the number of explosions per unit time in the internal combustion engine (30). ) And the correction control means (S600 to S900) for correcting and controlling the fan rotational speed so that the rotational vibration frequency (Ne) which is the rotational speed of the fan per unit time of the cooling fan (1a) becomes a different value. It is characterized by having.
[0006]
As a result, the correction control means makes the explosion vibration frequency, which is the number of explosions per unit time in the internal combustion engine, different from the rotation vibration frequency, which is the fan rotation number per unit time of the cooling fan. Generation of resonance vibration of the fan can be prevented beforehand. As a result, the vibration of the cooling fan can be significantly reduced, and noise due to the vibration can be reduced.
[0007]
According to a fourth aspect of the present invention, the correction control means corrects and controls the fan rotational speed only when the rotational speed of the internal combustion engine (30) is lower than a predetermined value (N1).
As a result, when the rotational speed of the internal combustion engine is higher than a predetermined value, the vibration and noise of the internal combustion engine are larger than the vibration noise of the cooling fan. In this case, the cooling fan is controlled according to the state of the cooling medium. However, when the rotational speed of the internal combustion engine is lower than the predetermined value, the vibration noise of the internal combustion engine is small and the vibration noise of the cooling fan is conspicuous. Prevent vibration.
[0008]
Accordingly, the fan rotation speed is controlled only when the vibration noise of the cooling fan is noticeable, and resonance vibration of the cooling fan is prevented. Therefore, the frequency of shifting the fan rotation speed determined according to the state of the cooling medium is shifted. Can be reduced.
According to a fifth aspect of the present invention, the correction control means reduces the fan rotational speed by a predetermined amount as compared with the case where the explosion vibration frequency (Na) and the rotational vibration frequency (Ne) coincide. It is a feature.
[0009]
As a result, as the means for reducing the resonance vibration of the cooling fan as compared with the case where the explosion vibration frequency and the rotation vibration frequency coincide with each other, the fan rotation speed is reduced by a predetermined amount. Fan vibration can be reduced.
In the invention according to claim 6, the cooling heat exchanger (4) is a radiator (4) for cooling at least the cooling water flowing in the internal combustion engine (30), and the target rotation of the cooling fan (1a). A target rotational speed calculation means (S200) for determining the number according to the temperature (Tw) of the cooling water, and when the temperature (Tw) of the cooling water is lower than a predetermined temperature (T1), the rotational speed is controlled by the control means. When the cooling water temperature (Tw) is higher than the predetermined temperature (T1), the correction control is prohibited, and the fan rotation speed becomes the target rotation speed calculated by the target rotation speed calculation means (S200). Thus, priority control is performed.
[0010]
Here, for example, when the vehicle travels uphill or the like for a long time, the cooling water temperature becomes high. When the vehicle stops in this state, the rotational speed of the internal combustion engine falls below a predetermined value, so that the fan rotational speed falls. . For this reason, cooling water cannot be sufficiently cooled.
Therefore, according to the sixth aspect of the present invention, when the temperature of the cooling water is higher than the predetermined temperature, the correction control is prohibited and the fan rotational speed becomes the target rotational speed calculated by the target rotational speed calculating means. Therefore, cooling water can be sufficiently cooled.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an overall structural diagram of an automotive cooling device according to an embodiment of the present invention.
The automobile cooling device of the present example includes a radiator 4 that cools cooling water flowing in an internal combustion engine (hereinafter referred to as an engine) 30 that is a vehicle drive travel source. Further, the automobile cooling device constitutes one component part of a refrigeration cycle of an air conditioner mounted on a vehicle, and has a condenser 3 in which a high-temperature and high-pressure refrigerant flows and cools the refrigerant to be condensed and liquefied.
[0012]
The radiator 4 and the condenser 3 are easy to receive the traveling wind, and are arranged in the front-rear direction of the vehicle in an engine room (not shown). The capacitor 3 is arranged on the vehicle front side from the radiator 4.
The radiator 4 and the condenser 3 are configured such that cooling water and refrigerant are cooled by blown air (cooling air) generated by the electric fan 1 on the rear side of the vehicle. The electric fan 1 includes two cooling fans 1a and two electric motors 1b (DC motors) that drive the two cooling fans 1a.
