work machine

Abstract

Working machine which features: an engine; a work unit designed to be driven by the motor; a coupling which is provided between an output shaft of the motor and a drive shaft of the working unit, and is designed to transmit power from the output shaft of the motor to the drive shaft or to interrupt the transmission; a sensor designed to detect the engine speed; and a control unit designed to control the motor and clutch based on the engine speed, the control unit features: a prediction unit designed to predict, based on the motor speed detected by the sensor, whether the working unit will be blocked by a load; and a clutch control unit designed to control the clutch to transition from a transmission state to an interruption state in response to the prediction unit's forecast that the working unit will become blocked, wherein in a case where the reduction amount of the motor speed detected by the sensor is greater than a first limit value, the prediction unit predicts that the working unit will be blocked, characterized in that the working machine further features, a power generator / motor designed to drive the output shaft of the motor and to generate electricity by being driven by the motor being driven; and a battery designed to be charged with electricity generated by the generator / engine when the generator / engine is operating as a generator, and to supply electricity to the generator / engine when the generator / engine is operating as a motor, In a case where the reduction in the motor speed detected by the sensor is less than the first limit but greater than a second limit, the control unit causes the battery to supply power to the generator / motor in order to cause the generator / motor to assist the motor.

Description

TECHNICAL APPLICATION AREA

[0001] The present invention relates to a working machine which is driven by a motor. BACKGROUND OF THE TECHNOLOGY

[0002] Patent literature 1 describes a motor-driven machine in which a generator can be used as a motor. Specifically, patent literature 1 describes a design in which, depending on the change in the throttle opening, the generator can be driven by the electric motor to generate electricity, or it can be powered by a battery, so that the generator functions as an electric motor to assist the motor.

[0003] EP 1 859 666 A1 describes a power transmission control mechanism of a lawn mower in which the power of an internal combustion engine is transmitted to a mower blade via an electromagnetic clutch.

[0004] US 2017 / 0265381 A1 describes a power machine with a multi-cylinder internal combustion engine configured to selectively disable at least one of several cylinders.

[0005] US 2012 / 0227368 A1 describes a moving work vehicle, wherein the work vehicle includes an override speed control to control an electric motor unit at an override speed. LIST OF CITED LITERATURE

[0006] PTL1: Japanese publicly disclosed patent publication no. JP 2004 - 266 933 A OVERVIEW OF THE INVENTIONAL PROBLEM STATEMENT

[0007] When a heavy load is suddenly applied to a working machine, a working unit or motor may stop. For example, if the blades of a mower strike a foreign object, such as a stone, the mower blades will stop. This phenomenon is called a blade jam. In a working machine such as a snowplow or a plow, a sudden application of a heavy load to a working unit will likewise stop the working unit and its motor. Such a blade jam can damage parts of the motor and the blades, and therefore it is desirable to avoid a blade jam whenever possible. In light of this, an objective of the present invention is to provide a working machine that can reduce damage to the working unit and the motor. SOLUTION TO THE PROBLEM

[0008] The present invention provides, for example, a working machine which is designed by having: an engine; a work unit designed to be driven by the motor; a coupling which is provided between an output shaft of the motor and a drive shaft of the working unit, and is designed to transfer power from the output shaft of the motor to the drive shaft and to interrupt the power transmission; a sensor designed to detect the engine speed; and a control unit designed to control the motor and clutch based on the engine speed, the control unit features: a prediction unit designed to predict, based on the motor speed detected by the sensor, whether the working unit will be blocked by a load; and a clutch control unit designed to control the clutch to transition from a transmission state to an interruption state in response to the prediction unit's forecast that the working unit will become blocked, wherein in a case where the reduction amount of the motor speed detected by the sensor is greater than a first limit value, the prediction unit predicts that the working unit will be blocked, characterized in that the working machine further features, a power generator / motor designed to drive the output shaft of the motor and to generate electricity by being driven by the motor being driven; and a battery designed to be charged with electricity generated by the generator / engine when the generator / engine is operating as a generator, and to supply electricity to the generator / engine when the generator / engine is operating as a motor, In a case where the reduction in the motor speed detected by the sensor is less than the first limit but greater than a second limit, the control unit causes the battery to supply power to the generator / motor in order to cause the generator / motor to assist the motor. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0009] According to the present invention, a working machine is provided which can reduce damage to the working unit and the motor. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a cross-sectional view that represents a design example of a working machine. Fig. Figure 2 is a block diagram representing a control system for the working machine. Fig. Figure 3 is a block diagram representing a control system for the working machine. Fig. Figure 4 is a flowchart that illustrates a procedure for controlling the working machine. Fig. Figure 5 is a flowchart that illustrates a work process control in detail. DESCRIPTION OF THE EXECUTION FORMS

