JP2021070361A - Work vehicle - Google Patents

Abstract

To provide a work vehicle which enables an engine to be used with high efficiency even with a work machine having wide fluctuations.SOLUTION: A work vehicle 1 includes: an engine 4 using a fossil fuel; a work machine 3 which is driven by power from the engine 4; an infinite variable-speed drive 9 which transmits power from the engine 4 to a power generator 11; a motor 10 which is electrically connected to the power generator 11 and drives a travel gear 13; and a control unit 8 which controls operations of the engine 4, the work machine 3, the infinite variable-speed drive 9, and the motor 10. The control unit 8 controls the infinite variable-speed drive 9 according to load fluctuations of the work machine 3 to keep the output of the engine 4 constant.SELECTED DRAWING: Figure 3

Description

The present invention relates to a work vehicle.

Conventionally, the engine, a power storage device, a load connected to the engine, and a control unit for controlling the engine, the power storage device, and the load are provided, and the control unit is the rotation speed of the engine based on the required power of the load. Is known as a work vehicle in which is set to any of the upper limit rotation range, the lower limit rotation range, and the intermediate rotation range (see Patent Document 1).

JP-A-2018-52468

However, there is still room for improvement in applying the above-mentioned prior art to a work vehicle using a work machine having a large load fluctuation.

The present invention has been made in view of the above, and an object of the present invention is to provide a work vehicle capable of using an engine with high efficiency even for a work machine having a large load fluctuation.

In order to solve the above-mentioned problems and achieve the object, the work vehicle (1) according to claim 1 is an engine (4) using fossil fuel and a work machine driven by power from the engine (4). (3), a stepless transmission (9) that transmits the power from the engine (4) to the generator (11), and the traveling device (13) that is electrically connected to the generator (11). A motor (5) to be driven, the engine (4), the working machine (3), the stepless speed changer (9), and a control unit (8) for controlling the operation of the motor (5) are provided. The control unit (8) is characterized in that the stepless transmission (9) is controlled according to a load fluctuation of the work machine (3) to maintain a constant output of the engine (4). ..

According to the work vehicle according to one aspect of the embodiment, the engine can be used with high efficiency even in a work machine having a large load fluctuation.

FIG. 1 is a schematic view of a work vehicle according to an embodiment. FIG. 2 is a block diagram centered on the control unit of the work vehicle of the above. FIG. 3 is an explanatory diagram showing a power distribution mechanism in the same work vehicle. FIG. 4 is an explanatory diagram showing power distribution in the same work vehicle. FIG. 5 is an explanatory diagram showing fluctuations in power distribution in the same work vehicle.

Hereinafter, embodiments of the work vehicle disclosed in the present application will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments shown below.

First, a schematic configuration of the work vehicle 1 according to the embodiment will be described with reference to FIG. FIG. 1 is a schematic view of the work vehicle 1 and is shown from the side view.

In the following, the front-rear direction of the work vehicle 1 refers to the straight-ahead direction of the work vehicle 1. Further, the left-right direction is a direction horizontally orthogonal to the front-rear direction, and here, the left-right direction is defined toward the "front" side in the front-rear direction. That is, when the operator arrives at the driver's seat (not shown) and faces forward, the left-hand side is "left" and the right-hand side is "right". Further, the vertical direction is a direction orthogonal to the front-rear direction and the left-right direction. Therefore, the front-back direction, the left-right direction, and the up-down direction are orthogonal to each other in three dimensions.

As shown in FIG. 1, the work vehicle 1 includes a tractor 2 and a mower device 3 arranged in front of the tractor 2. In addition. The tractor 2 is an example of a traveling vehicle body, and the mower device 3 is an example of a working machine.

The tractor 2 includes a front wheel 6 serving as a steering wheel, a rear wheel 7 serving as a driving wheel, an engine 4 serving as a driving source for the mower device 3, and a motor 5 serving as a driving source for the rear wheel 7 serving as a driving wheel. The traveling device 13 (see FIG. 3) includes the front wheels 6 and the rear wheels 7, and a mechanism for transmitting the rotational force from the motor 5 to these rotating shafts and rotating shafts.

