JP3056597B2 - Cooling fan drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling fan drive device in which a hydraulic motor is connected to a hydraulic pump driven by a prime mover, and the hydraulic motor drives a cooling fan for cooling water and hydraulic oil of the prime mover.

[0002]

2. Description of the Related Art An apparatus shown in FIG. 6 is known as a device for cooling a cooling water or a working oil of a prime mover provided in a construction machine such as a hydraulic shovel. In this apparatus, a hydraulic motor 3 is connected to a fixed displacement hydraulic pump 2 driven by a prime mover 1, a cooling fan 4 is connected to an output shaft of the hydraulic motor 3, and a radiator 5 and a radiator 5 are provided in front of the cooling fan 4. The cooling fan 4 is rotated at a speed corresponding to the rotation speed of the prime mover 1 to cool the cooling water in the radiator 5 and the working oil in the oil cooler 6. In the drawings, reference numeral 7 denotes a variable displacement hydraulic pump provided for driving a work attachment such as a boom and turning the upper part of the machine.

[0003]

The efficiency of the hydraulic pump 2 and the hydraulic motor 3 is 80 to 90 in the above-described apparatus.
%, A loss horsepower is generated in the drive system of the cooling fan 4. The energy consumed by the drive system of the cooling fan 4 reaches about 10% of the output of the prime mover 1 in the case of a general hydraulic excavator, and the energy distributed to the hydraulic pump such as a work attachment is reduced accordingly. Inconvenience had occurred. In this regard, if the discharge capacity of the hydraulic pump 2 or the hydraulic motor 3 for driving the cooling fan is reduced, the driving horsepower of the cooling fan 4 can be reduced and more energy can be distributed to the work attachment or the like. If the discharge capacity of the hydraulic motor 2 or the hydraulic motor 3 is reduced, the cooling performance is impaired, and overheating may occur frequently. An object of the present invention is to provide a cooling fan drive device that can distribute more energy to a work attachment or the like without impairing the cooling performance of cooling water or hydraulic oil.

[0004]

According to a first aspect of the present invention, there is provided a variable displacement hydraulic pump for a cooling fan driven by a prime mover, and cooling water and operation of the prime mover driven by discharge oil of the hydraulic pump. A hydraulic motor for rotating a cooling fan for cooling oil , a working variable displacement hydraulic pump driven by a prime mover, and a plurality of working actuators driven by oil discharged from the hydraulic pump; The present invention is applied to a hydraulic drive device by speed sensing control for increasing and decreasing the displacement of a working variable displacement hydraulic pump so that the number of revolutions becomes a preset target value. The above object, roughness of the plurality of working actuators
Multiple pre-defined working actuators
This is achieved by providing a torque control means for reducing the displacement volume of the variable displacement hydraulic pump for the cooling fan when it is detected that the displacement has occurred. (2) The invention according to claim 2, in the hydraulic drive system of claim 1, wherein the temperature of the cooling water and hydraulic oil when the predetermined value or more, a predetermined one of the plurality of working actuators
Checks that multiple operating actuators have been operated in combination.
Even when it is output, reduction of the displacement volume of the variable displacement hydraulic pump for the cooling fan by the torque control means is prohibited. (3) A third aspect of the present invention provides a fixed displacement hydraulic pump for a cooling fan driven by a prime mover, and a cooling fan driven by discharge oil of the hydraulic pump to cool cooling water and hydraulic oil of the prime mover. A hydraulic motor to be rotated, a working variable displacement hydraulic pump driven by the prime mover, and a plurality of working actuators driven by the discharge oil of the hydraulic pump, wherein the rotational speed of the prime mover is set to a target value set in advance. The present invention is applied to a hydraulic drive device based on speed sensing control for increasing and decreasing the displacement of a working variable displacement hydraulic pump. Then, a plurality of predetermined working actuators among the plurality of working actuators are combined.
The above-described object is achieved by providing a torque control unit that bypasses the discharge oil of the fixed displacement hydraulic pump for the cooling fan without supplying it to the hydraulic motor when the operation is detected. (4) a plurality of invention of claim 4, in the hydraulic drive system according to claim 3, the temperature of the cooling water and hydraulic oil when the predetermined value or more, a predetermined one of the plurality of working actuators
Even when it is detected that the work actuator of (1) is operated in combination, the bypass of the discharge oil of the fixed displacement hydraulic pump for the cooling fan by the torque control means is prohibited.

