JP2004068640A - Engine cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine cooling device comprising a temperature-sensitive cooling fan satisfying both of the prevention of overcooling of the engine cooling water and the hydraulic oil, and the proper cooling of an air conditioner condenser. <P>SOLUTION: This engine cooling device comprises the temperature-sensitive cooling fan 4 connected to a fan driving shaft 3 through a fluid coupling 2, and a controller 14. The fluid coupling 2 determines a sliding ratio to obtain a lower fan rotating frequency Nf1 of some degree even when a temperature of the cooling air after passed through a radiator 7 is less than a low sliding ratio switching temperature t1. The controller 14 outputs a driving signal e to raise the rotating frequency of the engine 1 higher than the rotating frequency of the engine in the warming operation, when the rotating frequency Nf1 of the lower fan does not reach the rotating frequency Nf3 to supply the cooling air of the minimum air volume necessary for cooling the air conditioner condenser 5, and the temperature of the cooling air after passed through the radiator 7 does not reach the low sliding rate switching temperature t1 of the fluid coupling 2, to adjust a volume of the cooling air supplied to the air conditioner condenser 5, to be the minimum air volume or more than that. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an engine cooling device mounted on a construction machine such as a hydraulic shovel or a work vehicle, and more particularly to an engine cooling device provided with a temperature-responsive cooling fan as an engine cooling fan.
[0002]
[Prior art]
DESCRIPTION OF RELATED ART Conventionally, as described in Unexamined-Japanese-Patent No. 11-93665, the engine cooling device for construction machines and work vehicles provided with the temperature-responsive cooling fan as an engine cooling fan is known. As described in the above-mentioned known document, the temperature-responsive cooling fan has a fan connected to a fan rotation shaft of an engine via a fluid coupling, and has a slip ratio (magnitude of transmitted torque) of the fluid coupling. Is switched in accordance with, for example, the outside air temperature, thereby automatically changing the fan rotation speed.
[0003]
The engine cooling device equipped with the temperature-sensitive cooling fan automatically stops the fan when the outside air temperature is equal to or lower than the slip rate switching temperature of the temperature-sensitive cooling fan, or sets the fan speed to a desired value. Since the number of revolutions can be reduced to a low value, it is possible to prevent engine cooling water and hydraulic oil from being excessively cooled, and to improve fuel efficiency and reduce fan noise.
[0004]
[Problems to be solved by the invention]
Meanwhile, in a construction machine or a work vehicle including an air conditioner device and a temperature-sensitive cooling fan as an engine cooling fan, cooling of the air-conditioner condenser is also performed by the temperature-sensitive cooling fan.
[0005]
However, the conventional engine cooling device does not consider a method of controlling the rotation of a temperature-responsive cooling fan that satisfies both prevention of supercooling of engine cooling water and hydraulic oil and proper cooling of an air conditioner condenser. If prioritizing the prevention of supercooling of the hydraulic oil, it would hinder proper cooling of the air conditioner condenser, and conversely, if prioritizing the proper cooling of the air conditioner condenser, it would hinder the prevention of supercooling of the engine cooling water and hydraulic oil. .
[0006]
That is, in order to give priority to the prevention of supercooling of the engine cooling water and the hydraulic oil, even when the engine is rotating at high speed, for example, if the outside air temperature is equal to or lower than the slip rate switching temperature of the temperature-responsive cooling fan, It is most preferable to stop the air conditioner. However, if the fan is stopped, the minimum air flow required for cooling the air conditioner condenser cannot be secured, which may hinder proper cooling of the air conditioner condenser. Conversely, in order to give priority to proper cooling of the air conditioner condenser, it is necessary to rotate the fan at a certain number of revolutions even when the engine is rotating at a low speed. When the slip ratio of the fluid coupling is adjusted, the fan speed increases with the engine speed, making it difficult to prevent overcooling of the engine cooling water and hydraulic oil.
