JP2010185307A - Control device for hydraulically driven cooling fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent the overheated condition of a cooled object while improving fuel economy. <P>SOLUTION: This control device for a hydraulically driven cooling fan includes a cooling fan 4, a hydraulic pump 2 to be driven by an engine 1, a hydraulic motor 3 to be driven by pressure oil discharged from the hydraulic pump 1 to rotate the cooling fan 4, temperature detecting means 11-13 for detecting the temperatures of the cooled objects, a revolving speed detecting means 14 for detecting an engine revolving speed Ne, a target fan rotating speed computing means 10 for computing a target fan rotating speed Nf in accordance with temperature detected values detected by the temperature detecting means 11-13, an upper limit value computing means 10 for computing an upper limit value Ns for the target fan rotating speed in accordance with the revolving speed detected value Ne detected by the revolving speed detecting means 14, and fan rotating speed control means 2a, 10 for controlling the fan rotating speed to be the target fan rotating speed Nf while using the upper limit value Ns for restricting the upper limit of the target fan rotating speed. As a difference ΔT between an upper limit temperature representing the overheated condition of the cooled object and the temperature detected value is greater, the upper limit value Ns is set smaller. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for a hydraulically driven cooling fan provided in a work vehicle such as a wheel loader.

  Conventionally, there has been known a device in which pressure oil from a variable hydraulic pump driven by an engine is guided to a hydraulic motor, and a cooling fan is rotated by driving the hydraulic motor to blow cooling air to a radiator or an oil cooler. (For example, refer to Patent Document 1). The device described in Patent Document 1 has such characteristics that the target fan speed increases as the engine coolant temperature and hydraulic oil temperature increase, and the target fan speed increases as the engine speed increases. The target fan speed set in advance and obtained from the former characteristic is limited by the latter characteristic.

JP 2007-127036 A

  However, if the target fan speed is uniformly limited by the latter characteristic, a necessary and sufficient fan speed cannot be obtained, for example, when an operation that increases the heat generation amount is performed in a region where the engine speed is low. In some cases, engine cooling water and hydraulic oil may be overheated.

  A cooling fan that blows cooling air for cooling a cooling target, a hydraulic pump driven by an engine, a hydraulic motor that is driven by pressure oil discharged from the hydraulic pump and rotates the cooling fan, and a cooling target Temperature detection means for detecting the temperature of the engine, rotation speed detection means for detecting the engine rotation speed, target fan rotation speed calculation means for calculating the target fan rotation speed based on the temperature detection value detected by the temperature detection means, Based on the rotation speed detection value detected by the rotation speed detection means, upper limit value calculation means for calculating the upper limit value of the target fan rotation speed calculated by the target fan rotation speed calculation means, and the upper limit value of the target fan rotation speed The fan speed is controlled to the target fan speed calculated by the target fan speed calculating means while being limited by the upper limit value calculated by the calculating means. An upper limit value calculating means, the upper limit value calculating means, the larger the difference between the preset upper limit temperature indicating the overheating state of the object to be cooled and the temperature detected value detected by the temperature detecting means, the higher the upper limit value. It is characterized by making small.

  According to the present invention, as the difference between the upper limit temperature representing the overheated state of the object to be cooled and the temperature detection value is larger, the upper limit value of the target fan speed is made smaller, so that the object to be cooled becomes overheated. Can be prevented.

The figure which shows schematic structure of the control apparatus of the hydraulic drive cooling fan which concerns on the 1st Embodiment of this invention. The side view of the wheel loader by which the control apparatus of FIG. 1 is mounted. The block diagram which shows an example of the process in the controller of FIG. The figure which shows the characteristic in the limit value calculating part 32 of FIG. The figure which shows the principal part structure of the control apparatus of the hydraulic drive cooling fan which concerns on the 2nd Embodiment of this invention. The figure which shows the modification of FIG. The figure which shows the 1st modification of FIG. The figure which shows the 2nd modification of FIG. The figure which shows the 3rd modification of FIG.

