JP7366811B2 - work equipment - Google Patents

Description

The present invention relates to a working machine.

BACKGROUND ART Working machines such as lawn mowers have been proposed that use a motor as a driving source for a working part. If the motor reaches an overload condition, it can cause the work equipment to malfunction. In such cases, power supply to the motor is cut off (for example, Patent Document 1).

JP2011-92178A

In a working machine that uses an internal combustion engine as a driving source for a working part, a worker can easily recognize the load state of the working part by changes in noise. However, in working equipment that uses a motor as the drive source, the change in noise depending on the load condition is small, making it difficult for workers to recognize the load condition, and giving the impression that the motor suddenly stops when an overload condition occurs. There is.

An object of the present invention is to provide a working machine that allows an operator to easily recognize the load state of a motor.

According to the invention,
Multiple working parts powered by motors,
A control means for controlling each motor of the plurality of working parts,
The control means includes:
When the load of any one of the motors reaches a first load, changing the rotation speed of at least one of the motors to generate a humming sound;
A working machine is provided.

According to the present invention, it is possible to provide a working machine in which a worker can easily recognize the load state of a motor.

FIG. 1 is a plan view of a work machine according to an embodiment of the present invention. FIG. 2 is a block diagram of the configuration of the electrical system of the work machine shown in FIG. 1. FIG. 3 is a flowchart showing an example of processing executed by the control unit in FIG. 2. FIG. (A) and (B) are diagrams showing changes in the rotational speed of the motor, and (C) are diagrams showing changes in beat sound. (A) and (B) are diagrams showing another change in the rotation speed of the motor, and (C) is a diagram showing another change in the beat sound. (A) to (C) are diagrams showing other changes in the rotation speed of the motor.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the claimed invention, and not all combinations of features described in the embodiments are essential to the invention. Two or more features among the plurality of features described in the embodiments may be arbitrarily combined. In addition, the same or similar configurations are given the same reference numerals, and duplicate explanations will be omitted.

<Work equipment configuration>
FIG. 1 is a plan view of a working machine 1 according to an embodiment of the present invention. The working machine 1 is a walking lawn mower that is mowed by a worker while pushing the working machine 1. The work machine 1 includes a main body 2. The main body 2 is provided with a total of four wheels 3 arranged on the left, right, front, and rear, and the main body 2 is driven by human power by rolling the wheels 3. A handle 4 is provided at the rear of the main body 2. The operator holds the handle 4 and moves the work machine 1 . The handle 4 is provided with an operating section 5. The operator can issue instructions to drive the working unit 6 by operating the operating unit 5 . The operation unit 5 includes sensors such as switches that detect operations by the operator.

In the case of this embodiment, three working sections 6 are provided. Each working section 6 includes a motor 7 mounted on the main body 2, and uses the motor 7 as a driving source. Each working part 6 has a blade 8 attached to the output shaft of a motor 7. The output shaft of the motor 7 is oriented in the vertical direction, and the blade 8 rotates on a horizontal plane below the main body 2 to mow the grass on the ground. The rotation centers of the three blades 8 (the arrangement of the three motors 7 ) are located at each vertex of the triangle, one of which is located at the front at the center of the vehicle width, and the remaining two are located at the front in the vehicle width direction. It is located at a distance from the rear.

The main body 2 is equipped with a battery 9 and a control unit 10 . The battery 9 is a power source that supplies power to the motor 7 and the like. The control unit 10 is an electric circuit that controls the work machine 1.

FIG. 2 is a block diagram of the electrical system of the working machine 1. The control unit 10 includes a processor represented by a CPU, a storage device such as a semiconductor memory, an input/output interface with an external device, a drive circuit for the motor 7, and the like. The storage device stores programs executed by the processor, data used by the processor for processing, and the like.

The control unit 10 drives the motor 7 when an operation on the operation unit 5 is detected. Although the motor 7 is an AC motor in this embodiment, it may be a DC motor. Each motor 7 is individually provided with a rotation speed sensor 12 that detects the rotation speed (rotational speed) of its output shaft. The rotation speed sensor 12 is, for example, a rotary encoder. The control unit 10 controls the number of rotations (rotational speed) of each motor 7 based on the detection result of the rotation number sensor 12, for example, by PWM control. Each motor 7 is also individually provided with a current sensor 11. Current sensor 11 detects the current supplied to motor 7. The control unit 10 determines the load of each motor 7 from the detection result of the current sensor 11.

<Control example>
An example of processing executed by the processor of the control unit 10 will be described. The control unit 10 drives each motor 7 in response to an operation on the operation section 5. Each motor 7 is basically driven at a constant rotation speed. In areas with dense grass, etc., the load on the motor 7, which is the drive source of the working section 6, increases. When the motor 7 becomes overloaded, the control unit 10 stops driving the motor 7. In order to prevent the motor 7 from suddenly stopping, this embodiment issues an alert to the operator when the load reaches a threshold value. As the alert, a humming sound caused by the difference in rotational speed between the motors 7 is used.