[0005]

(1) The displacement of the working variable displacement hydraulic pump is controlled so that the rotational speed of the prime mover becomes a preset target value. This is so-called speed sensing control. Then, predetermined among the plurality of working actuators
When it is detected that a plurality of working actuators are operated in combination, the displacement of the variable displacement hydraulic pump for the cooling fan is reduced by the torque control means, the absorption horsepower becomes smaller, and the rotation speed of the prime mover will increase. And As a result, the displacement volume of the working hydraulic pump is increased by the speed sensing control, and the rotation speed is kept constant by increasing the required torque. This increases the horsepower available to the working hydraulic pump. (2) When the temperature of the cooling water or the hydraulic oil is equal to or higher than a predetermined value, a plurality of predetermined working operations of the plurality of working actuators are performed.
Displacement of the cooling fan variable displacement hydraulic pump is not reduced even when it is detected that the combined operation of the cooling actuator is performed . As a result, the heat balance does not deteriorate. (3) The displacement of the working variable displacement hydraulic pump is controlled to increase or decrease so that the rotation speed of the prime mover becomes a preset target value. This is so-called speed sensing control. Then, predetermined among the plurality of working actuators
When it is detected that a plurality of working actuators are operated in combination, the discharge oil of the fixed displacement hydraulic pump for the cooling fan is bypassed without being supplied to the hydraulic motor by the torque control means. To reduce the absorption horsepower of the motor and increase the rotation speed of the prime mover. As a result, the displacement volume of the working hydraulic pump increases due to the speed sensing control, in other words, the horsepower available to the working hydraulic pump increases. (4) When the temperature of the cooling water or the hydraulic oil is equal to or higher than a predetermined value, a plurality of predetermined working operations of the plurality of working actuators are performed.
Displacement of the fixed hydraulic pump for the cooling fan is not reduced even when it is detected that the combined operation of the cooling actuator is performed . As a result, the heat balance does not deteriorate.

In the section of the means for solving the above-mentioned problems and the operation which explain the constitution of the present invention, the drawings of the embodiments are used to make the present invention easy to understand. However, the present invention is not limited to this.

[0007]

【Example】

First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. Note that the same reference numerals are given to portions common to the above-described conventional example, and description thereof will be omitted. As shown in FIG. 1, in this embodiment, two variable displacement hydraulic pumps 10 and 11 and one fixed displacement hydraulic pump 12 are connected to the output shaft of the prime mover 1. The first hydraulic pump 10 is for driving a work attachment or the like of a hydraulic shovel, and discharges oil from a hydraulic cylinder 14a for raising the boom and a hydraulic pressure for turning the upper part of the machine in accordance with the switching position of the switching valves 13a and 13b. It is guided to the motor 14b. The second hydraulic pump 11 is for driving the cooling fan 4, and the discharged oil is guided to the hydraulic motor 3 connected to the cooling fan 4. In addition,
Reference numeral 15 denotes a relief valve that regulates the maximum driving pressure of the hydraulic motor 3, and reference numeral 16 denotes a check valve that prevents cavitation.

The third hydraulic pump 12 generates a pilot hydraulic pressure or the like for the operation system of the hydraulic shovel, and a part of the discharge oil is guided to an electromagnetic proportional valve 18 via a pipe 17. The electromagnetic proportional valve 18 discharges pressure oil having a pressure proportional to the drive current supplied to the solenoid portion 18s, and its output side is a tilt regulator 11 of the second hydraulic pump 11.
a. Thereby, the second hydraulic pump 11
Changes according to the drive current of the solenoid 18s of the electromagnetic proportional valve 18. When the supply of the drive current to the solenoid portion 18s is stopped, the tilt regulator 11a
Is connected to the tank, and the discharge capacity of the second hydraulic pump 11 becomes zero. Reference numeral 19 denotes a relief valve that regulates the maximum pressure of the pipeline 17.

