Patent Application
20250074178
This application claims the benefit of priority to Japanese Patent Application No. 2023-138274 filed on Aug. 28, 2023 and Japanese Patent Application No. 2024-109731 filed on Jul. 8, 2024. The entire contents of this application are hereby incorporated herein by reference.
The present invention relates to fan control systems and work machines each including a fan control system.
Work machines include a cooling fan configured to rotate to introduce outside air for cooling heat generating components such as a radiator and an engine, and also include a dust barrier configured to prevent grass and dust from entering, together with the outside air (that is, cooling air), a space containing the heat generating components. Continuing to use the dust barrier for dust prevention, however, lets dust accumulate on the dust barrier in an increasing amount. This decreases the amount of cooling air to be introduced, and thereby decreases the effect of cooling the heat generating components with use of cooling air. To address this issue, Japanese Patent Application Publication, Tokukaihei, No. 11-36862, for example, discloses a conventional harvester configured to switch the rotation direction of a cooling fan from the normal direction to the reverse direction with each elapse of a reaping work time period set on the basis of a prediction of the amount of generation of dust. This allows the cooling fan to blow air toward a dust barrier in the opposite direction to blow dust off the dust barrier for removal, and thereby allows cooling air to be introduced into a heat generating component containing space in a recovered amount.
The fan control system disclosed in Japanese Patent Application Publication, Tokukaihei, No. 11-36862 is configured to reverse the rotation direction of the cooling fan at predetermined intervals regardless of whether the dust barrier has been clogged with grass, and does not necessarily drive the cooling fan efficiently. Unnecessarily reversing the rotation direction of the cooling fan will, for instance, waste energy in switching the rotation direction of the cooling fan and decrease the durability of the mechanism for switching the rotation direction.
Example embodiments of the present invention provide fan control systems to appropriately control how a fan is driven and work machines each provided with such a fan control system.
A fan control system according to an example embodiment of the present invention includes a fan, a dust barrier at or adjacent to the fan, a fan actuator to rotate the fan in a normal direction and a reverse direction, a fan controller configured or programmed to control a manner in which the fan actuator is driven, a clogging degree calculator configured or programmed to calculate a clogging degree of the dust barrier based on drive behavior of the fan, and a reverse rotation instructor configured or programmed to instruct the fan controller based on the clogging degree to rotate the fan in the reverse direction.
The term “clogging degree” as used herein refers to the degree of clogging of, for example, air flow holes in a dust barrier. The clogging degree of 0%, for example, indicates that the dust barrier is brand-new and its air flow holes are not clogged at all. The clogging degree of 100% indicates that the dust barrier has fully clogged air flow holes. The clogging degree is not necessarily expressed in percentages. The clogging degree for example embodiments of the present invention is based on drive behavior of the fan, and is calculable, for instance, with use of an experimentally or empirically determined function involving the drive behavior as a variable. The following formula holds true:
K=G(α1,α2,α3, . . . )
where K denotes the clogging degree, G denotes a function for deriving the clogging degree, and α1, α2, α3, . . . denote respective instances of the drive behavior.
Examples of the fan behavior parameter (α1, α2, α3, . . . ) include a fan drive time, a fan rotation speed, the difference between an intended number of fan revolutions and the actual number of fan revolutions, and the range of change in the number of fan revolutions. The function is advantageously in the form of a lookup table. The clogging degree may alternatively be determined with use of a decision tree algorithm.
The fan control system calculates the clogging degree of the dust barrier on the basis of the drive behavior of the fan. The fan control system, for instance, determines that the clogging degree is high if rotating the fan for a long time is not effective at an accordingly sufficient level. If the fan control system determines that the clogging degree is high, the reverse rotation instructor transmits a reverse rotation instruction to the fan controller to rotate the fan in the reverse direction for unclogging the dust barrier. The fan control system rotates the fan in the reverse direction in response to determining that the clogging degree is high as above. This configuration prevents the fan from unnecessarily rotating in the reverse direction, and allows the fan control system to appropriately control how the fan is driven.
