JP5211986B2 - Cooling fan control device - Google Patents

Description

  The present invention relates to control of a cooling fan that is driven by an internal combustion engine via a viscous coupling, and more particularly to control of a cooling fan that electrically adjusts the amount of hydraulic fluid in the coupling.

  As a cooling device for a vehicle internal combustion engine, a cooling fan driven by an internal combustion engine via a viscous coupling is known. Patent Document 1 discloses an engine coolant temperature, an actual fan rotation speed, a vehicle speed, and an engine rotation. A technique is disclosed in which a target fan rotation speed is set based on at least one of speed, air-conditioner compressor internal pressure, or air-conditioner panel switch, and the fan rotation speed is electrically adjusted.

Further, since sound is generated with the rotation of the fan, if the fan is rotated at a higher fan rotation speed than required for the cooling request, a noise problem occurs. In order to suppress such noise, Patent Document 2 discloses a technique for limiting the amount of change in the target fan speed or temporarily stopping the fan DUTY under a predetermined condition.
JP 2006-275110 A JP-A-5-26262

  By the way, the fan rotation speed is determined by the speed ratio of the viscous coupling, that is, the ratio of the coupling entry side rotation speed and the coupling exit side rotation speed. This speed ratio is determined mainly by the balance between the amount of hydraulic oil supplied to the hydraulic chamber and the amount of hydraulic oil discharged from the hydraulic chamber, but there are other factors such as engine speed and hydraulic oil temperature. Affect.

  When the speed ratio approaches zero, the supply amount into the coupling is small and the supply amount is less than the discharge amount, so the amount of hydraulic oil in the coupling becomes unstable, and as a result, the controllability of the fan rotation speed is reduced. descend.

  On the other hand, when the speed ratio approaches 1, the discharge amount decreases, and it takes time until the hydraulic oil accumulated in the coupling is discharged even if the supply amount is reduced. Responsiveness decreases.

  For this reason, for example, when the compressor internal pressure of the air conditioner is high in an idle state, it is necessary to increase the fan rotation speed in order to lower the evaporator ambient temperature. However, when the speed ratio approaches 1 by increasing the fan rotation speed, even if the fan rotation speed is decreased when the evaporator ambient temperature is decreased, the fan rotation speed is decreased due to the above-described decrease in responsiveness. It will take time. For this reason, until the fan rotation speed is reduced, the rotation speed becomes unnecessarily high by so-called rotation, and noise may be a problem.

  Therefore, an object of the present invention is to provide a cooling fan control device capable of avoiding the above-described deterioration in controllability and responsiveness of the fan rotation speed.

Cooling fan control apparatus of the present invention, a viscous coupling for transmitting the driving force of the internal combustion engine cooling fan, the hydraulic oil amount adjustment means for electrically adjusting the amount of hydraulic oil supplied to the viscous coupling, create aggressive media Rotational speed control means for controlling the driving force transmitted from the internal combustion engine by adjusting the amount to control the rotational speed of the cooling fan, and hydraulic oil temperature detection means for detecting the hydraulic oil temperature in the viscous coupling . Then, limit values on the upper limit side and the lower limit side are provided in the speed ratio, which is the ratio between the input rotation speed and the output rotation speed of the viscous coupling , according to the hydraulic oil temperature, and the speed ratio is set so as not to exceed these limit values. Limit and control the cooling fan speed.

According to the present invention, the lower limit side limit value and the upper limit side limit value are set so as not to enter, for example, a region where the controllability on the low speed ratio side decreases and a region where the control response on the high speed ratio side decreases. Thus, it is possible to avoid a decrease in controllability and responsiveness.

