JP2006057599A - Cooling system of construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reverse rotation of a cooling fan, while taking into consideration so as not to cause overheat of an engine. <P>SOLUTION: In this cooling system of a construction machine, when the temperature (t) of cooling water for cooling the engine 21 becomes the preset temperature T or more having a danger of, for example, the overheat, a control part 20 prohibits a direction change in a hydraulic fluid by a control valve 31, and a cooling fan 33 reverses so as to restrain reduction in cooling capacity to the engine 21. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cooling device for a construction machine such as a hydraulic excavator, and in particular, it is possible to switch between normal rotation and reverse rotation of a cooling fan that cools the engine, and the engine has reduced cooling capacity due to the reversal of the cooling fan. The present invention relates to a construction machine cooling apparatus that prevents overheating.

  2. Description of the Related Art Conventionally, in construction machines such as a hydraulic excavator, a structure is known in which a cooling fan is rotated in one direction by a hydraulic motor for cooling an engine and a radiator and is cooled by wind generated by the rotation of the cooling fan. (For example, refer to Patent Document 1).

Further, in the cooling structure in which the cooling fan is rotated in one direction, the direction in which the wind is sent is one direction, so dead leaves, dust, etc. are sent to the radiator or the like together with the cooling air, which may cause clogging. Therefore, a cooling structure is also known in which the rotation direction of the cooling fan can be switched between two forward and reverse directions, reverse air is generated by reversing the cooling fan, and dust clogged in the radiator or the like is sucked and discharged by the reverse air. (For example, see Patent Document 2).
Japanese Patent Laid-Open No. 11-158917. JP-A-10-68142.

  However, in the invention described in Patent Document 2, when the cooling fan is reversed, there is no wind blowing against the engine, and the cooling air volume is reduced, so that the heat dissipation of the engine and the radiator is lowered. For this reason, when the construction machine runs frequently or the working mechanism is frequently driven and the engine is in an overload state, if the cooling fan is reversely rotated for a certain period of time, the engine cooling capacity decreases. Overheating may cause damage to the engine and the like.

  Therefore, there is a technical problem to be solved in order to be able to reverse the rotation of the cooling fan while considering that the engine does not overheat, and the present invention aims to solve this problem. To do.

  The present invention has been proposed to achieve the above object, and the invention according to claim 1 is directed to an engine, a hydraulic pump rotated by the engine, and a flow of hydraulic oil supplied from the hydraulic pump. A hydraulic motor that rotates as a drive source, a cooling fan that rotates integrally with a rotary shaft of the hydraulic motor to generate wind for cooling the engine, and a direction in which the hydraulic oil flows is switched from a positive direction to a negative direction to change the hydraulic pressure. A construction machine cooling device comprising: a control valve for reversing the rotation of a motor; and a control means for prohibiting switching of the flow direction of the hydraulic oil by the control valve when the temperature of engine cooling water is higher than a set temperature. provide.

  According to this configuration, when the temperature of the cooling water for cooling the engine is equal to or higher than a set temperature at which there is a risk of overheating, for example, the control means switches the hydraulic oil flow from the positive direction to the negative direction. Is prohibited. That is, by switching the flow of hydraulic oil from the positive direction to the negative direction, the cooling fan is prohibited from reversing with the hydraulic motor, and the engine cooling capacity is prevented from being lowered due to the reversing of the cooling fan.

  According to a second aspect of the present invention, there is provided a construction machine cooling apparatus using a solenoid that operates the switching operation of the control valve in response to a signal from the control means.

  According to this configuration, when the solenoid is controlled by a signal from the control means, the solenoid operates the control valve, and the flow of hydraulic oil is switched from the positive direction to the negative direction.

  According to a third aspect of the present invention, there is provided an engine, a hydraulic pump rotated by the engine, a working mechanism driven by hydraulic oil supplied from the hydraulic pump, and a flow of hydraulic oil supplied from the hydraulic pump. A hydraulic motor that rotates as a drive source, a cooling fan that rotates integrally with a rotary shaft of the hydraulic motor to generate wind for cooling the engine, and a direction in which the hydraulic oil flows is switched from a positive direction to a negative direction to change the hydraulic pressure. A control valve for reversing the rotation of the motor; work mechanism operation prohibition lock means for locking so that the operation of the work mechanism cannot be performed; and a signal output for the work mechanism operation prohibition lock means to perform the lock, There is provided a cooling device for a construction machine, comprising control means for outputting when the oil flow direction is switched to a negative direction.

