JP2014065348A - Hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable energy-saving operation capable of easily responding to an increase in an engine load that is caused unexpectedly although reducing an engine speed to a limit for preventing engine stall during work traveling at a constant vehicle speed.SOLUTION: A hybrid vehicle includes: an engine control unit 5A for setting a speed of an engine E that supplies driving power to a traveling device via a transmission 10; a change gear control unit 20 for adjusting a change gear ratio of the transmission 10; a motor unit 4 for assisting the engine; a motor control unit 5B for performing assist control on the basis of load information indicating an increase in rotating load received by the engine; and operation devices 90, 91 for outputting operation commands. A speed reduction command for reducing the engine speed set based on the operation commands is issued to the engine control unit 5A, and to maintain a vehicle speed, the change gear ratio is changed to compensate reduction in the engine speed in accordance with the speed reduction command.

Description

  The present invention includes an engine that supplies driving force to a traveling device via power transmission means, an engine control unit that sets an engine speed of the engine, a transmission provided in the power transmission means, and the transmission The present invention relates to a hybrid vehicle including a transmission control unit that adjusts the transmission gear ratio.

  In the vehicle as described above, the vehicle speed can be maintained at a constant value even at a low engine speed and at a high engine speed by cooperatively controlling the engine control unit and the shift control unit. For example, Patent Document 1 describes a mobile agricultural machine that is provided with a speed change actuator that operates a continuously variable speed change mechanism, and that controls the travel speed (vehicle speed) in a stepless manner. This mobile agricultural machine is provided with a rotation sensor for detecting and adjusting the engine rotation and an accelerator actuator, and by operating each of the actuators so as to achieve a predetermined traveling speed, the gear ratio of the continuously variable transmission mechanism and the engine rotation are correlated. (Coordinated) control. It is intended to run the engine economically with a low fuel consumption rate during light load travel, and to drive the engine at a high output with high output during high load travel.

  If the engine speed can be reduced while the vehicle speed is kept constant, the fuel consumption rate becomes low, which is advantageous in terms of energy saving (hereinafter abbreviated as energy saving). However, if there is no margin in engine torque, the possibility of engine stall increases, which causes the inconvenience that running becomes unstable. The engine torque margin varies depending on the traveling state of the vehicle, for example, road conditions and work conditions. Obviously, the engine torque margin is small when the vehicle is traveling on a large slope or traveling on a muddy road. Although such a situation can be grasped by the driver, a shift operation system that can link such a situation of the driver to energy saving driving as described above is provided in the vehicle according to Patent Document 1. Not.

  Patent Document 2 discloses a vehicle that realizes a speed change operation that makes use of the driver's remaining engine power for energy-saving driving. In this vehicle, an engine speed reduction command for reducing the engine speed set in the engine control unit by a predetermined amount based on an operation command sent by the driver's operation is given to the engine control unit, and the vehicle speed is reduced. In order to maintain, a gear ratio change command for requesting the gear change control unit to change the gear ratio that compensates for a decrease in the engine speed due to the engine speed reduction command is given. Therefore, in this known vehicle, when the driver feels that the engine torque is sufficient and he wants to reduce the engine speed for the purpose of energy-saving operation, etc., the engine speed is reduced by operating the operating device. A number reduction command can be given to the engine control unit. In addition, the speed change ratio corresponding to the engine rotational speed that is reduced thereby is changed, and the vehicle speed is maintained. In other words, during operation of the vehicle cruise, the operation of lowering the engine speed can be realized by operating the operating device while maintaining the vehicle speed. However, if the engine speed is decreased too much while maintaining the vehicle speed, the engine torque will not be sufficient, and a slight increase in engine load will cause the vehicle to become unstable and may cause engine stall. It is necessary to restore the number based on it. In particular, if the person is not an expert, there is a disadvantage that the operation of lowering and increasing the engine speed is repeated.

Japanese Patent Laid-Open No. 5-338474 (paragraph number [0004], FIG. 10) JP 2012-162248 A (paragraph number [0020-0022], FIGS. 1 and 2)

  In view of the above circumstances, there is a demand for a vehicle that realizes an energy saving operation that can easily cope with an unexpected increase in engine load while reducing the engine speed to the limit at which engine stall does not occur.

  A hybrid vehicle according to the present invention includes an engine that supplies driving force to a traveling device via power transmission means, an engine control unit that sets an engine speed of the engine, a transmission provided in the power transmission means, A shift control unit that adjusts the transmission ratio of the transmission, a motor (electric motor) unit that assists the engine by outputting power to the power transmission means, and load information that represents an increase in rotational load received by the engine A load information generation unit that generates power, a motor control unit that performs assist control to output power from the motor unit to the power transmission unit based on the load information, a battery that supplies drive power to the motor unit, and a driver An operating device for sending an operation command by the operation of the engine, and the engine based on the operation command A rotational speed reduction command for reducing the engine rotational speed set in the control unit by a predetermined amount is given to the engine control unit, and in order to maintain the vehicle speed, the reduction of the engine rotational speed due to the rotational speed reduction command is compensated. Thus, a so-called hybrid vehicle is provided with a transmission module that gives a transmission ratio change command for requesting the transmission control unit to change the transmission ratio.