  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. DESCRIPTION OF SYMBOLS 1 is an engine, 2 is an automatic transmission which transmits the driving force of the engine 1 to a wheel, 3 is a transmission controller (ATCU), 4 is an electric fan coupling driven by the engine 1 via a viscous coupling, 5 Is a fan rotation sensor that detects the actual rotation speed (actual fan rotation speed) of the electric control fan coupling 4, and 6 is a hydraulic oil amount adjusting means that controls the flow of hydraulic oil in the coupling of the electric control fan coupling 4. An electromagnetic coil 7 is provided in the engine room, and an underhood switching module (USM) for sending an operation / stop command to the electromagnetic coil 6, 8 is a cooling fan rotational speed control means and an engine rotational speed correction means Engine control module (ECM), 9 is an air conditioner compressor, 10 is an air conditioner controller, 11 is an air conditioner controller A Pd pressure sensor that detects the internal pressure of the lesser 9, 12 an evaporator temperature sensor that detects the evaporator temperature, 13 an oil temperature sensor that detects the hydraulic oil temperature in the viscous coupling, and 14 an engine that detects the temperature in the engine room This is a room temperature sensor.

  The ECM 8 performs various controls based on detection signals from an accelerator opening sensor, a vehicle speed sensor, a coolant temperature sensor, a crank angle sensor, and the like (not shown). In addition to this, detection signals from the fan rotation sensor 5 and the Pd pressure sensor 11 are also read, the control duty of the electromagnetic coil 6 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. Based on this, the ON / OFF control of the clutch of the air conditioner compressor 9 and the electric fan coupling 4 and air conditioner described later are performed. Perform cooperative control.

  FIG. 2 is a cross-sectional view showing an example of the viscous coupling of the electric control fan coupling 4, and (A) and (B) show a state where an oil sump chamber 26 and a torque transmission chamber 27 described later are shut off, respectively. The state where it communicated with is shown.

  A body 34 is rotatably supported via a main bearing 31 on a drive shaft 21 that rotates when the engine 1 is driven. The body 34 includes a cover 22 and a case 23, and the interior thereof is partitioned into an oil reservoir chamber 26 and a torque transmission chamber 27 by a separate plate 25.

  A disk 24 is fixedly supported at the tip of the drive shaft 21, and this disk 24 is accommodated in the torque transmission chamber 27 so as to form a torque transmission gap between the inner periphery of the torque transmission chamber 27. ing. The case 23 is provided with an oil recovery path (not shown) that allows the torque transmission chamber 27 and the oil reservoir chamber 26 to communicate with each other.

  The separate plate 25 is provided with an oil supply hole 25 a that allows the oil reservoir chamber 26 and the torque transmission chamber 27 to communicate with each other. The oil supply hole 25 a is opened and closed by a leaf spring-like valve member 28, and in the opened state, the hydraulic oil in the oil reservoir chamber 26 is supplied to the torque transmission chamber 27. The hydraulic oil in the torque transmission chamber 27 is discharged from the torque transmission chamber 27 and then recovered in the oil reservoir chamber 26 through the oil recovery path.

  A part of the valve member 28 is fixed to the case 23 with a screw or the like, and an armature 29 made of a magnetic material is attached to a position close to the drive shaft 21.

  The drive shaft 21 supports the electromagnetic coil 6 via a coil bearing 32, and a ring-shaped loop element 30 is attached to the distal end portion of the drive shaft 21 of the electromagnetic coil 6 so as to face the armature 29. ing.

  The electromagnetic coil 6 has a magnetic coil, and generates a magnetic force by energizing the magnetic coil in accordance with a DUTY signal from the USM 7.

  Here, torque transmission of the electric control fan coupling 4 will be described.

  In a state in which the electromagnetic coil 6 generates a magnetic force, the armature 29 is attracted to the loop element 30 side against the action of the leaf spring by the magnetic force transmitted through the loop element 30. For this reason, as shown in FIG. 2B, the valve member 28 is separated from the separation plate 25, the oil supply hole 25 a is opened, and the hydraulic oil in the oil reservoir chamber 26 is supplied to the torque transmission chamber 27. Due to the hydraulic oil supplied to the torque transmission chamber 27, the drive torque of the disk 24 that rotates integrally with the drive shaft 21 is transmitted to the case 23, and the rotational speed of the cooling fan attached to the case 23 increases. The amount of hydraulic oil supplied from the oil reservoir chamber 26 to the torque transmission chamber 27 is determined by a DUTY signal to the electromagnetic coil 6.