  According to this configuration, when the rotation of the cooling fan is reversed and this is expected to reduce the cooling capacity for the engine, the operation mechanism is prohibited from being operated, and a new load is applied to the engine. To prevent.

  According to a fourth aspect of the present invention, there is provided a construction machine cooling apparatus using a solenoid operated by a signal from the control means for the switching control of the work mechanism operation prohibition lock means.

  According to this configuration, when the solenoid is controlled by the signal from the control means, the solenoid operates the work mechanism operation prohibition lock means, and the work mechanism operation prohibition lock means locks the work mechanism so that it cannot be operated.

  In the invention according to claim 1, when the temperature of the engine cooling water is equal to or higher than a set temperature at which there is a danger of overheating, for example, the cooling capacity of the engine is prevented from being reduced by reversing the cooling fan. Engine overheating can be prevented.

  According to the second aspect of the present invention, when the solenoid is controlled by a signal output from the control means and the control valve is operated by the solenoid, the flow of the hydraulic oil can be switched from the positive direction to the negative direction. In addition to the effect of the present invention, it is possible to easily perform the reversal switching of the rotation in the cooling fan.

  According to the third aspect of the present invention, when the rotation of the cooling fan is reversed and the cooling capacity for the engine is expected to be reduced, the operation mechanism is prohibited from being newly operated, and a new load is applied to the engine. Can be added to prevent overheating.

  According to a fourth aspect of the present invention, when the solenoid is controlled by a signal from the control means, the solenoid operates the work mechanism operation prohibition lock means and locks the work mechanism so that the operation mechanism cannot be operated. In addition to the effect of the present invention, the operation of the work mechanism operation prohibition lock means can be easily performed.

  The construction machine cooling apparatus according to the present invention will be described below with reference to preferred embodiments. For the purpose of enabling the rotation of the cooling fan to be reversed while taking into consideration that engine overheating does not occur, the temperature of the cooling water for cooling the engine becomes, for example, higher than the set temperature at risk of overheating. When the engine is in operation, switching of the direction of the flow of hydraulic oil by the control valve is prohibited under the control of the control means, and the engine cooling capacity is prevented from being lowered by the reversing of the cooling fan.

  FIG. 1 shows a hydraulic excavator to which a construction machine cooling apparatus according to the present invention is applied. In FIG. 1, a hydraulic excavator 10 includes a lower traveling body 11 and an upper revolving body 13 that is pivotably attached to the lower traveling body 11 via a revolving mechanism 12. Further, the upper swing body 13 is provided with a cab 14 at one front side thereof, and a work mechanism 18 for excavating earth and sand and other work at the front center portion. Further, the working mechanism 18 includes a boom 15 and an arm 16 that support the bucket 17, and an actuator that includes various hydraulic cylinders, link rods, and the like that operate these.

  FIG. 2 shows a circuit configuration of a main part in the construction machine cooling apparatus according to the present invention. In FIG. 2, the cooling device 19 is mounted on the upper swing body 13 of the excavator 10. The cooling device 19 includes a control unit 20 as a control means configured by a microcomputer in which a program for controlling the entire device is incorporated, an engine 21 that is a prime mover, and an ECM that controls driving of the engine 21. (Electronic control module) 22, a hydraulic pump 23 driven by the engine 21 as a drive source, a hydraulic motor 24 that rotates using a flow of pressure oil (hydraulic oil) discharged from the hydraulic pump 23 as a drive source, and a relay 25 or the like.

  The control unit 20 includes a throttle valve 26, a fan reverse switch 27, a key switch 28 for starting the engine 21, a monitor 29, a reverse sensor 30, a solenoid 31a for the control valve 31, a solenoid 32a for the motor speed control valve 32, A solenoid 25a or the like of the relay 25 is connected.

  The hydraulic motor 24 has an output shaft 24a, and a cooling fan 33 is attached to the output shaft 24a so as to be integrally rotatable. Between the hydraulic motor 24 and the hydraulic pump 23, the control valve 31 and the motor speed control valve 32 are disposed.