  According to this configuration, when the driver feels that the engine torque is sufficient and the engine speed is decreased for the purpose of energy-saving operation or the like, it is set in advance by operating an operating device such as a button or a lever. An engine speed reduction command for reducing the engine speed by a fixed amount is given to the engine control unit. At the same time, a transmission ratio change command is given to the transmission control unit so as to maintain the vehicle speed by changing the transmission ratio to meet the decreasing engine speed. As a result, it is possible to easily realize a driving operation for reducing the engine speed while maintaining the vehicle speed by simply operating the operating device during the vehicle cruising at a constant vehicle speed or during the working travel. Further, when the rotational load of the engine increases due to some factor, the load information generation unit generates load information indicating an increase in the rotational load. Based on this load information, power is transmitted from the motor unit to the power transmission means. Is output by the motor control unit. As a result, engine speed reduction and engine stall are avoided. In particular, since the motor generator has a quick response, it can reliably cope with a sudden load increase.

  Assisting the engine with a motor unit consumes a lot of battery power. For this reason, it is necessary to execute the assist control appropriately. When the engine speed is lowered for energy saving operation, the possibility of engine stall is increased with respect to a sudden increase in load, which is a suitable time for assist control. Therefore, in one preferred embodiment of the present invention, the assist control is performed with respect to an increase in rotational load that occurs after the rotation speed reduction command is given to the engine control unit.

  When dealing with an excessive engine load by motor assist by driving the motor unit, battery consumption becomes a problem when the motor assist time becomes longer. Therefore, in one preferred embodiment of the present invention, the motor unit is configured as a motor generator, and the battery can receive charging power from the motor generator. That is, when the motor assist is unnecessary, the motor unit is driven as a generator as necessary, and the battery is charged to suppress the battery exhaustion.

  When the vehicle starts off a hill or when the vehicle is a work vehicle that uses a working device, even during normal traveling work, the vehicle suddenly protrudes for a very short time, resulting in a high engine load increase. If the sudden increase in load can be cleared, an engine with a relatively small output can be used. Accordingly, in a preferred embodiment of the present invention, an assist characteristic determining unit that determines an assist characteristic that defines an assist amount and an assist time in the assist control based on the load information is provided, and a motor control unit is provided. Performs assist control by the motor unit based on the assist characteristics. According to this configuration, when a sudden high load occurs, the motor generator is driven to assist based on the assist characteristic set in advance to cope with the sudden load increase, so that a sudden load due to the high load is abrupt. The engine can be protected from rotation reduction and engine stall. Since the assist characteristic that determines the assist drive behavior of the motor generator defines not only the assist amount but also the assist time, it can be adapted only to a sudden load increase, and the battery is not consumed wastefully.

  Since the assist by the motor generator is basically intended for sudden load increase, if the assist is suddenly stopped at the end of the short-time assist process, the passenger feels uncomfortable. In order to suppress this problem, in one preferred embodiment of the present invention, the assist characteristic includes an initial assist characteristic region that maintains a constant assist amount for a predetermined time and an end assist that decreases the assist amount to zero over time. And a characteristic area. Thereby, the assist can be finished smoothly.

  In the case of special traveling, for example, when the vehicle is an off-road vehicle, when the vehicle is a work vehicle, and when the vehicle is a work vehicle, the tillage work is a ground work such as a front loader work, and a predictable sudden load increase occurs. However, the time for such a sudden load increase can be examined experimentally and empirically. Therefore, it is preferable to determine the assist characteristics in advance based on the statistical evaluation of such survey results. As one preferred embodiment of the present invention, the initial assist characteristic region has a time interval of 1.5 seconds to 2.5 seconds, and the final assist characteristic region is 1.5 seconds to 2.5 seconds. It is proposed to have a time interval. It is convenient to map some assist characteristics calculated under such conditions so that they can be selected according to the load and the work type.

  In the hybrid vehicle according to the present invention, energy is not saved by charging the battery using a regenerative brake as in a general hybrid vehicle, but the engine is assisted by assisting the motor generator when a sudden load occurs. The aim is to improve fuel efficiency by downsizing. For this reason, since a small battery is mounted, attention must be paid to running out of battery leading to engine stop. For this purpose, in one preferred embodiment of the present invention, after the assist control is executed, execution of the next assist control is prohibited for a predetermined time. Thereby, it is avoided that the assist control is continuously executed when the continuous load is generated and the battery is rapidly consumed. Furthermore, it is also preferable to have a function of forcibly prohibiting the engine assist by the motor generator when it is determined that the charge amount of the battery is less than a predetermined value.

