GB2142445A - A cooling-fan driving control system for a vehicle - Google Patents

Abstract

A control system has means for detecting the temperature of engine cooling water, at least one means for detecting the operating condition speed, acceleration, load of said engine, means for comparing a detected signal (T) from said water-temperature sensing means with a predetermined high level reference signal (TH) and with a predetermined low level reference signal (TL); means for comparing a detected signal from said operating condition detecting means with a predetermined parameter reference signal; and control circuit means generating a signal for driving said cooling fan when T > TH, blocking the generation of the driving signal when T < TL, and controlling the generation or blocking of the driving signal in response to the operating condition detected by said operational parameter sensing means when TL </= T </= TH. The driving signal may control a solenoid valve in an airline supplying a multi disc clutch connecting the fan to a drive shaft.

Description

SPECIFICATION A cooUing-fan driving control system for a vehicle This invention relates to an electronic control system for automatically controlling the stop or rotation of a cooling fan for an internal combustion engine in a vehicle.

Heretofore, as a way of automatically controlling the driving of a cooling fan in order to maintain cooling water at an optimized temperature and to reduce an amount of fuel consumption and wear of an engine cylinder, there have been provided, for example, a mechanical system using a viscous coupling means which utilizes changes in viscosity responsive to changes in temperature, a wax-sealed coupling means which utilizes changes in volume at the melting point of wax and the like, or an electric system using an electro-magnetic clutch. However, the mechanical system, the former, can not be satisfactory in responsiveness and adaptability to the control for rotation of the cooling fan and, on the other hand, the electric system, the latter, has a disadvantage that its shock is large at its ON or OFF operation.

In order to overcome the above disadvantages, the present invention has for its object to provide a cooling-fan control system in which a multi-disk clutch is used to drive the cooling fan and the clutch can be controlled by performing electronic logic operation in response to given operating parameters.

Another object of the present invention is to provide a cooling-fan control system for a vehicle which is capable of maintaining cooling water at an optimized temperature and stopping the rotation of the cooling fan to obtain the higher output efficiency of the engine and reduce the noise and vibration thereof within the predetermined permissible extent of temperature of the cooling water when the engine is accelerated or operated at a specific speed.

Accordingly, there is provided a control system for driving a cooling fan for an internal combustion engine in a vehicle, said system comprising water-temperature sensing means for detecting the temperature of cooling water; at least one operational parameter sensing means for detecting the operating condition of said engine; first water-temperature comparator means for comparing a detected signal (T) from said water-temperature sensing means with a predetermined high level reference signal (TH); second water-temperature comparator means for comparing said detected signal (T) from said water-temperature sensing means with a predetermined low level reference signal (T); parameter comparator means for comparing a detected signal from said operational parameter sensing means with a predetermined parameter reference signal; control circuit means for combining the output signals from said first and second water-temperature comparator means and said parameter comparator means, and generating a signal for driving said cooling fan when T > TH, blocking the generation of the driving signal when T ( TL, and controlling the generation or block of the driving signal in response to the operating condition detected by said operational parameter sensing means when TL T TH; and driving means for rotating said cooling fan in response to the driving signal output from said control circuit means.

According to the present invention, there is provided a cooling-fan control system for an internal combustion engine in a vehicle, in which the cooling fan is suitably driven to maintain cooling water at an optimized temperature to save energy consumption, and the cooling fan also is controlled within the permissible extent of temperature (TL - T ' TH) by setting reference values on the rotation, acceleration and load of the engine on the basis of data which have been acquired by way of experiment or experience, thereby obtaining the higher output efficiency of the engine and preventing the noise and vibration of the engine.

Also according to the present invention, there is provided a cooling-fan control system for an internal combustion engine in a vehicle, in which a multi-disk clutch is used to drive the cooling fan, whereby it is expected to reduce a shock at the ON or OFF operation of the clutch, minimize the area of the disk in the clutch and smooth the ON or OFF operation in comparison with a conventional electromagnetic clutch.

The invention will be described by way of example and with reference to accompanying drawings in which: Figure 1 shows a schematic diagram illustrating one preferred embodiment of the control system of the present invention; Figure 2 shows an electric block diagram of the controller as shown in Figure 1; Figures 3through 8 show logic circuit diagrams illustrating the embodiments of the logic circuit as shown in Figure 2; and Figure 9 shows the electric block diagram of an alarm system which may be incorporated in the control system of the present invention.

