JP4390201B2 - Drive control circuit for hydraulic motor for cooling fan in construction machinery - Google Patents

Description

  The present invention belongs to the technical field of drive circuits for hydraulic motors for cooling fans in construction machines such as hydraulic excavators and wheel loaders.

  In general, construction machines such as hydraulic excavators and wheel loaders are provided with a cooling package including a cooler such as a radiator or an oil cooler and a cooling fan for supplying cooling air to the cooler. In addition, a cooling package that requires an opening for inflow and outflow of cooling air and an engine that is a source of noise are arranged separately, and the engine is surrounded by a sound insulation enclosure. There are some which are designed to insulate engine noise. In the case where the cooling package and the engine are separately provided in this way, the cooling fan is usually connected to the output shaft of a dedicated hydraulic motor and is configured to rotate by driving the hydraulic motor. Has been.

  By the way, the cooling fan is conventionally configured so as to rotate only in one direction, and outside air serving as cooling air is sucked from one side of the cooling package and discharged from the other side. At this time, the outside dust is also sucked in together with the outside air, causing the cooling package to be clogged. However, if the cooling package is clogged, the cooling capacity cannot be fully exhibited, and problems such as engine overheating may occur. is there. For this reason, it is necessary to periodically clean the cooling package, but the cleaning work is troublesome and requires a lot of labor.

Therefore, the above-described cooling fan is configured to be rotated by driving the hydraulic motor, and is configured to be able to reverse the direction of rotation of the hydraulic motor based on the switching of the switching valve. A technique has been proposed in which the direction is reversed so that clogging of the cooling package can be removed (see, for example, Patent Document 1).
JP-A-10-68142

  By the way, in the thing of the said patent document 1, when the switching valve is switched so that a rotation direction may be reversed forward and backward in the state where the cooling fan is rotating at the rated rotation speed, the flow of the pressure oil supplied to the hydraulic motor is abrupt. In the opposite direction, an excessive load is generated, which may cause noise or damage to hydraulic equipment. Furthermore, when the cooling fan is rotating at the rated speed, the strength of the cooling air is constant, but it is desired to increase or decrease the cooling air according to the engine coolant temperature, hydraulic oil temperature, outside air temperature, etc. There is a demand, and there is a problem to be solved by the present invention.

SUMMARY OF THE INVENTION The present invention was created in view of the above-described circumstances to solve these problems. The invention of claim 1 is for supplying cooling air to a cooler such as a radiator or an oil cooler. In a construction machine configured to rotate the cooling fan by driving the hydraulic motor, a switching valve for switching the rotation direction of the hydraulic motor and the amount of oil supplied to the hydraulic motor are increased or decreased in the hydraulic motor drive circuit. A variable relief valve that is controlled so as to change the circuit pressure of the drive circuit and an overload relief valve for releasing the high pressure generated in the drive circuit are provided. When it is necessary to output a control signal to the relief valve to reduce the amount of oil supplied to the hydraulic motor to the set pressure for switching and to reduce the rotational speed of the hydraulic motor After, and it outputs a control signal for rotating the hydraulic motor in the reverse direction, thereafter, that the controller outputs a control signal so that the reverse rotation set pressure by increasing the set pressure of the variable relief valve is provided It is a drive control circuit of the hydraulic motor for cooling fans in the construction machine which is characterized.
According to a second aspect of the present invention, in the first aspect , the variable relief valve is controlled so as to change the set pressure of the drive circuit so as to increase or decrease the amount of oil supplied to the hydraulic motor in accordance with the engine coolant temperature. 5 is a drive control circuit of a hydraulic motor for a cooling fan in a construction machine.
According to a third aspect of the present invention, in any one of the first to second aspects, the variable relief valve changes the set pressure of the drive circuit so as to increase or decrease the amount of oil supplied to the hydraulic motor in accordance with the operating oil temperature. It is the drive control circuit of the hydraulic motor for cooling fans in the construction machine characterized by being controlled by.
According to a fourth aspect of the present invention, in any one of the first to third aspects, the variable relief valve changes the set pressure of the drive circuit so as to increase or decrease the amount of oil supplied to the hydraulic motor in accordance with the outside air temperature. It is the drive control circuit of the hydraulic motor for cooling fans in the construction machine characterized by being controlled.