[0010] In the following, embodiments of the present invention are described with reference to the drawings in the appendix. It should be emphasized that the drawings schematically depict the structures and configurations of the embodiments, and therefore the sizes of the elements and units shown here do not reflect their actual sizes. Furthermore, similar elements in the drawings are designated with similar reference numerals, and any redundant descriptions are simplified or omitted. work machine

[0011] Fig. Figure 1 is a cross-sectional view of a working machine according to one embodiment. In one embodiment, a mowing machine 1 is taken as an example of the working machine. The mowing machine 1 can be any type of remotely controlled machine, operated remotely by a user; an autonomous type, requiring no user operation; a push type, pushed by a user walking behind the mowing machine 1; or a ride type, driven by a user sitting on the mowing machine 1.

[0012] The mower 1 has a motor 2. The motor 2 has a crankshaft 3a, which projects upwards (rearwards) relative to the motor 2, and a crankshaft 3b, which projects downwards (frontwards) relative to the motor 2. The crankshafts 3a and 3b are connected or integrated within the motor 2, enabling them to rotate together. The crankshaft 3b is an output shaft of the motor 2.

[0013] A coupling 4 is provided between the crankshaft 3b and a drive shaft 5 of a working unit and is designed to transmit power from the crankshaft 3b to the drive shaft 5 or to interrupt the transmission. The coupling 4 can be any type of coupling, such as an electromagnetic coupling, as long as the coupling can be switched between a transmission state and an interruption state by a control unit 10. Blades 6 are an example of a working unit and have blades (cutting blades) for mowing meadows, which are a work objective. The blades 6 are driven and rotated by the motor 2, thereby mowing the meadows. The cut grass is thrown by a thrower 13 by an airflow generated by the rotation of the blades 6 and collected in a collection unit 14 above the thrower 13.

[0014] A BSG 7 is a power generator / motor for starting engine 2 by driving the crankshaft 3a of engine 2 and for generating electricity by being driven by the started engine 2. The term "BSG" stands for belt-driven starter generator. The BSG 7 is designed to transmit power to the crankshaft 3a via a transmission mechanism, such as a belt or a gear, and to receive power from the crankshaft 3a via the same transmission mechanism. A power supply circuit 15 includes circuits for converting the alternating current generated by the BSG 7 into direct current and for charging a 48 V battery 8 or a 12 V battery 11 (an AC / DC converter, an inverter, and a DC converter). The 48V battery 8 and the 12V battery 11 are designed to be charged with the current generated by the BSG 7 when the BSG 7 is operating as a power generator.The 48V battery 8 is designed to supply power to the drive motors 9. The drive motors 9 are designed to drive and rotate their respective wheels 12. Furthermore, the 48V battery 8 is an example of a battery used to supply power to the BSG 7 when the BSG 7 is operating as a motor. The control unit 10 can be designed to drive the motor 2, to supply power to the BSG 7 from the 48V battery, thus starting the motor 2 (start function) or assisting the motor 2 after it has started (torque assist function). The 12V battery 11 is designed to supply power to the control unit 10. tax system