Part of the discharge oil of the third hydraulic pump 12 is 2
Remote control valves (hereinafter referred to as remote control valves) 2
It is also led to 0,21. The first remote control valve 20
An operating lever 20a and a pair of pilot valves 20 for outputting pressure oil having a pressure proportional to the operation amount of the operating lever 20a.
b, 20c. By operating the operating lever 20a in the upward or downward direction, the pilot lines 22a, 22b
When the discharge oil of the third hydraulic pump 12 is guided to any one of the above, the switching valve 13a according to the operation direction of the operation lever 20a
Is switched, the pressure oil from the first hydraulic pump 10 is guided to one of the ports of the hydraulic cylinder 14a, and the boom (not shown) of the hydraulic shovel descends in a desired direction. When the operation lever 20a is in the neutral position, both the pilot lines 22a and 22b are connected to the tank and the switching valve 13
a returns to the neutral position, the supply of pressure oil to the hydraulic cylinder 14a is blocked, and the boom lowering operation stops.

Similarly, a second remote control valve 21 has an operation lever 21a and a pair of pilot valves 21b and 21c for outputting pressure oil having a pressure proportional to the operation amount of the operation lever 21a.
And By operating the operation lever 21a to the right turning side or the left turning side, the pilot lines 23a, 23b
When the discharge oil of the third hydraulic pump 12 is guided to any one of the above, the switching valve 13b according to the operation direction of the operation lever 21a
Is switched, the hydraulic oil from the first hydraulic pump 10 is guided to one of the ports of the hydraulic motor 14b, and the upper part of the body of the hydraulic shovel turns in a desired direction. Operation lever 2
When 1a is in the neutral position, pilot lines 23a, 2
3b are both connected to the tank, the switching valve 13b returns to the neutral position, the supply of pressure oil to the hydraulic motor 14b is blocked, and the turning operation of the upper part of the machine stops. In the illustrated example, the operation levers 20 of the first and second remote control valves 20 and 21 are shown.
Although a and 21a are separate bodies, these are integrated into one lever capable of turning 360 °, and pilot valves 20b and 20c of the first remote control valve 20 are provided around the lever,
The pilot valves 21b and 21c of the second remote control valve 21 may be arranged so that their arrangement directions are orthogonal to each other.

[0011] Between the pilot lines 22a and 22b,
A high-pressure selection valve 24 that outputs the higher pressure of the pilot lines 22a and 22b is connected. A high-pressure selection valve 25 that outputs the higher pressure of the pilot lines 23a and 23b is connected between the pilot lines 23a and 23b. Outputs of the high-pressure selection valves 24 and 25 are monitored by pressure sensors 26 and 27, and these pressure sensors 26 and 27 correspond to pressures (hereinafter, pilot pressures) P ₁ and P ₂ output from the high-pressure selection valves 24 and 25. The signal is output to the controller 30.

The controller 30 includes a target rotation speed Nr set by the fuel lever 31 and an actual motor rotation speed N detected by a rotation speed sensor 32 disposed opposite to the output shaft of the motor 1.
a, and controls the electric tilt regulator 10a of the first hydraulic pump 10 based on the deviation ΔN (= Nr−Na) from the pilot pressures P ₁ and P ₂ detected by the pressure sensors 26 and 27; Electromagnetic proportionality based on cooling water temperature t _W detected by water temperature sensor 33 installed near radiator 5 and hydraulic oil temperature t _O detected by oil temperature sensor 34 installed near oil cooler 6. The drive current to the solenoid 18s of the valve 18 is controlled. The control of the discharge capacity of the first hydraulic pump 10 is known as speed sensing control (for example, Japanese Patent Laid-Open No. 55-1224).
No. 5).

FIG. 2 is a flowchart showing a processing procedure in the controller 30. When the prime mover 1 is started, processing by the controller 30 is executed.
At target rotation speed Nr, prime mover actual rotation speed Na, water temperature t
_W , oil temperature t _O , and pilot pressures P ₁ and P ₂ are read. In step S2, the absolute value | ΔN | of the deviation ΔN (= Nr−Na) between the target rotation speed Nr and the actual motor rotation speed Na is compared with the reference rotation speed k. The difference ΔN from the reference rotational speed k is such that the discharge capacity of the first hydraulic pump 10 needs to be changed.
Is a value for determining whether or not has been enlarged. If it is determined in step S2 that the absolute value of the deviation ΔN is higher than the reference rotational speed k, the process proceeds to step S3. In step S3,
The discharge current of the first hydraulic pump 10 is increased or decreased by changing the drive current of the tilt regulator 10a according to the deviation ΔN. When it is determined in step S2 that the absolute value of the deviation ΔN is within the reference rotational speed k, the process proceeds to step S10, where the discharge capacity of the first hydraulic pump 10 is fixed at the current position, and the process proceeds to step S4.