The mower device 3 is a device provided on the lower side of the front portion of the tractor 2, for example, a mower rotary blade 300 (see FIG. 3) that serves as a cutting blade that rotates about an axis along the vertical direction to mow grass. In the example of FIG. 1, the mower device 3 is provided in front of the tractor 2, but may be provided behind the tractor 2 or on the left and right sides.

The front wheels 6 are a pair of left and right wheels, and are rotatably connected to the front axle to serve as steering wheels (steering wheels). The rear wheels 7 are a pair on the left and right, and are rotatably connected to the rear axle to form driving wheels (driving wheels). For convenience, the tractor 2 according to the present embodiment has a two-wheel drive (2WD) in which the rear wheel 7 which is one of the traveling devices 13 is a drive wheel, but a four-wheel drive (4WD) in which the front wheel 6 is also a drive wheel. ) Can be switched.

The tractor 2 is a vehicle operated by an operator (operator). For example, the tractor 2 travels by raising and lowering the mower device 3 by a lift arm (not shown) or supplying power to the mowing mechanism of the mower device 3. However, you can mow the grass. The tractor 2 has a collector (not shown) and can accommodate the grass cut by the mower device 3.

The engine 4 is a drive source for the work vehicle 1, is a heat engine such as a diesel engine or a gasoline engine, and is covered with a bonnet.

The cabin of the tractor 2 is equipped with various levers such as a forward / backward lever, a shift lever, and an auxiliary shift lever, as well as various pedals such as an accelerator pedal, a brake pedal, and a clutch pedal, as well as a driver's seat and a steering wheel (not shown). A control unit is provided. The control unit may be an open one that is not covered by the cabin.

When the operator operates the steering wheel, the front wheels 6, which are the steering wheels, are steered, and various information during traveling is displayed on a display panel (not shown) provided in front of the driver's seat.

Next, the control system of the work vehicle 1 will be described with reference to FIG. FIG. 2 is a block diagram centered on the control unit 8 of the work vehicle 1.

The control unit 8 can control each unit by electronic control, includes a processing unit having a CPU (Central Processing Unit), etc., and is necessary for executing various programs related to running and work and executing each program. A storage unit 84 is provided for storing various types of data.

The storage unit 84 is composed of a hard disk, a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.

Further, as the processing unit included in the control unit 8, there are an engine system ECU (Electronic Control Unit) 81, a traveling system ECU 82, a working machine system ECU 83, and a load calculation unit 85.

The engine system ECU 81 controls the output of the engine 4, and the traveling system ECU 82 controls a speed change device such as a braking device (not shown), a second electromagnetic clutch 102, a continuously variable transmission 9, and a motor 5. It controls the overall running of the tractor 2. The braking device is composed of a brake pedal provided in the cabin of the tractor 2 and a brake mechanism interlocked with the brake pedal.

The work machine system ECU 83 controls the overall drive of the mower device 3, for example, controls the PTO clutch (first electromagnetic clutch 101) provided in the power transmission path from the engine 4 to the mower device 3, and also controls the mower device 3. The elevating device (not shown) is controlled to control the elevating of the mower device 3.

The load calculation unit 85 calculates the work equipment load and the running load of the tractor 2. As will be described later, the load calculation unit 85 fluctuates the running load according to the fluctuation of the load applied to the mower device 3, and applies the load to the engine 4. I try to keep it constant.

Further, various sensors and devices are connected to the control unit 8. For example, as shown in FIG. 2, a combustion system sensor 91 for detecting the combustion system of the engine 4 and an engine speed sensor 92 are connected. The combustion system sensor 91 includes a knocking sensor and a CO ₂ sensor.

Further, a generator sensor 93, a battery sensor 94, and an accelerator sensor 95 are connected to the control unit 8.

The generator sensor 93 detects the driving state of the generator 11 (see FIG. 3) included in the tractor 2. The battery sensor 94 detects the state of charge of the battery 12 (see FIG. 3) connected to the generator 11. The accelerator sensor 95 detects the amount of operation of the accelerator pedal provided inside the cabin of the tractor 2, and the control unit 8 (traveling system ECU 82) controls the motor 5 according to the detected amount.