  If the engine load rises again during such an assist control prohibition period, there is no room for engine torque, the vehicle travel becomes unstable, and engine stall may occur. In order to avoid this, in a preferred embodiment of the present invention, a load determination unit that determines whether the engine load exceeds a predetermined level based on the load information is provided, and the assist control is prohibited during the prohibition period. When it is determined that the engine load exceeds the predetermined level, a return operation command for canceling a decrease in engine speed and a change in the compensation gear ratio based on the operation command is output. In this configuration, if the engine load increases during the prohibition period of the assist control, the engine speed can be forcibly increased to increase the engine torque.

  It is also possible to entrust the driver with an increase in engine speed during such assist control prohibition period. That is, the operating device is provided with a function that enables sending of a return operation command for canceling a decrease in engine speed and a change in the compensation gear ratio based on the operation command. According to this configuration, when the driver feels instability of the vehicle travel during the assist control prohibition period, the engine speed once lowered can be restored to the original state by a simple operation. It is preferable to notify the driver of the prohibition period of the assist control with a lamp or the like.

  Other features, operations and effects of the present invention will become apparent from the following description of the present invention using the drawings.

It is a schematic diagram which shows the basic flow of the power control at the time of the energy saving driving | operation of the hybrid vehicle by this invention. It is a schematic diagram which shows the basic flow in assist control. 1 is a perspective view of a tractor equipped with a transmission control system according to the present invention. It is a bird's-eye view of the driver's seat containing the various operation devices with which the operation part of the tractor was equipped. It is a functional block diagram which shows typically the power system of a tractor. It is a functional block diagram of an energy saving speed change module. It is a functional block diagram of an assist control module. It is sectional drawing of the motor generator with which the tractor was equipped. It is a schematic diagram which shows selection of the drive mode based on charge amount and an engine load factor (load amount). It is a flowchart which shows an example of the basic flow of the engine speed reduction process at the time of an energy saving operation, and a motor assist process.

Before specifically describing the embodiment of the present invention, the basic flow of engine speed reduction processing and motor assist processing during energy saving operation according to the present invention will be described using the schematic diagram of FIG.
FIG. 1 shows a vehicle speed (hereinafter simply referred to as a vehicle speed) by lowering the engine speed and changing the gear ratio using a driver's spontaneous operation input (in this case, operation of an engine speed reduction button 90 as an energy saving button) as a trigger. The flow of the control which maintains (it abbreviates as) is illustrated. When the driver drives the work vehicle and performs the tilling work at a constant vehicle speed, for example, when it is desired to reduce the engine speed for energy-saving operation, the engine speed reduction button 90 (hereinafter simply referred to as a lowering button). )push. In the figure, “−200”, which means that the rotational speed is reduced by 200 rpm, is drawn on the button operation surface, but this numerical value is only an example. When the lowering button 90 is operated, a lowering operation signal as a lowering operation command is output to the energy saving transmission module 7. The energy saving transmission module 7 generates a rotation speed reduction command and a gear ratio change command using the lowering operation command as a trigger. The rotation speed reduction command is a command that requests the engine control unit 5A to use the energy saving engine rotation speed that is reduced by a predetermined engine rotation speed that is set in advance based on the current engine rotation speed. The gear ratio change command is based on the current gear ratio in the transmission 10 to compensate for a decrease in vehicle speed caused by a decrease in engine speed performed for energy saving operation and maintain the current vehicle speed. That is, this is a command for requesting the transmission control unit 20 so that the transmission 10 generates a compensated transmission gear ratio.

  The energy saving process for outputting the rotation speed reduction command and the gear ratio change command can be performed a plurality of times. That is, every time the driver presses the engine speed reduction button 90, the engine speed reduction command and the gear ratio change command are output, and the engine speed that gradually decreases is generated. To prevent the vehicle speed from changing substantially.

  FIG. 1 also shows a flow of assist control of the motor unit 4 with respect to the engine E to cope with an unexpected increase in engine load (rotational load) that occurs during energy-saving operation with the engine speed reduced to the limit. Yes. In the following description, since the motor unit 4 is configured as a motor generator that also functions as a generator for charging a battery, the motor unit 4 is hereinafter referred to as a motor generator 4. A sudden increase in rotational load that occurs during energy-saving operation leads to a decrease in the rotational speed of the engine E, that is, a decrease in the vehicle speed, and further to an engine stall. In particular, in the case of a work vehicle working at a constant vehicle speed, the engine E is frequently operated in the constant speed control mode, and at that time, an abrupt load is applied to the power transmission means depending on the work situation and the grounding ground condition. As a result, a situation in which the rotational speed of the engine E is reduced occurs. A decrease in engine speed leads to a decrease in vehicle speed and insufficient driving force of the working device. In order to avoid this, the rotational load applied to the engine E and the power transmission means for transmitting the engine power is detected, the motor generator 4 is driven for a short time to at least partially compensate for the load, and the engine E is assisted. Is done. This is the assist control of the motor generator 4 for the engine E.

