JP2019007429A - Cooling control system for work machine, and work machine - Google Patents

Abstract

To actualize a change in the actual rotating speed of a fan in a well responsive and stable manner in connection with a change in the target rotating speed of the fan.SOLUTION: A cooling control system for a work machine includes an engine having an output shaft, a fan to be rotated by the rotational power of the output shaft of the engine, a housing mounted with the fan, a rotor to be rotated by the rotational power of the output shaft of the engine and to be rotated by fluid introduced into a gap formed between the housing and itself together with the housing, a fluid setting part for setting the introduction amount of the fluid introduced into the gap, a proportional control part for executing proportional control relative to a difference between the actual rotating speed of the fan and the target rotating speed of the fan, an integral control part for executing integral control relative to the difference, and a differential control part for executing differential control relative to the difference. The integral control part starts the integral control when the difference is smaller than a threshold value without executing the integral control when the difference is not smaller than the threshold value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cooling control system for a work machine such as a wheel loader, a skid steer loader, a compact truck loader, and the work machine.

  Conventionally, Patent Document 1 is known as a cooling control system for a work machine. The cooling control system for a work machine disclosed in Patent Document 1 includes a control device that controls the number of rotations of a cooling fan that introduces outside air as cooling air to cool a cooling fluid, and includes a fluid temperature sensor that detects the fluid temperature, and an outside air The outside air temperature sensor for detecting the temperature of the air and the difference between the fluid temperature and the outside air temperature are calculated, and the target rotational speed of the cooling fan is set according to the magnitude of the difference.

JP 2007-255216 A

  The cooling control system employed in Patent Document 1 has a structure (viscous clutch fan structure) in which power from an engine is transmitted by a viscous clutch (fluid coupling). In the viscous clutch fan structure, the torque transmitted to the fan changes depending on the amount of high-viscosity silicone oil, and changes the rotation speed of the cooling fan. In the viscous clutch fan structure, even if the target rotational speed of the cooling fan is changed from the control device, the actual rotational speed of the cooling fan may not be changed.

  The present invention has been made to solve the above-described problems of the prior art, and is a working machine capable of easily changing the actual rotational speed of the fan in accordance with the change of the target rotational speed of the fan. An object is to provide a cooling control system and a work machine.

The technical means of the present invention for solving this technical problem is as follows.
The work machine cooling control system according to the present invention includes a prime mover having an output shaft, a fan rotating by rotational power of the output shaft of the prime mover, a housing in which the fan is mounted, and rotational power of the output shaft of the prime mover. A rotor that rotates and rotates together with the housing by a fluid introduced into a gap formed between the housing, a fluid setting unit that sets an introduction amount of the fluid to be introduced into the gap, A fan rotation detection device that detects the actual rotation speed, a target rotation acquisition unit that acquires the target rotation speed of the fan, and a proportionality that performs proportional control on the difference between the actual rotation speed of the fan and the target rotation speed of the fan A control unit, an integration control unit that performs integral control on the difference, and a differential control unit that performs differential control on the difference. Without the integral control if the difference is equal to or greater than the threshold, the initiating integral control if the difference is less than the threshold value.

The work machine cooling control system includes: a storage unit that stores a first range of the rotation speed of the fan; and the fan rotation speed when the target rotation number of the fan is within the first range stored in the storage unit. And a target changing unit that changes the target rotational speed to a value outside the first range.
In the work machine cooling control system, the target changing unit changes the target rotational speed of the fan by adding or subtracting a predetermined set value to or from an upper limit value or a lower limit value of the first range.

The work machine cooling control system includes a drive rotation detection device that detects an actual rotation speed of the prime mover, and the target changing unit subtracts a predetermined rotation speed from the actual rotation speed of the drive motor detected by the drive rotation detection device. The subtracted value is set as the target rotational speed of the fan.
In the work equipment cooling control system, when the subtraction value is within the first range, the target changing unit subtracts a predetermined set value from the lower limit value of the first range, and subtracts the subtraction value. Set the value to the target speed of the fan.