[0015] Fig. Figure 2 shows a control system for the working machine. The control unit 10 has a CPU 24 and memory 25, such as RAM and ROM. It should be noted that the CPU 24 can have one or more processors. The ROM of the memory 25 stores a control program or similar data. The CPU 24 has a drive control unit 26, a work operation control unit 27, and a motor control unit 28. The drive control unit 26 is designed to control the drive unit 20, thus causing the mower 1 to move. The drive unit 20 can have a drive motor 9L to drive a wheel 12L on a left front side of the mower 1, and a drive motor 9R to drive a wheel 12R on a right front side of the mower 1.It should be emphasized that, instead of or in conjunction with wheel 12L on the front left side and wheel 12R on the front right side, the drive motors 9L and 9R can each be configured to drive one wheel located on the left rear side of the mower 1 and one wheel located on the right rear side of the mower 1. The configuration in which the drive motors 9L and 9R each rotate the different wheels 12 enables the mower 1 to turn. For example, if the rotational speed of wheel 12L is lower than that of wheel 12R, the mower 1 turns to the left. The mower 1 also turns if wheel 12L and wheel 12R rotate in opposite directions. The work operation control unit 27 is configured to control an operating unit 21. The operating unit 21 includes the BSP 7, the motor 2, the clutch 4 and the blades 6.The engine control unit 28 is designed to control a power supply device 41 to supply fuel to the engine 2 or not, and to control an ignition device 42 to ignite an air-fuel mixture that is compressed in a cylinder of the engine 2.

[0016] A power supply unit 30 comprises the power supply circuit 15, the 12 V battery 11, and the 48 V battery 8. The voltages supplied by the 12 V battery 11 and the 48 V battery 8 are only examples. The 12 V battery 11 and the 48 V battery 8 can be integrated into a single battery.

[0017] A sensing unit 22 includes a crank angle sensor 23 configured to detect a rotation angle (crank angle) of the crankshaft 3b of the engine 2. The engine control unit 28 is configured to detect or calculate an engine speed of the engine 2 based on a pulse signal output by the crank angle sensor 23. The crank angle sensor 23 can also be referred to as an engine speed sensor, since it is designed to indirectly detect the engine speed of the engine 2.

[0018] Fig. Figure 3 details the operation control unit 27 and the engine control unit 28. The engine control unit 28 includes an engine speed calculation unit 51, configured to calculate the engine speed of the engine 2 based on the pulse signal output by the crankshaft angle sensor 23. A fuel supply control unit 57 is configured to control the fuel-air ratio in the air-fuel mixture (air-fuel ratio) so that it remains at a specific value based on the oxygen concentration detected by an O2 sensor or similar device. The ignition control unit 58 is configured to control the ignition timing of the ignition device 42 based on a pulse signal output by the crankshaft angle sensor 23. The engine control unit 28 can be configured to adjust a target engine speed of the engine 2 by adjusting the throttle valve opening of the engine 2.

[0019] The work process control unit 27 has a prediction unit 50 designed to predict, based on the motor speed of motor 2 detected by the crank angle sensor 23, whether a load will block the blades 6, which serve as the working unit. Generally, a garden or field of grass has a mixture of areas with high grass density and areas with low grass density. In addition, there may be plants with thicker stems than grass or obstacles (for example, stones, rocks, dead trees, stumps, and the like) in the garden or field. If the amount of grass in contact with the blades 6 increases, the load exerted on motor 2 increases, thereby reducing the motor speed of motor 2. Furthermore, if an obstacle touches the blades 6, the motor speed of motor 2 is reduced to stop motor 2.Such a condition, in which motor 2 is stopped, is referred to as a "blockage." Specifically, in the technical field of the mower 1, this phenomenon is called a blade blockage. When a blade blockage occurs, a portion of the blades 6 can break off or shatter. Furthermore, such a blade blockage also exerts an excessive load on parts of motor 2, causing them to be negatively affected. Therefore, when the CPU 24 detects an impending blade blockage, it causes the clutch 4 to be switched from the transmission state to the disengaged state. This reduces the potential damage to the blades 6 or motor 2.

