JP2010059841A - Cooling fan control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit degradation of working fluid in a coupling while securing engine cooling performance. <P>SOLUTION: A control device 8 of a cooling fan 4 rotated by transmission of drive force of an internal combustion engine 1 through a fluid coupling includes an adjustment means 6 electrically adjusting quantity of working fluid in the fluid coupling contributing to transmission of the fluid coupling, a coupling operation quantity control means 7 adjusting rotation speed of the cooling fan by controlling coupling operation quantity which is operation quantity of the adjustment means 6, a working fluid temperature detection means detecting or estimating the temperature of working fluid in the coupling, and a cooling demand fan rotation speed upper limit calculation means 8 calculating a cooling demand fan rotation speed upper limit value which is rotation speed of the cooling fan when the temperature of the working fluid in the coupling is the upper limit value of a working fluid temperature range in which viscosity of the working fluid in the coupling reversibly changes, and controls the upper limit of rotation speed of the cooling fan based on the working fluid temperature and the cooling demand fan rotation speed upper limit value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to rotation speed control of a cooling fan of an internal combustion engine, and more particularly to rotation speed control of a cooling fan driven by an engine via a fluid coupling.

  In general, a so-called fan coupling that is driven by an engine via a fluid coupling is known as a cooling fan for suppressing an increase in temperature of engine cooling water.

  As control of the rotational speed of the fan coupling, Patent Document 1 discloses that the opening and closing of two communication holes that allow communication of hydraulic oil in the coupling is controlled according to the temperature of air passing through the radiator.

Specifically, when the temperature of the air passing through the radiator is low, such as when starting a cold machine, the fan is rotated in a low speed state with all the communication holes closed. When the temperature of the air passing through the radiator starts to rise, one communication hole is opened and the fan is rotated at a medium speed, and when the air temperature further rises, both communication holes are opened and the fan is rotated at a high speed. Yes.
JP-A-5-256327

  By the way, the hydraulic oil in the coupling has a characteristic that the higher the fan speed, the higher the temperature and the lower the viscosity. And when a viscosity falls, there exists a problem that the controllability of a fan coupling falls.

  However, in Patent Document 1, the temperature of the hydraulic oil in the coupling is not taken into account in the rotation speed control of the fan coupling. In other words, even if the temperature of the hydraulic oil in the coupling is high, the fan rotates at a high speed if the temperature of the air passing through the radiator is high, and the decrease in the viscosity of the hydraulic oil is promoted and the controllability is reduced. End up.

  Therefore, an object of the present invention is to provide a cooling fan control device capable of suppressing a decrease in viscosity of hydraulic fluid in the coupling.

  The cooling fan control device according to the present invention is a control device for a cooling fan that rotates when a driving force of an internal combustion engine is transmitted through the fluid coupling. The hydraulic oil in the fluid coupling contributes to the transmission of the fluid coupling. Adjusting means for electrically adjusting the amount, coupling operation amount control means for adjusting the rotational speed of the cooling fan by controlling the coupling operation amount, which is the operation amount of the adjusting means, and the operating oil in the coupling Hydraulic oil temperature detection means for detecting or estimating the temperature, and cooling request fan rotation speed upper limit that is the rotation speed of the cooling fan when the hydraulic oil in the coupling reaches the upper limit of the hydraulic oil temperature range in which the viscosity changes reversibly Cooling request fan rotation speed upper limit value calculating means for calculating a value, and limiting the upper limit of the cooling fan rotation speed based on the hydraulic oil temperature and the cooling request fan rotation speed upper limit value.