According to the first aspect of the present invention, the rotation direction of the hydraulic motor can be reversed reversely by switching the switching valve, and the rotational speed of the hydraulic motor can be controlled by changing the circuit pressure of the drive circuit with the variable relief valve. Therefore, by reversing the cooling fan, dust clogged in the radiator or oil cooler can be removed, and the load generated in the drive circuit during forward and reverse rotation of the hydraulic motor can be reduced. In order to reduce this, the variable control of the rotational speed of the hydraulic motor can be performed. In addition, the rotational speed of the hydraulic motor is slowed during forward and reverse reversal , and thus the load generated in the drive circuit when the hydraulic motor is reversed can be greatly reduced, contributing to noise reduction and protection of hydraulic equipment.
According to the invention of claim 2 , variable control of the rotational speed of the cooling fan can be performed corresponding to the engine coolant temperature.
By setting it as invention of Claim 3 , the variable control of the rotational speed of a cooling fan can be performed according to hydraulic fluid temperature.
According to the fourth aspect of the present invention, the rotational speed of the cooling fan can be variably controlled according to the outside air temperature.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partially cutaway plan view of an upper swing body 1 of a hydraulic excavator. The upper swing body 1 includes a swing device 2 at the center, and an engine 3 on the right side of the swing device 2. The engine room 4 is provided. The engine room 4 is surrounded by a sound insulation enclosure. Furthermore, a pump chamber 6 in which a hydraulic pump 5 driven by the engine 3 is housed is disposed behind the engine room 4. Further, a cooling package 7 described later is disposed behind the swivel device 2 and on the left side of the pump chamber 6. In FIG. 1, 8 is a cab and 9 is a counterweight.

  The cooling package 7 includes a radiator 10 for cooling engine cooling water, a cooler such as an oil cooler 11 for cooling hydraulic oil, and a cooling fan 12 for supplying cooling air to these coolers. The cooling fan 12 is directly connected to the output shaft of the hydraulic motor 13 and is configured to rotate based on the drive of the hydraulic motor 13.

  Next, a hydraulic control circuit of the hydraulic motor 13 is shown in FIG. 2, in which a reference numeral 5a denotes a first hydraulic pump serving as a pressure oil supply source of the hydraulic motor 13, and the first hydraulic pump 5a is An axial piston pump or a gear pump is used, and 5b is a second hydraulic pump that serves as a pressure oil supply source for the pilot pressure. The second hydraulic pump 5b is a gear pump.

Reference numeral 14 denotes a switching valve provided with a pilot port 14a. The switching valve 14 is positioned at the forward rotation position X when no pilot pressure is input to the pilot port 14a, but the pilot pressure is input. By doing so, it switches to the reverse rotation position Y. The switching valve 14 at the forward rotation position X supplies the pressure oil from the first hydraulic pump 5a to the first input / output port 13a of the hydraulic motor 13 via the first supply / discharge oil passage A, while the hydraulic motor 13, the oil flowing out from the second input / output port 13b flows to the oil tank 15 via the second supply / discharge oil passage B, whereby the output shaft of the hydraulic motor 13 rotates in the forward direction, and the cooling fan 12 It is designed to rotate in the positive direction. The switching valve 14 at the reverse rotation position Y supplies the pressure oil from the first hydraulic pump 5a to the second input / output port 13b of the hydraulic motor 13 via the second supply / discharge oil passage B, while the hydraulic motor 13 The oil flowing out from the first input / output port 13b flows into the oil tank 15 via the first supply / discharge oil passage A, whereby the output shaft of the hydraulic motor 13 rotates in the reverse direction and the cooling fan 12 is reversed. It is designed to rotate in the direction.
The cooling fan 12 rotates in the forward direction to suck cooling air into the cooling package 7 and cools the cooler, while rotating in the reverse direction blows out the dust sucked into the cooling package 7 to the outside. It is like that.

