JP2006097575A - Control device for cooling fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To drive a fan at a speed in middle between the maximum value and the minimum value at a time of failure of a regulator control system. <P>SOLUTION: A fan motor 12 as a drive source of a cooling fan 11 is driven by a variable displacement type hydraulic pump 13, speed of the fan motor 12 is controlled by adjusting displacement of the hydraulic pump 13 with a regulator 14. A controller 19, an electromagnetic proportional type first pressure setting valve 18 varying setting voltage according to command current from the controller, and a second pressure setting valve 22 outputting pressure setting speed of the fan motor at a middle speed between the maximum volume and the minimum value are provided as a means controlling the regulator 14. When irregularity of control of the regulator 14 by the controller 19 occurs, the regulator 14 is operated based on setting pressure of the second pressure setting valve 22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for a cooling fan driven by a hydraulic motor to cool a heat exchanger such as a radiator or an oil cooler.

  In construction machines such as hydraulic excavators, the cooling fan is driven by a hydraulic motor (fan motor), and the capacity of the hydraulic pump that is the hydraulic source of the fan motor is adjusted to change the pump pressure or discharge flow rate, and the motor rotates. It is configured to control the number.

  The prior art will be described by taking a pressure control system for controlling the pump pressure as an example.

  In FIG. 4, reference numeral 1 denotes a cooling fan for cooling a heat exchanger such as a radiator or an oil cooler, 2 denotes a fan motor for driving the cooling fan 1, and 3 denotes a variable capacity hydraulic pump as a hydraulic source for the fan motor 2. The regulator 4 adjusts the capacity (tilt) of the hydraulic pump 3 to control the pump pressure.

That is, if the fan drive torque (motor torque) is T and the fan rotation speed is N,
T = C × N × N (C is a coefficient)
It becomes.

Also,
T = motor capacity × pressure × a (a is mechanical efficiency)
Since the torque T is proportional to the pressure when the motor capacity is constant, the motor rotation speed (fan rotation speed) N can be arbitrarily controlled by adjusting the pump pressure with the regulator 4.

  The regulator 4 includes a displacement control valve 5 configured as a hydraulic pilot valve that is operated by a pilot pressure applied to both pilot ports 5a and 5b, a first piston 6 that is operated by a pressure output from the displacement control valve 5, It is comprised by the 2nd piston 7 which exhibits the thrust according to pump pressure as a force which opposes the 1st piston 6. FIG.

  In the displacement control valve 5, a pump pressure is applied to one pilot port (pump port) 5a and a control pressure is applied to the other pilot port (control port) 5b as a pilot pressure. The pressure (called capacity control pressure) Po applied to the piston 6 changes.

  As a result, the pump capacity changes and the pump pressure is controlled.

  Here, as means for changing the control pressure Po, conventionally, a pressure setting valve 8, which is an electromagnetic proportional relief valve, is connected between the control port 5 b of the capacity control valve 5 and the tank T, and a command from the controller 9. The configuration is such that the set pressure of the pressure setting valve 8 is changed by the current to change the capacity control pressure Po output from the capacity control valve 5 (see Patent Document 1).

  The controller 9 receives a signal from a temperature sensor 10 that detects the temperature of the object to be cooled (for example, the engine coolant temperature), and performs control to increase the motor speed when the detected temperature increases.

  Specifically, as the detected temperature increases, the command current value from the controller 9 to the pressure setting valve 8 decreases, and when the command current value decreases, the set pressure of the pressure setting valve 8 increases and the pump pressure increases. The relationship between the command current value and the pump pressure is shown in FIG.

When the pump pressure increases, the motor rotation speed (fan rotation speed) increases, and as a result, the relationship between the temperature of the object and the fan rotation speed is as shown in FIG.
JP 2001-20869 A

  However, according to the conventional configuration, the command current is sent from the controller 9 to the pressure setting valve 8 due to the failure of the controller 9, the disconnection of the signal line connecting the controller 9 and the pressure setting valve 8, the detection abnormality of the temperature sensor 10, or the like. When an abnormality occurs in the regulator control system that the pump is not sent, the set pressure of the pressure setting valve 8 is minimized based on the characteristics shown in FIG. 5, the pump pressure is maximized, and the motor rotation speed is maximized.