  For this assist control, the load information generation unit 81 and the assist control module 6 function. The load information generation unit 81 detects load information indicating the rotational load received by the power transmission means constituted by the engine E or the power transmission shaft and the transmission 10 by engine control information given from the engine control unit 5A or by various sensors. It has a function of generating based on input parameters extracted from information. The input parameters used in the load information generating unit 81 include the rotation speed (rotation speed) of the engine E, the rotation speed (rotation speed) of the power transmission means, the engine torque calculated by the engine control unit 5A, and the power transmission means. The torque, the vehicle speed, and the working state of the working device 9 (cultivation depth, traction force, load acting force, etc.) can be mentioned, but the actually used input parameters depend on the sensors equipped on the work vehicle. Since there is a high possibility that a rotation detection sensor and a vehicle speed sensor for the power transmission shaft are provided as standard, it is convenient to use the rotation speed fluctuation value or the vehicle speed fluctuation value of the power transmission means as the input parameter. These input parameters are sent through a vehicle state detection unit that processes signals from various sensors. The load information generation unit 81 may generate load information indicating a sudden increase in rotational load based on a differential value or a difference value of the rotational load with time in order to detect a sudden increase in rotational load. However, load information indicating an increase in rotational load that triggers assist control may be generated simply by threshold determination.

  The assist control module 6 determines whether to execute assist control for the engine E using the motor generator 4 based on the load information generated by the load information generation unit 81. For example, when the battery charge amount is equal to or less than a predetermined value, the assist control is stopped or the assist control is performed with a partial assist amount. Further, after the assist control is executed, execution of the next assist control is prohibited for a predetermined time. Furthermore, the assist control module 6 determines the assist characteristic that defines the assist amount and the assist time in the assist control based on the load information generated by the load information generating unit 81. Further, the assist control module 6 outputs an assist control signal to the motor control unit 5B based on the determined assist characteristic. The motor control unit 5B controls the motor generator 4 by outputting a motor control signal based on the assist control signal.

  If the driver feels that the vehicle is unstable when assist control by the motor generator 4 is prohibited, or when assist control can be executed only with a limited amount of assist, step processing is performed. It is necessary to return the energy-saving processing that has been done one step at a time. FIG. 1 also shows a control flow of the return processing performed for that purpose. Here, the driver's voluntary operation input (in this case, the operation of the engine speed lowering return button 91 as an energy saving button) is used as a trigger to gradually return the engine speed lowered for the energy saving operation. At the same time, the speed ratio is changed to maintain the vehicle speed (hereinafter simply referred to as vehicle speed). When the engine lowering process for energy saving operation has been performed over many stages, first, an engine speed lowering return button (hereinafter simply referred to as a return button) 91 is pressed. In the figure, “+200”, which means that the rotational speed is returned (increased) by 200 rpm, is drawn on the button operation surface, but this numerical value is only an example. When the return button 91 is operated, a return operation signal as a return operation command is output to the energy saving transmission module 7. The energy saving transmission module 7 generates a new rotation speed reduction command and a gear ratio change command using the return operation command as a trigger. The rotational speed reduction command here means a reduction from the engine rotational speed that has become the reference engine rotational speed in the first energy saving process, and is substantially a command to increase the current engine rotational speed. By supplying this engine speed reduction command to the engine control unit 5A, the engine engine speed is eliminated from the engine decrease performed at the corresponding stage in the energy saving process, and the engine engine speed is substantially increased. At the same time, it is necessary to create a gear ratio, that is, a compensated gear ratio for maintaining the current vehicle speed by compensating for the change in the engine speed due to the canceled engine decrease, and consequently the increase in the vehicle speed caused by the increase. . For this purpose, the gear ratio change command requests the gear shift control unit 20 so that the compensated gear ratio is generated by the transmission 10. This return process can be executed for the number of processing steps of the energy saving process performed based on the reference engine speed.

  The basic flow of information in the assist control by the motor generator 4 will be described in more detail with reference to FIG. First, the engine control unit 5A sends an engine control signal based on the setting value set by the accelerator setting device to the engine control device 50. The fuel injection amount and the like are adjusted based on the engine control signal, and the engine E is driven. Since the engine speed changes due to external factors, that is, load fluctuations such as travel load and work load, the fuel injection amount prevents the load fluctuation from causing an unexpected decrease in engine speed or engine stall. Adjust torque etc. to increase torque. However, since the rated output of the engine E is adjusted to the maximum torque required in normal work, if an unexpected sudden increase in load occurs, the rotational speed decreases, and in the worst case, the engine stalls. In order to avoid this, the motor control unit 5B sends an assist signal to the inverter 51 and uses the motor generator 4 to assist the engine E when the load increases.

  The load information generation unit 81 generates load information including a load amount based on the vehicle state information sent from the vehicle state detection unit 9 or the engine state information sent from the engine control device 50, and assist characteristics. The data is sent to the determination unit 61. The battery management unit 54 calculates the amount of charge (generally called SOC) based on the charging information from the battery B, and sends battery information including this amount of charging to the assist control module 6. Here, the assist control module 6 includes an assist characteristic determination unit 61 and an assist control determination unit 62 as two functional blocks.

