Cooling fan device

Abstract

To suppress deterioration of drivability due to fan noise.SOLUTION: An electronic control unit executes: first calculation processing (S1) of calculating a first water temperature request engagement rate FNR1 that is a request value of a fan engagement rate corresponding to a cooling request of engine cooling water; second calculation processing (S4) of calculating the fan engagement rate at which fan rotating speed becomes a first upper limit rotating speed as a value of a first guard value GRD1 on the basis of vehicle speed V; and upper limit guard processing (S7) of setting the first guard value GRD1 as a value of the first water temperature request engagement rate FNR1 when a calculation value of the first water temperature request engagement rate FNR1 is larger than the first guard value GRD1, and controls the fan engagement rate on the basis of the value of the first water temperature request engagement rate FNR1 after the upper limit guard processing is applied. When the vehicle speed V is low, the first upper limit rotating speed is set to be speed lower than that when the vehicle speed V is high.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a cooling fan device.

Background Art

[0002] Patent Document 1 describes a device for electronically controlling a cooling fan as a cooling fan device that generates cooling air for a radiator that cools engine cooling water.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the cooling fan device as described above, when the cooling fan is controlled to meet the cooling requirements of the engine, the rotational speed of the cooling fan may increase when the vehicle is accelerating or the like. Then, as the rotational speed increases, the fan noise becomes larger, which may lead to deterioration of drivability.

Means for Solving the Problems

[0005] The cooling fan device that solves the above problems is a device that generates cooling air for a radiator by a cooling fan connected to an engine via a fan clutch, and includes a control unit that controls the engagement rate of the fan clutch. The control unit performs a first arithmetic process of calculating a water temperature required engagement rate, which is a required value of the engagement rate according to the cooling requirement of the engine cooling water, and a second arithmetic process of calculating, based on the vehicle speed, the engagement rate at which the rotational speed of the cooling fan becomes a first upper limit rotational speed as a value of a first guard value, and an upper limit guard process of setting the first guard value as the value of the water temperature required engagement rate when the calculated value of the water temperature required engagement rate by the first arithmetic process is greater than the first guard value, and controls the engagement rate based on the value of the water temperature required engagement rate after the application of the upper limit guard process. Note that the first upper limit rotational speed is set to a lower speed when the vehicle speed is low than when the vehicle speed is high.

[0006] By performing the first arithmetic process, the second arithmetic process, and the upper limit guard process, the control unit controls the engagement rate of the fan clutch so that the rotational speed of the cooling fan is equal to or lower than the first upper limit rotational speed. The first upper limit rotational speed is set to a lower speed when the vehicle speed is low and the background noise is small than when the vehicle speed is high and the background noise is large. Therefore, the fan noise can be limited to a level that is less noticeable with respect to the background noise that changes with the vehicle speed. Accordingly, the above cooling fan device has an effect of suppressing the deterioration of drivability due to fan noise.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0008] Hereinafter, an embodiment of the cooling fan device will be described in detail with reference to FIGS. 1 to 3. <Configuration of the Cooling Fan Device> First, referring to FIG. 1, the configuration of the cooling fan device of the present embodiment will be described. The cooling fan device of the present embodiment is installed in the engine room of a vehicle. The cooling fan device includes a rotary input shaft 10, a fan clutch 11, and a cooling fan 12. The rotary input shaft 10 is connected to the crankshaft 16 of the engine 15 via a winding transmission mechanism 13. The cooling fan 12 generates cooling air for the radiator 17 in response to rotation. The radiator 17 is a heat exchanger for cooling the engine cooling water. The fan clutch 11 is interposed between the rotary input shaft 10 and the cooling fan 12. The fan clutch 11 is a fluid clutch that uses a viscous fluid such as silicone oil as a transmission medium for rotational torque. And the fan clutch 11 is configured to be able to change the engagement ratio between the rotary input shaft 10 and the cooling fan 12 by adjusting the amount of the viscous fluid in the working chamber. Details of such a fan clutch 11 are described in, for example, Patent Document 1.