  In this case, since the cooling fan 1 rotates at a higher speed than necessary, energy is wasted and the fan noise is increased.

  It should be noted that it is possible to set the reverse characteristics when the abnormality occurs in the regulator control system as described above, that is, the pump pressure is minimized and the motor rotation speed is minimized.

  However, if this is done, the cooling effect will be lost and the engine will overheat, which will hinder the work itself.

  Further, when a method of controlling the pump discharge flow rate instead of the pump pressure is taken, the same problem occurs because the pump discharge flow rate becomes maximum when an abnormality occurs.

  Therefore, the present invention provides a control device for a fan-driven pump that can operate a cooling fan at a rotation speed intermediate between a maximum value and a minimum value when an abnormality occurs in a regulator control system.

  The invention according to claim 1 is a fan motor as a driving source of a cooling fan, a variable displacement hydraulic pump that drives the fan motor, a regulator that adjusts the capacity of the hydraulic pump, and a regulator for operating the regulator A pressure setting valve for setting the pressure; and a controller. The controller controls the set pressure of the pressure setting valve, adjusts the capacity of the hydraulic pump by operating the regulator based on the set pressure, and controls the fan motor. In the cooling fan control device for controlling the rotation speed of the fan, as the pressure setting valve, an electromagnetic proportional first pressure setting valve whose setting pressure changes based on a command current from the controller, and the rotation speed of the fan motor A second pressure setting valve that applies to the regulator a pressure at an intermediate rotational speed that is between the maximum and minimum values. Only, only when abnormality occurs in which the command current from the controller to the first pressure setting valve stops, the second pressure setting valve is obtained by configured to connect to the regulator.

  According to a second aspect of the present invention, in the configuration of the first aspect, the pump pressure is controlled by adjusting the capacity of the pump by a regulator, and the pump pressure is adjusted based on the set pressure of the second pressure setting valve when an abnormality occurs. The number is controlled so as to be an intermediate rotational speed.

  According to a third aspect of the present invention, in the configuration of the first aspect, the pump discharge flow rate is controlled by adjusting the pump capacity by a regulator, and the pump discharge flow rate is determined based on the set pressure of the second pressure setting valve when an abnormality occurs. The fan rotational speed is controlled to a value that becomes the intermediate rotational speed.

  According to a fourth aspect of the present invention, in the configuration of any one of the first to third aspects, a solenoid valve is connected between the second pressure setting valve and the regulator, and the solenoid valve is operated only when an abnormality occurs to The setting valve is configured to be connected to the regulator.

  According to a fifth aspect of the present invention, in the configuration of the fourth aspect, an abnormality detection means for detecting the occurrence of abnormality is provided, and when the abnormality occurrence is detected by the abnormality detection means, the electromagnetic valve is operated by a signal from the controller. It is composed.

  According to the present invention, when an abnormality of the regulator control system occurs, the set pressure of the second pressure setting valve is applied to the regulator, and based on this, the pump pressure (Claim 2) or the pump discharge flow rate (Claim 3) Is controlled.

  Here, since the set pressure of the second pressure setting valve is a value at which the fan motor speed is an intermediate speed between the maximum value and the minimum value, the fan motor is operated at the intermediate speed when an abnormality occurs. The

  For this reason, it is possible to prevent adverse effects such as waste of energy and generation of noise as compared with the conventional case where the motor rotation speed becomes maximum.

  In this case, the set pressure of the second pressure setting valve, that is, the motor rotation speed (the intermediate rotation speed) determined thereby is set as a value that secures the cooling capacity necessary for the standard operation of the machine. For example, in the case of a hydraulic excavator, in the case of a machine having a fan rotation speed of 900 rpm and a maximum rotation speed of 1500 rpm in idling operation, the fan rotation speed is set to about 1100 rpm to 1300 rpm when an abnormality occurs.