The fan control system should include an electric motor rather than a mechanical power transmission mechanism to easily transmit motive power to the fan for its normal and reverse rotations and switch the rotation direction between the normal and reverse directions. The fan control system may thus be further configured or programmed such that the fan actuator is a fan motor configured to receive from the fan controller a drive signal to control the manner in which the fan motor is driven.
The clogging degree of the dust barrier tends to be high if the fan has been driven at a high level for a long time and low if the fan has been driven at a low level for a short time. The fan control system may thus be further configured such that the drive behavior is based on either or both of a rotation speed of the fan and a drive time of the fan.
This configuration allows the fan control system to appropriately calculate the clogging degree with use of an easily obtainable detection parameter.
Rotating the fan in the reverse direction for an excessively short time may not unclog the dust barrier sufficiently. Rotating the fan in the reverse direction for an excessively long time may, on the other hand, lead to a disadvantage due to the lack of the effect of the fan. The fan control system should thus suitably rotate the fan in the reverse direction over, for example, a time period with an experimentally or empirically predetermined value (or one selected from among two or more such values) or a time period determined with use of the calculated clogging degree as a parameter. The fan control system may thus be further configured in a mode such that the fan rotates in the reverse direction over a predetermined time period. The fan control system may be further configured in another mode such that the fan rotates in the reverse direction over a time period variable according to the clogging degree. The fan control system may also be configured to select either of the two modes.
The fan control system may be further configured as an example embodiment such that the fan is a cooling fan to cool at least one heat generating component with use of at least one cooling medium, the fan control system further includes an internal temperature detector to detect a temperature of the at least one cooling medium or a temperature of the at least one heat generating component, and the clogging degree calculator is configured or programmed to calculate the clogging degree based on the temperature detected by the internal temperature detector and the drive behavior. This example embodiment of the present invention is a fan control system configured to control a cooling fan of a cooling system for cooling a heat generating component. The fan control system calculates the clogging degree of the dust barrier on the basis of the temperature of a cooling medium or heat generating component detected by the internal temperature detector and the drive behavior of the cooling fan. Similarly to the above, the following formula holds true for this example embodiment:
K=G(α1,α2,α3, . . . ,β1,β2,β3, . . . )
where K denotes the clogging degree; G denotes a function for deriving the clogging degree; α1, α2, α3, . . . denote respective instances of the drive behavior of the cooling fan; and β1, β2, β3, . . . denote respective instances of the temperature parameter of the heat generating component.
Examples of the temperature parameter (β1, β2, β3, . . . ) include the temperature of a cooling medium or heat generating component that the internal temperature detector has detected, the outside air temperature that the external temperature detector has detected, and the rate of increase in the temperature (that is, a temperature change over a predetermined time period) of a heat generating component (that is, a cooling target component) such as the motor and the inverter. The use of the temperature increase rate is particularly effective as the rate increases in response to the dust barrier becoming clogged. The fan control system, for instance, determines that the clogging degree is high if rotating the fan for a long time fails to cause the detected temperature of the cooling medium or heat generating component to be lower than a predetermined value. If the fan control system determines that the clogging degree is high, the reverse rotation instructor transmits a reverse rotation instruction to the fan controller to rotate the cooling fan in the reverse direction to unclog the dust barrier. The fan control system rotates the cooling fan in response to determining that the clogging degree is high as above. This configuration prevents the cooling fan from unnecessarily rotating in the reverse direction, and allows the cooling fan to be driven appropriately.