-First embodiment-
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram illustrating a schematic configuration of a control device for a hydraulically driven cooling fan according to a first embodiment. This control device is mounted on, for example, a wheel loader as shown in FIG. As shown in FIG. 2, the wheel loader 100 includes a front vehicle body 110 having an arm 111, a bucket 112, a tire 113, and the like, and a rear vehicle body 120 having an operator cab 121, an engine compartment 122, a tire 123, and the like. The arm 111 rotates up and down (up and down) by driving the arm cylinder 114, and the bucket 112 rotates up and down (dump or cloud) by driving the bucket cylinder 115. The front vehicle body 110 and the rear vehicle body 120 are rotatably connected to each other by a center pin 101, and the front vehicle body 110 is refracted left and right with respect to the rear vehicle body 120 by expansion and contraction of a steering cylinder (not shown).

  The control device shown in FIG. 1 is rotated by a variable displacement hydraulic pump 2 driven by an engine 1, a fixed displacement hydraulic motor 3 driven by pressure oil discharged from the hydraulic pump 2, and the hydraulic motor 3. The cooling fan 4, the radiator 5 that exchanges heat between the cooling air blown by the cooling fan 4 and the engine cooling water for engine cooling, the cooling air blown by the cooling fan 4, and the hydraulic oil for driving the pump and the motor An oil cooler 6 that exchanges heat with the oil, an oil cooler 7 that exchanges heat between the cooling air blown by the cooling fan 4 and the lubricating oil for transmission, the engine cooling water temperature Ta, the hydraulic oil temperature Tb, and lubrication. From the temperature sensors 11 to 13 for detecting the oil temperature Tc, the rotational speed sensor 14 for detecting the engine rotational speed Ne, and the sensors 11 to 14, respectively. It outputs a control signal to the pump regulator 2a, based on the detection value, and a controller 10 for controlling the pump displacement (pump tilting angle).

  When the pump capacity is increased by a signal from the controller 10, the pump discharge amount increases, the rotational speed of the hydraulic motor 3 increases, and the rotational speed of the cooling fan 4 increases. Thus, there is a predetermined correlation between the pump capacity and the fan speed, and in this embodiment, the fan speed is controlled by controlling the pump capacity.

  FIG. 3 is a block diagram for explaining processing in the controller 10 according to the first embodiment. The target fan rotational speed calculation unit 21 calculates a target fan rotational speed Nfa corresponding to the engine coolant temperature Ta detected by the temperature sensor 11 based on a predetermined characteristic f21. According to the characteristic fa, the target fan speed Nfa increases as the engine coolant temperature Ta increases.

  The target fan speed calculation unit 22 calculates a target fan speed Nfb corresponding to the hydraulic oil temperature Tb detected by the temperature sensor 12 based on a predetermined characteristic f22. According to the characteristic f22, the higher the hydraulic oil temperature Tb, the higher the target fan speed Nfb.

  The target fan rotational speed calculation unit 23 calculates a target fan rotational speed Nfc corresponding to the lubricating oil temperature Tc detected by the temperature sensor 13 based on a predetermined characteristic f23. According to the characteristic f23, the higher the lubricating oil temperature Tc, the higher the target fan speed Nfc. In the characteristics f21 to f23, the upper limits of the target fan rotation speeds Nfa to Nfc are limited to, for example, a predetermined value Ns1 (FIG. 4) described later.

  The maximum value selection unit 24 selects the maximum value among the target fan rotation speeds Nfa, Nfb, and Nfc calculated by the target fan rotation speed calculation units 21 to 23, and uses this as the target fan rotation speed Nf, and the minimum value selection unit 25 To enter.

  The subtracting unit 27 subtracts the detected value Ta of the engine cooling water temperature from a predetermined upper limit temperature Ta1 representing an overheated state of the engine cooling water to obtain a difference ΔTa (= Ta1-Ta) of the engine cooling water temperature. The subtracting unit 28 subtracts the detected value Tb of the hydraulic oil temperature from a predetermined upper limit temperature Tb1 representing the overheated state of the hydraulic oil, and obtains the hydraulic oil temperature difference ΔTb (= Tb1−Tb). The subtracting unit 29 subtracts the detected value Tc of the lubricating oil temperature from a predetermined upper limit temperature Tc1 representing the overheated state of the lubricating oil to obtain a lubricating oil temperature difference ΔTc (= Tc1−Tc). In addition, upper limit temperature Ta1, Tb1, Tc1 showing the overheating state of each cooling target object is a temperature in an overheating state, for example.