In a cooling-fan control system of the present invention schematically shown in Figure 1, the operating conditions of a vehicle are detected by three sensors, that is, a water-temperature sensor 1 of cooling water, an engine rotation sensor 2 and an engine load sensor 3, and each of the detected signal is inputted to a controller 4 in which these signals are preferably combined and processed as described hereinafter. The controller 4 generates a valve driving signal to energize a valve solenoid Sunder a predetermined condition.

By the energization of the valve solenoid 5, the compressed air in an air tank 6 is fed to the operating cylinder 9 of a multi-disk clutch 8 mounted on an engine body 7 so that the multi-disk clutch is in a coupling condition to rotate a cooling fan 10. The reference numeral 11 denotes a crank pulley and 12 denotes a V-shaped belt.

In Figure 2 showing a block circuit illustrating a concrete construction of the controller 4 in Figure 1, a detected signal T outputted from the water-temperature sensor 1 is applied to both the second input of a first water-temperature comparator 20-1 and the first input of a second water-temperature comparator 20-2. The first water-temperature comparator 20-1 receives a high level reference signal TH at the first input thereof and, when T > TH, generates a logic signal "1". The second water-temperature comparator 20-2 receives a low level reference signal TL at the second input thereof and generates a logic signal "0" when T < TL. A detected signal N outputted from the rotation sensor 2 is applied through a pulse voltage converter 21 to both the second input of a first rotation comparator 22-1 and the first input of a second rotation comparator 22-2.The first rotation comparator 22-1 receives a high level reference signal NH at its first input and outputs a logic signal "0" when N > NH. The second rotation comparator 22-2 receives a low level reference signal NL at its second input and generates a logic signal "0" when N < NL. Appropriately, the reference signals NH and NL are predetermined with a view to prevent noise and vibration. Also, the detected signal N from the pulse voltage converter 21 is inputted to a differentiator 23 which acts as an acceleration sensor and then an acceleration signal A outputted from the sensor is applied to the second input of an acceleration comparator 24. The acceleration comparator 24 receives an acceleration reference signal Ao at its first input and generates a logic signal "0" when A # Ao.A detected signal L outputted from a load sensor3 is applied to the second input of a load comparator 25 which receives a load reference signal LO at its first input and generates a logic signal "0" when L # LO- All output signals from the water-temperature comparators 20-1 and 20-2, the rotation comparators 22-1 and 22-2, the acceleration comparator 24 and the load comparator 25 are applied to a logic circuit 26 which, by means of the execution of logical operation as described below, produces a valve driving signal to energize the valve solenoid 5 (Figure 1) on the basis of a predetermined condition which is required to drive the cooling fan. The valve driving signal outputted from the logic circuit 26 is applied through an amplifier 27 to the valve solenoid 5.

Basically, the logic circuit 26 is constructed to execute the logical operation in accorance with the detected signal from the water-temperature sensor 1. Namely, the control system of the present invention is constructed so that, with respect to the detected signal T from the water-temperature sensor, the cooling fan can be always rotated at T > TH and stopped at T < TL, and can be rotated or stopped within the permissible driving extent of the cooling fan, i.e., TL T TH in consideration of the output efficiency of the engine.

Accordingly, it should be noted that, although the water-temperature sensor 1, the rotation sensor 2, the load sensor 3 and the differentiator 23 for the detection of acceleration are shown in Figures 1 and 2, the water-temperature sensor 1 is the only element indispensable to the system and the remaining sensors may be provided in combination ofthewater-temperature sensor, if desired.

Figures 3 through 8 show the preferred embodiments, respectively, of the logic circuit 26 in Figure 2, which are formed by the combination of the water-temperature sensor 1 and the other sensors. The input lines al, a2, b1, b2, c and dofthe logic circuit 26 shown in Figure 2 correspond to the logical input terminals al, a2, ,b1, b2, c, and d, respectively, shown in Figures 3 to 8.

