JP2021050546A - Construction machine - Google Patents

Abstract

To provide a construction machine in which the idle rotation number of a motor can be set low since an operation state of an operation device can be detected even when the idle rotation number of a motor is set low.SOLUTION: A hydraulic shovel comprises: an operation device generating a pilot pressure corresponding to an operation amount of an operation lever and switching a control valve depending on the generated pilot pressure; and a control device 32 controlling the rotation number of a motor 23 to a preset idle rotation number when a non-operation state of the operation device continues. And the hydraulic shovel comprises: a hydraulic signal line 35 connected between a discharge side of a pilot pump 27 and a tank 36 and interposed by the control valve; a fixed throttle 37 provided between the discharge side of the pilot pump 27 and the control valve in the hydraulic signal line 35; and pressure sensors 38, 39 respectively detecting oil pressures at an upstream side and a downstream side of the fixed throttle 37. The control device 32 detects an operation state of the operation device based on a detection result of the pressure sensors 38, 39.SELECTED DRAWING: Figure 3

Description

The present invention relates to a construction machine having an auto idle control function.

A hydraulic excavator, which is one of construction machines, is a prime mover (specifically, for example, an engine or an electric motor), a hydraulic pump driven by the prime mover, a plurality of hydraulic actuators, and a pressure from the hydraulic pump to a plurality of hydraulic actuators. A plurality of control valves for controlling the flow of oil and a plurality of operating devices for switching the plurality of control valves are provided. In recent years, from the viewpoint of energy saving and noise reduction, an auto-idle control function has been provided to reduce the rotation speed of the prime mover from the standard rotation speed to the idle rotation speed when a plurality of operating devices continue to be in an unoperated state (). For example, see Patent Document 1).

The hydraulic excavator of Patent Document 1 is connected between a pilot pump driven by a prime mover, a discharge side of the pilot pump and a tank, and has a plurality of control valves described above intervening, and is one of a plurality of control valves. Is provided between the hydraulic signal line that is shut off when the engine is switched from the neutral position, the pilot relief valve provided on the discharge side of the pilot pump, and the discharge side of the pilot pump and a plurality of control valves in the hydraulic signal line. A fixed throttle, a pressure sensor that detects the flood pressure on the downstream side of the fixed throttle (in other words, between the fixed throttle and the control valve), and a control that detects the operating state of a plurality of operating devices based on the detection results of the pressure sensor. It is equipped with a device.

If any of the operating devices is operated (ie, if any of the control valves is switched from the neutral position), the hydraulic signal line will be shut off and the pressure sensor will be shut down. The oil pressure detected in is raised to near the relief pressure of the pilot relief valve. When all the operating devices are not operated (that is, when all the control valves are in the neutral position), the hydraulic signal line is in a communicating state, so that the oil pressure detected by the pressure sensor drops. The control device determines whether or not any of the operating devices has been operated based on whether or not the oil pressure detected by the pressure sensor exceeds a preset threshold value.

When the oil pressure detected by the pressure sensor is equal to or less than the threshold value, the control device determines that all the operating devices are not operated. Then, when the state in which all the operating devices are not operated continues for a predetermined time, the rotation speed of the prime mover is reduced to the idle rotation speed. Further, the control device determines that any of the operating devices has been operated when the oil pressure detected by the pressure sensor exceeds the threshold value. Then, the rotation speed of the prime mover is maintained or restored to the standard rotation speed.

Japanese Unexamined Patent Publication No. 2012-22050

In the above-mentioned prior art, a pressure sensor for detecting the oil pressure on the downstream side of the fixed throttle is provided, and the operating state of the operating device is detected by comparing the oil pressure detected by the pressure sensor with the threshold value. However, there is room for improvement in the above-mentioned prior art as follows.

The above-mentioned threshold is the oil pressure detected by the pressure sensor when the rotation speed of the prime mover is the standard rotation speed and the hydraulic signal line is in a continuous state (specifically, the portion of the hydraulic signal line from the pressure sensor to the tank). It is the pressure obtained by adding the pressure loss to the tank pressure, and increases when the oil temperature is low). It is necessary to set it higher. Further, it is necessary to set the rotation speed of the prime mover to be lower than the oil pressure detected by the pressure sensor when the rotation speed of the prime mover is the idle rotation speed and the hydraulic signal line is in the cutoff state.