  Further, 16 is an electromagnetic valve for outputting a pilot pressure to the pilot port 14a of the switching valve 14, and the electromagnetic valve 16 is based on an output signal from a controller 17 which will be described later. Switch to. The electromagnetic valve 16 at the OFF position X allows the pilot port 14a of the switching valve 14 to communicate with the oil tank 15, while the electromagnetic valve 16 at the ON position supplies pressure oil from the second hydraulic pump 5b to the pilot of the switching valve 14. It is configured to supply to the port 14a.

  On the other hand, a relief oil passage E leading to the oil tank 15 is branched in the pump oil passage P extending from the first hydraulic pump 5a to the switching valve 14, and the hydraulic motor 13 is driven in the relief oil passage E. A variable relief valve 20 for setting the circuit pressure (pressure in the upstream circuit of the hydraulic motor 13) is arranged. The variable relief valve 20 changes the set pressure based on the output signal from the controller 17, and changes the set pressure of the variable relief valve 20 to change the pressure of the drive circuit of the hydraulic motor 13. Although the height can be changed, the amount of oil supplied to the hydraulic motor 13 is increased or decreased by changing the pressure of the drive circuit, and thus the rotational speed of the hydraulic motor 13 is changed.

  Further, a makeup oil passage F is branched from the pump oil passage P to the oil tank 15 in parallel with the relief oil passage E. The makeup oil passage F includes an oil tank 15. Is provided with a check valve 21 that allows the flow of oil to the pump oil passage P but prevents the reverse flow. When the upstream side of the hydraulic motor 13 is in a negative pressure state by the hydraulic motor 13 that continues to rotate with inertia even when the first hydraulic pump 5a is stopped, the oil tank passes through the check valve 21. By supplying oil from 15 to the pump oil passage P, the occurrence of cavitation can be prevented.

  Furthermore, the pump oil passage P upstream from the branch point of the relief oil passage E and the makeup oil passage F reaches the oil tank 15 in a state parallel to the relief oil passage E and the makeup oil passage F. A bypass oil passage C is branched and a cross overload relief valve 18 is disposed in the bypass oil passage C. The cross overload relief valve 18 has an oil passage (the pump oil passage P and the first supply / discharge oil passage A or the second supply / discharge oil passage B) connecting the first hydraulic pump 5a and the hydraulic motor 13 in advance. When the pressure becomes higher than the set pressure, the pressure is released to the oil tank 15, thereby preventing the generation of high pressure in the oil passage between the hydraulic motor 13 and the hydraulic pump 5a. It can be done.

  On the other hand, the controller 17 is configured using a microcomputer or the like. The controller 17 includes an operation switch 22 described later, a cooling water temperature sensor 23 for detecting the temperature of engine cooling water, and hydraulic oil. A signal from the hydraulic oil temperature sensor 24 for detecting the temperature of the oil is input, and a control signal is output to the electromagnetic valve 16 and the variable relief valve 20 to control the drive of the hydraulic motor 13 based on the input signal. Is configured to do.

  Here, the operation switch 22 is a switch operated by an operator when the rotation direction of the cooling fan 12 is to be reversed in the forward and reverse directions. As will be described later, when the operation switch 22 is OFF, the cooling fan 12 is operated. 12 is controlled to rotate in the forward direction, and is controlled to rotate in the reverse direction when the operation switch 22 is ON.

  Next, the control of the hydraulic motor 13 in the controller 17 will be described based on the flowcharts shown in FIGS. 3 to 5. First, in the main routine shown in FIG. Then, it is determined whether the operation switch 22 is ON or OFF (Step S1. At the time of starting the system, the operation switch 22 is set to OFF). If it is determined in step S1 that the operation switch 22 is OFF, it is subsequently determined whether the electromagnetic valve 16 is in the OFF position X or the ON position Y (step S2). 16 is located at the OFF position X). If it is determined in step S2 that the solenoid valve 16 is in the OFF position X, “forward rotation control” is executed. If it is determined that the solenoid valve 16 is in the ON position Y, “first switching control” is performed. Is executed. On the other hand, if it is determined in step S1 that the operation switch 22 is ON, it is subsequently determined whether the electromagnetic valve 16 is in the OFF position X or the ON position Y (step S3). If it is determined in step 3 that the solenoid valve 16 is in the OFF position X, “second switching control” is executed. If it is determined that the solenoid valve 16 is in the ON position Y, “reverse rotation control” is performed. Is executed.

