JP2005240935A - Working fluid cooling device of construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase cooling efficiency of working fluid by an oil cooler. <P>SOLUTION: In an working oil cooling device, an oil cooler 9 for cooling the working oil is disposed to a return oil line 4 of a hydraulic actuator circuit 3, and a fan motor 11 is connected to be in parallel with the oil cooler 9 to drive a blower fan 10 with respect to the oil cooler 9. The fan motor 11 is constituted as a variable displacement type, a motor capacity is automatically controlled depending on an oil temperature detected by an oil temperature sensor 15 by a controller 13 and a regulator 14, in a direction reducing the capacity of the fan motor 11 when an oil temperature is increased. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hydraulic fluid cooling device that cools hydraulic fluid that operates an actuator in a construction machine such as a hydraulic excavator.

  Conventionally, as a hydraulic oil cooling device, an oil cooler is provided in a return oil line of a hydraulic actuator circuit that operates a work attachment or the like, and the hydraulic oil discharged from the actuator is cooled by the oil cooler and then returned to the tank. .

  However, this alone does not provide sufficient cooling capacity of the oil cooler, and the hydraulic oil temperature rises and may adversely affect circuit devices.

  On the other hand, as a radiator cooling device for construction machinery, a configuration is provided in which a hydraulic motor is provided in the return oil line of the actuator circuit and the radiator fan is driven by this hydraulic motor in order to reduce the portion of the engine horsepower spent for driving the radiator fan. Is known (see Patent Document 1).

Therefore, this known technology is diverted to a hydraulic oil cooling device, a hydraulic motor is provided in the return oil line of the actuator circuit, and a fan for the oil cooler is driven by this hydraulic motor to blow air to the oil cooler. It is conceivable to adopt a configuration that helps cooling.
Japanese Patent Laid-Open No. 10-184355

  However, even if air is blown to the oil cooler in this way, the cooling efficiency of the oil cooler is not sufficiently improved, and the effective oil cooling effect is particularly effective when the temperature of the oil rises due to continuous work for a long time. I can't hope.

  Accordingly, the present invention provides a hydraulic oil cooling device for construction machinery that can dramatically increase the hydraulic oil cooling efficiency.

  According to the first aspect of the present invention, there is provided an oil cooler for cooling the working oil provided in a return oil line for returning the working oil discharged from the hydraulic actuator to the tank, a cooling fan for blowing air to the oil cooler, and a state parallel to the oil cooler. And a fan motor composed of a variable displacement hydraulic motor connected to the return oil line and driving the cooling fan, and motor capacity control means for controlling the capacity of the fan motor.

  According to a second aspect of the present invention, in the configuration of the first aspect, the motor capacity control means includes an oil temperature sensor for detecting the temperature of the hydraulic oil, and when the oil temperature rises according to the temperature detected by the oil temperature sensor. The motor capacity is automatically controlled so as to reduce the capacity of the fan motor.

  According to the present invention, the cooling capacity of the oil cooler can be changed by changing the motor capacity as required.

  That is, if the capacity of the fan motor is reduced, the pressure of the motor is increased, and the flow rate of the oil cooler connected in parallel to this is increased, so that the cooling capacity of the oil cooler can be increased. Further, the cooling efficiency of the oil cooler can be further increased by increasing the rotation speed of the fan motor (fan rotation speed) and increasing the air flow rate.

  On the other hand, if the motor capacity is increased, the passage flow rate of the oil cooler can be reduced to reduce the pressure loss, and the heat generation of the oil cooler can be suppressed.

  In this case, according to the invention of claim 2, the temperature of the hydraulic oil is detected by the oil temperature sensor, and the capacity of the fan motor is reduced when the oil temperature rises according to the detected oil temperature (the capacity when the oil temperature falls). The motor capacity can be automatically controlled in the direction of increasing. For this reason, both the action of increasing the cooling capacity of the oil cooler and reducing the pressure loss are automatically and reliably performed.

  FIG. 1 shows a hydraulic actuator circuit.

  In the figure, reference numeral 1 denotes a hydraulic pump driven by an engine 2, and pressure oil from the hydraulic pump 1 is sent to a hydraulic actuator circuit 3 having a plurality of hydraulic actuators. After that, it is returned to the tank T.

  Here, a hydraulic cylinder 5 and a hydraulic motor 6 are shown as hydraulic actuators. 7 and 8 are control valves.

  An oil cooler 9 is provided in the return oil line 4, and hydraulic oil heated to a high temperature by the hydraulic actuator circuit 3 is cooled by the oil cooler 9.

  A fan 10 is provided to increase the cooling capacity of the oil cooler 9, and a fan motor (hydraulic motor) 11 that drives the fan 10 is connected to the return oil line 4 in parallel with the oil cooler 9.

  A check valve 12 is connected to the fan motor 11 in parallel.