However, when the rotation speed of the prime mover drops to the idle speed, the discharge flow rate of the pilot pump decreases. The pilot relief valve has an override characteristic in which the relief pressure decreases in proportion to the decrease in oil flow rate. Therefore, if the idle speed of the prime mover is too low, there is a possibility that the oil pressure detected by the pressure sensor does not exceed the threshold value when the rotation speed of the prime mover is the idle speed and the hydraulic signal line is in the cutoff state. .. That is, there is a possibility that the operating state of the operating device cannot be detected. Therefore, it is difficult to set the idle speed of the prime mover low.

The present invention has been made in view of the above circumstances, and an object of the present invention is to detect the operating state of the operating device even if the idle speed of the prime mover is set low, and to set the idle speed of the prime mover low. It is to provide construction machinery that can be used.

In order to achieve the above object, the present invention comprises a prime mover, a hydraulic pump driven by the prime mover, a hydraulic actuator, and a control valve for controlling the flow of pressure oil from the hydraulic pump to the hydraulic actuator. An operating device that generates a pilot pressure corresponding to the operating amount of the lever and switches the control valve according to the generated pilot pressure, and a rotation speed of the prime mover are preset when the operating device continues to be in an unoperated state. In a construction machine equipped with a control device for controlling an idle rotation speed, a pilot pump driven by the prime mover and using a discharge pressure as a source pressure of the pilot pressure, and a pilot relief provided on the discharge side of the pilot pump. In the hydraulic signal line, which is connected between the discharge side of the pilot pump and the tank and is interrupted when the control valve is interposed and the control valve is switched from the neutral position, and the hydraulic signal line. A fixed throttle provided between the discharge side of the pilot pump and the control valve, a first pressure sensor for detecting the hydraulic pressure on the upstream side of the fixed throttle, and a second for detecting the hydraulic pressure on the downstream side of the fixed throttle. The control device includes two pressure sensors, and the control device detects an operating state of the operating device based on the detection results of the first pressure sensor and the second pressure sensor.

According to the present invention, the operating state of the operating device can be detected even if the idle rotation speed of the prime mover is set low, and the idle rotation speed of the prime mover can be set low.

It is a side view which shows the structure of the hydraulic excavator in one Embodiment of this invention. It is a top view which shows the structure of the hydraulic excavator in one Embodiment of this invention. It is a figure which shows the structure of the hydraulic drive device in one Embodiment of this invention. It is a flowchart which shows the processing procedure of the control apparatus in one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings, taking a hydraulic excavator as an example of application of the present invention.

FIG. 1 is a side view showing the structure of the hydraulic excavator in the present embodiment, and FIG. 2 is a top view. After that, when the driver sits in the driver's seat with the hydraulic excavator in the state shown in FIGS. 1 and 2, the front side (right side of FIGS. 1 and 2) and the rear side (right side of FIGS. 1 and 2) and the rear side (FIGS. 1 and 2) of the driver. Left side), left side (back side toward the paper surface of FIG. 1, upper side of FIG. 2), right side (front side toward the paper surface of FIG. 1, lower side of FIG. 2) are simply front side, rear side, left side, right side. It is called.

The hydraulic excavator of the present embodiment includes a lower traveling body 1 that can travel, an upper rotating body 2 that is provided so as to be able to rotate above the lower traveling body 1, and a working device 3 that is connected to the front side of the upper rotating body 2. To be equipped.

The lower traveling body 1 includes an H-shaped track frame 4 when viewed from above. A driving wheel 5 and a trailing wheel 6 are provided on the right side of the track frame 4, and a crawler 7A on the right side is hung between them. The drive wheel 5 on the right side is rotated by the drive of the traveling motor 8 on the right side, and the track 7A on the right side is rotated. A driving wheel (not shown) and a trailing wheel (not shown) are also provided on the left side of the track frame 4, and a track 7B on the left side is hung between them. The left drive motor (not shown) rotates the left drive wheel, which in turn rotates the left track 7B.

A blade 9 for soil removal is provided on the front side of the track frame 4 so as to be movable up and down. The blade 9 moves up and down by driving a blade cylinder (not shown).