[0009] In addition, the cooling fan device includes an electronic control unit 20 as a control unit. The electronic control unit 20 has a ROM 21 and a CPU 22. The ROM 21 is a storage device that stores programs and data for controlling the fan clutch 11. The CPU 22 is a processing device that reads and executes the programs stored in the ROM 21. The electronic control unit 20 is connected to a first rotational speed sensor 23, a second rotational speed sensor 24, a water temperature sensor 25, and a vehicle speed sensor 26. The first rotational speed sensor 23 is a sensor that detects the engine rotational speed NE, which is the rotational speed of the crankshaft 16 of the engine 15. The second rotational speed sensor 24 is a sensor that detects the fan rotational speed NF, which is the rotational speed of the cooling fan 12. The water temperature sensor 25 is a sensor that detects the engine water temperature THW, which is the temperature of the engine cooling water. The vehicle speed sensor 26 is a sensor that detects the vehicle speed V.

[0010] The rotation input shaft 10 of the cooling fan device configured as described above rotates at a speed proportional to the engine rotation speed NE. The rotation of the rotation input shaft 10 is transmitted to the cooling fan 12 via the fan clutch 11. In the following description, the rotation speed of the rotation input shaft 10 is described as the input rotation speed NI. The electronic control unit 20 calculates the input rotation speed NI based on the detection result of the first rotation speed sensor 23.

[0011] The electronic control unit 20 controls the fan engagement ratio FN, which is the engagement ratio between the rotation input shaft 10 and the cooling fan 12, through the operation of the fan clutch 11. Here, the ratio of the fan rotation speed NF to the input rotation speed NI is used as the value of the fan engagement ratio FN. Note that the fan rotation speed NF when the value of the fan engagement ratio FN is "0" is "0". Also, the fan rotation speed NF when the value of the fan engagement ratio FN is "1" is equal to the input rotation speed NI.

[0012] <Cooling Fan Control> Next, with reference to FIG. 2, the cooling fan control executed by the electronic control unit 20 will be described. In the cooling fan control, the electronic control unit 20 sets the target engagement ratio FN*, which is the control target value of the fan engagement ratio FN. Then, the electronic control unit 20 operates the fan clutch 11 so that the fan engagement ratio FN becomes equal to the target engagement ratio FN*. The operation of the fan clutch 11 is performed by open control or feedback control.

[0013] FIG. 2 shows the processing flow of the electronic control unit 20 regarding the setting of the target engagement ratio FN*. The electronic control unit 20 repeats such setting of the target engagement ratio FN* for each predetermined control cycle.

[0014] When setting the target engagement ratio FN*, the electronic control unit 20 calculates three values, namely, the first water temperature required engagement ratio FNR1, the second water temperature required engagement ratio FNR2, and the third water temperature required engagement ratio FNR3, based on the engine coolant temperature THW, vehicle speed V, etc. (S1~S3). The first water temperature required engagement ratio FNR1 is the required value of the fan engagement ratio FN assuming general driving such as urban driving or highway driving. The second water temperature required engagement ratio FNR2 is the required value of the fan engagement ratio FN assuming relatively high-load driving such as towing driving or uphill driving. The third water temperature required engagement ratio FNR3 is the required value of the fan engagement ratio FN assuming extremely high-load driving such as off-road driving. The values of FNR1~FNR3 are calculated such that, under the respective assumed driving conditions, when continuing to drive while maintaining the current vehicle speed V, the air volume of the radiator 17 becomes an amount that can keep the engine coolant at an appropriate temperature, and the value of the fan engagement ratio FN is obtained.

[0015] On the other hand, the electronic control unit 20 calculates a first guard value GRD1 based on the vehicle speed V and the input rotation speed NI (S4). Further, the electronic control unit 20 calculates a second guard value GRD2 based on the engine coolant temperature THW and the input rotation speed NI (S5).