Figure 3 shows one of the preferred embodiments of the logic circuit 26 in Figure 2 in case of the combination of the water-temperature sensor 1 and the rotation sensor 2. As previously described, when the detected signal T from the water-temperature sensor 1 is in T > TH, the input terminal al represents the logic level "1 " and the output of an OR gate 30 goes to the logic level "1". The input terminal a2 also represents the logic level "1" and the output of an AND gate 31 goes to the logic level "1". This means the generation of the valve driving signal and thus the multidisk clutch 10 (Figure 1) is in an ON or coupling condition to rotate the cooling fan.Then, when T < TL, the input terminal a2 represents the logic level "0" and then the output of the AND gate 31 goes to the logic level "0" so that the multi-disk clutch is in an OFF condition to stop the operation of the cooling fan. Further, since the input terminals a1 and a2 represent the logic levels "0" and "1 ", respectively, when TL # T # TH, the output condition of the AND gate 31 is determined by the output level of the OR gate 30 or the detected signal N from the rotation sensor 2. As described above, when N > NH, the input terminals b1 and b2 are in the logic levels "0" and "1", respectively, and the output of an NAND gate 32 becomes the logic level "1" and the output of the AND gate 31 therefore becomes the logic level "1" to switch the multi-disk clutch 10 to the ON condition. Then, when N < NL, the input terminals b1 and b2 are in the logic level "1" and "0", respectively, and the output of the NAND gate 32 becomes the logic level "1", Accordingly, the output of the AND gate 31 goes to the logic level "1" to switch the multi-disk clutch 10 to the OFF condition. Finally, when NL # N '= NH, the input terminal b1 is in the logic level "1" and the input terminal b2 is in the logic level "1" and then the output of the NAND gate 32 is in the logic level "0". Thus, the output of the AND gate 31 becomes the logic level "0" to switch the clutch 10 to the OFF condition. The table I classifies the logical control, as described above, with respect to the ON and OFF conditions of the multi-disk clutch.

TABLE I Temperature T Rotation N Multi-Disk Clutch T > TH ON N > NH ON TH#T#TL NH#N#NL ON NNL OFF T < TL OFF Figure 4 shows one of the preferred embodiments of the logic circuit 26 in case of the combination of the water-temperature sensor 1 and the differentiator 23 for detecting the acceleration of engine and the relation of the logical control is as shown in the table II.In particular, this logic circuit is contructed so that, when the temperature T of the cooling water is in TL # T # TH, the multi-disk clutch 10 is switched to the OFF condition when the relation between an actual detected acceleration A and the reference acceleration Ao is A - Ao or the higher output of engine is required and, on the other hand, the clutch is switched to the ON condition when A < Ao.

TABLE II Temperature T Acceleration A Multi-Disk Clutch T > TH ON A'Ao OFF TH#T#TL Also ON T < T1 - OFF Figure 5 shows one of the preferred embodiments of the logic circuit 26 in case of the combination of the water-temperature 1, the rotation sensor 2 and the differentiator 23 for detecting the acceleration of engine, and the relation of the logical control is as shown in the table III. In this embodiment, it is noted that the circuit is constructed so that, when TL # T # TH and N1 ' N c NH, the multi-disk clutch 10 is switched to the OFF condition when A #Ao and the clutch is switched to the ON condition when A # Ao.

TABLE III Temperature T Rotation N Acceleration A Multi-Disk Clutch T > TH - - ON N gt: NH - ON A#Ao OFF TH#T#TL NH#N#NL A < Ao ON NNL - ON T < Th - - OFF Figure 6 is similar to Figure 5 and shows another embodiment of the logic circuit 26 in case of the combination of the water-temperature sensor 1, the rotation sensor 2 and the differentiator 23. The difference between Figures 5 and 6 is caused by, for example, the kind of vehicles to which the control system of the present invention may be applied. As shown in the table IV, the multi-disk clutch is switched to the OFF condition when TL # T ~ TH and NL # N = NH.When TL # T # TH and N > NH, the multi-disk clutch is switched to the OFF condition where A # Ao and switched to the ON condition when A < Ao. On the other hand, when TL # T # TH and N < NL, the clutch is switched to the OFF condition when A # Ao and switched to the ON condition when A < Ao.

TABLE IV Temperature T Rotation N Acceleration A Multi-Disk Clutch T > TH - - ON A#Ao OFF N > NH A < Ao ON TH#T#TL NH#N#NL - OFF A#Ao OFF N < NL A < Ao ON T < TL - - OFF Figure 7 shows one of the preferred embodiments of the logic circuit 26 in case of the combination of the water-temperature sensor 1 and the load sensor 3. As shown in the table V, the multi-disk clutch is in the OFF condition when TL =C T # TH and L - L0 and is in the ON condition when TL # T # TH and L < Lo.

TABLE V Temperature T Load L Multi-Disk Clutch T > TH ON L#Lo OFF TH#T#TL L < LO N T < TL OFF Figure 8 shows one of the preferred embodiments of the logic circuit 26 in case of the combination of the water-temperature sensor 1, the rotation sensor 2 (, provided that the associated rotation comparator 22-2 which receives the predetermined low level reference signal is used) and the load sensor 3. As shown in the table VI, when TL # T # TH and N N# NL the multi-disk clutch is in the ON condition. When TL # T # TH and N < NL, the clutch is switched to the OFF condition when L # Lo and is switched to the ON condition when L < Lo.