The work device 3 is rotatably connected to the swing post 10 and a swing post 10 rotatably connected to the front side of the upper slewing body 2 (more specifically, a slewing frame described later) in the left-right direction. The boom 11 is provided with an arm 12 rotatably connected to the boom 11 in the vertical direction, and a bucket 13 rotatably connected to the arm 12 in the vertical direction. The swing post 10, boom 11, arm 12, and bucket 13 are rotated by driving a swing cylinder (not shown), a boom cylinder 14, an arm cylinder 15, and a bucket cylinder 16, respectively. The bucket 13 can be replaced with an attachment (not shown) incorporating an optional hydraulic actuator.

The upper swivel body 2 includes a swivel frame 17 forming a basic structure, a canopy type cab 18 provided on the front left side of the swivel frame 17, and a counterweight 19 provided at the rear end of the swivel frame 17. Be prepared. The swivel frame 17 of the upper swivel body 2 is connected to the upper side of the track frame 4 of the lower traveling body 1 via a swivel wheel 20. The upper swivel body 2 is swiveled by driving a swivel motor (not shown).

At the entrance / exit of the driver's cab 18, a gate lock lever (not shown) that can be operated by the driver at the ascending position (boarding / alighting permitted position) and the descending position (boarding / alighting restricted position) is provided. Inside the driver's cab 18, a driver's seat 21 on which the driver sits, a plurality of operating lever devices (details will be described later) and a rotation speed indicator 22 (see FIG. 3 to be described later) that can be operated by the driver are provided. ing.

The hydraulic excavator is a plurality of hydraulic actuators (specifically, the right side traveling motor 8, the left side traveling motor, the blade cylinder, the swing cylinder, the boom cylinder 14, the arm cylinder 15, and the bucket cylinder described above in response to the operation of the plurality of operation lever devices. 16. A hydraulic drive device for driving an optional hydraulic actuator and a swivel motor) is provided. The configuration of this hydraulic drive device will be described with reference to FIG.

FIG. 3 is a diagram showing a configuration of a hydraulic drive device according to the present embodiment. Note that FIG. 3 shows, as a representative, the configuration of the right-side traveling motor 8 and the boom cylinder 14.

The hydraulic drive device of the present embodiment includes an electric motor 23 (motor), a battery 24 which is a power source of the electric motor 23, an inverter 25 which controls the rotation speed of the electric motor 23, a hydraulic pump 26 driven by the electric motor 23, and a pilot. The pump 27, the right side traveling control valve 28 that controls the flow of pressure oil from the hydraulic pump 26 to the right side traveling motor 8, and the boom control valve 29 that controls the flow of pressure oil from the hydraulic pump 26 to the boom cylinder 14. An operation lever device 30 for switching the right-side traveling control valve 28, an operation lever device 31 for switching the boom control valve 29, and a control device 32 are provided.

Although not shown, the operation lever device 30 includes a traveling operation lever that can be operated by the driver, a first pressure reducing valve that operates in response to a front operation of the traveling operation lever, and a rear operation of the traveling operation lever. It has a second pressure reducing valve that operates accordingly. The first pressure reducing valve uses the discharge pressure of the pilot pump 27 as the main pressure to generate a pilot pressure corresponding to the amount of operation on the front side of the traveling operation lever, and the generated pilot pressure is used on one side of the right traveling control valve 28. Output to the pressure receiving part. As a result, the right side traveling control valve 28 is switched from the neutral position to the switching position on one side, and the right side traveling motor 8 is rotated in one direction. The second pressure reducing valve uses the discharge pressure of the pilot pump 27 as the main pressure to generate a pilot pressure corresponding to the rear operation amount of the traveling operation lever, and the generated pilot pressure is used as the other side of the right traveling control valve 28. Output to the pressure receiving part of. As a result, the right side traveling control valve 28 is switched from the neutral position to the other side switching position, and the right side traveling motor 8 is rotated in the opposite direction.