  The minimum value selection unit 30 selects the minimum value from these temperature differences ΔTa, ΔTb, ΔTc, and inputs this to the table selection unit 31 as the minimum temperature difference ΔT. The table selection unit 31 selects a table corresponding to ΔT based on a predetermined illustrated characteristic f31. That is, when ΔT is less than a predetermined value ΔT1 (eg, 6 ° C.), the table III is selected, when ΔT is equal to or greater than the predetermined value ΔT1 and less than the predetermined value ΔT2 (eg, 10 ° C.), the table II is selected. Select table I.

  In each table I to III, characteristics f321 to f323 representing the relationship between the engine speed Ne and the upper limit value (revolution upper limit value) Ns of the target fan speed are stored in advance. FIG. 4 is a diagram showing these characteristics f321 to f333. A characteristic f320 in the figure is a reference characteristic representing the maximum rotational speed of the cooling fan 4, and the maximum rotational speed increases proportionally with an increase in the engine rotational speed Ne. This reference characteristic f320 is determined by the capacity of the hydraulic pump 2, the gear ratio of the drive shaft for driving the pump, the capacity of the hydraulic motor 3, the gear ratio of the connecting shaft of the hydraulic motor 3 and the cooling fan 4, and the like.

  The characteristic f323 is a characteristic in which the upper limit of the reference characteristic f320 is limited to the predetermined value Ns1. That is, until the engine speed upper limit Ns reaches the predetermined value Ns1, the engine speed upper limit Ns increases along the reference characteristic f320 as the engine speed Ne increases, and when the engine speed upper limit Ns reaches the predetermined value Ns1. Even if the engine speed Ne increases, the engine speed upper limit Ns is maintained at the predetermined value Ns1. The predetermined value Ns1 is the maximum number of revolutions that can be obtained in an actual working state or traveling state, and is determined by the specifications of the cooling fan driving hydraulic device, the cooling capacity, or the like.

  The characteristic f322 is a characteristic in which the rotation speed upper limit value Ns is smaller than the characteristic f323, and the characteristic f321 is a characteristic in which the rotation speed upper limit value Ns is further smaller than the characteristic f322. In other words, the limit amount of the fan speed is the largest in the characteristic f321 and the smallest in the characteristic f323. Also in the characteristics f321 and f322, until the rotational speed upper limit value Ns reaches the predetermined value Ns1, the rotational speed upper limit value Ns increases as the engine rotational speed Ne increases, and when the rotational speed upper limit value Ns reaches the predetermined value Ns1. Even if the engine speed Ne increases, the engine speed upper limit Ns is maintained at the predetermined value Ns1. In the characteristics f321 and f322, the rate of increase of the rotational speed upper limit value Ns is small in the region where the engine rotational speed Ne is low, and the rate of increase of the rotational speed upper limit value Ns is large in the region where the engine rotational speed Ne is high. However, the increase pattern of the rotation speed upper limit Ns is not limited to this.

  In the limit value calculation unit 32 of FIG. 3, the cooling fan according to the engine speed Ne detected by the speed sensor 14 based on any of the characteristics f321 to f333 of the tables I to III selected by the table selection unit 31. 4 is calculated. The minimum value selection unit 25 selects the minimum value of the target fan rotational speed Nf and the rotational speed upper limit Ns selected by the maximum value selection unit 24, and sets this as the target fan rotational speed Nf. That is, the upper limit of the target fan rotation speed Nf is limited by the rotation speed upper limit value Ns.

  The current calculation unit 26 calculates a target tilt angle of the hydraulic pump 2 for setting the fan rotation speed to the target fan rotation speed Ne from the engine rotation speed Ne detected by the rotation speed sensor 14 and the target fan rotation speed Na. To do. Further, a control current for setting the pump tilt angle to the target tilt angle is calculated and output to the regulator 2a. As a result, the pump tilt angle becomes the target tilt angle, and the fan speed is controlled to the target fan speed Nf.