The fan control system may further include an external temperature detector to detect a temperature of outside air (that is, ambient or environmental temperature), wherein the clogging degree calculator is configured or programmed to calculate the clogging degree based on the temperature of the outside air, the temperature detected by the internal temperature detector, and the drive behavior. The fan control system calculates the clogging degree of the dust barrier on the basis of not only the temperature of a cooling medium or heat generating component detected by the internal temperature detector and the drive behavior of the cooling fan, but also the outside air temperature. This inhibits the detected temperature from deviating from the temperature of the heat generating component due to whether the outside air temperature is high or low (for example, summer or winter, or day or night). This in turn improves the accuracy of calculating the clogging degree, and allows the fan control system to more appropriately control how the cooling fan is driven.
The cooling system described above is suitably provided for a harvester as it stirs up leaves, stalks, and the like when in operation or for a work machine such as a mower as it stirs up cut grass. The cooling system for such a work machine uses cooling air, cooling water, cooling liquid, a heat pipe, or the like as a cooling medium. The cooling fan may be configured to blow cooling air toward a heat generating component or toward a cooling medium that exchanges heat with the heat generating component.
Work machines include an engine, an electric motor, a hybrid engine, or the like as a power source. An engine-based work machine includes an engine and a radiator as its main heat generating components. An electric motor-based work machine includes an electric motor, an inverter, and a battery as its main heat generating components. The fan control system may thus be further configured as an example embodiment such that the at least one heat generating component is at least one of a radiator, an engine, an electric motor, an inverter, or a battery.
The cooling system described above is particularly suitably usable for a work machine as it allows the work machine to have the above features. A work machine according to an example embodiment of the present invention thus may include a cooling fan to cool a heat generating component with use of a cooling medium, a dust barrier near the cooling fan, a fan actuator to rotate the cooling fan in a normal direction and a reverse direction, a fan controller configured or programmed to control a manner in which the fan actuator is driven, an internal temperature detector to detect a temperature of the cooling medium or a temperature of the heat generating component, a clogging degree calculator configured or programmed to calculate a clogging degree of the dust barrier based on the temperature detected by the internal temperature detector and drive behavior of the cooling fan, and a reverse rotation instructor configured or programmed to instruct the fan controller based on the clogging degree to rotate the cooling fan in the reverse direction.
The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.
The description below relates to example embodiments of the present invention with reference to drawings. Unless otherwise specified, the description below uses terms such as “upward” to refer to the side indicated with arrow U in
The description below deals with a work machine as the present example embodiment with reference to
As illustrated in
As illustrated in
As illustrated in
The hydraulic actuators such as the lifting/lowering cylinder 15, the boom cylinders 21, and the bucket cylinder 22 are operable in response to operation of the manual operation members 10.
As illustrated in
The mower deck 24 contains three rotary blades (not illustrated in the drawings) arranged laterally and each rotatable about a vertical axis to cut grass. The body 3 includes a discharge section 25 disposed to the right of the mower deck 24 and configured to discharge the cut grass to the right.
As illustrated in
As illustrated in
The continuously variable transmission device 11 varies the motive power and transmits the varied motive power through an auxiliary transmission device (not illustrated in the drawings) and a rear-wheel differential device (not shown in the drawings) in the transmission 12 to the rear wheels 2. The continuously variable transmission device 11 transmits the varied motive power also through a power transmission shaft branching from a position immediately before the rear-wheel differential device to a front-wheel differential device (not illustrated in the drawings) in the front axle case 8 and then to the front wheels 1.
The transmission 12 includes a front lower portion provided with a front power take-off (PTO) shaft 37 extending forward and a back portion provided with a back PTO shaft 38 extending backward. The front and back PTO shafts 37 and 38 each receive motive power that the continuously variable transmission device 11 did not vary among other portions of the motive power transmitted through power transmission shafts.
The front PTO shaft 37 transmits motive power through a power transmission shaft (not illustrated in the drawings) to the mower deck 24. The back PTO shaft 38 transmits motive power through a power transmission shaft (not illustrated in the drawings) to the implement attached to the lifting/lowering link mechanism 14.