[0020] The prediction unit 50 includes a reduction amount calculation unit 52, which is configured to calculate a reduction amount ΔNe of a motor speed Ne of motor 2. For example, the reduction amount calculation unit 52 can be configured to sample the speed Ne of motor 2 at a specific interval and to calculate the reduction amount ΔNe as the difference between a motor speed Ne_i, which is the motor speed sampled at the i-th time, and a motor speed Ne_i+1, which is the motor speed sampled at the i+1-th time. A blockage determination unit 74 is configured to predict or determine that the work unit will be blocked if the reduction amount ΔNe of a motor speed Ne of motor 2 exceeds a first limit th1.The warning sign of a knife lockup is detected by sensing that the reduction ΔNe of the engine speed Ne of engine 2 exceeds the first limit th1. A clutch control unit 56 is configured to switch the clutch 4 to the open state or to keep the clutch 4 in the engaged state, depending on the prediction result (whether a warning sign of a lockup is present or not) of the prediction unit 50, i.e., the determination result (whether the reduction ΔNe of engine 2 exceeds the first limit th1 or not) of the lockup determination unit 54. The prediction result of the prediction unit 50 can be transmitted to the engine control unit 28 or the vehicle control unit 26.The fuel supply control unit 57 can be configured to control the fuel supply device 41 to terminate the supply of fuel to the engine 2 when the prediction unit 50 predicts that the working unit will stall. The ignition control unit 58 can be configured to terminate the supply of current to the ignition device 42 when the prediction unit 50 predicts that the working unit will stall. These configurations, in which the engine 2 is stopped as such, reduce damage to the engine 2.

[0021] The work process control unit 27 can be configured such that, after the fuel supply to the engine 2 and the power supply to the guide device 42 are stopped, the work process control unit 27 causes the BSG 7 to operate as a power generator by utilizing an initial rotation of the crankshafts 3a and 3b of the engine 2, so that the 48-volt battery 8 and the 12-volt battery 11 are charged with electricity generated by the power generator. This configuration improves energy efficiency.

[0022] A load determination unit 55 can be configured to determine a load exerted on the motor 2 based on the reduction amount ΔNe. For example, the load determination unit 55 can be configured such that if the reduction amount ΔNe is less than the first limit th1 but greater than a second limit th2, the load determination unit 55 causes the 48 V battery 8 to supply power to the BSG-7, so that the BSG-7 provides torque assistance to the motor 2. Since the first limit th1 is less than the second limit th2, the reduction amount ΔNe exceeds the second limit th2 and then the first limit th1. As described above, in areas with high grass density, the blades 6 can become entangled in a large amount of grass, increasing the load on the motor 2 and thus reducing the motor speed of the motor 2.Thus, when the load sensing unit 55 detects an increase in load, it causes the BSG 7 to switch from power generation mode to torque support mode to assist the motor 2. This design allows a user to continue mowing in such an area with high grass density.

[0023] The drive control unit 26 can be configured to stop the drive motor 9 when the prediction unit 50 predicts that the working unit will become blocked. Since the drive motors 9 are motors for driving wheels, when the drive motors 9 are stopped, the rotation of the wheels 12 is terminated, and the movement of the mower 1 is also terminated. This design simplifies the reduction of damage to the blades 6. Furthermore, if the mower 1 moves with the blades 6 stopped, some grass will not be cut, but if the movement of the mower 1 is also stopped, such uncut grass can be avoided.It should be emphasized that the drive control unit 26 can be designed such that if the prediction unit 50 predicts that the working unit will become blocked, the drive control unit 26 causes the drive motors 9 to rotate in the opposite direction for a specific period of time, so that the mower 1 moves backwards. This design makes it possible to move the mower 1 away from an obstacle and avoid the uncut grass described above.