As described above, the “forward control” is executed when the operation switch 22 is OFF and the electromagnetic valve 16 is in the OFF position Y. During the “forward control”, the electromagnetic valve 16 is OFF. Since it is located at the position Y, no pilot pressure is output to the pilot port 14a of the switching valve 14, so that the switching valve 14 is positioned at the forward rotation position X and the hydraulic motor 13 rotates in the forward direction. . Furthermore, during this “forward rotation control”, the control for the variable relief valve 20 is performed. The control 17 will be described based on the flowchart shown in FIG. Based on the input signal, it is determined whether or not the engine coolant temperature Tw is equal to or lower than a preset coolant temperature Tws (step S4). In step 4, when it is determined that the engine coolant temperature Tw is equal to or lower than the coolant setting temperature Tws (Tw ≦ Tws), the hydraulic fluid temperature is continuously determined based on the input signal from the hydraulic fluid temperature sensor 24. It is determined whether To is equal to or lower than a preset hydraulic oil set temperature Tos (step S5). When it is determined in step S5 that the hydraulic oil temperature To is equal to or lower than the hydraulic oil set temperature Tos (To ≦ Tos), the controller 17 sets a preset low-speed rotation setting for the variable relief valve 20. A control signal is output so as to be the pressure PL (step S6). On the other hand, when it is determined in step 4 that the engine coolant temperature Tw has exceeded the coolant setting temperature Tws (Tw> Tws), or in step 5, the hydraulic fluid temperature To has exceeded the hydraulic fluid set temperature Tos (To If it is determined that> Tos), the controller 17 outputs a control signal to the variable relief valve 20 so that the preset rotational pressure for rated rotation PH is obtained (step S7).
Here, the variable relief valve 20 is controlled so as to be at the low-speed rotation set pressure PL, so that the drive circuit of the hydraulic motor 13 is necessary for the cooling fan 12 to rotate at a preset low speed. This is the pressure at which the flow rate is supplied to the hydraulic motor 13. In addition, the variable relief valve 20 is controlled so as to have the rated rotation set pressure PH, so that the drive circuit of the hydraulic motor 13 has a flow rate necessary for the cooling fan 12 to rotate at a preset rated rotational speed. Becomes a pressure for supplying the pressure to the hydraulic motor 13.
Thus, during the “forward rotation control”, the cooling fan 12 rotates in the forward direction (the direction in which outside air is sucked into the cooling package 7), and the engine cooling water temperature Tw and the hydraulic oil temperature To are both the cooling water set temperature Tws. When the temperature is lower than the hydraulic oil set temperature Tos, the engine rotates at a low speed, so that it is possible to prevent the radiator 10 and the oil cooler 11 from being cooled more than necessary when the engine coolant temperature and the hydraulic oil temperature are low. It has become.
On the other hand, when at least one of the engine cooling water temperature Tw and the hydraulic oil temperature To becomes a high temperature exceeding the cooling water set temperature Tws and the hydraulic oil set temperature Tos, the cooling fan 12 rotates at the rated rotational speed. Sufficient cooling air can be supplied to the radiator 10 and the oil cooler 11.
This “forward rotation control” is continued unless the operator turns on the operation switch 22.