  The assist characteristic determination unit 61 determines an appropriate assist characteristic: W (t) based on the load amount: L read from the load information and the charge amount: SC read from the battery information. This assist characteristic is derived from a general expression such as W (t) = Γ [L, SC]. That is, the assist characteristic can be represented by a graph that determines the amount of assist over time. In practice, a configuration in which a plurality of assist characteristics are mapped and stored, and an optimum assist characteristic is selected from the load amount: L and the charge amount: SC is preferable.

  When the assist characteristic is determined, the motor control unit 5B generates an assist control signal based on the assist characteristic, drives and controls the motor generator 4 through the inverter 51, and increases the load generated in the engine E or the power transmission means. To compensate. Since the torque response of the electric motor is fast, even if a sudden increase in traveling load or work load occurs, a decrease in the rotational speed is avoided thereby. When the load increase continues or when there is no allowance for the charge amount of the battery B, this is dealt with by adjusting the gear ratio in the energy saving transmission module 7.

  In addition to the assist control, the motor control unit 5B can cause the motor generator 4 to function as a generator and charge the battery B by sending a power generation command to the inverter unit 51. Further, the motor control unit 5B sends a zero torque control signal to the inverter unit 51, so that the motor generator 4 performs zero torque drive.

  Next, specific embodiments of the present invention will be described. In this embodiment, the hybrid vehicle is a well-known general-purpose tractor as shown in FIGS. The power system of this tractor is schematically shown in FIG. The tractor vehicle body includes an engine E, a motor generator 4, a hydraulically driven main clutch 31, a transmission 10, a driving unit 3, a pair of left and right front wheels 2a and a rear wheel 2b as a traveling device 2. . Further, a tilling device as a working device W is mounted on the rear part of the vehicle body by an elevating mechanism. The lifting mechanism is operated by a hydraulic cylinder

  As schematically shown in FIG. 5, the engine E of the tractor is a diesel engine that is rotationally controlled by a common rail system, and includes a common rail control device as the engine control device 50. The transmission 10 includes a hydraulic mechanical continuously variable transmission (hereinafter abbreviated as HMT) 12, a forward / reverse switching device 13, a gear transmission 14 that performs a multi-stage shift, and a differential mechanism 15. The drive wheel (front wheel 2a and / or rear wheel 2b or both) 2 is finally rotated through the power transmission shaft 30. Each of the forward / reverse switching device 13 and the gear transmission 14 is provided with a hydraulically driven transmission clutch 10a. Further, the cultivator W mounted on the tractor can receive the rotational power via the PTO shaft W1 that constitutes a part of the power transmission shaft 30 that transmits the rotational power of the engine E and the motor generator 4, and thus the tillage power can be received. The rotor is driven to rotate at a predetermined tilling depth.

  The HMT 12 includes a hydrostatic transmission mechanism 12A including a swash plate type variable discharge hydraulic pump that receives power from the engine E and the motor generator 4, and a hydraulic motor that rotates by hydraulic pressure from the hydraulic pump and outputs power. And a gear mechanism 12B. The planetary gear mechanism 12B is configured to receive the power from the engine E and the motor generator 4 and the power from the hydraulic motor as inputs, and to supply the speed change output to the power transmission shaft 30 at the subsequent stage.

  In the hydrostatic transmission mechanism 12A, power from the engine E and the motor generator 4 is input to the pump shaft, whereby pressure oil is supplied from the hydraulic pump to the hydraulic motor, and the hydraulic motor is rotated by the hydraulic pressure from the hydraulic pump. Driven to rotate the motor shaft. The rotation of the hydraulic motor is transmitted to the planetary gear mechanism 12B through the motor shaft. The hydrostatic transmission mechanism 12A changes the angle of the swash plate 12a by displacing a cylinder interlocked with the swash plate 12a of the hydraulic pump, so that the forward rotation state, the reverse rotation state, and the forward rotation state are changed. A hydraulic motor that changes the rotational speed of the hydraulic pump steplessly, whether it is shifted to a neutral state located during the reverse rotation state, and shifted to the normal rotation state or the reverse rotation state. The rotation speed (number of rotations per hour) is changed steplessly. As a result, the rotational speed of the power output from the hydraulic motor to the planetary gear mechanism 12B is changed steplessly. The hydrostatic transmission mechanism 12A stops the rotation of the hydraulic motor by the hydraulic pump when the swash plate 12a is positioned in the neutral state, and consequently stops the output from the hydraulic motor to the planetary gear mechanism 12B.

  The planetary gear mechanism 12B meshes with the sun gear, the three planetary gears arranged at regular intervals around the sun gear, the carrier that rotatably supports each planetary gear, and the three planetary gears. A ring gear and an output shaft (one of the power transmission shafts 30) connected to the forward / reverse switching device 13 are provided. In this embodiment, the carrier forms a gear portion that meshes with an output gear attached to the power transmission shaft 30 on the engine E side on the outer periphery, and is supported by the boss portion of the sun gear so as to be relatively rotatable.