  Therefore, a cooling function necessary for work can be ensured even when an abnormality occurs.

  On the other hand, the occurrence of an abnormality in the regulator control system may be configured to switch the controller output by operating a manual switch or the like when the operator can recognize the abnormality. Thus, an abnormality detecting means and a solenoid valve are provided, and when the abnormality occurs, the solenoid valve is operated to function the second pressure setting valve.

  In this way, it is possible to reliably achieve the intended purpose of setting the fan rotation speed to the intermediate rotation speed when an abnormality occurs.

  An embodiment of the present invention will be described with reference to FIGS.

1st Embodiment (refer FIG. 1)
In the first embodiment, a pressure control system is employed in which the pump pressure is changed to control the motor rotation speed.

  The basic configuration and the basic principle of pump control in the first embodiment are the same as those of the conventional apparatus shown in FIG.

  That is, in FIG. 1, 11 is a cooling fan, 12 is a fan motor that drives the cooling fan 11, 13 is a variable displacement hydraulic pump as a hydraulic source of the fan motor 12, and the regulator 14 has a capacity of the hydraulic pump 13. Adjust the (tilt) to control the pump pressure and control the motor speed (fan speed).

  The regulator 14 includes a displacement control valve 15 configured as a hydraulic pilot valve that is operated by a pilot pressure applied to both pilot ports 15a and 15b, a first piston 16 that is operated by a pressure output from the displacement control valve 15, It is comprised by the 2nd piston 17 which exhibits the thrust according to pump pressure as a force which opposes the 1st piston 16.

  In the displacement control valve 15, a pump pressure is applied to one pilot port (pump port) 15a and a control pressure is applied to the other pilot port (control port) 15b as a pilot pressure. The capacity control pressure Po sent to the piston 16 changes.

  As a result, the pump capacity changes and the pump pressure is controlled.

  A first pressure setting valve 18, which is an electromagnetic proportional relief valve corresponding to the pressure setting valve 8 in FIG. 4, is connected between the control port 15 b of the capacity control valve 15 and the tank T. The set pressure of the first pressure setting valve 18 is changed by the command current, and the capacity control pressure Po output from the capacity control valve 15 is changed.

  A signal from a temperature sensor 20 that detects the temperature of the object to be cooled (for example, the engine coolant temperature) is input to the controller 19, and control according to the detected temperature based on the characteristics shown in FIG. 6, that is, the detected temperature increases. Control is performed in which the command current value to the first pressure setting valve 18 is decreased to increase the set pressure of the pressure setting valve 18, thereby increasing the pump pressure and increasing the motor rotation speed (fan rotation speed).

  In addition, the controller 19 is provided with an abnormality detection unit 21 as abnormality detection means, such as failure of the controller 19, disconnection of the signal line connecting the controller 19 and the first pressure setting valve 18, detection abnormality of the temperature sensor 20, etc. The abnormality detection unit 21 detects the occurrence of abnormality in the regulator control system.

  For example, the abnormality detection unit 21 can be configured to monitor a command current value sent from the controller 19 to the first pressure setting valve 18 and to determine that an abnormality has occurred when the value becomes equal to or less than a set value.

  On the other hand, in this embodiment, as a pressure setting valve for changing the capacity control pressure Pp, a second pressure setting valve 22 different from the first pressure setting valve 18 is in parallel with the first pressure setting valve 18 in the capacity. The control port 15 b of the control valve 15 is connected via an electromagnetic valve 23.

  The solenoid valve 23 is normally set to the closed position A on the upper side of the figure by a signal from the controller 19, and is switched to the open position B when an abnormality occurs.

  Accordingly, at the normal time, the second pressure setting valve 22 is disconnected from the control port 15b, and the setting pressure of the first pressure setting valve 18 is applied to the control port 15b, and the setting pressure of the second pressure setting valve 22 is changed only when an abnormality occurs. Added to the control port 15b.