  On the other hand, in a state where the electromagnetic coil 6 does not generate magnetic force, the valve member 28 is pressed against the separate plate 25 by the action of the leaf spring, and closes the oil supply hole 25a as shown in FIG. In this state, the supply of hydraulic oil from the oil reservoir chamber 26 to the torque transmission chamber 27 is stopped, and when there is hydraulic oil in the torque transmission chamber 27, the hydraulic oil is collected into the oil reservoir chamber 26. For this reason, the torque transmission rate from the drive shaft 21 to the case 23 via the disk 24 decreases, and the rotation speed of the cooling fan decreases.

  Next, the control of the electric control fan coupling 4 will be described.

  FIG. 3 is a flowchart of fan control executed by the ECM 8 in this embodiment. This calculation routine is repeatedly executed, for example, every 20 ms.

  In step S10, the control state is determined as follows.

  Mode 1 (ECPLGMD = 1) is set when the engine is stopped (# IGNSW = 0), when the engine is started (# STSW = 1), or when a predetermined time STTM # set in advance has elapsed after the start. The predetermined time STTM # is set to about 10 seconds, for example.

  In the case of acceleration or deceleration, mode 2 (ECPLGMD = 2) is set. The term “acceleration” here refers to a case where the change amount of the accelerator opening APO for 40 ms is larger than a preset change amount # DAPO40A, and the term “deceleration” means, for example, the accelerator opening APO for 40 [ms]. This is a case where the change amount is smaller than the preset change amount # DAPO40D. Note that #DAPO 40A and #DAPO 40D may be any value that can clearly determine that the acceleration / deceleration state is set, and is set to about 4 [deg], for example.

  When the difference between the previous value of the air conditioner cooling request target fan speed TFANSPAC [rpm] and the previous value of the basic target fan speed TFANSSPB [rpm] is equal to or greater than a predetermined value # DLTFAN1, or the engine cooling request target fan speed When the difference between the previous value of the number TFANSTPW [rpm] and the previous value of the basic target fan speed TFANSSPB [rpm] is equal to or larger than a predetermined value # DLTFAN2, the mode 3 (ECPLGMD = 3) is set.

  The air conditioner cooling request target fan speed TFANSPAC is a target value of the fan speed when the air conditioner is operating, and is determined according to the air conditioner condenser cooling request or the like. The engine cooling request target fan speed TFANSPTW is a fan speed required to adjust the coolant temperature to a desired value during engine operation. Then, the basic target fan speed TFANSSPB is set to a value smaller than the air conditioner cooling request target fan speed TFANSPAC and the engine cooling request target fan speed TFANSPTW.

  Also, # DLTFAN1 and # DLTFAN2 are set to 400 [rpm] in an idle state, for example.

  Mode 4 (ECPLGMD = 4) is the time from when the shift range of the automatic transmission 2 becomes the parking range (P range) until a predetermined time #PTIME elapses.

  Mode 5 (ECPLGMD = 5) is set during engine stall or during fail-safe control.

  If none of the above modes 1 to 5 corresponds, mode 6 (ECPLGMD = 6) is set. Note that the mode 6 state is a normal control state.

  In step S20, a basic target fan speed TFFANSPB [rpm] is calculated. Specifically, the basic target fan speed table is searched using the engine speed NE [rpm] detected by the crank angle sensor. In the basic target fan speed table, for example, as shown in FIG. 4, the horizontal axis is the engine speed NE, the vertical axis is the basic target fan speed TFANSPB, and the basic target fan speed TFANSPB is the engine speed in the low speed range. Regardless of NE, a constant value is set so as to increase proportionally as the engine speed NE increases in the middle and high engine speed range.

  Note that the constant speed in the low rotation range is that the torque is transmitted by the air in the torque transmission chamber 27 without supplying hydraulic oil due to the characteristics of the fan coupling, and the fan rotation speed can be made lower than this. This is because it cannot be done.

  In step S30, an engine cooling request target fan rotational speed TFANSPTW [rpm] is calculated. Specifically, it is calculated by searching an engine cooling request target fan speed map from the engine coolant temperature TW [° C.] and the vehicle speed VSP [km / h]. For example, as shown in FIG. 5, the engine cooling request target fan speed map has the vehicle speed VSP on the horizontal axis and the engine cooling request target fan speed TFANSPTW on the vertical axis, and the engine cooling request target fan speed increases as the engine coolant temperature TW increases. The number TFANSPTW is set to be large. When the engine coolant temperature TW is low, the engine cooling request target fan rotational speed TFANSPTW becomes a convex curve. When the engine coolant temperature TW is high, the engine coolant temperature TW is proportional to the vehicle speed VSP in the low vehicle speed range. It becomes large and becomes a constant value regardless of the vehicle speed in the medium and high speed range.