  The control valve 31 can be switched between a forward rotation position A and a reverse rotation position B by operation of a solenoid 31 a driven by a signal from the control unit 20. When the control valve 31 is switched to the forward rotation position A shown in FIG. 2, the hydraulic oil discharged from the hydraulic pump 23 flows in the forward direction in the hydraulic motor 24, and the hydraulic motor 24 is moved in the forward direction. Rotate to. On the contrary, when switched to the reverse rotation position B, the hydraulic oil flows in the reverse direction in the hydraulic motor 24, and the hydraulic motor 24 rotates in the negative direction.

  The fan reverse switch 27 is a switch for inputting a signal for switching the rotation of the hydraulic motor 24 from the positive direction to the negative direction to the control unit 20 from the outside. The fan reverse switch 27 is normally held in an off state, and is a momentary switch that switches to an on state when pressed by an operator or the like and automatically returns to an off state again when the pressing force is removed. Accordingly, the fan reverse switch 27 is always in an off state when the engine 21 is restarted, so that the hydraulic motor 24 and a cooling fan 33 to be described later are always set to start in the forward direction.

  The motor speed control valve 32 adjusts the flow rate of the hydraulic oil flowing in the hydraulic motor 24 by the operation of the solenoid 32a driven by a signal from the control unit 20, and the rotational speed of the hydraulic motor 24 and the rotational speed of the cooling fan 33 are adjusted. To control.

  The throttle valve 26 adjusts the output of the engine 21 according to the signal output of the control unit 20. The monitor 29 displays the operating state of the cooling device 19 externally.

  The relay 25 constitutes a work mechanism operation prohibition lock means 37 together with the gate switch 35 and the lever lock solenoid 36. The work mechanism operation prohibition lock means 37 is for temporarily preventing the operation of the work mechanism 18, and can be freely operated when a current is applied to the lever lock solenoid 36. When the current of the lever lock solenoid 36 is cut off, the operation of the work mechanism 18 is temporarily locked so that the operation of the work mechanism 18 cannot be performed while the current is cut off. . The gate switch 35 is a switch that is linked to an operating lever (not shown) for operating the working mechanism 18 by the operator. When the operating lever is moved to the operating position, the gate switch 35 is switched from OFF to ON, and the lever lock solenoid 36 is energized. When it is returned to the non-operation position, it is switched from on to off, and the operation of the lever lock solenoid 36 is cut off and the work is prohibited.

  3 and 4 show the control operation performed by the control unit 20, and FIG. 3 shows the direction of hydraulic oil by the control valve 31, that is, the hydraulic motor 24 when the cooling water temperature t of the engine 21 becomes equal to or higher than the set temperature T. This is a fan inversion prohibiting process routine that prohibits the rotation of the motor from rotating in the reverse direction, and is executed when the key switch 28 is turned on and power for the control circuit is supplied. FIG. 4 shows that when the rotation of the cooling fan 33 is reversed together with the hydraulic motor 24 and the cooling capacity for the engine 21 is expected to be reduced, the working mechanism 18 is further operated and a new load is applied to the engine 21. In addition, this is a work mechanism operation prohibition lock processing routine that prevents the engine 21 from overheating, and is executed when the key switch 28 is turned on and power for the control circuit is supplied.

  First, the fan inversion prohibiting process routine of FIG. 3 will be described. When the key switch 28 is turned on and the control circuit power is supplied, the control of the control unit 20 is started and the system is initialized (step S1). In this initialization, in addition to the fan reverse switch 27 being turned off, automatic forward rotation control is performed under the control of the control unit 20, and the control valve 31 is initially placed at the forward rotation position A. Therefore, when the engine 21 is initially started and restarted, the hydraulic motor 24 and the cooling fan 33 always rotate in the forward direction.

  Next, when the fan reverse switch 27 is turned on (step S2) or when the automatic reversal control by the control unit 20 is enabled (step S3), the ECM 22 is removed from the cooling water temperature sensor provided in the engine 21. Then, it is determined whether or not the temperature value t of the cooling water sent to the control unit 20 is higher than the set temperature T at which there is a risk of overheating (step S4).