In step S4, the water temperature t _W and the limit water temperature t _WL
Oil temperature t _O and critical oil temperature t _OL
Compare the size with. Here, the critical water temperature t _WL and the critical oil temperature t _OL are temperatures at which overheating does not occur immediately even when the cooling of the cooling water or the working oil by the cooling fan 4 is stopped. In step S4, the water temperature t _W becomes the limit water temperature t _WL
When it is determined that the temperature is lower and the oil temperature t _O is lower than the limit oil temperature t _{OL, the} process proceeds to step S5. In step S5 the pilot pressure P _1, P ₂ and the reference pressure P _1K, the size relationship between the P _2K respectively compared, the pilot pressure P _1, P ₂ is the reference pressure P _1K, P
_{When it is 2K} or more, the process proceeds to step S6. In addition, as an example,
The reference pressure P _1K is set equal to the pilot pressure P ₁ when the hydraulic cylinder 14a starts to _operate , and the reference pressure P _2K is set equal to the pilot pressure P2 when the hydraulic motor 14b starts to operate. In step S6, the electromagnetic proportional valve 18
Is reduced to zero over a certain period of time. As a result, the discharge capacity of the second hydraulic pump 11 gradually decreases toward zero. When step S4 or step S5 is denied, the process proceeds to step S11,
The drive current to the solenoid portion 18s of the electromagnetic proportional valve 18 is set to the maximum value to maximize the discharge capacity of the second hydraulic pump 11. After the end of step S6 or step S11, the process returns to step S1, and the same processing is repeated thereafter.

In the above processing procedure, when an overload is applied to the prime mover 1 and its actual rotational speed Na falls below the target rotational speed Nr beyond the reference rotational speed k, step S2 is affirmed and the first hydraulic pump 10 The discharge capacity is reduced. Due to the decrease in the discharge capacity of the first hydraulic pump 10, the actual rotational speed Na
Rises and the deviation ΔN decreases to within the reference rotational speed k, step S2 is denied, and the discharge displacement of the first hydraulic pump 10 is fixed in step S10. Remote control valve 20,
If the boom elevating operation and the upper body turning operation are simultaneously activated by simultaneously operating 21, step S <b> 5 is affirmed and the process of step S <b> 6 is executed, and the discharge capacity of the second hydraulic pump 11 decreases. The absorption torque of the second hydraulic pump 11 is reduced. As a result, the output of the prime mover 1 has a margin, and the frequency at which the discharge displacement of the first hydraulic pump 10 is reduced due to the decrease in the actual rotational speed Na of the prime mover is affirmed in step S2. For this reason, the discharge capacity of the first hydraulic pump 10 is maintained high, and the hydraulic cylinder 1
More energy is distributed to the hydraulic motor 4a and the hydraulic motor 14b, so that work with the same load can be performed at a higher speed than before.

When the discharge capacity of the second hydraulic pump 11 is reduced in step S6, the cooling effect of the cooling fan 4 is temporarily impaired, but the combined operation of boom elevating and turning is almost completed in a short time. Then, after the completion of the combined operation, step S5 is denied and the process of step S11 is executed, and the discharge capacity of the second hydraulic pump 11 immediately returns to the maximum value, so that the cooling performance is impaired as overheating occurs. Absent. Moreover, in the embodiment, if at least one of the water temperature t _W and the oil temperature t _O exceeds the limit water temperature t _WL and the limit oil temperature t _OL , step S4 is denied and the discharge of the second hydraulic pump 11 is performed in step S11. Since the capacity is returned to the maximum value, the water temperature t _W and the oil temperature t _O do not rise to a region where overheating occurs even if the combined operation of the boom raising and the body turning is continued for a long time.