  The work machine includes the above-described work machine cooling control system.

  According to the present invention, the actual rotational speed of the fan can be easily changed with the change of the target rotational speed of the fan.

It is a figure which shows the cooling control system of a working machine. It is a figure which shows the relationship between an engine and a cooling device. It is a figure which shows the test result at the time of not performing the response improvement process of the rotation speed of a fan. It is a figure which shows the test result at the time of performing the response improvement process of the rotation speed of a fan. It is a figure which shows the fan unstable area | region in a cooling control system. It is a figure which shows a control block diagram. 1 is an overall view of a wheel loader.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a work machine cooling control system and a work machine equipped with the cooling control system according to the invention will be described with reference to the drawings as appropriate.
FIG. 6 is an overall view of the wheel loader.
First, a wheel loader will be described as an example of a working machine. The work machine is not limited to a wheel loader, and may be a compact truck loader, a skid steer loader, a backhoe, or other work machine.

  As shown in FIG. 6, the wheel loader 1 is an articulated working machine, and includes a machine body 2 and a working device 3 capable of working in the front. The body 2 is provided with a front wheel 5 and a rear wheel 6. The body 2 is provided with a support frame 4. The work device 3 includes a lift arm 9 and a bucket 10. The lift arm 9 is supported on the support frame 4 so that the base end side thereof is swingable about an axis (horizontal axis) in the width direction. The lift arm 9 is operated by the expansion and contraction of the lift cylinder 12. That is, when the lift cylinder 12 is expanded and contracted, the lift arm 9 swings in the vertical direction. The bucket 10 is supported on the tip end side of the lift arm 9 so as to be swingable around the horizontal axis. The bucket 10 rotates in the vertical direction by expansion and contraction of the bucket cylinder 13. The bucket 10 is detachably provided, and a spare attachment such as a sweeper, mower, breaker or the like can be attached to the distal end side of the lift arm 9 instead of the bucket 10.

  The airframe 2 is provided with a driver's seat 14, a steering wheel 16, an operating device 17 for operating the work device 3, and a prime mover 18. The prime mover 18 is a diesel engine (engine). The prime mover 18 may be an electric motor or may be composed of both an electric motor and an engine. The wheel loader 1 is provided with a hydraulic pump that is operated by the rotational power of the output shaft 19 of the prime mover 18. The hydraulic pump can supply hydraulic oil to a hydraulic actuator (lift cylinder 12, bucket cylinder 13, etc.) provided in the wheel loader 1 or an attachment hydraulic actuator mounted in place of the bucket 10. Further, the wheel loader 1 is provided with a traveling device such as an HST (hydrostatic transmission).

Next, a working machine cooling control system provided in the wheel loader 1 will be described.
As shown in FIGS. 1 and 2, the work machine cooling control system includes a cooling device 20. The cooling device 20 is a device that drives the prime mover 18 as a power source, and is a viscous clutch fan that uses a viscous fluid. The cooling device 20 includes a rotating shaft 21, a rotor 22, a housing (case) 23, a fluid setting unit (fluid setting device) 24, and a fan 25.

  The rotating shaft 21 is a shaft that is rotated by the rotational power of the output shaft 19 of the engine 18. For example, the output shaft 19 of the engine 18 is provided with a pulley 30 that rotates together with the output shaft 19. The rotating shaft 21 is also provided with a pulley 31 that rotates together with the rotating shaft 21. A belt (drive belt) 32 is hung on the pulley 30 and the pulley 31, and the rotational power of the pulley 30 is transmitted to the pulley 31 via the drive belt 32. That is, the rotating shaft 21 is rotated by the rotational power of the output shaft 19 of the engine 18.

The rotor 22 is fixed to the rotating shaft 21 and rotates together with the rotating shaft 21. The rotor 22 has a disk shape, and an annular labyrinth portion (groove portion) 22a is formed on the outer surface. The rotor 22 is accommodated in the housing 23.
The housing 23 is rotatably supported on the rotary shaft 21 via a bearing 33. A fan 25 having a plurality of blades is mounted on the outside of the housing 23. Therefore, the fan 25 can be rotated by rotating the housing 23.