[0016] The electronic control unit 20 calculates, as the value of the first guard value GRD1, a value that satisfies the following relationship with respect to the vehicle speed V and the input rotation speed NI. Let the fan rotation speed NF at which the fan noise becomes the maximum allowable value at the current vehicle speed V be the first upper limit rotation speed NF1. When the vehicle speed V is high, the background noise becomes larger than when it is low, so the fan noise becomes less noticeable. Therefore, the first upper limit rotation speed NF1 is lower when the vehicle speed V is low than when it is high. The electronic control unit 20 calculates, as the value of the first guard value GRD1, the value of the fan engagement ratio FN at which the fan rotation speed NF becomes the first upper limit rotation speed NF1 at the current vehicle speed V and the input rotation speed NI.

[0017] Figure 3 shows the setting mode of the second guard value GRD2. In the figure, "NI1" indicates the current value of the input rotation speed NI, and "TH2" indicates the maximum value of the appropriate temperature range of the engine coolant temperature THW. Also, "TH1" in the figure is a constant, and a temperature slightly lower than TH2 is set as its value. Furthermore, "NF2" in the figure indicates the second upper limit rotation speed, which is the fan rotation speed NF at which the fan noise becomes the maximum value within the allowable range during engine stop or low-speed driving. When the engine coolant temperature THW is equal to or lower than TH1, the first guard value GRD1 is set to the quotient obtained by dividing the first upper limit rotation speed NF1 by NI1 (=NF1 / NI1). That is, at this time, the first guard value GRD1 is set to the fan engagement ratio FN at which the fan rotation speed NF becomes the second upper limit rotation speed NF2. On the other hand, when the engine coolant temperature THW is equal to or higher than TH2, "1" is set as the value of the first guard value GRD1. Note that the first guard value GRD1 when the engine coolant temperature THW is in the range from TH1 to TH2 is set as follows. That is, the first guard value GRD1 at this time is set to a value that gradually increases as the engine coolant temperature THW rises from the value "NF1 / NI1" when the engine coolant temperature THW is TH1 to the value "1" when the engine coolant temperature THW is TH2. In this way, the electronic control unit 20 calculates the fan engagement ratio FN, which sets the fan rotation speed NF to the second upper limit rotation speed NF2, as the value of the second guard value GRD2 when the engine coolant temperature THW is lower than TH1. Then, the electronic control unit 20 calculates the fan engagement ratio FN, which sets the fan rotation speed NF to a speed higher than the second upper limit rotation speed NF2, as the value of the second guard value GRD2 when the engine coolant temperature THW is higher than TH1.

[0018] The electronic control unit 20 sets the larger value of the first guard value GRD1 and the second guard value GRD2 as the value of the upper limit guard value GRD (S6). Then, the electronic control unit 20 performs upper limit guard processing on the value of the first water temperature required engagement ratio FNR1 so that it becomes a value equal to or less than the upper limit guard value GRD (S7). That is, when the first water temperature required engagement ratio FNR1 is equal to or less than the upper limit guard value GRD, the electronic control unit 20 maintains the value of the first water temperature required engagement ratio FNR1. On the other hand, when the first water temperature required engagement ratio FNR1 exceeds the upper limit guard value GRD, the electronic control unit 20 resets the value of the upper limit guard value GRD as the value of the first water temperature required engagement ratio FNR1.

[0019] After the above processing, the electronic control unit 20 selects, from among the first water temperature required engagement ratio FNR1, the second water temperature required engagement ratio FNR2, and the third water temperature required engagement ratio FNR3 after the upper limit guard processing, a value corresponding to the current driving situation as the value to be set for the target engagement ratio FN* (S8). In the case of this embodiment, the electronic control unit 20 performs the above selection based on the vehicle speed intake air volume ratio. The vehicle speed intake air volume ratio represents the ratio of the vehicle speed V to the moving average value of the intake air volume GA. When the vehicle speed intake air volume ratio is equal to or less than a predetermined first determination value, the electronic control unit 20 selects the value of the first water temperature required engagement ratio FNR1 after the upper limit guard processing as the value to be set for the target engagement ratio FN*. Also, when the vehicle speed intake air volume ratio exceeds the first determination value and is equal to or less than a predetermined second determination value larger than the first determination value, the electronic control unit 20 selects the value of the second water temperature required engagement ratio FNR2 as the value to be set for the target engagement ratio FN*. Further, when the vehicle speed intake air volume ratio exceeds the second determination value, the electronic control unit 20 selects the value of the third water temperature required engagement ratio FNR3 as the value to be set for the target engagement ratio FN*.