[0007]
The present invention has been made in order to solve the deficiencies of the related art, and an object of the present invention is to provide a temperature capable of satisfying both prevention of supercooling of engine cooling water and hydraulic oil and proper cooling of an air conditioner condenser. An object of the present invention is to provide an engine cooling device having a sensitive cooling fan.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a temperature-responsive cooling fan that connects an engine cooling device to an engine and a fan drive shaft of the engine via a fluid coupling and supplies cooling air to an air conditioner condenser and a radiator. A rotation speed sensor for detecting a rotation speed of the engine or a rotation speed of the fan drive shaft, a temperature sensor for detecting a cooling air temperature after passing through a radiator or a water temperature of an inlet of the radiator, and setting the air conditioner to an operating state or a stopped state. An air conditioner switch to be switched, a speed signal output from the speed sensor, a temperature signal output from the temperature sensor, and a switch signal output from the air conditioner switch, and the engine based on these signals. A controller for controlling the number of rotations of the fan, wherein the temperature-responsive cooling fan is set in advance. The slip rate of the fluid coupling is adjusted so that a predetermined torque is transmitted between the fan and the fan drive shaft even under a temperature condition equal to or lower than the slip rate switching temperature, and the controller sets the air conditioner switch to an operating state. When switched, it is determined whether or not the rotation speed of the temperature-responsive cooling fan has reached a rotation speed capable of supplying a minimum amount of cooling air required for cooling the air conditioner condenser from the rotation speed signal, It is determined from the temperature signal whether the cooling air temperature after passing through the radiator or the inlet water temperature of the radiator has reached the slip rate switching temperature of the fluid coupling, and the rotation speed of the temperature-responsive cooling fan determines whether the rotation speed of the air conditioner condenser is higher. The rotation speed at which the minimum amount of cooling air required for cooling cannot be supplied has not been reached, and the cooling air temperature after passing through the radiator or the radiator When it is determined that the mouth water temperature has not reached the slip rate switching temperature of the fluid coupling, the engine speed is increased to make the cooling air volume supplied to the air conditioner condenser to the minimum air volume or more. I made it.
[0009]
As described above, even when the slip rate of the fluid coupling provided in the temperature-responsive cooling fan is equal to or lower than the preset slip rate switching temperature, a predetermined torque is transmitted between the fan and the fan drive shaft. When the fan speed is Nf, the engine speed is Ne, and the slip ratio of the fluid coupling is η, the fan is constantly driven to rotate at Nf = Ne (1−η). However, the air conditioner switch is switched to the stop state, the cooling air temperature after passing through the radiator or the inlet water temperature of the radiator is equal to or lower than the slip ratio switching temperature of the fluid coupling, and the engine speed Ne is equal to or lower than the predetermined speed. For example, in the case of the rotation speed at the time of the warm-up operation, the fluid coupling of the fluid coupling at the slip rate switching temperature or lower is set so that the fan rotation speed Nf is equal to or lower than the rotation speed capable of supplying the minimum amount of cooling air required for cooling the air conditioner condenser. By setting the slip ratio η, it is possible to prevent overcooling of the engine cooling water and the working oil, and it is possible to minimize deterioration of fuel efficiency and increase in fan noise.
[0010]
Then, the air conditioner switch is switched to the operating state, the rotation speed of the temperature-responsive cooling fan has not reached the rotation speed capable of supplying the minimum amount of cooling air required for cooling the air conditioner condenser, and after the radiator has passed. If the engine speed Ne is increased when the controller determines that the cooling air temperature or the radiator inlet water temperature has not reached the slip rate switching temperature of the fluid coupling, the fan speed increases in proportion to the engine speed Ne. Since the engine speed Ne can be increased so that the fan speed Nf reaches a speed at which the minimum amount of cooling air required for cooling the air conditioner condenser can be supplied, the engine speed Ne can be increased. Cooling becomes possible.
[0011]
Therefore, according to the engine cooling device of the present invention, it is possible to satisfy both the prevention of supercooling of engine cooling water and hydraulic oil and the proper cooling of the air conditioner condenser.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an engine cooling device according to the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of an engine cooling device according to an embodiment, FIG. 2 is a cross-sectional view illustrating a configuration of a fluid coupling portion provided in a temperature-responsive cooling fan, and FIG. 3 is a graph illustrating rotation characteristics of the temperature-responsive cooling fan. FIG. 4 shows the relationship between the fan rotation speed, the cooling air temperature after passing through the radiator or the inlet water temperature of the radiator, the fan rotation speed capable of supplying the minimum amount of cooling air required for cooling the air conditioner condenser, and the engine rotation speed. FIG.