  Here, when the temperature value t of the cooling water is lower than the set temperature T (t <T), the control unit 20 switches the motor drive pressure to prevent surge and cavitation at the time of fan reverse switching. In order to reduce the rotational speed of the hydraulic motor 24 and the cooling fan 33 at that time, the rotational speed of the engine 21 is set to a preset minimum rotational speed NL regardless of the engine output adjustment of the throttle valve 26. , Outputs a signal to the ECM 22. At the same time, a signal is output to the solenoid 32a of the motor speed control valve 32 so that the rotational speeds of the hydraulic motor 24 and the cooling fan 33 become the lowest speed. As a result, the rotation of the engine 21 is switched to the lowest target rotation speed NL, and at the same time, the rotation speeds of the hydraulic motor 24 and the cooling fan 33 are set to the lowest speed (steps S5 and S6).

  Further, after the rotation of the engine 21 is switched to the lowest target rotation speed NL and the rotation speeds of the hydraulic motor 24 and the cooling fan 33 reach the lowest speed, the control unit 20 switches the switching signal to the solenoid 31a of the control valve 31. Is output (step S7). Upon receiving the switching signal, the solenoid 31a moves the control valve 31 from the forward rotation position A to the reverse rotation position B shown in FIG. Thereby, the direction of the hydraulic fluid discharged from the hydraulic pump 23 and flowing in the hydraulic motor 24 is switched to the opposite direction, and the rotation of the hydraulic pump 24 and the cooling fan 33 is reversed (step S8). As a result, it is possible to prevent overheating of the engine 21 during reversal and surge and cavitation of the motor driving pressure that are likely to occur in the hydraulic motor 24 during reversal switching of the hydraulic motor 24.

  On the other hand, when it is determined in step S4 that the temperature value t of the cooling water is equal to or higher than the set temperature T (t ≧ T), the control unit 20 does not output a switching signal to the solenoid 31a of the control valve 31, and the control valve 31 The switching of the direction of hydraulic fluid flowing through the hydraulic motor 24 is prohibited. As a result, the cooling fan 33 continues to rotate in the forward direction, and the cooling capacity of the engine 21 is prevented from being lowered due to the cooling fan 33 being reversed. The fact that the fan reversal prohibition mode is set is displayed on the monitor 29 (step S9).

  Further, from step S8 and step S9, the process returns to step S2 again, and the same processing is repeated.

  Therefore, in the case of the fan reversal prohibition processing routine, when the temperature t of the cooling water for cooling the engine 21 is equal to or higher than the set temperature T at which there is a risk of overheating, the control unit 20 as the control means Switching of the direction of the hydraulic oil by the control valve 31, that is, reversal of the hydraulic motor 24 that rotates together with the cooling fan 33 is prohibited, and the cooling capacity of the engine 21 is reduced due to the reversal of the cooling fan 33. Can be suppressed.

  The fan reverse switch 27 is normally formed as a momentary switch that is kept in an off state, and the cooling fan 33 is always set to start rotating in the forward direction when the engine 21 is restarted. Even when an operator who has stopped the engine 21 at the time of fan reversal and another operator restarts the engine 21, the rotation direction when the cooling fan 33 is restarted is always the normal rotation direction. I don't give it.

  Next, the work mechanism operation prohibition processing routine of FIG. 4 will be described. When the key switch 28 is turned on and the control circuit power is supplied, the control of the control unit 20 is started and the system is initialized (step S11). In this initialization, in addition to the fan reverse switch 27 being turned off, automatic forward rotation control is performed under the control of the control unit 20, and the control valve 31 is initially placed at the forward rotation position A. Therefore, when the engine 21 is initially started and restarted, the hydraulic motor 24 and the cooling fan 33 always rotate in the forward direction.

  Next, when the fan reverse switch 27 is turned on (step S12) or when the automatic reversal control by the control unit 20 is enabled (step S13), the control unit 20 determines the motor drive pressure at the time of fan reversal switching. In order to prevent surges and cavitation, the minimum speed that is set in advance is set regardless of the engine output adjustment of the throttle valve 26 in order to reduce the rotational speed of the hydraulic motor 24 and the cooling fan 33 at the time of switching. A signal is output to the ECM 22 so that the rotation speed is NL. At the same time, a signal is output to the solenoid 32a of the motor speed control valve 32 so that the rotational speeds of the hydraulic motor 24 and the cooling fan 33 become the lowest speed. As a result, the rotation of the engine 21 is switched to the lowest target rotation speed NL, and at the same time, the rotation speeds of the hydraulic motor 24 and the cooling fan 33 are set to the lowest speed (steps S14 and S15).