  With the above-described configuration, the HMT 12 changes the power transmission to the front wheels 2a and / or the rear wheels 2b that are drive wheels steplessly by changing the angle of the swash plate 12a of the hydrostatic transmission mechanism 12A. can do. The control of the swash plate 12 a is realized by hydraulic control of a hydraulic control unit 22 that operates based on a control command from the transmission control unit 20. In addition, a hydraulic pump P is provided as a hydraulic source of a hydraulic actuator such as the above-described hydraulically driven cylinder, the main clutch 31, and the transmission clutch 10a. The hydraulic pump P may employ a mechanical pump that receives rotational power from the power transmission shaft 30 or an electric pump that receives rotational power from an electric motor. In the case of an electric pump, the electric motor is controlled by the hydraulic control unit 22.

  The shift control unit 20 is constructed with various control functions for performing a shift operation on the transmission 10 based on a shift operation command from the shift operating tool and a gear ratio adjustment command from the energy saving shift module 7. In particular, the function related to the present invention is to adjust the gear ratio by changing the angle of the swash plate 12a of the HMT 12 based on a command from the energy saving transmission module 7.

  The shift control can be performed by both an operation signal input by human operation and a mechanically generated operation signal input. However, the shift pedal 25 that functions as a shift operation tool for human input has a driving operation area. It is placed on the right floor. The shift pedal 25 can be held at an arbitrary position for traveling at a constant vehicle speed. Also, in the driving operation area, as described above, an engine speed reduction button 90 and an engine speed return button 91 as operating devices for sending an operation command by a driver's operation to adjust the engine speed, And a shift lever 27 is provided. In this embodiment, the engine speed reduction button 90 and the engine speed return button 91 are provided together with the display 39 on the side panel covering the upper part of the rear wheel fender, as shown in FIG. It may be provided on the left side panel, the steering handle or the front panel in front of the handle.

  Control of the motor generator 4 in this power system, that is, assist control for the engine E, is performed by the assist control module 6. Here, the assist control module 6 uses the configuration described with reference to FIG. The load information generation unit 81 and the battery management unit 82 described above are built in the power management module 8. In this embodiment, the engine control unit 5A, the motor control unit 5B, the assist control module 6, the energy saving transmission module 7, the power management module 8, the vehicle state detection unit 9, the transmission control unit 20, and work for operating the work device W are performed. Various control units called ECUs such as the device control unit 21 are connected to each other by an in-vehicle LAN so that data transmission is possible. Of course, it is possible to freely integrate and further divide the various control units which are divided here, but the configuration in this embodiment gives priority to making the explanation in the present invention easy to understand. It is not intended to limit the invention.

  The vehicle state detection unit 9 inputs signals from various sensors arranged in the tractor and operation input signals indicating the state of the operating device operated by the driver, and performs signal conversion and evaluation calculation as necessary. The obtained signals and data are sent to the in-vehicle LAN. The sensor particularly related to the present invention generates a shift operation amount (here, a swing angle) generated by depressing the engine speed reduction button 90, the engine speed return button 91, and the speed change pedal 25 described above as a detection signal. A pedal sensor 92 that detects the operation position of the speed change lever 27, a lever sensor 93 that generates an operation signal, and a rotation speed sensor 94 that detects the rotation speed of the engine output shaft Ex. Of course, a configuration in which various sensors and buttons are directly connected to each control unit without using the vehicle state detection unit 9 may be adopted.

Hereinafter, power control according to the present invention will be described in more detail with reference to FIGS. 5, 6, and 7.
As is well known, the engine control unit 5A is a core function unit for electronically controlling the engine E. According to the operating state of the engine E estimated by an external operation input signal, an internal sensor signal, and the like, Various types of engine control such as control based on a preset program, such as constant rotation speed control and constant torque control, are performed.

The transmission control unit 20 controls the hydraulic control element of the transmission 10 described above via the hydraulic control unit 22 based on an external operation input signal, an internal sensor signal, etc., sets the transmission ratio of the transmission 10, and the tractor At a desired speed. The display control unit 38 generates a control signal for displaying various types of notification information on a display 39 made of liquid crystal or the like provided in the driving operation area. In this embodiment, as shown in FIG. 4, the display 39 is adjacent to a switch panel including an engine speed reduction button 90 and an engine speed return button 91 on the side panel in the hand (right side) area of the driver's seat. However, instead of or in addition to this, it can be incorporated into a front panel in which a vehicle speedometer, a tachometer, and the like are arranged. In any case, various information such as vehicle operation is displayed on the display 39, and the following display events are included as things related to the present invention.
(1) The engine speed reduction amount is displayed during the execution of the engine speed reduction process or the engine speed reduction process described with reference to FIG.
(2) A lighting display indicating that the engine speed reduction process or the engine speed reduction process is being performed is performed.
(3) Indicates that assist control by the motor generator 4 is being executed.
(4) The charge amount of the battery B is shown.