  In step S40, it is determined whether the air conditioner switch is ON / OFF. If it is OFF, the process proceeds to step S50, and if it is ON, the process proceeds to step S60.

  In step S50, an air conditioner cooling request target fan rotational speed TFANSPAC [rpm] is calculated by the equation (1).

    TFANSPAC = TFANSSPB (1)

  In step S60, an air conditioner cooling request target fan speed TFANSPAC [rpm] is obtained by searching an air conditioner cooling request target fan speed map from the compressor internal pressure PD [kPA] and the vehicle speed VSP [km / h]. The air conditioner cooling request target fan speed map is, for example, as shown in FIG. 6, where the horizontal axis is the vehicle speed VSP, the vertical axis is the air conditioner cooling request target fan speed TFANSPAC, and the higher the compressor internal pressure PD, Set to increase TFANSPAC. When the compressor internal pressure PD is the same, the air conditioner cooling request target fan rotational speed is a convex curve.

  In step S70, the higher one of the engine cooling request target fan speed TFANSPTW and the air conditioner cooling request target fan speed TFANSSPAC is selected, and this is set as the static target fan speed TFANSPS [rpm].

  In step S80, the dynamic target fan speed TFANSPD [rpm] is calculated as follows. The dynamic target fan rotational speed TFANSPD is a target value when the fan rotational speed is temporarily controlled as in acceleration or the like.

  First, the control state is determined. If the control state is any one of mode 1 (ECPLGMD = 1), mode 2 (ECPLGMD = 2), or mode 4 (ECPLGMD = 4) and mode 3 (ECPLGMD = 3), the basic target The fan speed TFANSPB is set as a dynamic target fan speed TFANSPD. In cases other than the above three control states, the static target fan speed TFANSPS is set as the dynamic target fan speed TFANSPD.

  In step S90, the coupling input rotational speed INPREVFN [rpm] is calculated from the engine rotational speed NE and the pulley ratio #PRATIO by the equation (2). The pulley ratio #PRATIO is a ratio of the diameters of the crankshaft side pulley and the drive shaft 21 side pulley on which a belt for transmitting a driving force from the crankshaft of the engine 1 to the drive shaft 21 is wound.

    INPREVFN = NE × # PRATIO (2)

  In step S100, the basic target fan speed ratio TFANR0 [−] is calculated from the dynamic target fan rotational speed TFANSPD and the coupling input rotational speed INPREVFN by the equation (3).

    TFANR0 = INPREVFFN / TFANSPD (3)

  The basic target fan speed ratio TFANR0 is greater than zero and less than 1.

  In step S110, the hydraulic oil temperature TOILFAN [° C.] in the coupling is read. The hydraulic oil temperature TOILFAN in the coupling may be directly detected by a sensor, or the temperature TEROOM [° C.] in the engine room may be regarded as the hydraulic oil temperature TOILFAN in the coupling.

  In step S120, the upper limit speed limit ratio HLTFANR [-] is calculated by searching the upper limit speed limit ratio table using the hydraulic oil temperature TOILFAN in the coupling. In the upper limit speed limit ratio table, as shown in FIG. 7, the horizontal axis represents the hydraulic oil temperature TOILFAN in the coupling, and the vertical axis represents the upper limit speed limit ratio HLTFANR. Then, TE1 to TE2 [° C.] increases the upper limit speed ratio HLTFANR to 0.75 as the hydraulic oil temperature TOILFAN in the coupling increases, and TE2 to TE3 [° C.] similarly sets the upper limit speed ratio HLTFANR to 0. It rises from .75 to 0.85, and the upper limit speed ratio HLTFANR is set to be constant at 0.85 above TE3 [° C.]. In the case of 10 [° C.] or less, the upper limit speed limit ratio HLTFANR may be constant at 0.75.