Further, a mower torque sensor 96 and a mower rotation sensor 97 are connected to the control unit 8. The mower torque sensor 96 is provided, for example, on a rotary shaft connecting the mower rotor blades 300 of the mower device 3, and detects the torque of the mower rotor blades 300. Similarly, the mower rotation sensor 97 is also provided on the rotation shaft connecting the mower rotor blades 300, and detects the rotation speed of the mower rotor blades 300.

From the detected torque and rotation speed of the mower rotor 300, the control unit 8 (load calculation unit 85) can calculate the output of the mower device 3, that is, the work equipment load. Since the mower torque sensor 96 and the mower rotation sensor 97 are provided on the rotating shaft connecting the mower rotary blades 300, the load of the mower device 3 which is easily fluctuated due to external factors such as grass conditions is directly detected. It is possible to obtain an accurate work equipment load.

Further, in addition to the sensors described above, the control unit 8 includes various sensors 98 for detecting various data necessary for smooth running and work, and for the operator to run and work. Various switches 99 for starting and stopping the devices and various actuators 100 described later are connected.

The control unit 8 drives and controls various devices based on the data obtained from these sensors. Examples of the drive-controlled device include the first electromagnetic clutch 101, the stepless transmission 9, the second electromagnetic clutch 102, and various other actuators 100, in addition to the engine 4, the mower device 3, and the motor 5 described above.

Here, the power distribution mechanism of the work vehicle 1 including the first electromagnetic clutch 101, the continuously variable transmission 9, the second electromagnetic clutch 102, and the like will be described. FIG. 3 is an explanatory diagram showing a power distribution mechanism in the work vehicle 1.

As shown in FIG. 3, the power distribution of the work vehicle 1 is driven by the engine 4, which is a heat engine that uses fossil fuels. Then, the power from the engine 4 is transmitted to the working machine system mechanism 830 via the first power transmission path 42a and to the traveling system mechanism 820 via the second power transmission path 42b.

The work machine system mechanism 830 has a first electromagnetic clutch 101 and a mower rotor 300, and power is transmitted in the order of engine 4 → first power transmission path 42a → first electromagnetic clutch 101 → mower rotor 300. .. That is, the mower device 3 which is the work machine of the work vehicle according to the present embodiment is driven by the power from the engine 4.

By the way, the mower rotor 300 of the mower device 3 and the power output shaft for outputting the power of the engine 4 in the present embodiment are connected via a gear mechanism. That is, the first power transmission path 42a is configured by a gear mechanism in which a plurality of gears are combined.

In this way, since the power from the engine 4 is driven to drive the mower rotor 300 via the gear mechanism, the energy loss is small, and the efficiency is higher than, for example, the motor drive. For example, the efficiency from fossil fuel to output when driven by a motor is about 31.1%, but the efficiency from fossil fuel to output when driven by an engine is about 38 to 47.5%. Has been done. The engine is driven when the engine output does not fluctuate and the most efficient band is used.

That is, compared to the case where power is transmitted from fossil fuel (for example, light oil) → prime mover → power generation → charge → discharge → motor → mower rotary blade, fossil fuel (for example, light oil) → engine 4 → gear mechanism → Comparing the case where the mower rotary blade 300 and the power are transmitted, it is possible to drive the mower rotary blade 300 with high efficiency by adopting the configuration of the present embodiment with a smaller number of energy conversions. _{In addition, the CO 2} emission factor, which is one of the grounds for promoting electrification, can be kept low.

On the other hand, the traveling system mechanism 820 has a second electromagnetic clutch 102, a continuously variable transmission 9, a battery 12, a motor 5, and a traveling device 13, and has an engine 4 → a second power transmission path 42b → a second. 2 Power is transmitted in the order of the electromagnetic clutch 102 → the continuously variable transmission 9. Then, power generated by the generator 11 is generated by the power transmitted from the continuously variable transmission 9 by appropriately shifting the speed, and is stored in the battery 12, the motor 5 is driven by the electricity supplied from the battery 12, and the traveling device 13 is driven. .. Since the motor 5 is driven by the electricity supplied from the battery 12, the tractor 2 can travel even if the generator 11 is not driven.

