JP4312681B2 - Construction machine cooling system - Google Patents

Description

  The present invention relates to a cooling device for a construction machine such as a hydraulic excavator, and more particularly to a cooling device for a construction machine that reduces the influence on the engine by a hydraulic motor for rotating an engine cooling fan when starting the engine. It is.

  Conventionally, in construction machines such as hydraulic excavators, as a method of cooling the engine, a cooling fan is rotated in one direction by a hydraulic motor that is rotated by the power of the engine, and the wind generated by the rotation of the cooling fan is blown to the engine or radiator. There is known a structure in which cooling is performed (see, for example, 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, refer to Patent Document 2).
JP-A-11-158917. JP-A-10-68142.

  However, in Patent Document 1 and Patent Document 2, including the conventional construction machine cooling apparatus in which the cooling fan is rotated by the hydraulic motor, the hydraulic motor that drives the cooling fan starts normal rotation simultaneously with the start of the engine. Has been done. For this reason, the rotation of the hydraulic motor becomes a heavy load when the engine is started, and there is a problem that startability is poor.

  Thus, there is a technical problem to be solved in order to improve the engine startability by reducing the influence on the engine by the hydraulic motor for rotating the engine cooling fan when the engine is started. Aims to solve this problem.

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 is rotationally driven as a drive source, and a cooling fan that rotates integrally with a rotary shaft of the hydraulic motor and generates wind for cooling the engine;
Motor speed control means for controlling the rotational speed of the hydraulic motor by adjusting the amount of the hydraulic oil flowing in the hydraulic motor, and at least the start of the engine at the start of the engine A cooling device for a construction machine comprising: control means for controlling speed control means to fix the rotation of the hydraulic motor below a set speed including rotation stop of the hydraulic motor;
The motor speed control means for controlling the rotational speed of the hydraulic motor, control of said control means for initiating an on the key switch, outputs a signal to the solenoid of the motor speed control valves, solenoid hydraulic pressure received the signal The motor and the cooling fan are configured to control the motor speed control valve so that the rotation of the motor and the cooling fan becomes the lowest speed including stop,
There is provided a cooling device for a construction machine that reduces the load on the engine when the engine is started.

  According to this configuration, at the time of starting the engine, at least until the start of the engine is started, the rotation of the hydraulic motor is fixed below the set speed including the rotation stop of the hydraulic motor, and the load on the engine is reduced. The starting operation can be performed in the state that has been performed.

  According to the first aspect of the present invention, since the influence of the hydraulic motor applied as a load to the engine can be reduced when the engine is started, the startability of the engine is improved.

  The construction machine cooling apparatus according to the present invention will be described below with reference to preferred embodiments. For the purpose of improving the engine startability by reducing the influence of the hydraulic motor for rotating the engine cooling fan at the engine start, the rotation of the hydraulic motor rotated by the driving force of the engine is at least started. Until the engine is started, control means is provided to fix the speed below the set speed including the rotation stop of the hydraulic motor and reduce the load on the engine starting operation.

  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. This 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. Therefore, 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. This work mechanism operation prohibition lock means 37 is provided to temporarily prevent the operation of the work mechanism 18, and the work mechanism 18 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. Thus, the work can be performed, and when it is returned to the non-operation position again, it is switched from on to off, and the lever lock solenoid 36 is de-energized and the work is prohibited.

(Example)
FIG. 3 is a flowchart showing an embodiment of a processing operation in which the control unit 20 controls the rotation of the hydraulic motor 24 and the cooling fan 33 when the engine 21 is started. The processing operation at the time of engine start of the circuit configuration shown in FIG. 2 will be described according to the flowchart of FIG. When the key switch 28 is turned on and a current is supplied to the control unit 20, the control of the control unit 20 is started. First, the control unit 20 outputs a signal to the solenoid 32 a of the motor speed control valve 32. Upon receiving this signal, the solenoid 32a controls the motor speed control valve 32 so that the rotation of the hydraulic motor 24 and the cooling fan 33 is at the lowest speed including the stop, that is, lower than the set speed (step S1). Thereby, the motor speed control valve 32 fixes the rotation of the hydraulic motor 24 and the cooling fan 33 below the set speed (step S2).

  Subsequently, the control unit 20 performs a start operation of the engine 21 via the ECM 22 (step S3). In this starting operation, since the rotation speeds of the hydraulic motor 24 and the cooling fan 33 are fixed below the set speed, the load applied to the engine 21 is small, and the engine 21 is started smoothly with a low load. In step S4, whether or not the engine 21 has been started is monitored from a signal sent from the engine 21 to the control unit 20 via the ECM 22. When the engine 21 is started, the process proceeds to step S5, and the control unit 20 outputs a signal to the solenoid 32a. Upon receiving the signal, the solenoid 32a cancels the holding operation in which the motor speed control valve 32 has fixed the rotational speeds of the hydraulic motor 24 and the cooling fan 33 below the set speed. Thereafter, control in a normal routine is entered.

  Therefore, in this embodiment, when the key switch 28 is turned on and the engine 21 is started, the rotation of the hydraulic motor 24 is stopped at least until the start of the engine 21 is started. Since the starting operation is performed in a state where the influence of the hydraulic motor 24 and the cooling fan 33 as a load on the engine 21 is reduced, the starting operation is smoothly performed and the startability of the engine can be improved. it can.

  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 the Example of the process routine in which a control part controls rotation of a hydraulic motor at the time of engine starting by embodiment apparatus same as the above.

Explanation of symbols

19 Cooling device 20 Control part (control means)
21 Engine 23 Hydraulic pump 24 Hydraulic motor 31 Control valve 31a Solenoid 32 Motor speed control valve 32a Solenoid 33 Cooling fan

Claims (1)

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;
Motor speed control means for controlling the rotational speed of the hydraulic motor by adjusting the amount of the hydraulic oil flowing in the hydraulic motor;
Control means for controlling the motor speed control means to fix the rotation of the hydraulic motor below a set speed including the rotation stop of the hydraulic motor, at least until the start of the engine is started at the time of starting the engine;
In a cooling device for a construction machine with
The motor speed control means for controlling the rotational speed of the hydraulic motor is:
Control of said control means for initiating an on the key switch, outputs a signal to the solenoid of the motor speed control valves, such that solenoid which received the signal rotation of the hydraulic motor and the cooling fan is slowest, including a stop Configured to control the motor speed control valve,
A cooling device for a construction machine, wherein a load on the engine at the time of starting the engine is reduced.

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