  According to the present invention, when the hydraulic oil temperature in the coupling is relatively low, the engine cooling performance is ensured without limiting the cooling fan rotational speed to a relatively high rotational speed, When the hydraulic oil temperature is relatively high, deterioration of the hydraulic oil can be prevented by limiting the cooling fan rotation speed to a relatively low rotation speed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a system according to the present embodiment. 1 is an engine, 2 is an automatic transmission that transmits the driving force of the engine 1 to wheels, 3 is a transmission controller (hereinafter referred to as ATCU), and 4 is an electric fan cup driven by the engine 1 via a fluid coupling. A ring 5 is a fan rotation sensor that detects an actual rotation speed of the electric control fan coupling 4 (hereinafter referred to as an actual fan rotation speed), and 6 is a control of the flow of hydraulic oil in the coupling of the electric control fan coupling 4. Solenoid as adjustment means, 7 is an underhood switching module (hereinafter referred to as USM) as a coupling operation amount control means for sending a control signal to the solenoid 6, 8 is an engine control module (hereinafter referred to as ECM), 9 is the air conditioner compressor, 10 is the air conditioner controller, 11 is the internal pressure of the air conditioner compressor 9 Pd pressure sensor output, 12 is the evaporator temperature sensor for detecting the evaporator temperature.

  The ECM 8 performs various controls based on detection signals from a vehicle speed sensor, a water temperature sensor, a crank angle sensor, and the like (not shown). In addition, detection signals from the fan rotation sensor 5 and the Pd pressure sensor 11 are also read, and hydraulic oil temperature detection means, cooling request fan rotation speed upper limit calculation means, fan rotation speed decrease detection means, and target fan rotation speed calculation. As a means, a target DUTY of a solenoid 6 described later is calculated and transmitted to the USM 7 by CAN communication.

  Further, the temperature immediately after the evaporator, the state of the air conditioner switch, and the like are sent from the air conditioner controller 10 by CAN communication. I do. Hereinafter, the rotational speed control of the electric control fan 4 executed by the ECM 8 will be described.

  FIG. 2 is a flowchart for fan rotation speed control executed by the ECM 8. This control is repeatedly executed at regular intervals, for example, every 10 ms.

  In step S100, the temperature of the hydraulic oil in the fan coupling (hereinafter referred to as hydraulic oil in the coupling) (hereinafter referred to as hydraulic oil temperature in the coupling) TOILFAN [° C.] is estimated. Specifically, the in-coupling operating oil temperature map shown in FIG. 3 is retrieved from the engine coolant temperature TW [° C.] and the fan coupling operation amount FANDUTY [%]. A temperature sensor that detects the hydraulic oil temperature may be provided to actually sense the temperature. In FIG. 3, the vertical axis represents the engine coolant temperature, and the horizontal axis represents the fan coupling operation amount. The higher the engine coolant temperature and the greater the fan coupling operation amount, the higher the hydraulic oil temperature in the coupling.

  In step S110, the coupling input rotational speed INPREVFAN [RPM] is calculated. Specifically, it is calculated by equation (1) using the engine speed NE [RPM] and the pulley ratio #PRATIO. The pulley ratio #PRATIO is an outer diameter ratio of a pulley for transmitting power from a crankshaft (not shown) to the input shaft of the electric control fan 4, that is, a reduction ratio between the crankshaft and the input shaft of the electric control fan 4. .

INPREVFN = NE × # PRATIO (1)
Here, the engine speed NE is calculated from a detection value of a crank angle sensor (not shown).

  In step S120, a cooling request fan rotational speed upper limit value BFANLMT [RPM], which is an upper limit value of the fan rotational speed capable of suppressing deterioration of the hydraulic oil in the coupling of the electric control fan 4, is calculated. Specifically, it is obtained by searching the cooling request fan rotational speed upper limit value table shown in FIG. 4 using the coupling input rotational speed INPREVFN [RPM] calculated in step S110.

  In FIG. 4, the vertical axis represents the fan rotational speed, the horizontal axis represents the coupling input rotational speed INPREVFN, and the solid line in the figure represents the boundary with the deterioration region, that is, the cooling request fan rotational speed upper limit BFANLMT.

  The hydraulic oil in the coupling has a characteristic that the viscosity decreases as the temperature rises. Since this characteristic is reversible below a predetermined temperature, the viscosity recovers when the temperature decreases, but becomes irreversible when the temperature exceeds the predetermined temperature, and the viscosity does not recover even when the temperature decreases. Since the controllability of the fan speed decreases when the viscosity of the hydraulic oil is lowered, it is desirable that the hydraulic oil temperature TOILFAN in the coupling is equal to or lower than a predetermined temperature, that is, the viscosity change is within a reversible range.