The cooling fan 32 and the fan motor 33 are elements of a cooling system (which is an example of the “fan control system”) for a work machine. The cooling fan 32 and the fan motor 33 are integral with each other and are attached to the lower cover 30. The lower cover 30 has an area facing the cooling fan 32 which area is provided with a dust barrier 31 including a dust mesh. The cooling fan 32 sucks outside air through the dust barrier 31 as cooling air to be introduced into the lower cover 30 to cool the inverter 28 and the electric motor 29 as heat generating components. The dust barrier 31 is, for example, a filter. The travel battery 27 is also a heat generating component. If the work machine includes an engine, the engine and auxiliary machines for the engine such as a radiator are also heat generating components. The fan motor 33 for the present example embodiment is an example of the “fan actuator”. The cooling air for the present example embodiment is an example of the “cooling medium”. Other examples of the cooling medium include a cooling liquid and a heat pipe.
The present example embodiment includes at least one internal temperature sensor 35 and at least one external temperature sensor 36 to detect temperature. The internal temperature sensor 35 is configured to detect the temperature of an internal space of the body 3 such as a space covered by the hood 4, a space covered by the lower cover 30, and a space covered by the transmission case 13. The internal temperature sensor 35 is also configured to directly or indirectly detect the temperature of cooling air as a cooling medium or that of a heat generating component. The external temperature sensor 36 is configured to detect the external temperature (that is, ambient or environmental temperature). Specific examples of the internal temperature sensor 35 include a water temperature sensor on a flow path for a radiator, an oil temperature sensor on an oil circuit, a temperature sensor in the electric motor 29, a temperature sensor in a battery, and a temperature sensor in a space through which cooling air flows from the cooling fan 32.
The external temperature sensor 36 is configured to detect an external temperature (that is, ambient or environmental temperature). The external temperature sensor 36 may be not only a temperature sensor disposed on an outer portion of the body 3 and configured to detect an external temperature (that is, ambient or environmental temperature), but also, for example, a temperature information receiver configured to receive information on the air temperature through a weather information service of a meteorological agency or the like. Specific examples of the temperature sensor on an outer portion of the body 3 include a temperature sensor on the driver section 5 and a temperature sensor on an outer portion of the hood 4.
The control system of the cooling system includes a computer-based controller 100 as a core element. The controller 100 is configured or programmed to include as control function sections an internal temperature detector 41, an external temperature detector 42, a fan controller 51, a drive behavior parameter generator 52, a clogging degree calculator 53, and a reverse rotation instructor 54.
The internal temperature detector 41 is configured to detect (or calculate), for example, the temperature of a heat generating component (that is, either or both of the inverter 28 and the electric motor 29) on the basis of a sensor signal from the internal temperature sensor 35 as an internally detected temperature for use by other control function sections. The external temperature detector 42 is configured to detect (or calculate) the outside air temperature, for example, the ambient temperature around the work machine, on the basis of a sensor signal from the external temperature sensor 36 as an externally detected temperature for use by other control function sections.
The fan controller 51 is configured or programmed to transmit a drive signal to the fan motor 33 (“fan actuator”) to rotate the cooling fan 32 in the normal and reverse directions. The drive behavior parameter generator 52 is configured or programmed to receive fan control information from the fan controller 51, obtain either or both of the rotation speed and drive time of the cooling fan 32 on the basis of the fan control information, and perform necessary operations on either or both into a fan behavior parameter indicative of the drive behavior of the cooling fan 32.
The clogging degree calculator 53 is configured or programmed to generate a temperature parameter on the basis of the internally detected temperature and the externally detected temperature. The temperature parameter, for example, results from normalizing the internally detected temperature with the externally detected temperature. The clogging degree calculator 53 may alternatively be configured or programmed to generate a temperature parameter with use of the internally detected temperature alone. The clogging degree calculator 53 is also configured or programmed to calculate the clogging degree of the dust barrier 31 on the basis of the temperature parameter and the fan behavior parameter, which the drive behavior parameter generator 52 has generated, with use of an operation expression or lookup table prepared in advance to determine the clogging degree from a temperature parameter and a fan behavior parameter. The controller 100 may store two or more such operation expressions or lookup tables to select from in accordance with the work status.