[0013]
As shown in FIG. 1, the engine cooling device of the present embodiment includes an engine 1, a temperature-sensitive cooling fan 4 connected to a fan drive shaft 3 via a fluid coupling 2, and the temperature-sensitive cooling fan 4. The air conditioner condenser 5, the oil cooler 6, and the radiator 7, which are cooled by the cooling air W drawn from outside the vehicle body, the rotation speed sensor 8 for detecting the rotation speed of the engine 1, and the cooling air temperature after passing through the radiator 7. A temperature sensor 9 for detecting, an air conditioner switch 10 for switching the air conditioner between an operating state and a stopped state, an engine speed setting dial 11 for setting the engine speed, and an engine speed setting device (governor) provided in the engine 1. ) 12, a motor 13 for operating the engine speed setting device 12, a speed signal a output from the speed sensor 8, A temperature signal b output from the air conditioner 9, a switch signal c output from the air conditioner switch 10, and an engine speed setting signal d output from the engine speed setting dial 11 are input. And an output controller 14.
[0014]
The fan drive shaft 3 is connected to a crankshaft (not shown) serving as a main shaft of the engine 1 via a belt or a gear mechanism.
[0015]
As shown in FIG. 2, the fluid coupling 2 is fixed to the fan drive shaft 3, a case 22 attached to the fan drive shaft 3 via a bearing 21, a cover 23 fastened to the case 22, A drive disk 25 housed in a torque transmission chamber 24 formed by joining the case 22 and the cover 23 and an oil storage chamber 26 set in the case 22 A valve plate 28 for adjusting an opening of an oil port 27 communicating with the torque transmission chamber 24, a linear weight 29 attached to the valve plate 28, a bimetal 30 attached to an outer surface of the case 22, A rod 31 having one end fixed to the bimetal 30 and the other end connected to the valve plate 28; Fan 4 is attached to the case 22 or cover 23. Oil such as silicone oil is stored in the oil storage chamber 26, and the amount of oil supplied from the oil storage chamber 26 to the torque transmission chamber 24 is adjusted by the valve plate 28. The slip ratio (transmitted torque) of the fan 4 with respect to the fan drive shaft 3 and the rotation speed are adjusted.
[0016]
That is, when the valve plate 28 completely blocks the oil port 27, the oil in the oil storage chamber 26 is not supplied into the torque transmission chamber 24, and the drive disk 25 idles in the torque transmission chamber 24, The rotation of the fan drive shaft 3 is not transmitted to the case 22, the cover 23, and the fan 4. At this time, the slip ratio of the fluid coupling 2 is 100%, and the transmission torque is 0. On the other hand, when the valve plate 28 is separated from the oil port 27 and the oil port 27 is opened, the oil in the oil storage chamber 26 is supplied into the torque transmission chamber 24 by an amount corresponding to the degree of opening of the oil port 27. Is done. When the oil is supplied into the torque transmission chamber 24 as described above, a frictional force based on the viscosity of the oil acts between the drive disk 25 and the case 22 and the cover 23, so that the oil is supplied into the torque transmission chamber 24. A transmission torque corresponding to the amount of oil is generated, and the rotation of the fan drive shaft 3 is transmitted to the case 22, the cover 23, and the fan 4 at a slip ratio corresponding to the amount of oil supplied into the torque transmission chamber 24.
[0017]
The opening and closing operation of the valve plate 28 with respect to the oil port 27 is performed by the bimetal 30 via the rod 31. That is, when the cooling air temperature after passing through the radiator 7 is low, such as immediately after the start of the engine 1, the valve plate 28 is operated in the closing direction by the bimetal 30 and the rod 31, and the cooling air temperature after passing through the radiator 7. Is raised, the valve plate 28 is operated by the bimetal 30 and the rod 31 in the opening direction. The opening degree of the oil port 27 at a low temperature, that is, the fan rotation speed at a low temperature (lower fan rotation speed), the opening degree of the oil port 27 at a high temperature, that is, the fan rotation speed at a high temperature (upper fan rotation speed), and the valve plate The temperature at which the opening operation of the valve 28 starts (lower sliding rate switching temperature) and the temperature at which the valve plate 28 stops the opening operation (upper sliding rate switching temperature) depend on the viscosity of the oil, the stroke of the rod 31, the weight of the linear weight 29, and the like. Can be adjusted by changing.