In this embodiment, an electromagnetic proportional valve 18 is used to control the tilt regulator 11a of the second hydraulic pump 11,
When it is necessary to reduce the discharge capacity, the drive current of the solenoid 18s is gradually reduced, so that the cavitation due to the sudden decrease in the discharge capacity of the second hydraulic pump 11 is prevented in combination with the function of the check valve 16. You.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted. As shown in FIG. 3, this embodiment is different from the first embodiment in that the remote control valves 20, 2
The pressure sensor for monitoring the pilot pressure output from the motor 1 is omitted, and the controller 40 detects the target rotation speed Nr set by the fuel lever 31 and the rotation speed sensor 32 arranged opposite to the output shaft of the prime mover 1. Actual motor rotation speed Na
And the temperature t _{W of the} cooling water detected by the water temperature sensor 33,
The point is that the displacements of the first and second hydraulic pumps 10 and 11 are controlled based on the operating oil temperature t _O detected by the oil temperature sensor 34.

FIG. 4 is a flowchart showing the processing of the controller 40. The controller 40 first proceeds to step S
At 21, the target rotational speed Nr, the prime mover actual rotational speed Na, the water temperature t _W , and the oil temperature t _O are read, and at the next step S22, the deviation ΔN (= Nr−N) between the target rotational speed Nr and the prime mover actual rotational speed Na.
The absolute value | ΔN | of Na) is compared with the reference rotation speed k. When it is determined that the absolute value of the deviation ΔN is higher than the reference rotational speed k, the process proceeds to step S23. In step S23, the magnitudes of the actual rotation speed Na and the target rotation speed Nr are compared,
When it is determined that the actual rotational speed Na is lower, step S24
Proceed to. In step S24, the water temperature t _W and the limit water temperature t _WL
Oil temperature t _O and critical oil temperature t _OL
Compare the size with.

In step S24, the water temperature t _W is reduced to the limit water temperature t _WL
When it is determined that the temperature is lower and the oil temperature t _O is lower than the limit oil temperature t _{OL, the} process proceeds to step S25. In step S25, the drive current to the solenoid 18s of the electromagnetic proportional valve 18 is reduced to zero over a certain period of time, and the discharge capacity of the second hydraulic pump 11 is gradually reduced toward zero. Next step S26
Then, the actual rotation speed Na of the prime mover after the discharge capacity of the second hydraulic pump 11 is reduced is read. In the next step S27, the deviation Δ between the newly read actual rotation speed Na and the target rotation speed Nr is read.
The absolute value | ΔN | of N (= Nr−Na) is compared in magnitude with the reference rotation speed k. When it is determined that the absolute value of the deviation ΔN is larger than the reference rotation speed k, the process proceeds to step S28, and the discharge capacity of the first hydraulic pump 10 is changed according to ΔN.

If step S22 is denied, the process proceeds to step S30, in which the displacement of the first hydraulic pump 10 is fixed. In the next step S31, the water temperature t _W and the limit water temperature t
As well as comparing the magnitudes of the _WL, oil temperature t _O and limit oil temperature t
Compare the size with _OL . The water temperature t _W is higher than the limit water temperature t _WL ,
Alternatively, when the oil temperature t _O is equal to or higher than the limit oil temperature t _OL , the process proceeds to step S32, and the discharge capacity of the second hydraulic pump 11 is maximized. If step S23 is negative, step S
The process proceeds to step S28 without performing the processing from step 24 to step S27. If step S24 is denied, the process proceeds to step S40, where the discharge capacity of the second hydraulic pump 11 is maximized, and then the process proceeds to step S26. Step S31
Is affirmative, and step S28, step S28
After the end of S32, the process returns to step S21, and the same processing is repeated thereafter.

In the above-described processing procedure, when an overload is applied to the prime mover 1 and its actual rotational speed Na falls below the target rotational speed Nr beyond the reference rotational speed k, first, in step S25, the second rotational speed
The discharge capacity of the hydraulic pump 11 is reduced, and the absorption torque of the second hydraulic pump 11 is reduced. As a result, when the overload of the prime mover 1 is eliminated and the absolute value of the rotational speed deviation ΔN falls within the reference rotational speed k, step S27 is affirmed and step S22 is negative, and the rotational speed deviation ΔN is reduced by the load fluctuation. Exceeding several k or step S31
Unless the condition is denied, the first and second hydraulic pumps 10 and 11
Is fixed.