FIG. 3 is a flowchart showing an example of processing executed by the processor of the control unit 10. The control unit 10 executes the process shown in the figure while the operator instructs the operation section 5 to drive each working section 6 .

In S1, all motors 7 are driven at a predetermined rotation speed. In S2, the load on each motor 7 is determined. In this embodiment, the load is determined based on the detection result of the current sensor 11 of each motor 7. In S3, it is determined whether the load of each motor 7 determined in S2 has reached the threshold value TH1. More specifically, it is determined whether the current value of any one motor 7 is equal to or greater than a threshold value TH1.

If the loads on all motors 7 are less than the threshold value TH1, the process returns to S1 and all motors 7 continue to be driven at a constant rotation speed. If the load on any one motor 7 is equal to or greater than the threshold value TH1, the process advances to S4. In S4, it is determined whether the load of each motor 7 determined in S2 has reached a threshold value TH2 (>TH1). More specifically, it is determined whether the current value of any one motor 7 is equal to or greater than a threshold value TH2. If the loads on all the motors 7 are less than the threshold value TH2, the process advances to S5 and rotation speed change control is performed. If the load on any one motor 7 is equal to or greater than the threshold value TH2, the process advances to S6, where the supply of electric power to each motor 7 is stopped, and the rotation of all motors 7 is stopped.

In the rotational speed change control of S5, the rotational speed of at least one of the motors 7 is changed to generate a humming sound. FIGS. 4(A) and 4(B) show an example of rotation speed change control. In the case of this embodiment, the rotation speed of one motor 7 is changed as illustrated in FIG. 4(A), and the rotation speeds of the remaining two motors 7 are maintained as illustrated in FIG. 4(B). The rotational speed V is the rotational speed at constant speed controlled by S1.

In the example of FIG. 4(A), the rotation speed is intermittently changed in accordance with an increase in the load on the motor 7. More specifically, when the load on the motor 7 becomes equal to or greater than the threshold value TH1, the rotation speed is reduced. When the load on the motor 7 increases, the rotation speed is returned to V. When the load on the motor 7 further increases, the rotation speed is reduced again. After that, the process is repeated as the load increases.

When the rotational speed of one motor 7 is varied in this way, a humming sound can be generated as shown in FIG. 4(C) due to the rotational speed difference between the two motors 7 that rotate at a constant speed. This humming noise is caused by resonance of vibrations in or around the motor 7 due to the rotational speed of the motor 7. As shown in FIG. 4A, since the rotational speed is changed intermittently as the load on the motor 7 increases, the intensity of the humming noise also varies as the load on the motor 7 increases. When the load on any one motor 7 becomes equal to or greater than the threshold value TH2, all motors 7 are stopped.

The operator can recognize that the load is increasing from the whirring sound before all motors 7 are stopped due to overload. By issuing an alert with a buzzing sound that utilizes the difference in rotational speed between the motors 7, a dedicated device such as a display or a speaker is not required.

Note that the changing rotation speed of the motor 7 can be specified through prior experiments. At the time of identification, if the generated beat sound has a frequency of about 1 Hz to 10 Hz, it will be easily recognized by the operator. Further, the motor 7 whose rotational speed is to be changed as shown in FIG. 4(A) may be the motor 7 whose load has reached the threshold value TH1, or may be another motor 7. In a configuration in which three motors 7 are arranged at each vertex of a triangle as in this embodiment, the rotation speed of the front motor 7 may be changed, and the rotation speed of the two rear motors 7 may be maintained. It is possible to prevent large deviations in lawn mowing ability between the left and right sides.

<Other example 1 of change control>
The change pattern in the rotation speed change control in S5 is not limited to the example shown in FIG. 4(A). FIGS. 5A and 5B show another example of rotation speed change control. In this example, the rotation speed of one motor 7 is changed as illustrated in FIG. 5(A), and the rotation speeds of the remaining two motors 7 are maintained as illustrated in FIG. 5(B).

In the example of FIG. 5(A), the rotation speed is continuously changed according to an increase in the load on the motor 7. More specifically, when the load on the motor 7 becomes equal to or greater than the threshold value TH1, the rotation speed is reduced. As the load on the motor 7 increases, the rotational speed is continuously increased so as to approach V.

When the rotational speed of one motor 7 is varied in this manner, a humming sound can be generated as shown in FIG. 5(C) due to the rotational speed difference between the two motors 7 that rotate at a constant speed. In the example of FIG. 5(C), the volume of the humming sound is changing. It is also possible to vary the frequency of the beat.

In the example of FIG. 5(A), the rotation speed is made to increase continuously as the load on the motor 7 increases, but it may be made to decrease conversely. At this time, when the load on the motor 7 becomes equal to or higher than the threshold value TH1, the rotation speed may be increased above V and then lowered so as to approach V.