[0018]
In this embodiment, as shown in FIG. 3, even when the cooling air temperature after passing through the radiator 7 is lower than the lower slip rate switching temperature t1, a certain lower fan rotation speed Nf1 is obtained, and the lower slip rate switching is performed. The fan rotation speed linearly increases from the temperature t1 to the upper slip ratio switching temperature t2, and is set so that the fan rotation speed becomes a constant value Nf2 above the upper slip ratio switching temperature t2. The lower fan rotation speed Nf1 is set to be equal to or lower than the rotation speed Nf3 at which the minimum amount of cooling air required for cooling the air conditioner condenser 5 can be supplied when the engine rotation speed is the rotation speed during the warm-up operation. . As a result, it is possible to prevent the engine cooling water and the working oil from being excessively cooled, and it is possible to minimize deterioration of fuel efficiency and increase in fan noise. On the other hand, the upper fan rotation speed Nf2 is set to be equal to or higher than the rotation speed at which the minimum amount of cooling air required for cooling the oil cooler 6 and the radiator can be supplied when the engine rotation speed is the maximum rotation speed. Thus, it is possible to prevent the engine cooling water and the hydraulic oil from being excessively heated. As shown in FIG. 3, in order to prevent hunting of the fan speed, a hysteresis is provided between the fan rotation speed when the temperature rises and the fan rotation speed when the temperature falls.
[0019]
When the air conditioner switch 10 is switched to the operating state, the controller 14 determines the rotation speed signal a output from the rotation speed sensor 8, the slip rate of the fluid coupling 2, and the lower fan rotation speed Nf 1 of the temperature-sensitive cooling fan 4. It is determined whether the calculated lower fan rotation speed Nf1 has reached the rotation speed Nf3 at which the minimum amount of cooling air W required for cooling the air conditioner condenser 5 can be supplied, and is output from the temperature sensor 9. From the temperature signal b, it is determined whether the cooling air temperature after passing through the radiator 7 has reached the lower slip rate switching temperature t1 of the fluid coupling 2 and the lower fan rotation speed Nf1 is necessary for cooling the air conditioner condenser 5. The rotation speed Nf3 at which the minimum amount of cooling air can be supplied has not reached, and the temperature of the cooling air after passing through the radiator 7 has reached the lower slip ratio switching temperature t1 of the fluid coupling 2. When it is determined that the engine speed has not been increased, a drive signal e for increasing the rotation speed of the engine 1 higher than the engine rotation speed during the warm-up operation is output, and the cooling air volume supplied to the air conditioner condenser 5 is reduced to the minimum air volume or more. . By doing so, the lower fan rotation speed Nf1 can be increased to the rotation speed Nf3 or more at which the minimum amount of cooling air W required for cooling the air conditioner condenser 5 can be supplied with the increase in the engine rotation speed. Insufficient cooling of the condenser 5 can be prevented.
[0020]
In the above embodiment, the rotation speed sensor 8 for detecting the rotation speed of the engine 1 is provided. However, instead of such a configuration, a rotation speed sensor for detecting the rotation speed of the fan drive shaft 3 may be provided. . In addition, both a rotation speed sensor 8 for detecting the rotation speed of the engine 1 and a rotation speed sensor for detecting the rotation speed of the fan drive shaft 3 may be provided.
[0021]
Further, in the above embodiment, the temperature sensor 9 for detecting the temperature of the cooling air after passing through the radiator 7 is provided, but instead of such a configuration, a temperature sensor for detecting the inlet water temperature of the radiator 7 and / or A temperature sensor for detecting air temperature may be provided. In addition, both the temperature sensor 9 for detecting the temperature of the cooling air after passing through the radiator 7 and the temperature sensor for detecting the inlet water temperature of the radiator 7 and / or the temperature sensor for detecting the outside air temperature may be provided.