On the other hand, if the operator turns on the operation switch 22 while the “forward rotation control” is being executed, the solenoid valve 16 is located at the OFF position X at this point, and the process proceeds to “second switching control”. To do. The “second switching control” is a control for switching the rotation direction of the hydraulic motor 13 from normal rotation to reverse rotation. The control will be described based on the flowchart shown in FIG. Then, the controller 17 outputs a control signal to the variable relief valve 20 so as to lower it to a preset switching set pressure PC (step 8). Here, the switching set pressure PC is the same as the drive circuit pressure of the hydraulic motor 13, even if the rotation direction of the hydraulic motor 13 is reversed in the forward and reverse directions, the hydraulic motor 13 and the first and second supply / discharge oil passages A and B. This is the set pressure of the variable relief valve 20 for reducing the pressure so that an excessive load is not applied to the piping to be formed. Next, the controller 17 outputs a control signal to the variable relief valve 20 so as to become the switching set pressure PC, and then elapses after a predetermined time (a predetermined time necessary for the rotation speed of the hydraulic motor 13 to decrease) (step). 9) A control signal is output to the electromagnetic valve 16 so as to switch from the OFF position X to the ON position Y (step 10). As a result, the pilot pressure is output from the electromagnetic valve 16 to the pilot port 14a of the switching valve 14, and the switching valve 14 is switched to the reverse rotation position Y, so that the rotation direction of the hydraulic motor 13 is reversed. Thereafter, the controller 17 outputs a control signal to the variable relief valve 20 so as to gradually increase the set pressure to become the reverse set pressure PB (step 11), and returns to the main routine. Here, the reverse set pressure PB is the pressure required to rotate the drive circuit pressure of the hydraulic motor 13 at a predetermined reverse rotation speed suitable for the cooling fan 12 to blow off the clogging of the cooling package 7. This is the set pressure of the variable relief valve 20 for adjusting the pressure.
Thus, when the operator turns on the operation switch 22, the operation proceeds to "second switching control", and the hydraulic motor 13 is reversed from the forward direction to the reverse direction. In this case, the hydraulic motor 13 is temporarily turned on. The rotation is reversed after the rotation speed is decreased, and thereafter, the rotation speed is gradually increased to be a predetermined reverse rotation speed.

When returning to the main routine from the “second switching control” described above, since the operation switch 22 is ON and the electromagnetic valve 16 is located at the ON position Y, the process proceeds to “reverse rotation control”. During the “reverse rotation control”, since the electromagnetic valve 16 is located at the ON position Y, the hydraulic motor 13 rotates in the reverse direction and the variable release valve 16 holds the set pressure PB for reverse rotation. Thus, a control signal is output.
Thus, during the “reverse rotation control”, the cooling fan 12 is controlled to rotate in the reverse direction at a predetermined reverse rotation speed. In this “reverse rotation control”, the operator turns off the operation switch 22 or Or it continues until the predetermined reverse rotation time T preset as a control parameter passes.

  On the other hand, if the operator turns off the operation switch 22 in the state where the “reverse rotation control” is being executed, the solenoid valve 16 is located at the ON position X at this point, and therefore the process proceeds to “first switching control”. . Also, when the “reverse rotation control” is continued for the predetermined reverse rotation time, the process proceeds to “first switching control”. The “first switching control” is a control for switching the rotation direction of the hydraulic motor 13 from reverse rotation to forward rotation. In the “second switching control” described above, the electromagnetic valve 16 is changed from the OFF position X to the ON position Y. Since the control is the same as the “second switching control” except that the solenoid valve 16 is controlled to be switched from the ON position Y to the OFF position X instead of the switching control (step 10), the detailed description is omitted. No. 13 is controlled so as to reverse once the rotational speed has decreased, and then gradually increase the rotational speed to reach the rated rotational speed. After the hydraulic motor 13 reaches the rated speed, the process returns to the main routine. In this state, however, the operation switch 22 is OFF and the solenoid valve 16 is in the OFF position X. Shift to “rotation control”.

  In the embodiment configured as described above, the drive circuit of the hydraulic motor 13 for rotating the cooling fan 12 can change the switching valve 14 for switching the rotation direction of the hydraulic motor 13 and the circuit pressure of the drive circuit. The variable relief valve 20 is provided, so that the direction of rotation of the hydraulic motor 13 can be reversed reversely by switching the switching valve 14, and the hydraulic pressure can be changed by changing the circuit pressure of the drive circuit. The rotational speed of the motor 13 can be variably controlled.

  As a result, the cooling fan 12 is rotated forward and the outside air is sucked into the cooling package 7 to supply cooling air to the cooler such as the radiator 10 and the oil cooler 11, while the cooling fan 12 is reversed to cool the cooling package 7. The dust sucked in can be blown off to the outside, and the cooling package 7 can be effectively prevented from being clogged. Thus, the number of cleaning operations for the cooling package 7 can be reduced, and the cleaning can be facilitated, which contributes to improvement in maintainability.