Here, examples of the continuously variable transmission 9 include a CVT (Continuously Variable Transmission) and an HST (Hydro Static Transmission), but in the present embodiment, a CVT having excellent response performance is used.

In the present embodiment, the generator 11 is not included in the traveling system mechanism 820, but the traveling system mechanism 820 may include the generator 11.

As described above, in the work vehicle 1 according to the present embodiment, the mower device 3 known as the work machine having a relatively large load fluctuation is driven by the power from only the engine 4, while the traveling device 13 having the drive wheels is driven. The power of is supplied only from the motor 5.

In the work vehicle 1 having such a configuration, the control unit 8 controls the continuously variable transmission (CVT) 9 according to the load fluctuation of the mower device 3 to maintain the output of the engine 4 at a constant level. This is because, as described above, it is considered that the output efficiency of the mower device 3 becomes the highest efficiency when the output of the engine 4 does not fluctuate and the most efficient band is used.

Therefore, the control unit 8 controls the power distribution from the engine 4 so as to keep the rotation speed of the engine 4 and the torque of the engine 4 constant.

That is, the continuously variable transmission 9 is controlled according to the load fluctuation of the mower device 3 to make the sum of the work equipment load of the mower device and the power generation load of the generator constant.

For example, the load calculation unit 85 of the control unit 8 derives the load fluctuation of the mower device 3 from the detection results from the mower torque sensor 96 and the mower rotation sensor 97. Then, the continuously variable transmission (CVT) 9 is controlled to change the power generation load so that the output of the engine 4 becomes constant according to the load fluctuation, and the sum of the power generation load and the work equipment load becomes constant. .. That is, the continuously variable transmission (CVT) 9 is controlled so that the work equipment load is absorbed by the power generation load.

With reference to FIGS. 4 and 5, the distribution of power according to the load fluctuation of the mower device 3 in the work vehicle 1 will be specifically described. FIG. 4 is an explanatory diagram showing the power distribution in the work vehicle 1, and FIG. 5 is an explanatory diagram showing the fluctuation of the power distribution in the work vehicle 1.

As shown in FIG. 4, a state in which the power from the engine 4 is distributed 1: 1 between the working machine system and the traveling system is defined as a basic power distribution state for convenience. That is, in the basic distribution state, the load of the mower device 3 is medium in the large, medium and small categories, and the gear ratio of the continuously variable transmission 9 is also medium in the large, medium and small categories, and the output of the engine 4 is 50. % Each is transmitted to the work equipment system and the traveling system.

By the way, the output of the engine 4 depends on the load. In addition, the load of the working machine may fluctuate due to external factors. For example, the load of the mower rotary blade 300 of the mower device 3 varies depending on the state of the grass, such as the degree of density of the grass, the posture of the grass, and the degree of wetness (dryness) of the grass. Therefore, when the load on the mower device 3 increases, the load on the engine 4 also increases, and there is a possibility that a band having poor combustion efficiency is used.

Therefore, in the present embodiment, the control unit 8 controls the continuously variable transmission 9 so that the output of the engine 4 can be maintained constant. That is, the continuously variable transmission 9 is controlled so as to absorb the load fluctuation of the mower device 3, and the sum of the work equipment load by the mower device 3 and the power generation load of the generator 11 is controlled to be constant. The load fluctuation of the mower device 3 can be accurately and instantly acquired by the control unit 8 by the mower torque sensor 96 and the mower rotation sensor 97 shown in FIG.

By such control, it is possible to always maintain a band in which the combustion efficiency of the engine 4 is good, and it is possible to operate the engine 4 with high efficiency.

For example, as shown in FIG. 5A, when the load on the mower rotor 300 (mower device 3) increases and the work equipment load rises to 70%, the control unit 8 sets the continuously variable transmission 9 The gear ratio of the engine 4 is controlled to be large so that the power generation load becomes 30%, and the output of the engine 4 is maintained constant.