[0020] <Operational effects of the embodiment> In S1 to S3 of FIG. 2, the electronic control unit 20 calculates a first water temperature required engagement ratio FNR1, a second water temperature required engagement ratio FNR2, and a third water temperature required engagement ratio FNR3, which are required values of the fan engagement ratio FN according to the cooling requirement of the engine cooling water. In the present embodiment, the processes of S1 to S3 correspond to a first calculation process for calculating a water temperature required engagement ratio, which is a required value of the fan engagement ratio FN according to the cooling requirement of the engine cooling water.

[0021] Further, in S4 of FIG. 2, the electronic control unit 20 calculates, based on the vehicle speed V, the fan engagement ratio FN at which the fan rotation speed NF becomes the first upper limit rotation speed NF1 as the value of the first guard value GRD1. The first upper limit rotation speed NF1 is set to a lower speed when the vehicle speed V is low than when the vehicle speed V is high. In the present embodiment, the process of S4 corresponds to a second calculation process for calculating the fan engagement ratio FN at which the fan rotation speed NF becomes the first upper limit rotation speed NF1 as the value of the first guard value GRD1.

[0022] Further, in S5 of FIG. 2, the electronic control unit 20 calculates the second guard value GRD2 based on the engine water temperature THW. At this time, when the engine water temperature THW is lower than the predetermined temperature (TH1), the electronic control unit 20 calculates the fan engagement ratio FN at which the fan rotation speed NF becomes the second upper limit rotation speed NF2 as the value of the second guard value GRD2. Also, when the engine water temperature THW is higher than the predetermined temperature (TH1), the electronic control unit 20 calculates the fan engagement ratio FN at which the fan rotation speed NF is higher than the second upper limit rotation speed NF2 as the value of the second guard value GRD2. In the present embodiment, the process of S5 corresponds to a third calculation process for calculating the second guard value GRD2 based on the engine water temperature THW.

[0023] Furthermore, in S6 of FIG. 2, the electronic control unit 20 sets the larger value of the first guard value GRD1 and the second guard value GRD2 as the value of the upper limit guard value GRD. Then, in S7 of FIG. 2, the electronic control unit 20 performs an upper limit guard on the first water temperature required engagement ratio FNR1 so that the value is equal to or less than the upper limit guard value GRD. When the first guard value GRD1 is larger than the second guard value GRD2, the first guard value GRD1 is set as the value of the upper limit guard value GRD. Therefore, the process of S7 in this case is a process of setting the first guard value GRD1 as the value of the first water temperature required engagement ratio FNR1 when the calculated value of the first water temperature required engagement ratio FNR1 in S1 is larger than the first guard value GRD1. On the other hand, when the second guard value GRD2 is larger than the first guard value GRD1, the second guard value GRD2 is set as the value of the upper limit guard value GRD. Therefore, the process of S7 in this case is a process of setting the second guard value GRD2 as the value of the first water temperature required engagement ratio FNR1 when the calculated value of the first water temperature required engagement ratio FNR1 in S1 is larger than the second guard value GRD2. In the present embodiment, the processes of S6 and S7 correspond to the upper limit guard process.

[0024] Note that the electronic control unit 20 calculates the first water temperature required engagement ratio FNR1 as a value to be set to the target engagement ratio FN* when the driving load of the vehicle is not too high. On the other hand, the electronic control unit 20 calculates the second water temperature required engagement ratio FNR2 and the third water temperature required engagement ratio FNR3 as values to be set to the target engagement ratio FN* during high-load driving of the vehicle. Then, the electronic control unit 20 applies the upper limit guard process in S7 of FIG. 2 only to the first water temperature required engagement ratio FNR1. Therefore, during high-load driving of the vehicle, the electronic control unit 20 controls the fan engagement ratio FN based on the calculated value of the water temperature required engagement ratio in the first calculation process (S1 to S3) to which the upper limit guard process (S6, S7) is not applied.