The reverse rotation instructor 54 is configured or programmed to, if the clogging degree of the dust barrier 31 (which the clogging degree calculator 53 has calculated) exceeds a threshold, transmit a reverse rotation instruction to the fan controller 51 to rotate the cooling fan 32 in the reverse direction for blowing grain culms, grass, and plant roots off the dust barrier 31. The fan controller 51, in response to receiving a reverse rotation instruction, generates a control signal for reverse rotation and transmits the control signal to the fan motor 33 to rotate the cooling fan 32 in the reverse direction.
The cooling fan 32 may rotate in the reverse direction over a predetermined time period or a time period variable according to the clogging degree. The cooling fan 32 may, for example, rotate in the reverse direction over a predetermined time period if the clogging degree is low and over a time period longer than the predetermined time period if the clogging degree is high. The cooling fan 32 may alternatively rotate in the reverse direction at a speed higher in a continuous or stepwise manner with a higher clogging degree.
The description below deals with an example of how the cooling system described above controls a cooling fan, with reference to the flowchart in
The cooling system starts the cooling fan control with an initial setting step (#01) to set, for example, a threshold for the clogging degree as a condition for the reverse rotation of the cooling fan 32 and a reverse rotation time period for the cooling fan 32. Next, a control manager in the controller 100 transmits a normal rotation instruction to the fan controller 51, which in response transmits a control signal for normal rotation of the cooling fan 32 to the fan motor 33 (#02). This causes the cooling fan 32 to start rotating in the normal direction (#03).
Next, the cooling system generates parameters of temperature and drive behavior that are necessary to calculate the clogging degree of the dust barrier 31. To generate a temperature parameter, the clogging degree calculator 53 receives information on the internally detected temperature from the internal temperature detector 41 (#11) and information on the externally detected temperature from the external temperature detector 42 (#12). The clogging degree calculator 53 generates from the internally detected temperature and the externally detected temperature a temperature parameter for use to determine whether to rotate the cooling fan 32 in the reverse direction (#13). The clogging degree calculator 53 may alternatively omit receiving information on the externally detected temperature to generate a temperature parameter from the internally detected temperature alone. The drive behavior parameter generator 52 obtains the drive behavior generated (#21), and generates from the drive behavior a fan behavior parameter indicative of the drive behavior of the cooling fan 32 (#22).
The clogging degree calculator 53 calculates the clogging degree of the dust barrier 31 with use of the temperature parameter and the fan behavior parameter (#31). The cooling system compares the clogging degree with the initially set threshold (#32) If the clogging degree is not higher than the threshold (No in #32), the control process returns to steps #11 and #21 to repeat the parameter generation.
If the clogging degree is higher than the threshold (Yes in #32), the reverse rotation instructor 54 transmits a reverse rotation instruction to the fan controller 51 (#41). The fan controller 51, in response, transmits a control signal for reverse rotation of the cooling fan 32 to the fan motor 33 to rotate the cooling fan 32 in the reverse direction (#42).
The cooling system then checks how long the cooling fan 32 has been rotating in the reverse direction (#43). If the reverse rotation time period is shorter than a predetermined time period (No in #43), the cooling system lets the fan motor 33 continue to rotate in the reverse direction. If the reverse rotation time period is not shorter than the predetermined time period (Yes in #43), the controller 100 transmits a normal rotation instruction to the fan controller 51 (#51) to rotate the fan motor 33 in the normal direction and thereby rotate the cooling fan 32 in the normal direction again (#52). The control process then returns to steps #11 and #21 to repeat the parameter generation.