[0024] A gradient calculation unit 53 can be optionally provided. The gradient calculation unit 53 is designed to detect the absolute value of a gradient a of the motor speed Ne of the motor 2, which is detected when the motor speed of the motor 2 decreases. If the absolute value of the gradient a is greater than a certain value tha1, the blockage determination unit 54 predicts that the working unit will block. If the absolute value of the gradient a is greater than a certain value tha2 but less than a certain value tha1, the load determination unit 55 predicts that the load will increase. If the blades 6 touch an obstacle, the motor speed Ne drops quite suddenly. Furthermore, if the blades 6 touch a large amount of grass, or if cut grass becomes caught between the blades 6 and the housing of the mower 1, the motor speed Ne drops more gradually.Therefore, by checking the slope a of the motor speed Ne, the prediction unit 50 can distinguish between whether the blades 6 have touched an obstacle, or whether the blades 6 have come into contact with a large amount of grass or are clogged with grass. Flowchart

[0025] Fig. Figure 4 illustrates a control procedure executed by the CPU 24 according to a control program.

[0026] In S401, the CPU 24 (engine control unit 28) starts engine 2 when a user commands it to start. For example, the fuel supply unit 57 begins supplying fuel to engine 2 by controlling the fuel supply device 41. Additionally, the ignition control unit 58 causes the ignition device 42 to fire at a specified ignition point.

[0027] In S402, the CPU 24 (motor control unit 28) determines whether the motor speed Ne has reached a target motor speed. This determination corresponds to the determination of whether or not motor 2 can drive the blades 6. Furthermore, a target motor speed is a motor speed that is higher than the speed at which motor 2 can rotate in a self-sustaining manner. When the motor speed Ne reaches the target motor speed, the CPU 24 proceeds to S403. It is important to note that when the motor speed Ne reaches the target speed, the CPU 24 (load determination unit 55) sets the operating mode of the BSG 7 to power generation mode.

[0028] In S403, CPU 24 (Operation Control Unit 27) performs the operation control. The details of the operation control will be discussed later with reference to... Fig. 5 described.

[0029] In S404, CPU 24 (motor control unit 28) determines whether the user has issued a command to stop motor 2. If the user has not issued a command to stop motor 2, CPU 24 returns to S403 to continue work control. However, if the user has issued a command to stop motor 2, CPU 24 proceeds to S405.

[0030] In S405, the CPU 24 (engine control unit 28) causes the fuel supply device 41 to stop supplying fuel to the engine 2 and causes the ignition device 42 to stop the ignition, causing the engine 2 to stop.

[0031] Fig. Figure 5 is a flowchart that shows details of the work process control that is executed by the CPU 24 according to the control program.

[0032] In S501, the CPU 24 (load determination unit 55) determines, based on the motor speed Ne, the reduction amount ΔNe, or the slope a, whether the load exerted on the motor 2 has temporarily increased. If the load has temporarily increased as a result of the blades 6 touching a large amount of grass, the CPU 24 proceeds to S502. Conversely, if the load has not temporarily increased, for example, if the load is constant, the CPU 24 proceeds to S503. For example, the load determination unit 55 can be configured such that if the motor speed Ne has dropped to a certain motor speed or lower, the load determination unit 55 determines that the load has temporarily increased. The load determination unit 55 can also be configured such that if the reduction amount ΔNe exceeds the second limit th2, the load determination unit 55 determines that the load has temporarily increased.For example, the load determination unit 55 can be designed such that if the slope a is negative and has an absolute value exceeding a certain threshold, the load determination unit 55 determines that the load has temporarily increased. A possible design is such that, when the batteries are sufficiently charged, the BSG 7 is set to support mode regardless of the load's size.

[0033] In S502, the CPU 24 (load determination unit 55) sets the operating mode of the BSG 7 to the torque support mode.

[0034] In S503, the CPU 24 (load determination unit 55) determines, based on the motor speed Ne, the reduction amount ΔNe, or the slope a, whether the load temporarily applied to motor 2 has been resolved. If the torque support by the BSG 7 has resolved the temporary increase, the CPU 24 proceeds to S504. Conversely, if the torque support by the BSG 7 has not resolved the temporary increase, the CPU 24 proceeds to S505. For example, the load determination unit 55 can be configured such that if the motor speed Ne exceeds a certain motor speed, the load determination unit 55 determines that the temporary increase of the load has been resolved. The load determination unit 55 can also be configured such that if the reduction amount ΔNe becomes equal to or less than the second limit th2, the load determination unit 55 determines that the temporary increase of the load has been resolved.The load determination unit 55 can be configured such that if the slope a becomes positive, the load determination unit 55 determines that the temporary increase of the load has been resolved. The load determination unit 55 can be configured such that if the slope a is negative but has an absolute value equal to or less than a certain value, the load determination unit 55 determines that the temporary increase of the load has been resolved.