[0025] Note that when the vehicle speed intake air ratio, which is the ratio of the moving average value of the intake air amount GA of the engine 15 to the vehicle speed V, is equal to or less than a predetermined first determination value, the electronic control unit 20 sets the first coolant temperature required engagement ratio FNR1 to which the upper limit guard process is applied as the value of the target engagement ratio FN*. On the other hand, when the vehicle speed intake air ratio exceeds the first determination value, the electronic control unit 20 sets either the second coolant temperature required engagement ratio FNR2 or the third coolant temperature required engagement ratio FNR3, to which the upper limit guard process is not applied, as the value of the target engagement ratio FN*.

[0026] According to the cooling fan device of the present embodiment described above, the following effects can be achieved. (1) By performing the above-described first arithmetic process (S1 to S3), second arithmetic process (S4), and upper limit guard process (S6, S7), the electronic control unit 20 controls the fan engagement ratio FN so that the fan rotation speed NF becomes equal to or less than the first upper limit rotation speed NF1. The first upper limit rotation speed NF1 is set to a lower speed when the vehicle speed V is low and the background noise is small than when the vehicle speed V is high and the background noise is large. Therefore, the fan noise can be limited to a level that is less noticeable with respect to the background noise that changes according to the vehicle speed V. Accordingly, deterioration of drivability due to fan noise can be suppressed.

[0027] (2) The electronic control unit 20 performs the above-described third arithmetic process (S5) and upper limit guard process (S6, S7). As a result, when the engine coolant temperature THW is lower than a predetermined temperature, the electronic control unit 20 controls the fan engagement ratio FN so that the fan rotation speed NF becomes equal to or less than the second upper limit rotation speed NF2. Further, when the engine coolant temperature THW is lower than a predetermined temperature, the electronic control unit 20 allows the fan rotation speed NF to exceed the second upper limit rotation speed NF2. Therefore, when the engine coolant temperature THW is not too high, the fan noise can be suppressed, and when the engine coolant temperature THW is high, the engine coolant can be quickly cooled.

[0028] (3) When the vehicle is running under high load, the electronic control unit 20 does not perform the upper limit guard process (S6, S7) on the calculated value of the water temperature requirement engagement ratio. Therefore, when the vehicle is running under high load where the heat generation amount of the engine 15 increases and the engine water temperature THW is likely to rise, cooling of the engine coolant can be prioritized over suppression of fan noise.

[0029] (4) The electronic control unit 20 determines the necessity of applying the above upper limit guard process when the ratio of the intake air amount GA of the engine 15 to the vehicle speed V exceeds a predetermined value as the vehicle running under high load. When the vehicle is running under high load, a larger driving torque is required for running than when running under low load. Therefore, when the vehicle is running under high load, the intake air amount GA of the engine 15 at the same vehicle speed V tends to be larger than when running under low load. Therefore, based on the above ratio, it is possible to accurately determine whether the vehicle is running under high load.

[0030] <Other Embodiments> This embodiment can be implemented with the following modifications. This embodiment and the following modification examples can be implemented in combination with each other within a technically non - conflicting range.

[0031] · Whether the vehicle is running under high load or not may be determined in a manner different from the above embodiment. For example, it may be determined whether the vehicle is running under high load based on the integrated value of the intake air amount GA over a certain period.

[0032] · Even when the vehicle is running under high load, the upper limit guard process for the calculated value of the water temperature requirement engagement ratio may be applied. This can be realized by applying the process of S7 also to the calculated value of the second water temperature requirement engagement ratio FNR2 in S2 and the calculated value of the third water temperature requirement engagement ratio FNR3 in S3 in FIG. 2.

[0033] · In S4 of FIG. 2, the first guard value GRD1 may be calculated based on the vehicle speed V without using the input rotation speed NI. For example, during steady running of the vehicle, the engine rotation speed NE for each vehicle speed V falls within a certain range. Therefore, if the first guard value GRD1 is set such that it has a smaller value when the vehicle speed V is low than when it is high, the fan noise can be limited to a level that does not become noise in response to the background noise.