Further, as shown in FIG. 5B, for example, when the load on the mower rotor 300 (mower device 3) is significantly increased, the control unit 8 turns off the second electromagnetic clutch 102 (first electromagnetic). The clutch 101 is naturally ON), so that 100% of the output of the engine 4 is transmitted to the work machine system mechanism 830.

On the other hand, as shown in FIG. 5C, when the load on the mower rotary blade 300 (mower device 3) is significantly reduced to zero, the control unit 8 turns off the first electromagnetic clutch 101 and turns it off. (The second electromagnetic clutch 102 is naturally ON), and the gear ratio of the continuously variable transmission 9 is reduced so that 100% of the output of the engine 4 is transmitted to the generator 11.

Even in the states shown in FIGS. 5 (b) and 5 (c), the engine 4 maintains a band with good combustion efficiency, and can improve fuel efficiency.

In the work vehicle 1 according to the present embodiment described above, the output of the engine 4 is constant, and the power thereof is not directly used for the traveling device 13 but is used only for the work machine system mechanism 830. The uptime can be calculated. Therefore, the continuous operation time can be calculated from the remaining amount of the fuel tank (not shown). Such continuous operation time can be configured to be displayable on a display panel in the cabin.

Further, the size and battery capacity of the engine 4 in the tractor 2 of the work vehicle 1 are determined by the necessary and sufficient optimum design according to the maximum load assumed for the mower device 3, the assumed non-charging work time, or the vehicle body space. can do. Further, the capacity of the fuel tank can be easily designed depending on the assumed oil-free working time of the mower device 3.

As shown in FIG. 3, the tractor 2 according to the present embodiment includes a combustion system sensor 91 such as a _{knocking sensor or a CO 2 sensor, for example.} Therefore, the control unit 8 can also estimate from the value of the combustion system sensor 91 that the engine 4 is overloaded. That is, the engine load is estimated in a pseudo manner by monitoring the abnormal combustion of the engine 4 when an excessive load is generated.

With such a configuration, for example, the control unit 8 determines that the load can be made larger than the current one if there is no abnormal combustion such as knocking, controls the continuously variable transmission 9, and controls the engine to some extent. It is also possible to increase the load applied to 4. On the contrary, if it is determined that abnormal combustion such as knocking has occurred, the control unit 8 can control the continuously variable transmission 9 to reduce the load applied to the engine 4.

As described above, even in the configuration in which the combustion state of the engine 4 is directly monitored, the engine output can be maintained in a band in which the combustion efficiency is good.

Further, although the battery 12 is charged via the generator 11 of the tractor 2, it can also be charged from external power. In this case, by using the natural energy outside the tractor 2 or the electric power from the dedicated power generation facility, the running cost can be reduced, and the energy can be used efficiently in the whole society, which has an adverse effect on the environment. It can be made smaller.

In the above-described embodiment, the work vehicle 1 uses the mower device 3 as the work machine, but the work machine is not necessarily limited to the mower device 3.

According to the above-described embodiment, the following work vehicle 1 is realized.

(1) An engine 4 using fossil fuel, a working machine driven by power from the engine 4, a stepless transmission (CVT) 9 for transmitting the power from the engine 4 to the generator 11, and electricity to the generator 11. A motor 5 for driving the traveling device 13 and a control unit 8 for controlling the operation of the engine 4, the work machine, the stepless transmission 9 and the motor 5 are provided, and the control unit 8 is a load of the work machine. A work vehicle 1 that controls a stepless transmission 9 according to fluctuations to maintain a constant output of the engine 4.

According to the work vehicle 1, the work machine is driven by an engine and the traveling device 13 is driven by a motor, so that energy can be used without waste. By making it possible to maintain the output of the engine 4 at a constant level, it is possible to maintain a band with good combustion efficiency, and the engine 4 can be operated with high efficiency even when the mower device 3 having a large load fluctuation is used. Can be done. Therefore, it is possible to avoid load fluctuations, partial loads, pumping losses, and the like.

(2) In the above (1), the control unit 8 is a work vehicle 1 that maintains a constant rotation speed of the engine 4.