  The reason why the upper limit speed ratio HLTFANR is set as described above and the effect thereof will be described later.

  In step S130, the feedback control stop flag #FBSTOP, the basic fan rotation control flag #FFBASE, and the lower limit speed limit ratio LLTFANR are set as shown in the following (i) to (iii). The feedback control here is energization control to the electromagnetic coil 6 performed in order to make the fan rotation speed coincide with the target value.

  (I) When Expressions (4) and (5) are satisfied, the feedback control stop flag #FBSTOP is set to 1, the basic fan rotation control flag #FFBASE is set to 1, and the lower limit speed limit ratio LLTFANR is set to zero. That is, the supply of hydraulic oil is stopped. Even in this case, since the torque is slightly transmitted by the air in the torque transmission chamber 27, the fan rotation speed does not become zero.

TFANSSPB <INPREVFN × # LLTFANR (4)
TFANSPD = TFANSPB (5)
#LLTFANR: Basic lower limit speed ratio

  (Ii) When Expression (4) is satisfied and Expression (5) is not satisfied, the feedback control stop flag #FBSTOP is 1, the basic fan rotation control flag #FFBASE is zero, and the lower limit speed limit ratio LLTFANR is 0.25. And set.

  (Iii) When Expression (6) is satisfied, the feedback control stop flag #FBSTOP is set to 1, the basic fan rotation control flag #FFBASE is set to zero, and the lower limit speed limit ratio LLTFANR is set to 0.25.

    TFANSSPB ≧ INPREVFN × # LLTFANR (6)

  It should be noted that the basic lower limit speed limit ratio #LLTFANR in the equations (4) and (6) is set to a value of about 0.25. The reason for the setting and the effect will be described later.

  In step S140, the target fan speed ratio TFANR [-] is set as follows (i) to (iii).

  (I) When Expression (7) is satisfied, the lower limit speed limit ratio LLTFANR is set as the target fan speed ratio TFANR.

    TFANR0 <LLTFANR (7)

  (Ii) When the expression (8) is satisfied, the basic target fan speed ratio TFANR0 is set as the target fan speed ratio TFANR.

    LLTFANR ≦ TFAN0 ≦ HLTFANR (8)

  (Iii) When the expression (9) is satisfied, the upper limit speed limit ratio HLTFANR is set as the target fan speed ratio TFANR.

    HLTFANR <TFAN0 (9)

  In step S150, the first target fan rotational speed TGFANSP1 [rpm] is calculated from the target fan speed ratio TFANR and the coupling input rotational speed INPREVFN by the equation (10).

    TGFANSP1 = TFAN × INPREVFN (10)

  In step S160, the basic fan rotation control flag #FFBASE is determined. If the basic fan rotation control flag #FFBASE is 1, the process proceeds to step S170, and if it is zero, the process proceeds to step S180.

  In step S170, the basic target fan speed TFANSPB is set as the target fan speed TGFANSP.

  In step S180, the first target fan speed TGFANSP1 is set as the target fan speed TGFANSP.

  In step S190, the target idle speed of the engine 1 is controlled as follows.

  When the control state is mode 3 (ECPLGMD = 3), the engine is idle, and the upper limit speed limit ratio HLTFANR is smaller than the basic target fan speed ratio TFANR0, the upper limit speed limit ratio HLTFANR is equal to or higher than the basic target fan speed ratio TFANR0. , Increase the target idle speed. In cases other than the above, the target idle speed is not changed.

  The idle speed is controlled by controlling the opening of an idle speed control valve (not shown) or the throttle valve according to the target idle speed.

  In step S200, the actual fan speed (actual fan speed RFANSP [rpm]) is read. Specifically, the detection signal of the rotation sensor attached in the coupling is read.

  In Step S210, the fan rotation knitting ERR [rpm] is calculated by Expression (11).

    ERR = TGFANSP−RFANSP (11)

  In step S220, a P gain KPGAIN [% / rpm] and an I gain KIGAIN [% / rpm] are calculated. Specifically, the calculation is performed by searching the tables shown in FIGS. 8 and 9 using the engine speed NE.