[0035] In S504, the CPU 24 (load determination unit 55) sets the operating mode of the BSG 7 to the power generation mode.

[0036] In S505, CPU 24 (blockage detection unit 54) determines whether a blockage warning sign is present based on the motor speed Ne, the reduction amount ΔNe, or the slope a. If a blockage of the blades 6 is predicted, for example, because the reduction amount ΔNe exceeds the first limit th1, CPU 24 proceeds to S506. If a blockage of the blades 6 is not predicted, CPU 24 skips S506. For example, load detection unit 55 can be configured such that if the motor speed Ne becomes equal to or less than a certain motor speed, load detection unit 55 determines that a blockage warning sign is present. Load detection unit 55 can also be configured such that if the reduction amount ΔNe exceeds the first limit th1, load detection unit 55 determines that a blockage warning sign is present.The load determination unit 55 can be designed such that if the slope a is negative and the absolute value of the slope a exceeds another specified value, the load determination unit 55 determines that an announcement signal for a blockage is present.

[0037] In S506, the CPU 24 (clutch control unit 56) switches off the clutch 4. That is, the clutch control unit 56 switches from the transmission state (ON) to the interruption state (OFF) via the clutch 4. Summary

[0038] According to a first aspect, a working machine is provided, which is configured to include: a motor 2; a working unit configured to be driven by the motor 2; a clutch 4, which is provided between an output shaft of the motor 2 and a drive shaft of the working unit and is configured to transmit power from the output shaft of the motor 2 to the drive shaft or to interrupt the transmission; a sensor (for example, a crankshaft angle sensor 23) configured to detect the motor speed of the motor 2; and a control unit 10 configured to control the motor 2 and the clutch 4 based on the motor speed Ne of the motor 2. The control unit 10 is configured to predict, based on the motor speed Ne of the motor 2 detected by the sensor, whether the working unit will be blocked by a load or not.Furthermore, the control unit 10 includes a clutch control unit 56 configured to control the clutch 4 to transition from a transmission state to an interruption state when the prediction unit 50 predicts that the working unit will become blocked. With this configuration, in which the clutch 4 disconnects the motor 2 from the working unit when it is predicted that the working unit will become blocked, damage to the working unit or to parts of the motor 2 is reduced.

[0039] According to a second aspect, if the reduction ΔNe of the motor speed Ne of motor 2, as detected by the sensor, is greater than a first limit th1, the prediction unit forecasts that the working unit will lock up. In a state where the working unit can lock up, the load exerted on the working unit suddenly increases, which suddenly reduces the motor speed Ne. Thus, because the control unit 10 takes the reduction ΔNe into account, a lockup can be predicted exactly.

[0040] According to a third aspect, the BSG 7 is an example of a generator / motor designed to drive the output shaft of motor 2 and to generate electricity by being driven by the motor 2. The 48 V battery 8 is an example of a battery designed to be charged with electricity generated by the generator / motor when the generator / motor is operating as a generator, and to supply power to the generator / motor when the generator / motor is operating as a motor. When the reduction ΔNe of the motor speed of motor 2 detected by the sensor is less than the first limit th1 but greater than a second limit th2, the control unit 10 causes the battery to supply power to the generator / motor, thus causing the generator / motor to assist motor 2.In this configuration, where the BSG 7 or similar assists the motor 2 when a load increases but is not large enough to cause a blockage, the working machine can continue to operate. It is important to note that blockage prediction can be performed while assistance is being provided. If the motor speed of motor 2 continues to decrease, even when the BSG 7 is assisting its torque, there is a high probability that the working unit will block. Therefore, the control unit 10 can be configured such that if the motor speed of motor 2 continues to decrease despite the BSG 7 assisting its torque, the control unit 10 determines that a blockage may occur. This configuration allows for the accurate detection of a blockage in the working unit.