  This predetermined temperature is the basic coupling hydraulic oil temperature #BTOILFAN, and the region in which the viscosity change becomes irreversible is defined as a deterioration region. Then, the rotational speed of the electric fan 4 at which the hydraulic oil temperature TOILFAN in the coupling becomes the basic hydraulic oil temperature #BTOILFAN in the coupling is set as the cooling request fan rotational speed upper limit BFANLMT. The cooling request fan rotation speed upper limit BFANLMT is determined by the hydraulic oil temperature-viscosity characteristic, hydraulic oil amount, and coupling diameter at the basic coupling hydraulic oil temperature #BTOILFAN. Further, the fan coupling operation amount FANDUTY is sensitive to the in-coupling operating oil temperature TOILFAN, and the lower the in-coupling operating oil temperature, the higher the required cooling fan speed upper limit value BFANLMT.

  In step S130, the hydraulic oil temperature ratio TOILRATIO [-] in the coupling is calculated from the equation (2).

TOILRATIO = TOILFAN / # BTOILFAN (2)
In step S140, the basic fan rotation speed upper limit value FANLMTOOL [RPM] is calculated by equation (3).

FANLMTOM = BFANLMMT × TOILRATIO (3)
In step S150, the fan rotational speed upper limit value FAN LMT [RPM] is calculated by equation (4).

FNLMT = max (FANLMTOL, BFNLMT) (4)
As in steps S100 to S150, the engine cooling performance and the hydraulic oil in coupling are calculated by calculating the fan rotational speed upper limit value FANLMT on the basis of the hydraulic oil temperature TOILFAN in coupling and the cooling request fan rotational speed upper limit value BFNLMT. It is possible to prevent both deterioration. That is, when the hydraulic oil temperature TOILFAN in the coupling is low, a high fan speed upper limit value FNLMT is set to ensure engine cooling performance, and when it is high, a low fan speed upper limit value FNLMT is set. Thus, deterioration of the hydraulic fluid in the coupling can be prevented. Hereinafter, the description returns to the flowchart.

  In step S160, an engine cooling request target fan rotational speed TFANSPTW [RPM] that is a target rotational speed of the electric control fan 4 determined from the engine cooling request is calculated. Specifically, the engine cooling request target fan speed map shown in FIG. 5 is searched from the engine coolant temperature TW [° C.] and the vehicle speed VSP [km / h].

  In FIG. 5, the vertical axis represents the fan speed, and the horizontal axis represents the vehicle speed VSP. If the vehicle speed is the same, the higher the engine coolant temperature TW, the greater the engine cooling request target fan speed TFANSPTW. On the other hand, if the cooling water temperature TW is the same, the higher the vehicle speed, the higher the engine cooling request target fan speed TFANSPTW. Note that the map shown in FIG. 5 is merely an example, and details are determined by adaptation.

  In step S170, it is determined whether the air conditioner switch is OFF. If it is OFF, the process proceeds to step S180. If it is ON, the process proceeds to step S190.

  In step S180, the air conditioner cooling request target fan rotational speed TFANSPAC [RPM] is set to zero.

  In step S190, the air conditioner cooling request target fan speed TFANSPAC is searched by searching the air conditioner cooling request target fan speed map as shown in FIG. 6 from the air conditioner compressor internal pressure Pd [kPA] and the vehicle speed VSP [km / h]. [RPM] is calculated.

  In FIG. 6, the vertical axis represents the fan speed, and the horizontal axis represents the vehicle speed VSP. If the vehicle speed is the same, the higher the air conditioner compressor internal pressure Pd, the greater the air conditioner cooling request target fan speed TFANSPAC. On the other hand, if the air-conditioner compressor internal pressure Pd is the same, the air-conditioner cooling request target fan rotational speed TFANSPAC is a curve that is convex upward with respect to the increase in the vehicle speed VSP. In addition, this map shall be determined by adaptation as in FIG.