According to the work vehicle 1, the torque of the engine 4 can be made constant, and the effect of the above (1) can be surely achieved.

(3) The work vehicle 1 provided with the battery 12 connected to the generator 11 and the motor 5 in the above (1) or (2).

According to the work vehicle 1, in addition to the effects of (1) or (2) above, by mounting the generator 11, the battery 12 can be miniaturized, thereby suppressing the cost increase and securing the battery mounting space. Is also easy.

(4) In any of the above (1) to (3), the work machine is the work vehicle 1 which is the mower device 3.

According to the work vehicle 1, since the mower device 3 that easily fluctuates due to external factors such as the condition of grass is provided as the work machine, the effect of any of the above (1) to (3) appears more greatly.

(5) In the above (4), the work of controlling the continuously variable transmission 9 according to the load fluctuation of the mower device 3 to make the sum of the work machine load of the mower device 3 and the power generation load of the generator 11 constant. Vehicle 1.

According to the work vehicle 1, the mower device 3 can always be used with high efficiency.

(6) In the above (4) or (5), a work vehicle 1 including a mower torque sensor 96 for detecting the torque of the mower device 3 and a mower rotation sensor 97 for detecting the rotation speed of the mower device 3.

According to the work vehicle 1, in addition to the effects of (4) or (5) above, power distribution from the engine 4 can be performed more accurately.

(7) In the above (4) to (6), the work vehicle 1 in which the mower rotor 300 of the mower device 3 and the power output shaft for transmitting the power of the engine 4 are connected via a gear mechanism.

According to the work vehicle 1, in addition to the effects of (4) to (6), energy loss is reduced and power transmission efficiency is improved.

(8) In the above (1) to (7), a work vehicle 1 provided with a combustion system sensor 91 for detecting the combustion state of the engine 4 and controlling the continuously variable transmission 9 according to the detection result of the combustion system sensor 91. ..

According to the work vehicle 1, in addition to the effects of (1) to (7), the state of the engine 4 is monitored from the combustion state, and the engine output is kept constant in a pseudo manner without adding any parts. can do.

Further effects and variations can be easily derived by those skilled in the art. For this reason, the broader aspects of the invention are not limited to the particular details and representative embodiments expressed and described as described above. Therefore, various modifications can be made without departing from the spirit or scope of the general concept of the invention as defined by the appended claims and their equivalents.

1 Work vehicle 2 Tractor 3 Mower device (work machine)
4 Engine 5 Motor 8 Control 9 Continuously variable transmission 11 Generator 12 Battery 91 Combustion system sensor 96 More torque sensor 97 More rotation sensor

Claims (8)

Engines that use fossil fuels and
A work machine driven by power from the engine,
A continuously variable transmission that transmits power from the engine to the generator,
A motor that is electrically connected to the generator and drives a traveling device,
A control unit that controls the operation of the engine, the working machine, the continuously variable transmission, and the motor.
With
The control unit
A work vehicle characterized in that the continuously variable transmission is controlled according to a load fluctuation of the work machine to maintain a constant output of the engine. The control unit
The work vehicle according to claim 1, wherein the engine speed is maintained constant. The work vehicle according to claim 1 or 2, further comprising a battery connected to the generator and the motor. The work vehicle according to any one of claims 1 to 3, wherein the work machine is a mower device. The fourth aspect of claim 4, wherein the continuously variable transmission is controlled according to the load fluctuation of the mower device to make the sum of the work equipment load of the mower device and the power generation load of the generator constant. Work vehicle. The work vehicle according to claim 4 or 5, further comprising a torque sensor for detecting the torque of the mower device and a rotation sensor for detecting the rotation speed of the mower device. The work vehicle according to any one of claims 4 to 6, wherein the rotary blade of the mower device and the power output shaft for transmitting the power of the engine are connected via a gear mechanism. The invention according to any one of claims 1 to 7, wherein the combustion system sensor for detecting the combustion state of the engine is provided, and the continuously variable transmission is controlled according to the detection result of the combustion system sensor. Work vehicle.

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