  The housing 23 has a wall portion 23 a adjacent to the labyrinth portion 22 a of the rotor 22. A gap (operation gap) 23 b is formed between the wall portion 23 a of the housing 23 and the labyrinth portion 22 a of the rotor 22. By introducing a viscous fluid (for example, silicon oil) into the gap 23 b, the rotational power of the rotor 22 is transmitted to the housing 23. The housing 23 is rotated by the rotational power of the rotor 22.

  The housing 23 has a storage chamber 23c and a flow path 23d. The storage chamber 23 c is a chamber for temporarily storing silicon oil, and is provided on the distal end side of the rotating shaft 21. The flow path 23d is a circulation-type flow path that connects the storage chamber 23c and the gap 23b. That is, the channel 23d is a channel that connects the outlet side 23b1 of the gap 23b and the storage chamber 23c, and connects the inlet side 23b2 of the gap 23b and the storage chamber 23c. Accordingly, the silicon oil introduced into the gap 23b can pass through the flow path 23d and enter the storage chamber 23c, then enter the flow path 23d from the storage chamber 23c, and return to the gap 23b.

  The fluid setting unit (fluid setting device) 24 is a device that sets the amount of silicon oil introduced into the gap 23b. The fluid setting device 24 is an electromagnetic valve capable of closing the middle part of the flow path 23d. That is, the fluid setting device 24 includes a coil (solenoid), a pin that can be moved by excitation of the coil, and a valve body provided at the tip of the pin. The pin and the valve body of the fluid setting device 24 are provided in the flow path 23d, and the inside of the flow path 23d can be opened or closed by moving the bottle. If the opening degree is changed by operating the fluid setting device 24, the introduction amount introduced from the storage chamber 23c through the fluid setting device 24 into the gap 23b can be adjusted.

  The silicon oil that has entered the gap 23b passes through the flow path 23d and enters the storage chamber 23c. Here, in a state where the flow path 23d is completely closed by the fluid setting unit 24, the silicon oil cannot flow from the storage chamber 23 into the gap 23b. If the valve body of the fluid setting unit 24 is opened, the silicon oil in the storage chamber 23c can pass through the fluid setting unit 24 and flow into the gap 23b. The rotational speed of the fan 25 (housing 23) can be changed according to the amount of silicon oil introduced into the gap 23b.

  For example, by increasing the amount of silicon oil introduced into the gap 23b, the actual rotational speed (actual rotational speed) of the fan 25 is increased until it substantially matches the actual rotational speed (actual rotational speed) of the engine 18. be able to. Further, by reducing the amount of silicon oil introduced into the gap 23b, the torque transmitted from the rotary shaft 19 of the engine 18 to the housing 23 via the rotor 22 is reduced. That is, by reducing the amount of silicon oil introduced into the gap 23b, the ratio of the actual rotational speed of the fan 25 to the actual rotational speed of the engine 18 is reduced.

The cooling device 20 is controlled by a control device 40 configured by a CPU or the like. The control device 40 outputs a control signal to the fluid setting device 24 to change the opening degree of the fluid setting device 24, thereby controlling the rotation speed of the fan 25. That is, the control device 40 controls the fluid setting device 24 so that the target rotation speed of the fan 25 matches the actual rotation speed of the fan 25.
As shown in FIG. 1, the control device 40 includes a first detection device (primary rotation detection device) 41, a second detection device 43, a proportional control unit 44, an integral control unit 45, and a differential control unit 46. And. The first detection device 41 is a device that detects the actual rotational speed (actual rotational speed) of the engine 18. That is, the first detection device 41 is provided in the vicinity of the output shaft 19 and detects the actual rotational speed of the output shaft 19 of the engine 18. The second detection device 43 is a device that detects the actual rotational speed of the fan 25 (housing 23). That is, it is provided in the vicinity of the fan 25 or the housing 23 and detects the actual rotational speed of the fan 25.