Although not shown, the operation lever device 31 is used for a work operation lever that can be operated by the driver, a third pressure reducing valve that operates in response to a front operation of the work operation lever, and a rear operation of the work operation lever. It has a fourth pressure reducing valve that operates accordingly. The third pressure reducing valve uses the discharge pressure of the pilot pump 27 as the main pressure to generate a pilot pressure corresponding to the amount of operation on the front side of the working operation lever, and the generated pilot pressure is used as the pressure received on one side of the boom control valve 29. Output to the unit. As a result, the boom control valve 29 is switched from the neutral position to the switching position on one side, and the boom cylinder 14 is shortened. The fourth pressure reducing valve uses the discharge pressure of the pilot pump 27 as the main pressure to generate a pilot pressure corresponding to the amount of operation on the rear side of the working operation lever, and the generated pilot pressure is used on one side of the boom control valve 29. Output to the pressure receiving part. As a result, the boom control valve 29 is switched from the neutral position to the switching position on the other side, and the boom cylinder 14 is extended.

The operating lever devices 30 and 31 constitute an operating device that generates a pilot pressure corresponding to the operating amount of the operating lever and switches the control valve according to the generated pilot pressure. Although not shown, the configurations of the left-side traveling motor, the blade cylinder, the swing cylinder, the arm cylinder 15, the bucket cylinder 16, the optional hydraulic actuator, and the swivel motor are almost the same.

A pilot relief valve 33 and a lock valve 34 are provided on the discharge side of the pilot pump 27. The pilot relief valve 33 is opened when the discharge pressure of the pilot pump 27 is equal to or higher than the relief pressure, and a part of the pressure oil discharged from the pilot pump 27 is returned to the tank. As a result, the discharge pressure of the pilot pump 27 is maintained at the relief pressure.

The lock valve 34 is switched according to the operation of the gate lock lever described above. Specifically, a lock switch (not shown) is provided that opens when the gate lock lever is in the lowered position and opens when the gate lock lever is in the raised position. Then, when the lock switch is closed, the solenoid portion of the lock valve 34 is energized via the lock switch, and the lock valve 34 is switched from the neutral position to the switching position. As a result, the discharge line of the pilot pump 27 is communicated, and the discharge pressure of the pilot pump 27 is introduced into the operation lever devices 30, 31 and the like. On the other hand, when the lock switch is opened, the solenoid portion of the lock valve 34 is not energized, and the lock valve 34 is in the neutral position due to the urging force of the spring. As a result, the discharge line of the pilot pump 27 is cut off. As a result, even if the operating lever devices 30, 31 and the like are operated, the pilot pressure is not generated and the plurality of hydraulic actuators do not operate.

A flood control signal line 35 is connected to the discharge side of the pilot pump 27. The hydraulic signal line 35 is connected between the discharge side of the pilot pump 27 and the tank 36, and has a plurality of control valves (specifically, not only the right side traveling control valve 28 and the boom control valve 29 described above, but also illustrated. Not including left-side running control valve, blade control valve, swing post control valve, arm control valve, bucket control valve, optional control valve, and turning control valve), and all controls When the valve is in the neutral position, the communication state is set, and when any of the control valves is switched from the neutral position, the shutoff state is set.

A fixed throttle 37 is provided between the discharge side of the pilot pump 27 and the plurality of control valves in the hydraulic signal line 35. Then, the pressure sensor 38 (first pressure sensor) that detects the hydraulic pressure on the upstream side of the fixed throttle 37 and the pressure that detects the hydraulic pressure on the downstream side of the fixed throttle 37 (in other words, between the fixed throttle 37 and the control valve). A sensor 39 (second pressure sensor) is provided.

The rotation speed indicator 22 makes it possible to indicate the standard rotation speed of the electric motor 23 within a predetermined range (specifically, for example, 2000 to 1500 rpm) by the rotation operation position of the dial, and outputs a signal corresponding to this. The control device 32 sets the standard rotation speed of the electric motor 23 in response to the signal from the rotation speed indicator 22, and controls the inverter 25 so that the rotation speed of the electric motor 23 becomes the standard rotation speed.