  As a result, the capacity control valve 15 outputs a capacity control pressure Po corresponding to the set pressure of the second pressure setting valve 22 to the first piston 16 when an abnormality occurs, and the pump capacity is adjusted based on this to control the pump pressure (fan Motor rotation speed) is controlled.

  Here, the set pressure of the second pressure setting valve 22 is a value at which the rotation speed of the fan motor is an intermediate rotation speed that is intermediate between the maximum value and the minimum value, and is required for the standard operation of the machine. It is set as a value that realizes the motor rotation speed (fan rotation speed) for obtaining the capability.

  In this way, when the abnormality occurs, the fan motor speed is set to the intermediate speed, so that the harmful effects of wasted energy and noise are prevented compared to the conventional case where the fan motor speed reaches the maximum value. can do.

  In addition, the fan motor speed at this time is set to a value that ensures the cooling capacity required for the standard operation of the machine, so that the cooling function necessary to continue the operation even when an abnormality occurs is provided. Can be secured.

  In addition, since the control when the abnormality occurs is automatically performed by the abnormality detection unit 21, the controller 19, and the solenoid valve 23, the intended purpose of setting the fan motor rotational speed to the intermediate rotational speed when the abnormality occurs is provided. Can be reliably achieved.

Second embodiment (see FIGS. 2 and 3)
The second embodiment adopts a pressure control system that controls the motor rotation speed by changing the pump discharge flow rate.

  In FIG. 2, the same parts as those in FIG.

  The regulator 24 for adjusting the pump capacity includes a capacity control valve 25 having a spool valve structure, a first piston 26 for applying a thrust according to a pressure given from the outside to the spool of the capacity control valve 25, a pump pressure and a capacity control valve. 25, and the displacement (tilt) of the pump 13 is adjusted by the movement of the second piston 27, whereby the pump discharge flow rate is adjusted. Be controlled.

  Therefore, the pump capacity (pump discharge flow rate) can be controlled by changing the external pressure applied to the first piston 26, and the motor rotation speed can be controlled.

  As a pressure setting valve for applying an external pressure to the first piston 26, a first pressure setting valve 28, which is an electromagnetic proportional pressure reducing valve, is provided. During normal times, the set pressure of the first pressure setting valve 28 is supplied from the temperature sensor 30. The pump discharge flow rate changes according to the command current from the controller 29 based on the temperature signal.

  FIG. 3 shows the relationship between the command current and the pump discharge flow rate. As shown in the figure, the pump discharge flow rate (motor rotation speed) decreases in proportion to the increase in the command current value.

  As in the first embodiment, the controller 29 is provided with an abnormality detection unit 31 that detects the occurrence of abnormality in the regulator control system, and the command current sent from the controller 29 to the first pressure setting valve 28 when the abnormality occurs becomes zero.

  Therefore, since the pump discharge flow rate becomes maximum at this rate, as a means for avoiding this, the second pressure setting valve 32 and the electromagnetic corresponding to the series circuit of the second pressure setting valve 22 and the electromagnetic valve 23 of the first embodiment are used. A series circuit of the valve 33 is connected in parallel with the first pressure setting valve 28 between the first piston 26 and the tank T.

  Similar to the solenoid valve 23 of the first embodiment, the solenoid valve 33 is switched from the closed position A to the open position B based on a signal from the controller 29 when an abnormality occurs, and the second pressure setting valve 32 is switched to the first piston. 26.

  As in the case of the first embodiment, the set pressure of the second pressure setting valve 32 is a value at which the rotational speed of the fan motor is an intermediate rotational speed that is intermediate between the maximum value and the minimum value, and It is set as a value that realizes the motor rotation speed (fan rotation speed) to obtain the cooling capacity required for standard work.

  In FIG. 2, 34 is a pilot hydraulic pressure source that serves as a primary pressure source for the first pressure setting valve 28.