  When the air conditioner cooling request target fan rotational speed TFANSPAC is thus set, the process proceeds to step S200.

  In step S200, the basic target fan speed BTFANRPM [RPM] is calculated by equation (5).

BTFANRPM = max (TFANSPTW, TFANSPAC) (5)
In step S210, the target fan rotational speed TFANRPM [RPM] is calculated by equation (6).

TFANRP = min (FANLMT, BTFANRPM) (6)
In step S220, the actual fan speed REFANSP [RPM], which is the actual speed of the electric control fan 4, is read. Specifically, the detection signal of the fan rotation sensor 5 is read.

  In step S230, it is determined whether or not the state in which the target fan rotational speed TFANRPM is higher than the actual fan rotational speed REFANSP has exceeded the fan rotational decrease determination time #TFANLOW [sec]. If it has elapsed, the process proceeds to step S250, and if it has not elapsed, the process proceeds to step S240.

  In step S240, it is determined whether or not a state where the fan coupling operation amount FANDUTY is greater than the fan rotation decrease determination operation amount #HFANDUTY [%] has elapsed for the fan rotation decrease determination time #TFANLOW [sec]. If it has elapsed, the process proceeds to step S250, and if it has not elapsed, the process proceeds to step S260.

  The fan rotation decrease determination operation amount #HFANDUTY is set to a value of about 90 to 95%, for example.

  In step S250, fan rotation speed decrease determination flag #TFANLOW is set to 1, and the process proceeds to step S270.

  In step S260, the fan rotation speed decrease determination flag #TFANLOW is set to zero, and the process ends.

  When the actual fan speed REFANSP does not follow the target fan speed TFANSPM using the fan coupling operation amount FANDUTY, the target fan speed TFANSPM and the actual fan speed REFANSP as in steps S230 to S260 above, Since it is determined that the rotational speed is decreasing, it is possible to appropriately determine the decrease in fan rotational speed.

  In step S270, a fan coupling rotation lowering limiter torque LFANTRQ [Nm] is calculated. Specifically, an engine torque limit map as shown in FIG. 7 is searched from the engine speed NE and the engine coolant temperature TW.

  In FIG. 7, the vertical axis represents torque and the horizontal axis represents engine speed NE. If the engine speed is the same, the lower the engine coolant temperature TW, the larger the limit torque LFANTRQ at the time of fan coupling rotation decrease. Note that the details of this map are determined by adaptation as in FIGS. 5 and 6.

  In step S280, the gear position of the automatic transmission 2 is fixed at, for example, the third speed. Thereby, an engine speed can be restrict | limited.

  The reason why the engine torque and the engine speed are limited in steps S270 and S280 is to avoid an increase in the engine coolant temperature TW when the fan speed decreases. That is, by limiting the engine torque and the engine speed, the engine heat generation amount is reduced and the increase in the engine coolant temperature TW is avoided. Note that only one of the engine torque limit and the engine speed limit may be performed.

  In step S290, target fan rotation speed limit processing is performed. Specifically, the target fan rotational speed TFANRPM is set to a limit rotational speed reduction rate #FANDUTY [RPM / 100 ms], for example, about 10 [RPM / 100 ms]. Decrease until amount #FANDUTYL [%]. The fan coupling limit manipulated variable #FANDUTYL may be a value smaller than the fan rotation decrease determining manipulated variable #HFANDUTY, and is set to about 85%, for example.

  This is to prevent deterioration of the hydraulic fluid in the coupling based on the tendency that when the fan coupling operation amount FANDUTY is high, the hydraulic fluid temperature TOILFAN in the coupling is high and the fan rotation speed is likely to decrease. is there. That is, when the fan rotation speed decreases, the target fan rotation speed TFANRPM is decreased to suppress further temperature rise and prevent deterioration.

  As described above, according to the present embodiment, the following effects can be obtained.