  In addition, in this case, since the rotational speed of the hydraulic motor 13 can be variably controlled by changing the circuit pressure of the drive circuit by the variable relief valve 20, the circuit pressure of the drive circuit is changed when the rotation direction of the hydraulic motor 13 is reversed. By controlling so that the rotational speed of the hydraulic motor 13 is lowered, the load generated in the drive circuit when the hydraulic motor 13 is reversed can be greatly reduced, thereby contributing to noise reduction and protection of hydraulic equipment. it can.

  Further, a bypass oil passage that reaches the oil tank 15 via the cross overload relief valve 18 is branched in the pump oil passage P that leads from the first hydraulic pump 15a to the switching valve 16. The high pressure generated in the oil passage between the first hydraulic pump 5a and the hydraulic motor 13 when the motor 13 is reversed can be released by the cross overload relief valve 18, thereby contributing to further noise reduction and protection of the hydraulic equipment.

  When the cooling fan 12 is rotated forward to supply cooling air to a cooler such as the radiator 10 or the oil cooler 11, the hydraulic motor 13 is changed by changing the circuit pressure of the drive circuit of the hydraulic motor 13 by the variable relief valve 20. By variably controlling the rotation speed of the engine, the rotation speed of the cooling fan 12 corresponding to the engine coolant temperature and the hydraulic oil temperature can be obtained, so that the load generated when the hydraulic motor 13 is reversed is operated. By using the variable relief valve 20, it is possible to control the strength of the cooling air corresponding to the engine coolant temperature and the hydraulic oil temperature.

  In the present embodiment, two rotation speeds, that is, the low speed rotation speed and the rated rotation speed, are set as the rotation speed of the cooling fan 12 during normal rotation. Or the controller 17 calculates the fan rotation speed corresponding to the engine coolant temperature and the hydraulic oil temperature, and controls the variable relief valve 20 so as to obtain the calculated rotation speed. Further, a temperature sensor for measuring the outside air temperature can be provided, and the rotation speed of the cooling fan 12 can be changed based on an input signal from the temperature sensor. It is possible to control the strength of the cooling air corresponding to the above.

It is a partially notched top view of an upper revolving structure. It is a control circuit diagram of a hydraulic motor. It is a flowchart figure which shows the main routine of drive control of a hydraulic motor. It is a flowchart figure of forward rotation control. It is a flowchart figure of 2nd switching control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Radiator 11 Oil cooler 12 Cooling fan 13 Hydraulic motor 14 Switching valve 17 Controller 18 Cross overload relief valve 20 Variable relief valve

Claims (4)

In a construction machine configured to rotate a cooling fan for supplying cooling air to a cooler such as a radiator or an oil cooler by driving the hydraulic motor, the rotation direction of the hydraulic motor is included in the drive circuit of the hydraulic motor. A switching valve for switching between, a variable relief valve controlled to change the circuit pressure of the drive circuit to increase or decrease the amount of oil supplied to the hydraulic motor, and an overload relief valve for releasing the high pressure generated in the drive circuit When the switching valve is switched, a control signal is output to the variable relief valve to reduce the amount of oil supplied to the hydraulic motor to the set pressure for switching, and the rotational speed of the hydraulic motor decreases. After the necessary time has elapsed, a control signal for rotating the hydraulic motor in the reverse direction is output. Drive control circuit of the hydraulic motor for the cooling fan in the construction machine, wherein the controller outputs a control signal so as to be pressure is provided. In the construction machine according to claim 1, wherein the variable relief valve is controlled so as to change the set pressure of the drive circuit so as to increase or decrease the amount of oil supplied to the hydraulic motor in accordance with the engine coolant temperature. Drive control circuit for cooling fan hydraulic motor. 3. The variable relief valve according to claim 1, wherein the variable relief valve is controlled so as to change the set pressure of the drive circuit so as to increase or decrease the amount of oil supplied to the hydraulic motor in accordance with the hydraulic oil temperature. A drive control circuit for a cooling fan hydraulic motor in a construction machine. 4. The variable relief valve according to claim 1, wherein the variable relief valve is controlled so as to change a set pressure of the drive circuit so as to increase or decrease the amount of oil supplied to the hydraulic motor in accordance with the outside air temperature. A drive control circuit for a hydraulic motor for a cooling fan in a construction machine.

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