  The main operation of the first embodiment will be described. If engine cooling water temperature Ta, hydraulic oil temperature Tb, and lubricating oil temperature Tc are all low and differences ΔTa, ΔTb, ΔTc from upper limit temperatures Ta1, Tb1, Tc1 are all greater than a predetermined value ΔT2, table selection unit 31 sets the upper limit of rotation speed. A value characteristic f321 is selected. Accordingly, the fan speed limit amount is particularly large (the limit value Ns is small) in a region where the engine speed Ne is low, the pump discharge amount is suppressed, and fuel consumption can be improved. In this case, since the temperature difference ΔTa to ΔTc between the temperature Ta to Tc and the upper limit temperature Ta1 to Tc1 of the engine coolant, hydraulic oil, and lubricating oil to be cooled is large, for example, the engine coolant temperature Even if Ta becomes high, the upper limit temperature Ta1 is not immediately exceeded and there is no problem.

  On the other hand, when the engine heating speed Ne is low, an operation for increasing the heat generation amount of the engine 1 is performed. For example, when the engine cooling water temperature Ta rises and the temperature difference ΔTa becomes smaller than the predetermined value ΔT1, the table selection unit 31 rotates. The number f upper limit characteristic f323 is selected. Therefore, the limit amount of the fan speed is small (the limit value Ns is large), and the fan speed is the target fan speed Nfa determined by the characteristic f21 in FIG. As a result, sufficient cooling performance of the engine cooling water can be secured, and the engine cooling water temperature Ta can be suppressed to the upper limit temperature Ta1 or lower.

According to 1st Embodiment, there can exist the following effects.
(1) A plurality of tables I to III representing the relationship between the engine rotational speed Ne and the rotational speed upper limit value Ns are set, and an upper limit temperature Ta1 representing an overheated state of the object to be cooled (engine cooling water, hydraulic oil, lubricating oil) The rotation speed upper limit Ns is decreased as the difference ΔTa to ΔTc between the temperature detection values Ta to Tc of the object to be cooled and Tc1 increases. As a result, even when an operation in which the heat generation amount is increased in a region where the engine speed is low, a necessary and sufficient fan speed is obtained, and overheating of the engine 1 can be reliably prevented. Fan speed does not increase more than necessary, and fuel consumption can be improved.
(2) Since the minimum value is selected from the temperature differences ΔTa to ΔTc of the plurality of cooling objects and the rotation speed upper limit value Ns is calculated based on the characteristics corresponding to the minimum difference ΔT, all the cooling The object can be prevented from being overheated.

-Second Embodiment-
A second embodiment of the present invention will be described with reference to FIGS.
The second embodiment differs from the first embodiment in the processing in the controller 10. That is, in the first embodiment, a characteristic corresponding to the temperature difference ΔT is selected from the plurality of tables I to III, and the rotation speed upper limit value Ns is set based on this characteristic. In the second embodiment, The reference value of the rotational speed upper limit value Ns is corrected according to the temperature difference ΔT to set the rotational speed upper limit value Ns. In the following description, differences from the first embodiment will be mainly described.

  FIG. 5 is a block diagram for explaining an example of processing in the controller 10 according to the second embodiment. In addition, the same code | symbol is attached | subjected to the location which performs the same process as FIG. The corrected rotation speed calculation unit 40 calculates a corrected rotation speed ΔNa corresponding to the temperature difference ΔTa (= Ta1-Ta) of the engine coolant temperature Ta based on a predetermined characteristic f40. According to the characteristic f40, the higher the temperature difference ΔTa, the lower the correction rotation speed ΔNa.

  The corrected rotation speed calculation unit 41 calculates a corrected rotation speed ΔNb corresponding to the temperature difference ΔTb (= Tb1−Tb) of the hydraulic oil temperature Tb based on a predetermined characteristic f41. According to the characteristic f41, the higher the temperature difference ΔTb, the lower the corrected rotation speed ΔNb.

  The corrected rotation speed calculator 42 calculates a corrected rotation speed ΔNc corresponding to the temperature difference ΔTc (= Tc1−Tc) of the lubricating oil temperature Tc based on a predetermined characteristic f42. According to the characteristic f42, the higher the temperature difference ΔTc, the lower the corrected rotation speed ΔNc.

  The maximum value selection unit 43 selects the maximum value among the correction rotation speeds ΔNa, ΔNb, ΔNc calculated by the correction rotation speed calculation sections 41 to 43 and inputs this to the addition section 45 as the correction rotation speed ΔN.