[0022]
Further, in the above-described embodiment, the lower fan speed Nf1 is set based on the engine speed during the warm-up operation. However, the gist of the present invention is not limited to this, and the lower fan speed Nf1 is not more than the maximum speed. The lower fan speed Nf1 can be set based on the engine speed.
[0023]
【The invention's effect】
As described above, according to the present invention, the slip ratio of the fluid coupling provided in the temperature-responsive cooling fan is controlled between the fan and the fan drive shaft even under a temperature condition equal to or lower than a predetermined slip ratio switching temperature. The air conditioner switch is switched to the operating state while adjusting so that the specified torque is transmitted, and the rotation speed of the temperature-responsive cooling fan is reduced to the rotation speed capable of supplying the minimum amount of cooling air required for cooling the air conditioner condenser. If the controller determines that the cooling air temperature after passing through the radiator or the inlet water temperature of the radiator has not reached the slip rate switching temperature of the fluid coupling, the engine speed is increased and the fan speed is increased. The number of engine air is raised to the number of revolutions that can supply the minimum amount of cooling air required to cool the air conditioner condenser, preventing overcooling of engine cooling water and hydraulic oil. It is possible to satisfy the proper cooling of the air conditioning condenser together.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an engine cooling device according to an embodiment.
FIG. 2 is a cross-sectional view illustrating a configuration of a fluid coupling unit provided in the temperature-responsive cooling fan.
FIG. 3 is a graph showing rotation characteristics of a temperature-responsive cooling fan.
FIG. 4 is a graph showing a relationship between a fan rotation speed, a cooling air temperature after passing through a radiator or an inlet water temperature of a radiator, and a fan rotation speed capable of supplying a minimum amount of cooling air required for cooling an air conditioner condenser, and an engine rotation speed. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine 2 Fluid coupling 3 Fan drive shaft 4 Temperature sensitive cooling fan 5 Air conditioner condenser 6 Oil cooler 7 Radiator 8 Rotation speed sensor 9 Temperature sensor 10 Air conditioner switch 11 Engine speed setting dial 12 Engine speed setting device (governor)
13 Motor 14 Controller a Speed signal a
b Temperature signal c Switch signal d Engine speed setting signal e Motor drive signal W Cooling air

Claims (1)

An engine, a temperature-responsive cooling fan connected to a fan drive shaft of the engine via a fluid coupling to supply cooling air to an air conditioner condenser and a radiator, and detecting a rotation speed of the engine or a rotation speed of the fan drive shaft; A rotation speed sensor, a temperature sensor for detecting a cooling air temperature after passing through the radiator or an inlet water temperature of the radiator, an air conditioner switch for switching an air conditioner to an operation state or a stop state, a rotation speed signal output from the rotation speed sensor, A controller that inputs a temperature signal output from the temperature sensor and a switch signal output from the air conditioner switch, and controls a rotation speed of the engine based on each of the signals.
In the temperature-responsive cooling fan, the slip ratio of the fluid coupling is adjusted such that a predetermined torque is transmitted between the fan and the fan drive shaft even under a temperature condition equal to or lower than a preset slip ratio switching temperature,
When the air conditioner switch is switched to the operating state, the controller determines that the rotation speed of the temperature-responsive cooling fan is equal to the rotation speed capable of supplying the minimum amount of cooling air required for cooling the air conditioner condenser from the rotation speed signal. And whether or not the cooling air temperature after passing through the radiator or the inlet water temperature of the radiator has reached the slip rate switching temperature of the fluid coupling based on the temperature signal. The rotation speed of the mold cooling fan has not reached the rotation speed capable of supplying the minimum amount of cooling air required for cooling the air conditioner condenser, and the cooling air temperature after passing through the radiator or the inlet water temperature of the radiator is the fluid. When it is determined that the slip rate switching temperature of the joint has not been reached, the engine speed is increased and supplied to the air conditioner condenser. Engine cooling system, characterized by a cooling air flow to the minimum air volume or more.

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