[0034] · The processes of S5 and S6 in FIG. 2 may be omitted, and the first guard value GRD1 may be directly set as the value of the upper limit guard value GRD, and the process of S7 may be performed. That is, the third arithmetic process may be omitted, and the upper limit guard process may be performed based only on the first guard value GRD1 calculated in the second arithmetic process.

[0035] · The target engagement ratio FN* may be calculated as a value corresponding to requirements other than the cooling requirement of the engine cooling water, for example, and the cooling requirement of the air conditioner refrigerant and the requirement for protecting the components of the cooling fan device. For example, in the series of processes in FIG. 2, a process of calculating the required value of the fan engagement ratio FN corresponding to other requirements may be added, and the setting of the target engagement ratio FN* in S8 may be performed based on that required value as well.

Explanation of Reference Numerals

[0036] 10... Rotating input shaft 11... Fan clutch 12... Cooling fan 13... Wrapping transmission mechanism 15... Engine 16... Crankshaft 17... Radiator 20... Electronic control unit 21... ROM 22... CPU 23... First rotation speed sensor 24... Second rotation speed sensor 25... Water temperature sensor 26... Vehicle speed sensor

Claims

1. A cooling fan device that generates cooling air for a radiator by a cooling fan connected to an engine via a fan clutch, comprising a control unit that controls the engagement ratio of the fan clutch, wherein the control unit performs a first arithmetic process of calculating a water temperature required engagement ratio, which is a required value of the engagement ratio according to the cooling requirement of engine cooling water, a second arithmetic process of calculating, based on the vehicle speed, the engagement ratio at which the rotational speed of the cooling fan becomes a first upper limit rotational speed as a value of a first guard value, an upper limit guard process of setting the first guard value as the value of the water temperature required engagement ratio when the calculated value of the water temperature required engagement ratio by the first arithmetic process is greater than the first guard value, and controls the engagement ratio based on the value of the water temperature required engagement ratio after application of the upper limit guard process, wherein the first upper limit rotational speed is set to a lower speed when the vehicle speed is low than when the vehicle speed is high, and further, the control unit performs a third arithmetic process of calculating a second guard value based on the temperature of the engine cooling water, wherein the upper limit guard process becomes a process of setting the second guard value as the value of the water temperature required engagement ratio when the calculated value of the water temperature required engagement ratio by the first arithmetic process is greater than the second guard value if the second guard value is greater than the first guard value, and the third arithmetic process is a process of calculating the engagement ratio such that the rotational speed of the cooling fan is a predetermined second upper limit rotational speed when the temperature of the engine cooling water is lower than a predetermined temperature, and the rotational speed of the cooling fan is higher than the second upper limit rotational speed when the temperature is higher than the predetermined temperature as a value of the second guard value Cooling fan device.

2. A cooling fan device that generates cooling air for a radiator by a cooling fan connected to an engine via a fan clutch, comprising a control unit that controls the engagement ratio of the fan clutch, wherein the control unit performs a first arithmetic process of calculating a water temperature required engagement ratio, which is a required value of the engagement ratio according to the cooling requirement of engine cooling water, a second arithmetic process of calculating, based on the vehicle speed, the engagement ratio at which the rotational speed of the cooling fan becomes a first upper limit rotational speed as a value of a first guard value, an upper limit guard process of setting the first guard value as the value of the water temperature required engagement ratio when the calculated value of the water temperature required engagement ratio by the first arithmetic process is greater than the first guard value, It implements to control the engagement ratio based on the value of the water temperature required engagement ratio after the application of the upper limit guard process. The first upper limit rotation speed is set to a lower speed when the vehicle speed is low than when the vehicle speed is high. The control unit is a cooling fan device that controls the engagement ratio based on the calculated value of the water temperature required engagement ratio in the first arithmetic process to which the upper limit guard process is not applied during high-load running of the vehicle.

3. The cooling fan device according to claim 2, wherein the high-load running is defined as the case where the ratio of the intake air amount of the engine to the vehicle speed exceeds a predetermined value.

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