  The limit value calculation unit 44 calculates a rotation speed upper limit value Ns0 corresponding to the engine rotation speed Ne based on a reference characteristic f44 representing a relationship between a predetermined engine rotation speed Ne and a rotation speed upper limit value Ns0. The characteristic f44 is the same as the characteristic f321 in FIG. 4, and the fan rotational speed is limited to be larger than the maximum rotational speed particularly in a region where the engine rotational speed is low.

  The adder 45 adds the corrected rotation speed ΔN selected by the maximum value selector 43 to the rotation speed upper limit Ns0 calculated by the limit value calculator 44. That is, the rotation speed upper limit value Ns0 is corrected with the correction rotation speed ΔN, and this is input to the minimum value selection unit 25 as the correction rotation speed Ns.

  The main operation of the second embodiment will be described. For example, when the engine coolant temperature Ta is low, the difference ΔTa from the upper limit temperature Ta1 increases, and the correction rotational speed ΔNa decreases. Therefore, when the correction rotation speed ΔNa is selected by the maximum value selection unit 43, the increment of the rotation speed upper limit value Ns from the reference rotation speed Ns0 is small, and the target fan rotation speed Nf is largely limited.

  On the other hand, an operation for increasing the heat generation amount of the engine 1 is performed in a region where the engine rotational speed Ne is low. For example, when the engine cooling water temperature Ta rises and the temperature difference ΔTa decreases, the corrected rotational speed ΔNa increases. Accordingly, when the correction rotation speed ΔNa is selected by the maximum value selection unit 43, the increment of the rotation speed upper limit value Ns from the reference rotation speed Ns0 is increased, and the limit amount of the target fan rotation speed Nf is decreased. As a result, sufficient cooling performance of the engine cooling water can be secured, and the engine cooling water temperature Ta can be suppressed to the upper limit temperature Ta1 or lower.

According to 2nd Embodiment, there can exist the following effects.
(1) A reference characteristic representing the relationship between the engine speed Ne and the upper limit value Ns0 of the fan speed is set in advance, and the correction speed ΔN to be added to the reference characteristic is increased as the temperature difference ΔT is smaller. Therefore, even when an operation that increases the heat generation amount is performed in a region where the engine speed is low, a necessary and sufficient fan speed can be obtained, and overheating of the engine 1 can be reliably prevented. Fan speed does not increase more than necessary, and fuel consumption can be improved.
(2) Since the correction rotation speeds ΔNa to ΔNc are respectively obtained for the temperature differences ΔTa to ΔTc of a plurality of cooling objects, the maximum value is selected from among them, and the reference characteristics are corrected. Things can be kept from overheating.

  FIG. 6 is a diagram illustrating a modification of the second embodiment. In FIG. 5, the maximum value ΔN of the corrected rotational speed is added to the rotational speed upper limit value Ns0. However, in FIG. 6, the ratio calculator 46 obtains the ratio α of the corrected rotational speed to the engine rotational speed Ne, and this ratio The multiplication unit 43 multiplies the maximum value ΔN of the corrected rotational speed and adds it to the rotational speed upper limit value Ns0. The ratio α is small in the region where the engine speed Ne is low as indicated by the characteristic f46 of the ratio calculation unit 46, and is large in the region where the engine speed Ne is large. The shape of the characteristic f46 is not limited to this.

  In the above embodiment, the fan speed is controlled to the target fan speed Nf while controlling the pump capacity to limit the upper limit of the fan speed to the speed upper limit value Ns. The configuration of the control means is not limited to this. For example, as shown in FIG. 7, the hydraulic motor 3 may be configured as a variable displacement motor, and a control signal may be output from the controller 10 to the motor regulator 3a to control the fan speed. As shown in FIG. 8, an electromagnetic switching valve 8 may be connected to the pump discharge side pipe, and the fan rotation speed may be controlled by adjusting the switching amount of the electromagnetic switching valve 8 by a control signal from the controller 10. As shown in FIG. 9, the variable relief valve 9 may be connected to the hydraulic pump 2, and the fan pressure may be controlled by setting the relief pressure of the variable relief valve 9 by a control signal from the controller 10.