  (1) Since the upper limit of the rotational speed of the electric control fan 4 is limited based on the hydraulic oil temperature and the cooling request fan rotational speed upper limit value, the viscosity of the hydraulic oil in the coupling is reduced while ensuring the engine cooling performance. Can be suppressed.

  (2) Since the hydraulic oil temperature is estimated based on the coupling operation amount and the cooling water temperature, a temperature sensor for detecting the hydraulic oil temperature becomes unnecessary.

  (3) When a reduction in the rotational speed of the electric control fan 4 is detected, the output or the rotational speed of the engine 1 is limited, so that overheating of the engine 1 can be prevented.

  (4) When a decrease in the rotational speed of the electric control fan 4 is detected, the target fan rotational speed is decreased according to the coupling operation amount, so that the temperature rise of the hydraulic oil can be suppressed and deterioration can be prevented.

  (5) Since the decrease in the fan speed is detected based on at least one of the deviation between the target fan speed and the actual fan speed or the coupling operation amount, the decrease in the fan speed can be appropriately detected.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

It is a figure which shows the structure of the system of this embodiment. It is a flowchart about fan rotation speed control. It is an example of the hydraulic oil temperature map in a coupling. It is an example of a cooling request fan rotation speed upper limit table. It is an example of an engine cooling request | requirement target fan rotation speed map. It is an example of an air-conditioner cooling request | requirement target fan rotation speed map. It is an example of an engine torque restriction map.

Explanation of symbols

1 Engine 2 Automatic transmission 3 Transmission controller (ATCU)
4 Electric fan 5 Fan rotation sensor 6 Solenoid 7 Underhood switching module (USM)
8 Engine control module (ECM)
9 Air conditioner compressor 10 Air conditioner controller 11 Pd pressure sensor 12 Evaporator temperature sensor

Claims (6)

In a control device for a cooling fan that rotates when a driving force of an internal combustion engine is transmitted through a fluid coupling,
Adjusting means for electrically adjusting the amount of hydraulic oil in the fluid coupling that contributes to transmission of the fluid coupling;
Coupling operation amount control means for adjusting the rotation speed of the cooling fan by controlling the coupling operation amount that is the operation amount of the adjustment means;
Hydraulic oil temperature detection means for detecting or estimating the temperature of the hydraulic oil in the coupling;
Cooling request fan rotation speed upper limit value for calculating a cooling request fan rotation speed upper limit value that is the rotation speed of the cooling fan when the hydraulic oil in the coupling reaches the upper limit value of the hydraulic oil temperature range in which the viscosity changes reversibly. A calculation means;
With
A cooling fan control device that limits an upper limit of the number of rotations of the cooling fan based on the hydraulic oil temperature and the cooling request fan rotation number upper limit value.   2. The cooling fan control device according to claim 1, wherein the hydraulic oil temperature detection unit estimates the hydraulic oil temperature based on the coupling operation amount and a cooling water temperature of the internal combustion engine. Fan speed reduction detecting means for detecting a reduction in the speed of the cooling fan;
Limiting means for limiting the output or rotational speed of the internal combustion engine when detecting a decrease in the rotational speed of the cooling fan;
The cooling fan control device according to claim 1, further comprising:   4. The cooling fan control device according to claim 3, wherein the limiting means limits the rotational speed of the internal combustion engine by fixing a shift stage of an automatic transmission connected to the internal combustion engine. A target fan rotational speed calculating means for setting a target fan rotational speed that is a target rotational speed of the cooling fan in accordance with an operating state of the internal combustion engine;
Fan speed reduction detecting means for detecting a reduction in the speed of the cooling fan;
Further comprising
3. The cooling fan according to claim 1, wherein the target fan rotation speed calculation unit decreases the target fan rotation speed in accordance with the coupling operation amount when a decrease in the rotation speed of the cooling fan is detected. Control device.   The fan speed reduction detecting means detects a cooling fan speed reduction based on at least one of a deviation between the target fan speed and an actual fan speed or the coupling operation amount. Item 6. The cooling fan control device according to any one of Items 3 to 5.

Images