[0013]
The electric motor 1b operates by receiving a battery voltage supplied from an in-vehicle battery B via an ignition switch (not shown). The electric motor 1 b is controlled by the motor control device 10. The motor control device 10 includes a MOS transistor 11 as a semiconductor switching element that drives the electric motor 1b, a control unit 12 that outputs a pulse signal for pulse width modulation (PWM) control of the electric motor 1b, and a control unit 12 Are provided with a transistor driver 13 for amplifying the pulse signal to drive the MOS transistor 11 and a back electromotive force absorbing diode 14.
[0014]
The control unit 12 receives a water temperature control signal for maintaining the cooling water temperature at a predetermined temperature from the engine control ECU (engine electronic control unit) 20, and outputs a pulse signal for performing the above-described PWM control.
The engine control ECU 20 performs engine control by taking in sensor signals from various sensors necessary for engine control. The various sensors include a water temperature sensor 21 that detects the temperature of the engine cooling water (cooling water temperature), a pressure sensor 22 that detects the high pressure of the high-pressure refrigerant flowing in the condenser 3, and a rotation speed sensor 23 that detects the engine speed. include. Further, the engine control ECU 20 outputs a water temperature control signal for maintaining the cooling water temperature at an appropriate temperature based on the cooling water temperature detected by the water temperature sensor 21 to the control unit 12.
[0015]
In the above configuration, the operation will be described according to the control process in the control unit 12 shown in FIG.
First, in step S100, the detection signal Tw (hereinafter, water temperature Tw) of the water temperature sensor 21 and the detection signal Pc (hereinafter, pressure Pc) of the high pressure sensor 22 are read. Next, in step S200, based on the detection signals Tw and Pc, duty ratios D1 and D2 that are first and second target rotational speeds of the electric motor 1b (cooling fan 1a) are determined. Specifically, the fan speed Nf, that is, the duty ratio D1, which is the first target speed, is determined according to the water temperature Tw as shown in FIG. Then, as shown in FIG. 3, the duty ratio D1 becomes 0 when the water temperature Tw is equal to or lower than a predetermined temperature T1 (for example, 90 ° C.), since the cooling water does not need to be cooled, and as the water temperature Tw becomes higher than T1. , Set to be large. Further, when the water temperature Tw is equal to or higher than T2 (for example, 100), the duty ratio D1 becomes 1, which is the maximum.
[0016]
On the other hand, as shown in FIG. 4, the fan rotational speed Nf, that is, the duty ratio D2, which is the second target rotational speed, is determined according to the pressure Pc. Then, as shown in FIG. 4, when the pressure Pc is equal to or lower than a predetermined pressure P1 (for example, 10 kgf / cm ² ), the duty ratio D2 becomes 0 because there is no need to cool the refrigerant, and the pressure Pc becomes higher than P1. Is set so as to increase. Further, when the pressure Pc is equal to or higher than P2 (for example, 15 kgf / cm ² ), the duty ratio D2 becomes 1 at the maximum.
[0017]
Subsequently, in step S300, the larger one of the duty ratios D1 and D2 determined in step S200 is selected. That is, if the larger one of the duty ratios D1 and D2 is selected, the cooling water and the refrigerant can be sufficiently cooled.
In step S400, it is determined whether or not the detection signal Ne (hereinafter referred to as the rotational speed Ne) of the rotational speed sensor 23 is lower than a predetermined rotational speed N1 (for example, 800 rpm). In step S400 here, it is determined whether the vehicle is stopped and the engine 30 is idling.
[0018]
If the decision result in the step S400 is NO and it is judged that the vehicle is not in an idling state but the vehicle is running, the process proceeds to a step S900 and the larger one of the duty ratios D1 and D2 selected in the step S300 is controlled. Output as a signal.
On the other hand, if the determination result in step S400 is YES and it is determined that the vehicle is in the idling state, the process proceeds to step S500 to determine whether or not the water temperature Tw is higher than a predetermined temperature T1 (for example, 100 ° C.). If NO is determined in step S500, the larger one of the duty ratios D1 and D2 selected in step S300 is output as a control signal.
[0019]
If the determination result in step S500 is NO, the process proceeds to step S600, and thereafter, in steps S600 to S800, correction control is performed to prevent resonance vibration of the cooling fan 1a and the electric motor 1b.
This will be described below. First, in step S600, the fan rotational speed Nf per unit time of the cooling fan 1a, that is, the rotational vibration frequency Nf is set. Here, the duty ratio D1 or D2 output in the previous step S900 is used, and step S600 does not need to be provided separately in actual processing.