The energy saving transmission module 7 is a control module that realizes a temporary engine speed reduction process. The important functions of the energy saving transmission module 7 are the following two.
(1) In this embodiment, an operation that is configured by an engine speed reduction button (hereinafter abbreviated as a lower button) 90 and an engine speed return button (hereinafter abbreviated as a return button) 91 and that is operated by a driver. Based on the operation command sent from the device, the engine control unit 5A is provided with a rotation speed reduction command that is set by the engine control unit 5A to reduce the engine rotation speed for constant rotation speed control by a predetermined amount.
(2) In order to maintain the vehicle speed during the constant speed traveling control, the speed change control unit 20 is changed to change the speed ratio so as to compensate for the engine speed reduction caused by the rotation speed reduction command based on the operation of the lowering button 90. An operating device is provided that gives a required gear ratio change command. In this embodiment, the return operation command is sent out by operating the return button 91.
In the specific example of this embodiment, every time the lowering button 90 is operated, the engine speed decreases by 200 rpm from the set speed: N0 set for constant speed traveling control, and the return button 91 Is operated once, the decrease in the engine speed and the change in the compensation gear ratio due to the previous lowering button operation are canceled, and the state before the previous lowering button operation is restored.
Further, it is preferable that the number of reductions in the engine speed by the lowering button 90 is limited to a predetermined number. For example, in this embodiment, it is possible to limit the engine speed reduction to 800 rpm by setting the limit number to 4 times. Of course, this limit number is preferably set to an arbitrary number.

  The energy saving transmission module 7 is constructed by a computer capable of exchanging data with the assist control module 6, the power management module 8, and the like, and its function is mainly created by a computer program. As shown in FIG. 6, in order to realize the above functions, the energy saving transmission module 7 has a rotation speed reduction command generation unit 71, a gear ratio change command generation unit 72, a lowering processing history memory 73, a load determination unit 74, a forced return. A control unit 75 is included.

  The rotation speed reduction command generation unit 71 generates a rotation speed reduction command for reducing the current engine rotation speed by 200 rpm based on the operation command by the driver pressing the lowering button 90, and sends it to the engine control unit 5A. At that time, the gear ratio change command generation unit 72 obtains a change value of the gear ratio that compensates for the decrease so that the decrease in the engine speed due to the rotation speed decrease command does not cause a decrease in the vehicle speed. A transmission ratio change command based on the above is generated, and this transmission ratio change command is sent to the transmission control unit 20. The engine control unit 8 controls the rotational speed of the engine E with the basic engine rotational speed set according to the operation position of the accelerator lever 32 as a control target. This rotational speed reduction command decreases the basic engine rotational speed. In this embodiment, it is possible to command a decrease in the rotational speed a plurality of times, for example, four times. In other words, a 200 rpm decrease from the basic engine speed is commanded by the first rotation speed reduction command, and a 200 rpm, that is, a 400 rpm decrease from the basic engine rotation speed is commanded by the second rotation speed decrease command. Of course, the decrease in the vehicle speed due to the decrease in the engine speed is compensated by the gear ratio change command from the gear ratio change command generator 72 each time.

  Further, when the driver depresses the return button 91, a return operation command is given to the energy-saving speed change module 7, and the rotation speed reduction command generation unit 71 determines the accumulated number of rotation speed reduction commands set at the present time. A return command for canceling one step is sent to the engine control unit 8. As a result, if the engine speed reduction command is only set once, the engine speed decrease for one time is canceled, and the target engine speed of the engine E in the engine control unit 8 is the original basic engine speed. Number. If the rotational speed reduction command is set twice, the engine rotational speed reduction for one time is canceled, and the target rotational speed of the engine E in the engine control unit 8 is reduced by 200 rpm from the basic engine rotational speed. Number. Even if the return button 91 is pressed in a state where the engine speed reduction by the rotation speed reduction command is not set, the rotation speed reduction command is not generated. The return button 91 only performs a cancellation process for the rotation speed reduction command. Naturally, when the engine speed reduction is corrected by the return operation command by the operation of the return button 91, at the same time, the increase in the vehicle speed due to the correction is determined by the gear ratio change command from the gear ratio change command generator 72. Compensated and the vehicle speed is kept constant.

  For this reason, it is necessary to record the number of rotation speed reduction commands set in the engine control unit 5A by the rotation speed reduction command generation unit 71. For this reason, a reduction processing history memory 73 is provided. The lowering processing history memory 73 is suitable for a memory structure such as a stack memory. When a rotation speed reduction command is generated, information on the rotation speed reduction is written (push) to the lowering processing history memory 73 and a return command is generated. Then, the last written information on the rotational speed reduction is read and erased (popped). Of course, a memory structure such as a history memory that records the rotation speed reduction command and the return operation command in time series may be adopted. In any case, when a rotation speed reduction command is sent to the engine control unit 5A by the rotation speed reduction command generation unit 71, information on a decrease in engine speed of 200 rpm due to one operation of the lowering button 90 is obtained as necessary. The information on the change in gear ratio is also written in the lowering processing history memory 73. Then, by accessing the lowering processing history memory 73, it is possible to know the current operation history of the lowering button 90, the reduction amount of the engine speed commanded to the current engine control unit 5A, and the current gear ratio.