The flowchart of
The example embodiments described above relate to fan control systems of the present invention as cooling systems for work machines. Example embodiments of the present invention are, however, also applicable to a cooling system for a vehicle other than a work machine or for a stationary machine. The fan control systems according to example embodiments of the present invention are also applicable to heating systems including fans and air circulating or air cleaning system including a fan.
(1) The fan actuator for the example embodiments described above is a fan motor 33 drivable by the fan controller 51 such that the cooling fan 32 rotates under electric control. The fan actuator may alternatively be a mechanism configured to mechanically switch the rotation direction such as a belt-based power transmission mechanism or a gear-based power transmission mechanism.
(2) The work machine for the example embodiments described above is an electric vehicle including an electric motor 29 as a travel driving source. The work machine may alternatively be a conventional vehicle including an internal combustion engine as a travel driving source or a hybrid vehicle including both an electric motor 29 and an internal combustion engine as travel driving sources. If the engine is of an air-cooling type, the cooling fan 32 directly cools the engine with use of cooling air (which is an example of the “cooling medium”). If the engine is of a liquid-cooling type, the cooling fan 32 cools (i) a radiator configured to circulate cooling liquid (which is an example of the “cooling medium”) through the engine and (ii) the cooling liquid.
(3) If the cooling fan 32 is incapable of bringing cooling air into direct contact with a heat generating component, the cooling fan 32 may alternatively be configured to bring cooling air into contact with a heat pipe (which is an example of the “cooling medium”) connected to the heat generating component.
(4) The clogging degree calculator 53 for the example embodiments described above is configured to calculate the clogging degree of the dust barrier 31 on the basis of (i) a temperature parameter generated from the internally detected temperature and the externally detected temperature that the clogging degree calculator 53 has received and (ii) a fan behavior parameter the drive behavior parameter generator 52 has generated from drive behavior. The clogging degree calculator 53, in other words, calculates the clogging degree K with use of the following relational expression (an example of which is a lookup table).
K=G(α1,α2,α3, . . . ,β1,β2,β3, . . . )
Examples of the fan behavior parameter (α1, α2, α3, . . . ) include a fan drive time, a fan rotation speed, the difference between an intended number of fan revolutions and the actual number of fan revolutions, and the range of change in the number of fan revolutions. Examples of the temperature parameter (β1, β2, β3, . . . ) include the temperature of a cooling medium or heat generating component that the internal temperature detector 41 has detected, the outside air temperature that the external temperature detector 42 has detected, and the rate of increase in the temperature (that is, a temperature change over a predetermined time period) of a heat generating component (that is, a cooling target component) such as the electric motor 29 and the inverter 28. The clogging degree calculator 53 may alternatively calculate the clogging degree K on the basis of the fan behavior parameter alone.
(5) The clogging degree calculator 53 may alternatively be configured to estimate the clogging degree K through recognition of an image of the dust barrier 31. The clogging degree calculator 53 may calculate the clogging degree on the basis of, for example, the result of recognizing grass on a filter portion of the dust barrier 31 in an image captured of the filter portion. Example embodiments of the present invention may use, as a camera for that use, an existing camera for detecting an obstacle or a dedicated camera. Example embodiments of the present invention may combine the result of calculating the clogging degree through image recognition as above with the result of calculating the clogging degree on the basis of the fan behavior parameter and the temperature parameter.
The arrangements disclosed for the above example embodiments (including the alternative example embodiments; hereinafter the same applies) may each be combined with an arrangement disclosed for another example embodiment, as long as such a combination does not cause a contradiction. Further, the example embodiments disclosed in the present specification are mere examples. The present invention is not limited to those example embodiments, and may be altered as appropriate, as long as such an alteration does not result in a failure to attain an object of the present invention.
Example embodiments of the present invention are applicable to any of various fan control systems for controlling a fan operable in collaboration with a dust barrier and to any apparatus and equipment including such a fan control system.
While example embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-138274 | Aug 2023 | JP | national |
| 2024-109731 | Jul 2024 | JP | national |