If the absolute value of the deviation ΔN exceeds the reference rotational speed k even after the absorption torque of the second hydraulic pump 11 is reduced,
In step S28, the discharge capacity of the first hydraulic pump 10 is adjusted. When the deviation ΔN falls within the reference rotational speed k, step S22 is denied, and the first and second hydraulic pumps 1
The discharge capacities of 0 and 11 are fixed. Step S2
The process 8 is performed not only when the actual rotation speed Na remains low even when the absorption torque of the second hydraulic pump 11 is reduced, but also when the actual rotation speed Na increases from the target rotation speed Nr beyond the reference rotation speed k. It is also performed when you do. In this case, the discharge capacity of the first hydraulic pump 10 is increased so that the actual rotational speed Na decreases, so that the input horsepower of the first hydraulic pump 10 further increases.

As is apparent from the above description, in this embodiment, when an overload is applied to the prime mover 1, the discharge capacity of the second hydraulic pump 11 for cooling is first reduced preferentially, and
, The input horsepower of the first hydraulic pump 10 increases, and the hydraulic cylinder 14a and the hydraulic motor 14b
More energy is distributed to the Even when the combined operation of raising and turning the boom is performed, the discharge capacity of the second hydraulic pump 11 for cooling is not reduced as long as the output of the prime mover has a margin, so that the cooling effect is maintained at a high level. The engine 1 determines whether to reduce the discharge capacity of the second hydraulic pump 11.
Since the determination is made based on the relative relationship between the target rotation speed Nr and the actual rotation speed Na, there is no need to provide a means for detecting activation of a specific work attachment as in the first embodiment. When one of the water temperature t _W and the oil temperature t _O exceeds the limit water temperature t _WL and the limit oil temperature t _OL , step S32 or step S32 is performed.
At 40, the discharge capacity of the second hydraulic pump 11 is returned to the maximum value, and the cooling by the cooling fan 4 is restarted. Thus, as in the first embodiment, the water temperature t _W and the oil temperature t _O reach the region where overheating occurs. There is no risk of rising.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted. As shown in FIG. 5, in the present embodiment, the second hydraulic pump 11 </ b> A for driving the cooling fan 4 is changed to a fixed displacement type, and the second hydraulic pump 11 </ b> A is unloaded into the bypass pipe 50 that bypasses the hydraulic motor 3. A valve 51 is provided, and a pilot line 52 of the unload valve 51 is connected to an output side of the proportional solenoid valve 18 controlled by the controller 30. When the electromagnetic proportional valve 18 is at the maximum opening, the pressure of the pilot line 52 switches the unload valve 51 to a position where the unload valve 51 communicates with the bypass line 50. Electromagnetic proportional valve 1
When the opening of 8 is zero, the pilot line 52 is connected to the tank.

According to the present embodiment, similarly to the first embodiment, when the pressure sensors 26 and 27 detect that the combined operation of raising and lowering the boom has been started, the controller 30 operates the solenoid unit of the electromagnetic proportional valve 18. Drive current to 18s,
When the electromagnetic proportional valve 18 reaches the maximum opening degree, the unload valve 51 switches to the side where the bypass pipe 50 is opened. As a result, the discharge oil of the second hydraulic pump 11A bypasses the hydraulic motor 3 and flows out of the bypass pipe 50 into the tank.
The absorption torque of the second hydraulic pump 11A is reduced,
Input horsepower of the hydraulic motor 10 increases. When the combined operation is not performed, or when the water temperature sensor 33 and the oil temperature sensor 34
When one of the water temperature t _W and the oil temperature t _O detected at the time exceeds the limit water temperature t _WL and the limit oil temperature t _OL , the electromagnetic proportional valve 18 closes and the unload valve 51 closes the bypass line 50. Therefore, the hydraulic motor 3 is driven by the discharge oil of the second hydraulic pump 11A.
Is driven to perform cooling by the cooling fan 4.

In the first and third embodiments, the absorption torque of the hydraulic pump for driving the cooling fan is reduced in advance when the load due to the combined operation of the boom elevating and the upper body turning is applied to the prime mover. In the second embodiment, when the prime mover 1 is actually overloaded, the absorption torque of the hydraulic pump for driving the cooling fan is reduced. However, the present invention is not limited to such an embodiment, When the load of the front attachment is applied, the absorption torque on the cooling fan side is reduced, or the absorption torque is started before the overload is applied to the prime mover, for example, when the maximum output of the prime mover exceeds 90%. For example, the timing of reducing the absorption torque of the cooling fan hydraulic pump can be variously changed.