[0020]
Next, in step S700, an explosion vibration frequency Na that is the number of explosions per unit time in the engine 30 is calculated by the following formula 1.
[0021]
[Expression 1]
Na = (Ne × the number of cylinders of the internal combustion engine) / (60 × 2) (Hz)
The engine 30 of this example is a 4-stroke engine and has 4 cylinders. In addition, 60 in Equation 1 is provided for conversion to a frequency because the rotation speed is rpm per minute. Furthermore, x2 in Formula 1 is because the engine speed of the 4-stroke engine is rotated twice by one explosion.
[0022]
Next, in step S800, Nf is corrected so as to satisfy Equation 2 below.
[0023]
[Expression 2]
Nf ≦ Na−X (Hz)
However, X is a constant (frequency) for shifting the rotational vibration frequency Nf so that the rotational vibration frequency Nf and the explosion vibration frequency Na do not coincide with each other so that the resonance vibration of the cooling fan 1a and the electric motor 1b can be surely prevented. Depending on the vehicle.
[0024]
For reference, Equation 3 is expressed as Equation 3 when the unit is rpm.
[0025]
[Equation 3]
Nf ≦ (Na−X) × 60 (rpm)
Here, Nf is the number of revolutions per minute.
The function of step S800 is as follows. First, assume that X in Formula 3 is 10, for example. It is assumed that the engine 30 is idling and the engine speed Ne is 600 rpm. Then, the right side in Equation 3 is 600 rpm. On the other hand, the left side in Equation 3 changes with the water temperature Tw and the pressure Pc, but is assumed to be 600 rpm, for example. If this is the case, the rotational vibration frequency Nf and the explosion vibration frequency Na coincide with each other, so Nf is corrected and controlled based on Equation 3.
[0026]
That is, Nf is corrected so as to be (Na−X) × 60 (rpm), and Nf is corrected so as to be smaller than when the rotational vibration frequency Nf and the explosion vibration frequency Na coincide with each other. . That is, the fan rotational speed Nf is decreased by a predetermined amount so that the difference between the explosion vibration frequency Na and the rotation vibration frequency Nf is always a constant value so that the rotation vibration frequency Nf and the explosion vibration frequency Na have different values. It is corrected to.
[0027]
Therefore, the generation of resonance vibration of the cooling fan 1a can be prevented, and as a result, the vibration of the cooling fan 1a and the electric motor 1b can be remarkably reduced, and noise due to vibration can be reduced.
In this example, the correction control is performed only when the rotational speed Ne of the engine 30 is lower than the predetermined value N1. For this reason, when the rotational speed Ne of the engine 30 is higher than the predetermined value N1, the vibration and noise of the engine 30 are smaller than the vibration noise of the cooling fan 1a. Therefore, in this case, the cooling fan 1a is controlled according to the state of the cooling water and the refrigerant. On the other hand, when the rotational speed Ne of the engine 30 is lower than the predetermined value N1, the vibration noise of the engine 30 is small and the vibration noise of the cooling fan 1a is conspicuous. The resonance vibration of the fan 1a can be prevented in advance.
[0028]
Therefore, the fan rotation speed Nf is controlled only when the vibration noise of the cooling fan 1a is conspicuous, and the resonance vibration of the cooling fan 1a is prevented. Therefore, the fan determined according to the state of the cooling water and the refrigerant The frequency of shifting the rotational speed Nf can be reduced.
In the present invention, the above-described resonance vibration may be prevented by correcting the fan rotational speed Nf to be large. In this example, however, the fan rotational speed Nf is decreased by a predetermined amount as compared with such a case. Therefore, vibrations of the electric motor 1b and the cooling fan 1a can be further reduced.
[0029]
Further, in this example, the correction control is performed when the water temperature Tw is lower than the predetermined temperature T1 in step S500. For example, when the vehicle travels uphill or the like for a long time, the cooling water temperature becomes high. However, when the vehicle stops in this state, the engine 1 is in an idling state, so that it falls below a predetermined value N1 and the fan rotation speed Nf decreases. . For this reason, cooling water cannot be sufficiently cooled.
[0030]
Therefore, in this example, when the water temperature Tw is lower than the predetermined temperature T1, the correction control is performed. When the water temperature Tw is higher than the predetermined temperature T1, the correction control is prohibited, and the fan rotation speed Nf is determined in step S300. Priority is given to the specified value. For this reason, cooling water can be sufficiently cooled.