  FIG. 8 is a table for calculating the P gain KPGAIN, where the vertical axis represents the P gain KPGAIN and the horizontal axis represents the engine speed NE. As the engine speed NE increases, the P gain KPGAIN decreases.

  FIG. 9 is a table for calculating the I gain KIGAIN, where the vertical axis represents the I gain KIGAIN and the horizontal axis represents the engine speed NE. The I gain KIGAIN is a relatively high constant value in the low engine speed range, and a relatively low constant value in the high engine speed range. In the medium engine speed range, the I gain KIGAIN is relatively increased from a relatively high value as the engine speed NE increases. To a low value.

  In step S230, the control DUTY of the electromagnetic coil 6 is calculated as follows. First, IDUTY, which is DUTY for I, is calculated by the equation (12).

    IDUTY = ERR × KIGAIN (12)

  For IDUTY, there is a restriction that it is larger than the Lo-side I accumulation amount #LILIMIT and smaller than the Hi-side I accumulation amount #HILIMIT.

  Next, the control DUTY is calculated by the equation (13).

DUTY = ERR × KPGAIN + IDUTY (previous value) + IDUTY
... (13)

  In step S240, the electromagnetic coil 6 is subjected to PWM control based on the control DUTY calculated in step S230, thereby controlling the amount of hydraulic oil supplied in the coupling and controlling the fan speed.

  Here, basic lower limit speed limit ratio #LLTFANR will be described.

  FIG. 10 is a diagram showing the relationship between the speed ratio (= fan rotation speed / rotation speed of the drive shaft 21) and control DUTY when the rotation speed of the drive shaft 21 is constant.

  In the fan coupling, in the region where the speed ratio is small (region (a) in FIG. 10), the smaller the speed ratio, the more the torque transmission than the oil supply amount from the oil reservoir chamber 26 to the torque transmission chamber 27. There is a characteristic that the amount of recovery from the chamber 27 to the oil reservoir chamber 26 is larger. That is, the hydraulic oil supplied to the torque transmission chamber 27 is collected without remaining in the torque transmission chamber 27. On the other hand, due to the structure of the fan coupling, there is a characteristic that even if the supply amount is small, a slight transmission torque is generated when the hydraulic oil passes through the torque transmission chamber 27.

  For this reason, as shown in FIG. 10, in the region (a), the feedback center for feedback control for converging the fan rotational speed to the target value is not stable, and the fan rotational speed is not stable.

  Therefore, in order to ensure controllability of the fan speed, the basic lower limit speed limit ratio #LLTFANR is set to a speed ratio 0.25 which is the upper limit of the region (a).

  Next, the upper limit speed ratio HLTFANR will be described.

  In the region (b) of FIG. 10, the feedback center is stable, and the speed ratio changes almost proportionally to the change of the control DUTY. This is because the supply amount and the recovery amount of hydraulic oil are almost equal. However, in a region where the speed ratio is larger than that in region (b), the amount of recovered hydraulic oil is greatly reduced. For this reason, the responsiveness from when the control duty is lowered to when the amount of hydraulic oil in the torque transmission chamber 27 is reduced is lowered. FIG. 11 shows the experimental results regarding the relationship between the decrease in response and the speed ratio.

  FIG. 11 shows, for each speed ratio, how the fan rotation speed changes when the control duty is changed while the engine rotation speed and the rotation speed of the drive shaft 21 are constant. Note that the measured speed ratios are four types of 0.80, 0.85, 0.90, and 0.95, and the control duty is set to zero when 60 seconds have elapsed.

  At a speed ratio of 0.80 to 0.90, the smaller the speed ratio, the faster the fan speed decreases. On the other hand, at a speed ratio of 0.95, the fan speed does not decrease even after TI10 has elapsed after the control duty is set to zero. That is, if the speed ratio exceeds 0.90 during DUTY control, it takes a long time until the fan speed decreases, even if DUTY control is performed to reduce the speed ratio thereafter. Will be out of control.

  From this, the upper limit speed limit ratio HLTFANR may be 0.90 or less, but even when the duty ratio control is performed at 0.90, it is assumed that the speed ratio exceeds 0.90 due to overshoot. Therefore, the upper limit speed limit ratio HLTFANR is set to 0.85.