<Other example 2 of change control>
In the examples of FIGS. 4(A) and 5(A), the rotation speed of one of the three motors 7 is changed, but it is also possible to change the rotation speed of two or all motors 7. Good too. At this time, the manner of changing the rotation speed of the motor 7 may be different between the motors. 6(A) to 6(C), the rotation speed of two of the three motors 7 is changed (FIGS. 6(A) and 6(B)), and the rotation speed of the remaining one motor 7 is changed. The numbers indicate an example in which the voltage is maintained at V (FIG. 6(C)) .

In the example of FIG. 6(A), similarly to the example of FIG. 4(A), when the load on the motor 7 becomes equal to or greater than the threshold value TH1, the rotation speed is reduced. When the load on the motor 7 increases, the rotation speed is returned to V. When the load on the motor 7 further increases, the rotation speed is reduced again. After that, the process is repeated as the load increases. In the example of FIG. 6(B), the change in rotation speed is reversed from that of FIG. 6(A). When the load on the motor 7 becomes equal to or greater than the threshold value TH1, the rotation speed is increased. When the load on the motor 7 increases, the rotation speed is returned to V. When the load on the motor 7 further increases, the rotation speed is increased again. After that, the process is repeated as the load increases.

<Other embodiments>
In the above embodiment, the working machine 1 is illustrated as having three working parts 6, but the number of working parts 6 (the number of motors 7) may be two or four or more. . Further, in the above embodiment, a walking lawn mower is exemplified as the working machine 1, but other types of lawn mowers such as a riding lawn mower may be used.Furthermore, a snow blower equipped with a plurality of augers as the working part, a working part Other types of work machines, such as a street sweeper equipped with a plurality of cleaning sections, may also be used.

<Summary of embodiments>
1. The work machine (1) of the above embodiment is
A plurality of working parts (6) using a motor (7) as a driving source,
A control means (10) for controlling each motor (7) of the plurality of working parts (6),
The control means (10) includes:
When the load of any one of the motors reaches the first load (TH1), the rotational speed of at least one of the motors is changed to generate a humming sound (S5).
According to this embodiment, it is possible to provide a working machine in which the operator can easily recognize the load state of the motor. Generating a humming sound eliminates the need for a dedicated display or speaker.

2. In the above embodiment,
The control means stops supplying power to each of the motors when the load of any one of the motors reaches a second load (TH2) that is larger than the first load (TH1) (S6). .
According to this embodiment, when the motor reaches an overload state, it can be stopped, and the operator can be informed by a humming sound that the load is increasing before the motor reaches an overload state.

3. The work machine (1) of the above embodiment is
comprising a sensor (11) that detects the current supplied to each motor (7),
The control means (10) determines the load of the motor based on the detection result of the sensor.
According to this embodiment, the load can be determined by the sensor.

4. In the above embodiment,
The control means (10) includes:
Each motor is controlled to the same rotation speed until the load on any one of the motors (7) reaches the first load (TH1) (S1).
According to this embodiment, each working part is normally driven under the same conditions so that there is virtually no whining noise, making it easier for the worker to recognize the occurrence of whining noise due to an increase in motor load. .

5. In the above embodiment,
The control means (10) includes:
After the load on any one of the motors reaches the first load, the rotation speed of at least one of the motors is intermittently changed in accordance with the increase in the load on the motor.
According to this embodiment, the generation of the humming noise becomes intermittent as the load increases, and it is possible to make it easier for the operator to recognize the generation of the humming noise.

6. In the above embodiment,
The control means (10) includes:
After the load on any one of the motors reaches the first load, the rotation speed of at least one of the motors is continuously changed in accordance with the increase in the load on the motor.
According to this embodiment, the volume or frequency of the whining sound changes as the load increases, making it easier for the operator to recognize the occurrence of the whining sound.

Although the embodiments of the invention have been described above, the invention is not limited to the above embodiments, and various modifications and changes can be made within the scope of the gist of the invention.

1 Working machine, 6 Working part, 7 Motor, 10 Control unit

Claims (6)

Multiple working parts powered by motors,
A control means for controlling each motor of the plurality of working parts,
The control means includes:
When the load of any one of the motors reaches a first load, changing the rotation speed of at least one of the motors to generate a humming sound;
A work machine characterized by: The working machine according to claim 1,
The control means stops supplying power to each of the motors when the load of any one of the motors reaches a second load that is larger than the first load.
A work machine characterized by: The working machine according to claim 1 or claim 2,
comprising a sensor that detects the current supplied to each of the motors,
The control means determines the load of the motor based on the detection result of the sensor.
A work machine characterized by: The working machine according to any one of claims 1 to 3,
The control means includes:
controlling each of the motors to the same rotation speed until the load of any one of the motors reaches the first load;
A work machine characterized by: The working machine according to any one of claims 1 to 4,
The control means includes:
After the load on any one of the motors reaches the first load, the rotation speed of at least one of the motors is intermittently changed in accordance with the increase in the load on the motor.
A work machine characterized by: The working machine according to any one of claims 1 to 4,
The control means includes:
After the load on any one of the motors reaches the first load, the rotation speed of at least one of the motors is continuously changed according to the increase in the load on the motor.
A work machine characterized by:

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