[0041] According to a fourth aspect, the fuel supply device 41 is an example of a supply unit designed to supply fuel to the engine 2. The fuel supply device 41 may include a fuel injection device to inject the fuel into an intake port or combustion chamber of the engine 2. The ignition device 42 is an example of an ignition device (for example, a spark plug or the like) provided for the engine 2. If the prediction unit 5 predicts that the working unit will stall, the control unit 10 causes the supply unit to stop supplying fuel to the engine 2 and terminates the power supply to the ignition device 42. With this design, the occurrence of a stall can be prevented, or the extent of a stall that may occur can be mitigated.

[0042] According to a fifth aspect, the control unit 10 can be configured such that if the prediction unit 50 predicts that the working unit will be blocked, the control unit 10 causes the supply unit to terminate the fuel supply to the engine 2 and terminates the power supply to the ignition device. Subsequently, the control unit 10 causes the generator / engine to operate as a generator by utilizing an initial rotation of the output shaft of the engine 2 to charge the battery with the current generated by the generator. The crankshafts 3a and 3b are connected to a counterweight or similar device so that an initial rotation of the crankshafts 3a and 3b continues even if the fuel supply is stopped. Thus, by causing the BSG 7 to generate current by utilizing the initial rotation of the engine 2, regenerative charging of the battery is achieved.Furthermore, the BSG 7, which generates electricity, becomes a load on motor 2, and thus the initial rotation of motor 2 can be brought to a stop in a shorter period of time.

[0043] According to a sixth aspect, the wheels 12 are examples of drive wheels. The drive motors 9 are an example of drive wheel motors designed to rotate the respective drive wheels. The control unit 10 can be designed such that if the prediction unit 50 predicts that the working unit will become blocked, the control unit 10 stops the drive wheel motors. If it is predicted that the working unit will become blocked, there is a high probability that the working unit has come into contact with a foreign object. Furthermore, the working machine performs work at the work target while the working machine is moving. In addition, even if the clutch 4 is in a disengaged state, the working unit will rotate due to gravity. Therefore, if the working machine continues to move even after it has come into contact with a foreign object, the damage to the working unit will worsen.Thus, with this design, in which the movement of the working machine is stopped, the damage that the working unit would receive can be reduced.

[0044] According to a seventh aspect, the prediction unit can be designed such that when the motor speed of motor 2 decreases, the prediction unit receives an absolute value of the slope a of the motor speed of motor 2 as detected by the sensor. If the absolute value of the slope a is greater than a certain value tha1, the prediction unit predicts that the working unit will become jammed. If the working unit has come into contact with a foreign object, the load increases suddenly. If the working unit has come into contact with a large amount of the work target, the load increases gradually. Therefore, the design, which takes into account the slope a of the motor speed Ne, allows the control unit 10 to determine with good accuracy whether the increase in load is a warning sign of a jamming.

[0045] According to an eighth aspect, the prediction unit 50 can be designed such that if the absolute value of the slope a is greater than the specified value, the prediction unit 50 determines that the work unit has touched a foreign object, and if the absolute value of the slope is not greater than the specified value, the prediction unit 50 determines that the work unit has touched a large quantity of the work target. This design enables the control unit 10 to determine with good accuracy whether the increase in load is a warning sign of a blockage.Furthermore, the control unit 10 can be configured such that, if the prediction unit determines that the working unit has touched a foreign object, the control unit 10 controls the clutch to transition from the transmission state to the interrupted state, terminates the fuel supply to a supply unit configured to supply fuel to the engine, and terminates the power supply to an ignition device provided for the engine. This configuration reduces damage to the working unit.

[0046] According to a ninth aspect, the working unit can be blade 6 for mowing grass. In other words, the working machine can be a mowing machine 1.

[0047] According to a tenth aspect, the working unit can be a rotary device for plowing soil. In other words, the working machine can be a plow.