The proportional control unit 44, the integral control unit 45, and the differential control unit 46 are configured by electric / electronic components that constitute the control device 40, programs installed in the control device 40, and the like. FIG. 5 shows a control block of the control device 40. Based on FIG. 5, the proportional control unit 44, the integral control unit 45, and the differential control unit 46 will be described.
As shown in FIG. 5, the control device 40 obtains a difference (F1−F2) between the actual rotational speed (F2) of the fan detected by the second detection device 43 and the target rotational speed (F1) of the fan. The proportional control unit 44 multiplies (multiplies) a preset proportional gain by multiplying the difference (F1-F2) between the actual rotational speed F2 of the fan and the target rotational speed F1 of the fan. (P control) is performed.

The integral control unit 45 executes an integration start timing change process on the difference (F1-F2) between the actual fan speed F2 and the target fan speed F1, and sets the integral gain (0 or positive). The integral control (I control) is performed by multiplying (multiplying by) the constant B).
The differential control unit 46 multiplies the differential (F1-F2) between the actual fan speed F2 and the target fan speed F1 by multiplying (multiplying) a preset differential gain. (D control) is performed.

As described above, the control device 40 determines the control value (operation amount) by PID control, and outputs the control signal corresponding to the control value to the coil of the fluid setting device 24, thereby setting the rotation of the fan. . The control signal is a signal in which the duty ratio is set according to the control value, and the control device 40 sets the opening degree of the fluid setting device 24 by PWM control.
When control including at least integral control (I control) is executed in PID control, the P component that is the difference (F1-F2) between the actual rotational speed F2 of the fan and the target rotational speed F1 of the fan is integrated and calculated. The calculated integral component (I component) may be excessively integrated, and the transition of the actual rotation speed F2 of the fan may become unstable. That is, the PID control system is not stabilized due to excessive integration of the integral component, and the fan If the target rotational speed F1 is changed, the actual rotational speed F2 of the fan will overshoot. As a result, the time required for the fan's actual rotation speed F2 to follow the fan's target rotation speed F1 may become longer, or noise (a roaring sound) may be generated due to the vibration of the fan's actual rotation speed F2.

Therefore, the integration control unit 45 does not perform integration control when the difference is greater than or equal to the threshold value, and starts integration control when the difference becomes less than the threshold value.
For example, when the absolute value of the difference between the target rotation speed F1 (rpm) of the fan and the actual rotation speed F2 (rpm) of the fan is larger than a predetermined threshold A, the integration control unit 45 stores, for example, a storage unit in advance. Instead of using the integral gain stored in 47, by setting the control gain used in the processing to zero, the integral control is not substantially executed. Further, the integral control unit 45 stores the storage unit in advance when the absolute value of the difference between the target rotational speed F1 (rpm) of the fan and the actual rotational speed F2 (rpm) of the fan becomes smaller than a predetermined threshold A. The integral control is executed by the integral gain stored in 47.

  As a result, the absolute value of the difference between the target rotational speed F1 (rpm) of the fan and the actual rotational speed F2 (rpm) of the fan is greater than the threshold A even if the target rotational speed F1 of the fan is suddenly increased during overheating. Therefore, the integral control is not executed, so that it is possible to prevent the integral component (I component) from being accumulated excessively. As a result, it is possible to prevent fan noises and the like from occurring.

  FIG. 4 shows the change over time of the actual rotational speed F2 of the fan with respect to the target rotational speed F1 of the fan when the conventional PID control is executed in the cooling system. The target rotation speed F1 of the fan is changed according to the oil temperature, the water temperature, the use / non-use of the air conditioner, etc., but as shown in FIG. May end up. That is, there is an unstable region (region) L in which the actual rotational speed F2 of the fan vibrates. The control device 40 performs a process (an unstable section avoidance process) for improving the responsiveness and stability of the actual rotational speed F2 of the fan when the target rotational speed F1 of the fan is changed in PID control including at least integral control (I control). )It is carried out.