  By the way, the balance between the supply amount and the recovery amount of the hydraulic oil varies depending on the viscosity of the hydraulic oil. For example, when the temperature in the engine room rises due to heat generated by the engine 1 during traveling of the vehicle, the temperature of the hydraulic oil rises and the viscosity decreases. When the viscosity decreases, the slip amount of the case 23 with respect to the disk 24 increases, and the transmission torque decreases. On the other hand, when the viscosity of the hydraulic oil is low as in cold start, the slip amount is reduced and the transmission torque is increased. The influence of such a difference in the viscosity of the hydraulic oil on the speed ratio control is shown in FIG.

  FIG. 12 is a diagram showing the same diagram as FIG. 10 for a relatively low viscosity (solid line A) and a relatively high viscosity (solid line B). The solid line A is the characteristic shown in FIG.

  As shown in FIG. 12, in the case of a relatively high viscosity, the characteristic in the case of a relatively low viscosity is a characteristic that is compressed in the vertical axis direction, and the speed ratio that is substantially uncontrollable is small. It has become. This is because the supply amount becomes smaller than the recovered amount from a smaller speed ratio because the viscosity of the hydraulic oil is high. Therefore, as shown in the upper limit speed limit ratio table in FIG. 7, the upper limit speed limit ratio HLTFANR is set according to the hydraulic oil temperature.

  As described above, the basic lower limit speed ratio #LLTFANR is 0.25, the upper limit speed limit ratio HLTFANR is 0.85, and the upper limit speed limit ratio HLTFANR is changed according to the hydraulic oil temperature. Thereby, it can avoid that the controllability of a fan rotation speed deteriorates by the influence of the viscosity change of hydraulic fluid.

  Next, the control region when the speed ratio is controlled according to the flowchart of FIG. 3 will be described with reference to FIG.

  The vertical axis in FIG. 13 is the fan rotation speed, and the horizontal axis is the rotation speed of the drive shaft 21 (input rotation speed). The broken line A in the figure indicates the target engine rotation speed required for engine cooling, the point B indicates the required fan speed when idling and the air conditioner switch is ON, and the solid line C indicates the fan speed required from the fuel efficiency. The fan rotation speed required from the fuel efficiency is the fan rotation speed in a state where the supply of hydraulic oil is stopped. That is, it is the number of fan rotations in a state where there is only air in the torque transmission chamber 27.

  The solid line indicating the speed ratio 0.85 has a smaller inclination on the high rotation side because the slip amount increases as the rotation speed increases, and the increase in the fan rotation speed with respect to the rotation increase in the drive shaft 21 decreases. It is.

  As described above, since the speed ratio is basically controlled in the range of 0.25 to 0.85, the control is performed in the hatched area in FIG. Even if the speed ratio is greater than 0.25, the area smaller than the solid line C does not fall within the control range. This is because the rotational speed of the fan does not become lower than the solid line C due to the structure even if the supply of hydraulic oil is stopped.

  By the way, as indicated by a point B, the required fan rotation speed in the case of idle rotation and air conditioner switch ON is larger than the fan rotation speed in the case where the speed ratio is 0.85. In this case, the idling speed is increased so that the process of step S190 of FIG. 3, that is, the point B becomes a speed ratio of 0.85 or less.

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

  (1) An upper limit speed limit ratio HLTFANR and a lower limit speed limit ratio LLTFANR are provided for the target fan speed ratio TFANR of the electric fan coupling 4, and the fan speed is controlled by limiting the target fan speed ratio TFANR so as not to exceed these. Therefore, it is possible to avoid control instability on the low speed ratio side and deterioration of responsiveness on the high speed ratio side.

  (2) When the speed ratio for realizing the fan speed according to the engine load exceeds the upper limit speed limit ratio HLTFANR, such as when the air conditioner switch is ON, the engine is used until the upper limit speed limit ratio HLTFANR or less. Since the rotational speed is increased, it is possible to prevent deterioration of control response when the speed ratio is high. Further, in the conventional fan coupling in which the hydraulic oil amount is not electrically adjusted, it is necessary to set the lower limit value of the fan rotational speed in accordance with the highest air conditioner compressor internal pressure. When the air conditioner is OFF, a lower fan rotation speed can be set, thereby improving fuel consumption.