[0048] According to an eleventh aspect, the work unit can be a screw conveyor for clearing snow. In other words, the working machine can be a snowplow.

Claims

[1] Working machine which features: an engine; a work unit designed to be driven by the motor; a coupling which is provided between an output shaft of the motor and a drive shaft of the working unit, and is designed to transmit power from the output shaft of the motor to the drive shaft or to interrupt the transmission; a sensor designed to detect the engine speed; and a control unit designed to control the engine and clutch based on the engine speed, the control unit features: a prediction unit designed to predict, based on the motor speed detected by the sensor, whether the working unit will be blocked by a load; and a clutch control unit designed to control the clutch to transition from a transmission state to an interruption state in response to the prediction unit's forecast that the working unit will become blocked, wherein in a case where the reduction amount of the motor speed detected by the sensor is greater than a first limit value, the prediction unit predicts that the working unit will be blocked, characterized by that the machine still exhibits, a power generator / motor designed to drive the output shaft of the motor and to generate electricity by being driven by the motor being driven; and a battery designed to be charged with electricity generated by the generator / engine when the generator / engine is operating as a generator, and to supply electricity to the generator / engine when the generator / engine is operating as a motor, In a case where the reduction in the motor speed detected by the sensor is less than the first limit but greater than a second limit, the control unit causes the battery to supply power to the generator / motor in order to cause the generator / motor to assist the motor. [2] Working machine according to claim 1, characterized by that it continues to exhibit: a supply unit designed to supply fuel to the engine; and an ignition device intended for the engine, wherein, in a case where the prediction unit predicts that the working unit will be blocked, the control unit causes the supply unit to stop supplying fuel to the engine and stops supplying power to the ignition device. [3] Working machine according to claim 2, characterized by , that in a case where the prediction unit predicts that the working unit will be blocked, the control unit causes the supply unit to terminate the supply of fuel to the engine and the supply of electricity to the ignition device, and thereafter the control unit causes the generator / engine to operate as a generator by utilizing an initial rotation of the engine's output shaft to charge the battery with the electricity generated by the generator. [4] Working machine according to one of claims 1 and 2 to 3, characterized by that it continues to exhibit: a drive wheel; and a drive wheel motor designed to rotate the drive wheel, in a case where the prediction unit predicts that the working unit will be blocked, the control unit stops the drive wheel motor. [5] Working machine, characterized by , that it exhibits: an engine; a work unit designed to be driven by the motor; a coupling which is provided between an output shaft of the motor and a drive shaft of the working unit, and is designed to transmit power from the output shaft of the motor to the drive shaft or to interrupt the transmission; a sensor designed to detect the engine speed; and a control unit designed to control the engine and clutch based on the engine speed, the control unit features: a prediction unit designed to predict, based on the motor speed detected by the sensor, whether the working unit will be blocked by a load; and a clutch control unit designed to control the clutch to transition from a transmission state to an interruption state in response to the prediction unit's forecast that the working unit will become blocked, characterized by , that In a case where the motor speed decreases, the prediction unit receives an absolute value of a slope of the motor speed detected by the sensor, and in a case where the absolute value of the slope is greater than a certain value, the prediction unit predicts that the working unit will be blocked. [6] Working machine according to claim 5, characterized by, that in a case where the absolute value of the slope is greater than the determined value, the prediction unit determines that the work unit has touched a foreign object, and In a case where the prediction unit determines that the working unit has touched a foreign object, the control unit controls the clutch to transition from the transmission state to the interrupted state, terminates a fuel supply to a supply unit configured to supply fuel to the engine, and terminates a current supply to an ignition device provided for the engine. [7] Working machine according to one of claims 1 and 2 to 6, characterized by that the work unit is a knife for mowing grass. [8] Working machine according to any one of claims 1 and 2 to 6, characterized by that the working unit is a rotary device for plowing soil. [9] Working machine according to any one of claims 1 and 2 to 6, characterized by that the work unit is a screw conveyor for shoveling away snow.

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