Hereinafter, the unstable section avoidance process will be described in detail.
The storage unit 47 of the control device 40 stores a first range that is an unstable region L at the target rotational speed F1 of the fan. The unstable region L1 is a range obtained by changing the target rotational speed F1 of the fan from the minimum to the maximum and measuring the behavior of the actual rotational speed F2 of the fan.
The control device 40 includes a target changing unit 48. The target changing unit 48 includes an electric / electronic component constituting the control device 40, a program incorporated in the control device 40, and the like.

The target changing unit 48 changes the target rotational speed F1 of the fan to a value outside the first range L1 when the target rotational speed F1 of the fan is within the first range L1 stored in the storage unit 47. As shown in FIG. 4, the target changing unit 48 sets the target rotation speed F1 of the fan to the range [a, b] between the upper limit value a and the lower limit value b of the first range L1 (both a and b are positive constants). When entered, the target rotation speed F1 of the fan is changed to a value outside the first range. The target change section 48 refers to the area [a, b] of the target rotation speed F1 of the fan stored in the storage section 47. When the target rotational speed F1 of the fan is included in the area [a, b], a predetermined set value c is added to the upper limit value a (a + c), and the added value is set to the target rotational speed F1 of the fan. . Alternatively, the target changing unit 48 refers to the area [a, b] of the target rotational speed F1 of the fan, and when the target rotational speed F1 of the fan is included in the area [a, b], the set value c is set to the lower limit value b. Is subtracted (bc), and the subtraction value (first subtraction value) is set to the target rotational speed F1 of the fan. The positive set value c added to the upper limit value a may be different from the positive set value c subtracted from the lower limit value b. In this embodiment, the set value c is 50 rpm, but is not limited thereto.

Further, the target changing unit 48 refers to the area [a, b] of the target rotational speed F1 of the fan stored in the storage unit 47, and the target rotational speed F1 of the fan is not included in the area [a, b]. Is set without changing the target rotational speed F1 of the fan.
In addition, when the target rotational speed F1 of the fan changed by the target changing unit 48 is more than the maximum rotational speed of the fan or less than the minimum rotational speed in the cooling device 20, the target rotational speed F1 of the fan is set to the maximum rotational speed or the minimum rotational speed. The rotational speed is fixed, or the target speed F1 of the fan is not temporarily changed by the target changing unit 48.

In the embodiment described above, excessive accumulation of I components and avoidance of an unstable region of the target rotational speed of the fan are performed, but in addition to this, response improvement processing described below may be performed.
The target changing unit 48 improves the responsiveness of the actual rotational speed F2 of the fan when the target rotational speed F1 of the fan is changed by setting the target rotational speed F1 of the fan lower than the actual rotational speed E1 of the engine in advance. Yes. That is, the target changing unit 48 sets a subtraction value (second subtraction value) obtained by subtracting the predetermined rotation speed from the actual rotation speed E1 of the engine detected by the first detection device 41 as the target rotation speed F1 of the fan. Thus, the responsiveness of the actual rotation speed F2 of the fan is improved.

  Specifically, the target changing unit 48 sets a value obtained by subtracting a predetermined rotational speed determined based on responsiveness from the actual rotational speed of the engine as the target rotational speed of the fan. That is, the target changing unit 48 sets [target fan rotational speed (second subtraction value) F1 (rpm) = engine actual rotational speed E1 (rpm) −predetermined rotational speed (rpm)]. Here, the predetermined rotational speed is a rotational speed determined based on responsiveness, and is a rotational speed capable of suppressing the sticking phenomenon (sticking prevention rotational speed). The predetermined rotational speed is a value determined by various experiments and the like. At least the target rotational speed F1 of the fan is 150 rpm lower than the actual rotational speed E1 of the engine, so that the actual rotational speed of the fan is changed when the target rotational speed of the fan is changed. Number responsiveness is improved.