TABLE VI Temperature T Rotation N Load L Multi-Disk Clutch T > TH - - ON N#NL - ON TH#T#TL L#Lo OFF N < NL L < LO ON T < Th - - OFF With respect to the preferred embodiments as shown in Figures 3 through 8, it has been explained that the presence of the output signal from the logic circuit 26 is to be used as the valve driving signal. Alternatively, the absence of the output signal from the circuit 26 also may be used to signal the energization of the solenoid valve thereto and this modification can be easily effected by those skilled in the art.

Figure 9 shows an alarm system which can be added to the control system as previously explained. A first sensor 90 for detecting the disconnection of the water-temperature sensor, a second sensor 91 for detecting the disconnection of the rotation sensor, a third sensor 92 for detecting the disconnection of the valve solenoid and a fourth sensor 93 for detecting the overheat of the engine are connected to the respective inputs of an OR gate 94, and the output of the OR gate 94 is connected through an amplifier 95 to an alarm buzzer 96. The engine-overheat sensor 93 also is connected through an amplifier 97 to an alarm lamp 98.

Accordingly, if the fault of the disconnected condition is detected by any one of the four sensors 90,91, 92 and 93, the alarm buzzer 96 is energized to sound the alarm. Additionally, if the overheat condition is detected by the engine-overheat sensor 93, the alarm buzzer 96 is operated as described above and, at the same time, the alarm lamp 98 is turned-on.

Claims (8)

1. A control system for driving a cooling fan for an internal combustion engine in a vehicle, said system comprising: water-temperature sensing means for detecting the temperature of cooling water; at least one operational parameter sensing means for detecting the operating condition of said engine; first water-temperature comparator means for comparing a detected signal (T) from said watertemperature sensing means with a predetermined high level reference signal (TH); second water-temperature comparator means for comparing said detected signal (T) from said water-temperature sensing means with a predetermined low level reference signal (T,);; parameter comparator means for comparing a detected signal from said operational parameter sensing means with a predetermined parameter reference signal; control circuit means for combining the output signals from said first and second water-temperature comparator means and said parameter comparator means, and generating a signal for driving said cooling fan when T > TH, blocking the generation of the driving signal when T < T" and controlling the generation or blocking of the driving signal in response to the operating condition detected by said operational parameter sensing means when TL ' T ' TH; and driving means for rotating said cooling fan in response to the driving signal output from said control circuit means.

2. The system as set forth in Claim 1 characterized in that said operational parameter sensing means is an engine rotation sensor and said parameter comparator means comprises a first rotation comparator for comparing a detected signal (N) from the rotation sensor with a predetermined high level reference signal (NH) and a second rotation comparator for comparing the detected signal from the rotation sensor with a predetermined low level reference signal (ill.

3. The system as set forth in Claim 1 characterized in that said operational parameter sensing means is an engine acceleration sensor and said parameter comparator means is an acceleration comparator for comparing an output signal (A) from the acceleration sensor with a predetermined acceleration reference signal (Ao).

4. The system as set forth in Claim 1 characterized in that said operational parameter sensing means comprises an engine rotation sensor and an engine acceleration sensor, and said parameter comparator means comprises a first rqtation comparator for comparing a detected signal from the rotation sensor with a predetermined high level reference signal, a second rotation comparator for comparing the detected signal from the rotation sensor with a predetermined low level reference signal and an acceleration comparatorfor comparing an output signal from the acceleration sensor with a predetermined acceleration reference signal.

5. The system as set forth in Claim 1 characterized in that said operational parameter sensing means is an engine load sensor and said parameter comparator means is a load sensor for comparing a detected signal (L) from the load sensor with a predetermined load reference signal (leo)

6. The system as set forth in Claim 1 characterized in that said operational parameter sensing means comprises an engine rotation sensor and an engine load sensor, and said parameter comparator means comprises a rotation comparator for comparing a detected signal from the rotation sensor with a predetermined low level reference signal and a load comparator for comparing a detected signal from the load sensor with a predetermined load reference signal.

7. The system as set forth in any one of Claims 1 through 6 characterized in that said driving means for rotating the cooling fan includes a multi-disk clutch which is controlled by compressed air.

8. The system substantially as hereinbefore described with reference to the accompanying drawing.