  (3) Since the upper limit speed ratio HLTFANR is set according to the hydraulic oil temperature or the engine room temperature, it is possible to prevent controllability from being deteriorated due to a change in viscosity accompanying a change in the hydraulic oil temperature.

  (4) Since the speed ratio is limited according to the engine speed, it is possible to prevent deterioration in controllability due to a change in the engine speed.

  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 block diagram of the system to which this embodiment is applied. (A), (B) is sectional drawing of a fan coupling. It is a flowchart of cooling fan rotation speed control of this embodiment. It is a basic target fan rotation speed table. It is an engine cooling request | requirement target fan speed map. It is an air-conditioner cooling request | requirement target fan rotation speed map. It is an upper limit speed limit ratio table. It is a P gain table. It is an I gain table. It is a figure which shows the relationship between speed ratio and control DUTY. It is a figure shown about the responsiveness with respect to control DUTY of fan rotation speed. It is the figure which showed the relationship between speed ratio and control DUTY according to the viscosity of hydraulic fluid. It is a figure which shows the control area | region of a fan rotation speed.

Explanation of symbols

1 Engine 2 Automatic transmission 3 Transmission controller (ATCU)
4 Electric fan coupling 5 Fan rotation sensor 6 Electromagnetic coil 7 Underhood switching module (USM)
8 Engine control module (ECM)
DESCRIPTION OF SYMBOLS 9 Air conditioner compressor 10 Air conditioner controller 11 Pd pressure sensor 12 Evaporator temperature sensor 13 Oil temperature sensor 14 Engine room temperature sensor 21 Drive shaft 22 Cover 23 Case 24 Disc 25 Separate plate 26 Oil reservoir chamber 27 Torque transmission chamber 28 Valve member 29 Armature 30 Loop element

Claims (4)

A viscous coupling that changes the driving force transmitted from the internal combustion engine to the cooling fan in accordance with the amount of hydraulic oil;
Hydraulic oil amount adjusting means for electrically adjusting the hydraulic oil amount supplied to the viscous coupling;
A cooling fan rotational speed control means for controlling the driving speed transmitted from the internal combustion engine by adjusting the hydraulic oil amount to control the cooling fan rotational speed;
Hydraulic oil temperature detecting means for detecting hydraulic oil temperature in the viscous coupling ;
In a control device for a cooling fan having
The cooling fan rotation speed control means provides upper limit and lower limit limit values for the speed ratio, which is the ratio of the input rotation speed and the output rotation speed of the viscous coupling , according to the hydraulic oil temperature. A cooling fan control device that controls the rotation speed of the cooling fan by limiting the speed ratio so as not to exceed. A viscous coupling that changes the driving force transmitted from the internal combustion engine to the cooling fan in accordance with the amount of hydraulic oil;
Hydraulic oil amount adjusting means for electrically adjusting the hydraulic oil amount supplied to the viscous coupling;
A cooling fan rotational speed control means for controlling the driving speed transmitted from the internal combustion engine by adjusting the hydraulic oil amount to control the cooling fan rotational speed;
Atmospheric temperature detection means for detecting the atmospheric temperature in the engine room;
In a control device for a cooling fan having
The cooling fan rotation speed control means provides upper limit and lower limit limit values for the speed ratio which is the ratio of the input rotation speed and the output rotation speed of the viscous coupling according to the ambient temperature in the engine room. A cooling fan control device that controls the number of rotations of the cooling fan by limiting the speed ratio so as not to exceed the limit value. The cooling fan rotation speed control means includes a limit value on an upper limit side of the speed ratio within a range in which the amount of hydraulic oil supplied to the viscous coupling and the amount of hydraulic oil discharged from the viscous coupling are substantially equal. cooling fan control apparatus according to claim 1 or 2, characterized in that to set the lower side of the limit value. When the engine speed is low and the speed ratio for realizing the cooling fan speed according to the engine load exceeds the upper limit value, the engine speed is increased until the speed ratio falls below the upper limit value. The cooling fan control device according to any one of claims 1 to 3, further comprising engine speed correction means.

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