Further, in the control device 32, when all the operating devices are not operated for a predetermined time, the rotation speed of the electric motor 23 is set to be lower than the idle rotation speed (specifically, the standard rotation speed described above). The inverter 25 is controlled so as to have a set low-speed rotation speed (auto idle control). Here, the most important feature of the present embodiment is that the control device 32 detects the operating states of the plurality of operating devices based on the detection results of the pressure sensors 38 and 39. More specifically, the control device 32 operates a plurality of operating devices based on the differential pressure between the oil pressure detected by the pressure sensor 38 and the oil pressure detected by the pressure sensor 39 (hereinafter referred to as the differential pressure of the fixed throttle 37). Detect the condition.

When all the operating devices are not operated (that is, when all the control valves are in the neutral position), the hydraulic signal line 35 is in a continuous state, so that the differential pressure of the fixed throttle 37 becomes large. On the other hand, when any of the operating devices is operated (that is, when any of the control valves is switched from the neutral position), the hydraulic signal line 35 is shut off, so that the differential pressure of the fixed throttle 37 is increased. It becomes small to near zero. When the differential pressure of the fixed throttle 37 is equal to or higher than a preset threshold value, the control device 32 determines that all the operating devices are not operated. Then, when the state in which all the operating devices are not operated continues for a predetermined time, the rotation speed of the electric motor 23 is reduced to the idle rotation speed. Further, the control device 32 determines that any of the operating devices is being operated when the differential pressure of the fixed throttle 37 is less than the threshold value. Then, the rotation speed of the electric motor 23 is maintained or restored to the standard rotation speed.

Next, the processing procedure of the control device of this embodiment will be described. FIG. 4 is a flowchart showing a processing procedure of the control device according to the present embodiment. The process shown in FIG. 4 is assumed to be executed periodically.

In step S1, the control device 32 calculates the differential pressure of the fixed throttle 37 based on the detection results of the pressure sensors 38 and 39. Then, the process proceeds to step S2, and it is determined whether or not the differential pressure of the fixed throttle 37 is equal to or greater than the threshold value. If the differential pressure of the fixed throttle 37 is equal to or greater than the threshold value (that is, all the operating devices are not operated), the process proceeds to step S3.

In step S3, the control device 32 determines whether or not the rotation speed of the electric motor 23 is controlled by the idle rotation speed (in other words, whether or not the electric motor 23 is in the idle state). If the rotation speed of the electric motor 23 is not controlled by the idle rotation speed (in other words, the electric motor 23 is not in the idle state), the process proceeds to step S4.

In step S4, the control device 32 counts up the non-operation duration. Then, the process proceeds to step S5, and it is determined whether or not the non-operation duration has reached the predetermined time.

If the non-operation duration has not reached the predetermined time in step S5, the process proceeds to step S6. In step S6, the control device 32 drives the electric motor 23 at a standard rotation speed. On the other hand, when the non-operation duration reaches the predetermined time in step S5, the process proceeds to step S7. In step S7, the control device 32 drives the electric motor 23 at an idle speed. If the rotation speed of the electric motor 23 is controlled to the idle rotation speed in step S3 (in other words, the electric motor 23 is in the idle state), the process proceeds to step S7 without going through steps S4 and S5 described above.

If the differential pressure of the fixed throttle 37 is less than the threshold value in step S2 (that is, one of the control valves is operated), the process proceeds to step S6 described above via step S8. In step S8, the control device 32 counts and clears the non-operation duration.

As described above, in the present embodiment, the control device 32 calculates the differential pressure of the fixed throttle 37 based on the detection results of the pressure sensors 38 and 39, and detects the operating state of the plurality of operating devices based on the differential pressure. To do. The differential pressure of the fixed throttle 37 used in the present embodiment can suppress the influence of the rotation speed of the electric motor 23 and the like as compared with the hydraulic pressure on the downstream side of the fixed throttle 37 used in the prior art. More specifically, when the rotation speed of the electric motor 23 is low and the oil pressure on the upstream side of the fixed throttle 37 is low, or when the pressure loss of the portion from the fixed throttle 37 to the tank 36 in the hydraulic signal line 35 is high, the fixed throttle 37 Even when the flood pressure on the downstream side becomes high, the differential pressure of the fixed throttle 37 when any of the operating devices is operated decreases to near zero, and the differential pressure when all the operating devices are not operated is large. Become. Therefore, it is possible to easily set a threshold value for determining the operating state of a plurality of operating devices. Further, even if the idle speed of the electric motor 23 is set low, the operating state of the operating device can be detected. Therefore, the idle speed of the electric motor 23 can be set low.