  Further, after the rotation of the engine 21 is switched to the lowest target rotation speed NL and the rotation speeds of the hydraulic motor 24 and the cooling fan 33 reach the lowest speed, the control unit 20 switches the switching signal to the solenoid 31a of the control valve 31. Is output (step S16). Upon receiving the switching signal, the solenoid 31a moves the control valve 31 from the normal rotation position A to the reverse position B shown in FIG. Thereby, the direction of the hydraulic oil discharged from the hydraulic pump 23 and flowing in the hydraulic motor 24 is reversed, and the rotation of the cooling fan 33 is reversed (step S17). As a result, it is possible to prevent overheating of the engine 21 at the time of reversal and surge and cavitation at the time of switching between the hydraulic motor 24 and the fan reversal.

  On the other hand, when the fan reverse switch 27 is turned on (step S12) or when the automatic reverse control by the control unit 20 is enabled (step S13), the control unit 20 outputs a switching signal to the relay 25, The movable contact 25b of the relay 25 is switched from the contact 25c side to the contact 25d side, and the current to the lever lock solenoid 36 is cut off (step S18). Thereby, when the rotation of the cooling fan 33 is reversed, the operation of the working mechanism 18 is prohibited.

  Further, from step S17 and step S18, the process returns to step S12 again, and the same processing is repeated.

  Therefore, in the case of this work mechanism operation prohibition processing routine, the operation of the work mechanism 18 is prohibited when the rotation of the cooling fan 33 is reversed and the cooling capacity for the engine 21 is expected to decrease. It is possible to prevent the engine 21 from being overheated due to a new load.

  It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

1 is an overall side view of a hydraulic excavator to which a cooling device of the present invention is applied. The principal part structure circuit diagram of the cooling device in one embodiment of this invention. The flowchart which shows an example of the fan inversion prohibition process routine in the control part of embodiment apparatus same as the above. The flowchart which shows an example of the working mechanism operation prohibition process routine in the control part of embodiment apparatus same as the above.

Explanation of symbols

18 Working mechanism 19 Cooling device 20 Control unit (control means)
21 Engine 23 Hydraulic pump 24 Hydraulic motor 25 Relay 26 Throttle valve 27 Fan reverse switch 30 Reverse sensor 31 Control valve 31a Solenoid 32 Motor speed control valve 32a Solenoid 33 Cooling fan 35 Gate switch 36 Lever lock solenoid 37 Work mechanism operation prohibition lock means

Claims (4)

Engine,
A hydraulic pump rotated by the engine;
A hydraulic motor that rotationally drives the flow of hydraulic oil supplied from the hydraulic pump as a drive source;
A cooling fan that rotates integrally with the rotating shaft of the hydraulic motor and generates wind for cooling the engine;
A control valve that reverses the rotation of the hydraulic motor by switching the direction in which the hydraulic oil flows from a positive direction to a negative direction;
Control means for prohibiting switching of the flow direction of the hydraulic oil by the control valve when the temperature of the engine cooling water is equal to or higher than a set temperature;
And a cooling device for a construction machine.   The cooling device for a construction machine according to claim 1, wherein the switching operation of the control valve is performed by using a solenoid that operates in response to a signal from the control means. Engine,
A hydraulic pump rotated by the engine;
A working mechanism driven by hydraulic oil supplied from the hydraulic pump;
A hydraulic motor that rotationally drives the flow of hydraulic oil supplied from the hydraulic pump as a drive source;
A cooling fan that rotates integrally with the rotating shaft of the hydraulic motor and generates wind for cooling the engine;
A control valve that reverses the rotation of the hydraulic motor by switching the direction in which the hydraulic oil flows from a positive direction to a negative direction;
A working mechanism operation prohibition locking means for locking so that the working mechanism cannot be operated;
Control means for outputting a signal output for the work mechanism operation prohibition lock means to perform the lock, when the flow direction of the hydraulic oil is switched to a negative direction;
And a cooling device for a construction machine.   4. The construction machine cooling apparatus according to claim 3, wherein the switching control of the work mechanism operation prohibition lock means is performed using a solenoid that operates in response to a signal from the control means.

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