  In the above embodiment, engine cooling water, hydraulic oil, and lubricating oil have been described as objects to be cooled, but the object to be cooled is not limited to this. For example, it is good also considering the hydraulic fluid for torque converters as a cooling target. The number of objects to be cooled is not limited to three, but may be four or more, or one. When the number of cooling objects is one, the maximum value selection unit 24, the minimum value selection unit 30, and the like can be omitted. In the above embodiment, the target fan speed Nf is calculated by the target fan speed calculators 21 to 23, but the configuration of the target fan speed calculator is not limited to that described above.

  The upper limit value Ns of the target fan speed is calculated based on the detected value Ne of the engine speed, and the differences ΔTa to ΔTc between the upper limit temperatures Ta1 to Tc1 representing the overheating state of the object to be cooled and the detected temperature values Ta to Tc are large. As long as the upper limit value Ns is made smaller, the limit value calculation means may have any configuration. The temperature sensors 11 to 13 as temperature detection means and the rotation speed sensor 14 as rotation speed detection means may have any configuration.

  The example in which the present invention is applied to a wheel loader has been described above, but the present invention can be similarly applied to other work vehicles having a hydraulically driven cooling fan. That is, as long as the features and functions of the present invention can be realized, the present invention is not limited to the hydraulically driven cooling fan control device of the embodiment.

DESCRIPTION OF SYMBOLS 1 Engine 2 Hydraulic pump 2a Pump regulator 3 Hydraulic motor 3a Motor regulator 4 Cooling fan 10 Controller 11-13 Temperature sensor 14 Speed sensor 21-23 Target fan speed calculating part 31 Table selection part 32 Limit value calculating part 40-42 Correction Rotational speed calculation unit 44 Limit value calculation unit

Claims (5)

A cooling fan that blows cooling air to cool the object to be cooled;
A hydraulic pump driven by an engine;
A hydraulic motor driven by pressure oil discharged from the hydraulic pump and rotating the cooling fan;
Temperature detecting means for detecting the temperature of the cooling object;
A rotational speed detecting means for detecting the engine rotational speed;
Target fan speed calculating means for calculating a target fan speed based on the temperature detection value detected by the temperature detecting means;
Upper limit value calculating means for calculating an upper limit value of the target fan rotational speed calculated by the target fan rotational speed calculating means based on the rotational speed detected value detected by the rotational speed detecting means;
Fan speed control for controlling the fan speed to the target fan speed calculated by the target fan speed calculating means while limiting the upper limit of the target fan speed by the upper limit value calculated by the upper limit value calculating means Means and
The upper limit calculating means decreases the upper limit value as the difference between a preset upper limit temperature indicating an overheated state of the cooling object and the temperature detection value detected by the temperature detection means is larger. Control device for hydraulically driven cooling fan. The control device for a hydraulically driven cooling fan according to claim 1,
The upper limit calculating means is configured to respond to a difference between the upper limit temperature of the cooling object and the temperature detection value from among a plurality of characteristics representing a relationship between a preset engine speed and an upper limit value of the fan speed. A control device for a hydraulically driven cooling fan, wherein the upper limit value is calculated based on the selected characteristic. The control device for a hydraulically driven cooling fan according to claim 2,
There are a plurality of the cooling objects, and the upper limit calculating means selects the minimum difference from the differences between the upper limit temperature set for each cooling object and the temperature detection value of each cooling object, and this minimum A control device for a hydraulically driven cooling fan, wherein the upper limit value is calculated based on a characteristic corresponding to a difference. The control device for a hydraulically driven cooling fan according to claim 1,
The upper limit calculating means calculates a correction rotational speed corresponding to a difference between the upper limit temperature of the cooling object and the detected temperature value, and sets a relationship between a preset engine rotational speed and an upper limit value of the fan rotational speed. A control device for a hydraulically driven cooling fan, wherein the upper limit value is calculated by correcting a reference characteristic to be expressed by the corrected rotational speed. The control device for a hydraulically driven cooling fan according to claim 4,
There are a plurality of the objects to be cooled, and the upper limit calculating means calculates a correction rotation number corresponding to the difference between the upper limit temperature set for each cooling object and the temperature detection value of each cooling object, A control device for a hydraulically driven cooling fan, wherein the maximum correction rotation speed is selected from the correction rotation speeds, and the upper limit value is calculated by correcting the reference characteristic based on the maximum correction rotation speed.

Images