In the above embodiment, the control device 32 calculates the differential pressure of the fixed throttle 37 (specifically, the differential pressure between the oil pressure detected by the pressure sensor 38 and the oil pressure detected by the pressure sensor 39). The case where the operating state of a plurality of operating devices is determined by comparing the differential pressure with the threshold value has been described as an example, but the present invention is not limited to this. The control device adds a predetermined differential pressure to the oil pressure detected by the pressure sensor 39 to set a threshold value, compares the oil pressure detected by the pressure sensor 38 with the threshold value, and determines the operating state of a plurality of operating devices. You may. Even in such a modified example, the same effect as described above can be obtained.

Further, in the above embodiment, the operation lever device uses the discharge pressure of the pilot pump 27 as the original pressure to generate a pilot pressure corresponding to the operation amount of the operation lever, and outputs the generated pilot pressure to the pressure receiving portion of the control valve. The case where the pressure reducing valve is provided (in other words, the operating device for switching the control valve is composed of only the operating lever device) has been described as an example, but the present invention is not limited to this. The operation lever device may have, for example, a potentiometer that detects the operation amount of the operation lever and outputs a corresponding electric operation signal. Then, the control device generates a command current in response to the electric operation signal from the operation lever device and outputs the command current to the electromagnetic proportional valve. The electromagnetic proportional valve uses the discharge pressure of the pilot pump 27 as the main pressure to generate a pilot pressure corresponding to the command current from the control device, and outputs the generated pilot pressure to the pressure receiving portion of the control valve. That is, the operation device for switching the control valve may be composed of an operation lever device, a control device, and an electromagnetic proportional valve. Even in such a modified example, the same effect as described above can be obtained.

Further, in the above-described embodiment, the hydraulic excavator has been described by taking the case where the electric motor 23 is provided as the prime mover as an example, but the present invention is not limited to this, and the hydraulic excavator may be provided with an engine.

In the above description, the hydraulic excavator has been described as an example of application of the present invention, but the present invention is not limited to this, and other construction machines such as wheel loaders may be used.

8 Right-side traveling motor 14 Boom cylinder 15 Arm cylinder 16 Bucket cylinder 23 Electric motor (motor)
26 Hydraulic pump 27 Pilot pump 28 Right side running control valve 29 Boom control valve 30 Operation lever device 31 Operation lever device 32 Control device 33 Pilot relief valve 35 Hydraulic signal line 36 Tank 37 Fixed throttle 38 Pressure sensor (first pressure sensor) )
39 Pressure sensor (second pressure sensor)

Claims (3)

A prime mover, a hydraulic pump driven by the prime mover, a hydraulic actuator, a control valve for controlling the flow of pressure oil from the hydraulic pump to the hydraulic actuator, and a pilot pressure corresponding to the operation amount of the operation lever are generated. The control device is provided with an operating device for switching the control valve according to the generated pilot pressure, and a control device for controlling the rotation speed of the prime mover to a preset idle rotation speed when the non-operating state of the operating device continues. In construction machinery
A pilot pump that is driven by the prime mover and whose discharge pressure is used as the source pressure for the pilot pressure.
A pilot relief valve provided on the discharge side of the pilot pump and
A hydraulic signal line that is connected between the discharge side of the pilot pump and the tank and is interrupted when the control valve is interposed and the control valve is switched from the neutral position.
A fixed throttle provided between the discharge side of the pilot pump and the control valve in the hydraulic signal line, and
A first pressure sensor that detects the flood pressure on the upstream side of the fixed throttle, and
A second pressure sensor for detecting the oil pressure on the downstream side of the fixed throttle is provided.
The control device is a construction machine characterized in that it detects an operating state of the operating device based on the detection results of the first pressure sensor and the second pressure sensor. In the construction machine according to claim 1,
The control device is constructed, characterized in that the operating state of the operating device is detected based on the differential pressure between the oil pressure detected by the first pressure sensor and the oil pressure detected by the second pressure sensor. machine. In the construction machine according to claim 1,
The prime mover is a construction machine characterized by being an electric motor.

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