In each of the embodiments, the discharge capacity of the second hydraulic pump is reduced to zero. However, it is not always necessary. In a case where the water temperature rises immediately after the cooling fan is stopped, it is about half of the normal time. Various changes may be made according to the performance of the construction machine to which the present invention is applied, such as by reducing the cooling effect to the cooling effect of the cooling fan. In addition, the hydraulic shovel has been described as an example, but the present invention is also applicable to other construction machines.

In the above embodiment, the pressure sensors 26 and 27
And the controller 30 constitute a simultaneous drive detecting means, and the controller 30 constitutes a speed sensing control means.

As described above, according to the present invention, the following functions and effects can be obtained. In a hydraulic drive device by speed sensing control for increasing or decreasing the displacement of the working variable displacement hydraulic pump so that the rotation speed of the prime mover becomes a preset target value, a plurality of working actuators among a plurality of working actuators are determined in advance. For work
When it is detected that the actuator has been operated in combination, the displacement of the variable displacement hydraulic pump for the cooling fan is reduced, or the discharge oil of the fixed displacement hydraulic pump for the cooling fan is bypassed without being supplied to the hydraulic motor. By doing so, the absorption torque of the hydraulic pump for driving the cooling fan is reduced, so that the displacement of the working hydraulic pump such as the work attachment or the turning actuator is increased by the speed sensing control. That is, much energy is distributed to the working hydraulic pump.
If the heat load is large, overheating can be prevented by continuing the driving of the cooling fan even after the above-described combined operation is performed.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure in a controller 30 of FIG. 1;

FIG. 3 is a hydraulic circuit diagram according to a second embodiment of the present invention.

FIG. 4 is a flowchart showing a processing procedure in a controller 40 of FIG. 3;

FIG. 5 is a hydraulic circuit diagram according to a third embodiment of the present invention.

FIG. 6 is a circuit diagram of a conventional cooling fan driving device.

Claims (4)

(57) [Claims] 1. A variable displacement hydraulic pump for a cooling fan driven by a prime mover, and a hydraulic motor driven by discharge oil of the hydraulic pump to rotate a cooling fan for cooling cooling water and hydraulic oil of the prime mover And a working variable displacement hydraulic pump driven by the prime mover, and a plurality of working actuators driven by the discharge oil of the hydraulic pump, wherein the rotation speed of the prime mover is a preset target value. in the hydraulic drive device according to the speed sensing control to increase or decrease control displacement volume of the working variable displacement hydraulic pump as, predetermined one of said plurality of working actuators
A hydraulic drive device comprising: a torque control unit configured to reduce a displacement volume of the variable displacement hydraulic pump for a cooling fan when detecting that a plurality of working actuators are combinedly operated . In the hydraulic drive system of the claim 1, double the temperature of the cooling water and hydraulic oil when the predetermined value or more, a predetermined one of said plurality of working actuators
Detects that multiple work actuators have been combined
A hydraulic drive device for prohibiting a reduction in the displacement of the variable displacement hydraulic pump for the cooling fan by the torque control means even when the torque control is performed. 3. A fixed displacement hydraulic pump for a cooling fan driven by a prime mover, and a hydraulic motor driven by discharge oil of the hydraulic pump to rotate a cooling fan for cooling cooling water and hydraulic oil of the prime mover. And a working variable displacement hydraulic pump driven by the prime mover, and a plurality of working actuators driven by the discharge oil of the hydraulic pump, wherein the rotation speed of the prime mover is a preset target value. in the hydraulic drive device according to the speed sensing control to increase or decrease control displacement volume of the working variable displacement hydraulic pump as, predetermined one of said plurality of working actuators
A torque control unit that bypasses the discharge oil of the fixed displacement hydraulic pump for the cooling fan without supplying the hydraulic motor to the hydraulic motor when it is detected that the plurality of working actuators are operated in combination. A hydraulic drive device characterized by the above-mentioned. In the hydraulic drive system of claim 3, double the temperature of the cooling water and hydraulic oil when the predetermined value or more, a predetermined one of said plurality of working actuators
A hydraulic drive device wherein the bypass of the discharge oil of the fixed displacement hydraulic pump for the cooling fan by the torque control means is prohibited even when it is detected that a plurality of work actuators are operated in combination .