  Even in the configuration of the second embodiment, similarly to the first embodiment, when the abnormality occurs, the motor rotation speed is an intermediate value between the maximum value and the minimum value, and a value that can ensure a cooling function necessary for standard work. It can be automatically set to prevent harmful effects such as wasted energy and generation of noise.

  By the way, the occurrence of an abnormality in the regulator control system is normally not recognized by the operator. Therefore, it is desirable that the abnormality detection units 21 and 31 automatically detect the occurrence of the abnormality as in both the above embodiments. If it is in an environment to obtain, the controller output may be switched by operating a manual switch or the like.

  Further, the second pressure setting valves 22 and 32 in both embodiments may be variable in pressure so that the set pressure can be manually adjusted arbitrarily.

It is a figure which shows the structure of the control apparatus concerning 1st Embodiment of this invention. It is a figure which shows the structure of the control apparatus concerning 2nd Embodiment of this invention. It is a figure which shows the relationship between the command electric current value with respect to the 1st pressure setting valve in the same apparatus, and a pump discharge flow rate. It is a figure which shows the structure of the conventional apparatus. It is a figure which shows the relationship between the command electric current value with respect to the pressure setting valve in the same apparatus, and pump pressure. It is a figure which shows the relationship between the temperature of the cooling target in this apparatus, and fan rotation speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Cooling fan 12 Fan motor 13 Hydraulic pump 14 Regulator 15 Capacity | capacitance control valve which comprises a regulator 16 Same 1st piston 17 Same 2nd piston 18 1st pressure setting valve 19 Controller 20 Temperature sensor 21 Abnormality detection part (abnormality detection means)
DESCRIPTION OF SYMBOLS 22 2nd pressure setting valve 23 Solenoid valve 24 Regulator 25 Capacity | capacitance control valve which comprises a regulator 26 Same 1st piston 27 2nd piston 28 1st pressure setting valve 29 Controller 30 Temperature sensor 31 Abnormality detection part (abnormality detection means)
32 Second pressure setting valve 33 Solenoid valve

Claims (5)

  A fan motor as a driving source of the cooling fan, a variable displacement hydraulic pump that drives the fan motor, a regulator that adjusts the capacity of the hydraulic pump, and a pressure setting valve that sets a pressure for operating the regulator And a controller for controlling the set pressure of the pressure setting valve by the controller, adjusting the capacity of the hydraulic pump by operating the regulator based on the set pressure, and controlling the rotational speed of the fan motor In the fan control device, as the pressure setting valve, an electromagnetic proportional first pressure setting valve whose setting pressure changes based on a command current from the controller, and the rotation speed of the fan motor has a maximum value and a minimum value. A second pressure setting valve for applying a pressure at an intermediate rotational speed to the regulator, La only when abnormality occurs in which the command current to the first pressure setting valve is stopped, the cooling fan controller, characterized in that the second pressure setting valve is configured to be connected to the regulator.   2. The cooling fan control device according to claim 1, wherein the pump pressure is controlled by adjusting a pump capacity by a regulator, and the pump pressure is determined based on a set pressure of the second pressure setting valve when an abnormality occurs. A control device for a cooling fan, wherein the control device is configured to control to a value at an intermediate rotational speed.   2. The cooling fan control device according to claim 1, wherein the pump discharge flow rate is controlled by adjusting the pump capacity by a regulator, and the pump discharge flow rate is determined based on the set pressure of the second pressure setting valve when an abnormality occurs. A control device for a cooling fan, wherein the number is controlled to a value that becomes an intermediate rotational speed.   4. The cooling fan control device according to claim 1, wherein a solenoid valve is connected between the second pressure setting valve and the regulator, and the solenoid valve is operated only when an abnormality occurs, so that the second A control device for a cooling fan, wherein the pressure setting valve is connected to a regulator.   5. The cooling fan control device according to claim 4, wherein abnormality detection means for detecting occurrence of abnormality is provided, and the electromagnetic valve is operated by a signal from the controller when occurrence of abnormality is detected by the abnormality detection means. The cooling fan control device according to claim 4.

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