In this example, since the electric motor 1b is PWM-controlled, the rotation speed of the electric motor 1a, that is, the fan rotation speed Nf of the cooling fan can be controlled linearly. For this reason, the resonance vibration can be reduced without largely shifting the fan rotation speed Nf determined by the water temperature Tw and the pressure Pc. As a result, the cooling capacity as set can be exhibited.
[0031]
When the above equation 3 is satisfied in the idling state, the correction control is not performed, and the fan rotational speed Nf determined and selected in step S300 is obtained.
(Other embodiments)
In the above embodiment, the fan rotation speed Nf is decreased in the correction control, but it may be increased.
[0032]
Moreover, in each said embodiment, about the cooling device for motor vehicles, the radiator 4 and the capacitor | condenser 3 are arrange | positioned so that it may rank with a vehicle front-back direction, and it cools cooling water and a refrigerant | coolant simultaneously by the common cooling fan 1a. As described above, the present invention may be applied to an automotive cooling device that cools only the cooling water, or may be applied to an automotive cooling device that cools only the refrigerant.
[0033]
In the above embodiments, the electric motor 1b is PWM controlled. However, the current value flowing through the electric motor 1b may be controlled by a variable resistor or a power transistor. Furthermore, the rotational speed of the electric motor 1b (fan rotational speed Nf) may be controlled stepwise.
Further, in each of the above embodiments, the engine speed is used to detect the idling state of the engine 30, but it may be detected by the opening degree of the accelerator pedal (throttle opening degree).
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an automotive cooling device according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a control process of a control unit 12 in the embodiment.
FIG. 3 is a diagram showing a method for determining a fan rotation speed Nf in the embodiment.
FIG. 4 is a diagram illustrating a method for determining a fan rotation speed Nf in the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1a ... Cooling fan, 1b ... Electric motor, 3 ... Condenser, 4 ... Radiator, 12 ... Control part, 13 ... Transistor drive part, 20 ... Engine control ECU, 23 ... Speed sensor, 30 ... Engine.

Claims (6)

Heat exchange for cooling mounted on the vehicle with air blown from a cooling fan (1a) applied to a vehicle on which the internal combustion engine (30) is mounted as a vehicle driving source, and driven by an electric motor (1b). A cooling device for an automobile that cools a cooling medium flowing in a vessel (4), and determines and controls an air flow rate of the cooling fan (1a) based on a state of the cooling medium,
The explosion vibration frequency (Na) that is the number of explosions per unit time in the internal combustion engine (30) is different from the rotation vibration frequency (Ne) that is the number of fan rotations per unit time of the cooling fan (1a). The automobile cooling device according to claim 1, further comprising correction control means (S600 to S900) for correcting and controlling the fan rotation speed so as to be a value. The said correction control means carries out correction | amendment control of the said fan rotation speed so that the difference of the said explosion vibration frequency (Na) and the said rotation vibration frequency (Ne) may become predetermined value (X). The automobile cooling device as described. The correction control means includes
Explosion frequency calculation means (S700) for calculating the explosion vibration frequency based on the number of cylinders of the internal combustion engine (30) and the rotation speed of the internal combustion engine (30);
The vehicle cooling according to claim 1 or 2, further comprising: a rotational frequency calculating means (S200, S600) for calculating the rotational frequency (Ne) from a signal corresponding to the fan rotational frequency (Ne). apparatus. The correction control means corrects and controls the fan rotation speed only when the rotation speed of the internal combustion engine (30) is lower than a predetermined value (N1). Automotive cooling system. 5. The automobile according to claim 4, wherein the correction control means lowers the fan rotational speed by a predetermined amount compared to a case where the explosion vibration frequency (Na) and the rotational vibration frequency (Ne) coincide with each other. Cooling device. The cooling heat exchanger (4) is a radiator (4) that cools at least cooling water that is the cooling medium flowing in the internal combustion engine (30).
A target rotational speed calculation means (S300) for determining a target rotational speed (D1) of the cooling fan (1a) according to a temperature of the cooling water;
When the cooling water temperature (Tw) is lower than the predetermined temperature (T1), the correction control means corrects and controls the fan rotation speed, and when the cooling water temperature (Tw) is higher than the predetermined temperature (T1). 7. The control according to claim 6, wherein the correction control is prohibited and priority control is performed so that the fan rotational speed becomes the target rotational speed calculated by the target rotational speed calculating means (S300). Automotive cooling device.

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