  The fan motor 11 is configured as a variable capacity type whose capacity changes in size, and the capacity changes by the operation of the regulator 14 based on a control signal from the controller 13.

  The controller 13 receives a signal from an oil temperature sensor 15 that detects the operating oil temperature of the return oil line 4, and the controller 13 sends a motor capacity to the regulator 14 when the oil temperature rises according to the detected oil temperature. A control signal in the direction of decreasing is output.

  The operation of this point will be described in detail.

  FIG. 2 shows the relationship between motor capacity and motor pressure when the motor capacity is maximum and minimum. As can be seen from the figure, the motor capacity and the motor pressure are in a proportional relationship as shown, and the motor pressure decreases as the motor capacity increases.

  Therefore, in the circuit in which the oil cooler 9 and the fan motor 11 are connected in parallel as shown in FIG. 1, as the motor capacity is increased, the pressure of the fan motor 11 decreases and the oil flows more easily into the motor 11. The passage flow rate of the oil cooler 9 decreases. On the other hand, for the fan motor 11, the flow rate increases as the capacity increases, but the rotational speed (fan rotational speed = air flow rate) decreases.

  Conversely, the smaller the motor capacity, the higher the pressure of the fan motor 11, thereby increasing the passage flow rate of the oil cooler 9, while increasing the rotational speed of the fan motor 11.

  FIG. 3 shows that the relationship between the passage flow rate and the pressure loss of the oil cooler 9 changes according to the change in the oil temperature. The passage flow rate and the pressure loss are in a proportional relationship, but the pressure loss increases as the oil temperature decreases. , The amount of heat generation increases accordingly. (A) shows the case where the oil temperature is 90 ° C, and (B) shows the case where the oil temperature is 0 ° C.

  Therefore, when the oil temperature is low, by reducing the passage flow rate of the oil cooler 9, the pressure loss can be reduced and heat generation can be suppressed.

  FIG. 4 shows that the relationship between the core front wind speed and the heat radiation amount of the oil cooler 9 changes depending on the flow rate of the oil cooler 9 (300 L / min, 400 L / min, 500 L / min in the example). Even if it is the same, the greater the passing flow rate, the greater the heat dissipation.

  In this apparatus, from the above points, when the temperature of the hydraulic oil increases, the capacity of the fan motor 11 is set to be small, thereby increasing the passage flow rate of the oil cooler 9 and the rotational speed of the fan motor 11 to cool the hydraulic oil. When the capacity is increased and the capacity of the hydraulic oil is lowered, the capacity of the fan motor 11 is set to be large, so that the flow rate of the oil cooler 9 is reduced to suppress the heat generation.

  In this case, the controller 13 may make a table in advance regarding the relationship between the oil temperature and the motor capacity, and may perform control to continuously change the motor capacity in accordance with the change in the oil temperature, or based on a preset temperature. Thus, control may be performed in which the motor capacity is changed by a predetermined value (for example, a minimum value and a maximum value) depending on whether it is greater than or less than the reference value.

  In the above embodiment, the controller 13, the regulator 14, and the oil temperature sensor 15 constitute motor capacity control means, and the motor capacity is automatically controlled according to the oil temperature detected by the oil temperature sensor 15. As another configuration, for example, a configuration in which the motor capacity is controlled based on a switch operation may be employed.

  Alternatively, the operation / non-operation of the hydraulic actuator may be detected, and the automatic control may be performed in the direction of reducing the motor capacity during the operation.

1 is a configuration diagram of a hydraulic circuit and a control system showing an embodiment of the present invention. It is a figure which shows the relationship between the motor flow rate and motor pressure in the state where the motor capacity is maximum and minimum. (A) is a diagram showing a relationship between an oil cooler passage flow rate and a pressure loss when the oil temperature is 90 ° C. and (B) is an oil temperature of 0 ° C. FIG. It is a figure which shows that the relationship between the front wind speed of an oil cooler and the amount of heat radiation changes with the flow volume of an oil cooler.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Hydraulic actuator circuit 4 Return oil line 9 Oil cooler 10 Fan 11 Fan motor 13 Controller 14 which comprises motor capacity control means Same as above, Regulator 15 Same as above, Oil temperature sensor

Claims (2)

  Connected to the return oil line in parallel with the oil cooler, an oil cooler for cooling the hydraulic oil provided in the return oil line that returns the hydraulic oil from the hydraulic actuator to the tank, a cooling fan that blows air to the oil cooler A hydraulic fluid cooling device for construction machinery, comprising: a fan motor including a variable displacement hydraulic motor that drives the cooling fan; and motor capacity control means for controlling the capacity of the fan motor.   The hydraulic oil cooling device for a construction machine according to claim 1, wherein the motor capacity control means includes an oil temperature sensor for detecting the temperature of the hydraulic oil, and when the oil temperature rises according to the temperature detected by the oil temperature sensor. A hydraulic fluid cooling device configured to automatically control a motor capacity in a direction to reduce the capacity of the fan motor.

Images