  FIG. 3A and FIG. 3B compare the test results when the fan rotation speed response improvement process is performed and when the response improvement process is not performed. In the test, the conditions are the same for both. In the test, after the actual engine speed was rapidly reduced, the actual engine speed was changed in a short time. As shown in FIG. 3A, when the response improvement process is not performed, the actual rotational speed F2 of the fan follows the actual rotational speed E1 of the engine. Further, hunting occurred when the actual rotational speed of the fan reached the vicinity of the target rotational speed F1 of the fan. On the other hand, as shown in FIG. 3B, when response improvement processing is performed, the actual rotational speed F2 of the fan does not follow the actual rotational speed E1 of the engine, and the actual rotational speed E1 of the fan is the target rotational speed of the fan. Hunting did not occur substantially in accordance with F1.

  As described above, when the subtraction value obtained by subtracting the predetermined rotation speed from the actual rotation speed E1 of the engine is set as the target rotation speed F1 of the fan, the target rotation speed F1 of the fan can be included in the region [a, b]. There is sex. When the second subtraction value is in the region [a, b], the target changing unit 48 subtracts the predetermined set value d from the lower limit value b in the region [a, b], and the subtracted value is obtained. The target rotational speed F1 of the fan is set (target rotational speed F1 of the fan = lower limit value b−set value d).

According to the above, since excessive I component accumulation avoidance, fan target rotation speed unstable region avoidance, and sticking prevention processing are performed, the rotating shaft 21, rotor 22, housing (case) 23, fluid setting are performed. Even in the cooling device 20 including the section (fluid setting device) 24 and the fan 25, the actual rotational speed of the fan can be easily changed with the change of the target rotational speed of the fan.
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Work machine 2 Machine body 3 Work device 4 Support frame 5 Front wheel 6 Rear wheel 9 Lift arm 10 Bucket 12 Lift cylinder 13 Bucket cylinder 14 Driver's seat 16 Steering 17 Operation device 18 Motor 19 Output shaft 20 Cooling device 21 Rotating shaft 22 Rotor 22a Labyrinth Part 23 housing 23a wall part 23b gap 23c storage chamber 23d flow path 24 fluid setting part (fluid setting device)
25 Fan 30 Pulley 31 Pulley 32 Drive belt 33 Bearing 40 Control device 41 First detection device 43 Second detection device 44 Proportional control unit 45 Integral control unit 46 Differential control unit 47 Storage unit 48 Target change unit

Claims (6)

A prime mover having an output shaft;
A fan that is rotated by the rotational power of the output shaft of the prime mover;
A housing in which the fan is mounted;
A rotor that rotates with the rotational power of the output shaft of the prime mover and that rotates together with the housing by a fluid introduced into a gap formed between the housing and the housing;
A fluid setting unit for setting an introduction amount of the fluid to be introduced into the gap;
A fan rotation detection device for detecting the actual rotation speed of the fan;
A target rotation acquisition unit for acquiring a target rotation speed of the fan;
A proportional control unit that performs proportional control on the difference between the actual rotational speed of the fan and the target rotational speed of the fan;
An integral control unit for performing integral control on the difference;
A differential control unit for performing differential control on the difference;
With
The integration control unit does not perform the integration control when the difference is greater than or equal to a threshold value, and starts the integration control when the difference becomes less than the threshold value. A storage unit for storing a first range of the rotational speed of the fan;
A target changing unit for changing the target rotational speed of the fan to a value outside the first range when the target rotational speed of the fan is within the first range stored in the storage unit;
The work machine cooling control system according to claim 1, comprising:   The work machine cooling according to claim 2, wherein the target changing unit changes the target rotational speed of the fan by adding or subtracting a predetermined set value to or from an upper limit value or a lower limit value of the first range. Control system. Comprising a prime rotation detection device for detecting the actual rotational speed of the prime mover;
The work machine cooling control according to claim 2 or 3, wherein the target changing unit sets a subtraction value obtained by subtracting a predetermined rotation speed from an actual rotation speed of the prime mover detected by the prime rotation detection device as a target rotation speed of the fan. system.   When the subtraction value is within the first range, the target changing unit subtracts a predetermined set value from the lower limit value of the first range, and uses the subtracted value as the target rotational speed of the fan. The work machine cooling control system according to claim 4, wherein   A working machine comprising the cooling control system for a working machine according to claim 1.

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