  The load determination unit 74 has a function of determining whether or not the engine load has exceeded a predetermined level, and when the engine load exceeding the predetermined level is determined, the target engine rotation speed set by the rotation speed decrease command is decreased. And a return command for canceling the change in the compensation gear ratio. For example, when the engine load exceeding a predetermined level is determined in the prohibition period in which the assist control by the assist control module 6 is prohibited, the load determination unit 74 reduces the engine speed and changes the compensation gear ratio performed previously. Outputs a return operation command to cancel.

  The forcible return control unit 75 forcibly outputs a return operation command when a predetermined cancel condition set in advance other than the engine load is satisfied, and decreases the engine speed set in the engine control unit 5A. And the change of the compensation gear ratio applied to the shift control unit 20 is canceled. This cancellation condition detects a situation in which constant speed travel is not required, such as when the vehicle travels from a work travel mode that requires constant speed travel to a general road travel mode that requires traveling while adjusting the vehicle speed. This is a typical condition. Also, when the vehicle operation is terminated with the engine key turned off, it is preferable to forcibly cancel the decrease in engine speed.

  Note that, when the basic engine speed is adjusted by operating the accelerator operating device, the engine speed is artificially changed, but at that time, it is configured to take over the rotation speed reduction command. Thereby, even if the accelerator operating device is frequently operated, the energy saving operation can be maintained. Similarly, the speed change ratio of the transmission 10 is also artificially changed by the speed change pedal 25 that is a speed change operation device. Even at this time, the engine speed change due to the change in the speed change ratio, the subsequent decrease in the speed and the rotation speed The compensation gear ratio is set in accordance with the decrease in the number.

  FIG. 7 shows an assist control module 6 that appropriately drives and assists the motor generator 4 when the rotational load received by the engine E suddenly increases when the engine speed is lowered to perform energy saving operation. As described above, an assist characteristic determination unit 61 and an assist control determination unit 62 are provided. The assist characteristic determination unit 61 is provided with an assist characteristic map storage unit 51a. The assist characteristic map storage unit 61a has a function of creating and storing a plurality of assist characteristic maps M in which assist characteristics are mapped in advance, or creating and setting an appropriate assist characteristic map M as necessary. As schematically illustrated, this assist characteristic can be represented by a graph that determines the amount of assist over time. In the example of FIG. 7, the horizontal axis is time, and the vertical axis is assist gain. The assist gain is a ratio to the maximum assist amount (motor torque) calculated according to the load amount read from the load information, and takes a numerical value between 0% and 100%. That is, by multiplying the maximum assist amount by the assist gain obtained from the assist characteristic map M, the assist amount actually assisted by the motor generator 4 is obtained. The assist characteristic in this embodiment includes an initial assist characteristic area S that maintains a constant assist amount for a predetermined time and an end assist characteristic area E that reduces the assist amount to zero over time. The time interval t1 of the initial assist characteristic region S is 1.5 to 2.5 seconds, preferably 2 seconds, and the time interval t2 of the final assist characteristic region E is 1.5 to 2.5 seconds, preferably 2 Seconds. In the illustrated assist characteristic map M, the assist gain in the initial assist characteristic region S is constant at 100%, and the final assist characteristic region E is linear. Of course, an arbitrary shape can be adopted for the decreasing tendency. It is also possible to employ a non-linear graph in both the initial assist characteristic region S and the final assist characteristic region E. The assist characteristic determination unit 61 determines an optimum assist characteristic map M from the load amount read from the load information and the charge amount read from the battery information. In the other assist characteristic map M, various assist characteristics are described such that the assist gain in the initial assist characteristic region S ranges from about 10% to less than 100%, and the final assist characteristic region E is a decreasing function. Has been. That is, the assist amount actually generated by the motor generator 4 varies each time depending on the load amount and / or the charge amount. It should be noted that continuous execution of assist control based on the assist characteristics is prohibited by the assist control determination unit 62. The execution interval of the assist control, that is, the prohibition time may be changed according to the charge amount of the battery B, or may be determined in advance according to the capacity of the battery B. Further, it may be varied depending on the work. In any case, it is set so as not to cause a rapid decrease in the battery charge amount.

  The power management module 8 includes the load information generation unit 81, the battery management unit 82, and the operation mode selection unit 83 described above. The battery management unit 82 calculates the charge amount based on the charge information from the battery B, and outputs battery information including this charge amount. The operation mode selection unit 83 is used when working with the working device W that takes out rotational power of a constant rotational speed from the PTO shaft W0 and uses it for work, or when the work vehicle travels at a predetermined speed (cruising travel). The constant speed control mode is maintained to keep the rotation speed constant. When this constant speed control mode is set, the engine control unit 5A controls the engine control device 50 so as to maintain the rotational speed of the engine E at the set predetermined value.

  As shown in FIG. 8, a motor housing 40 that houses the motor generator 4 and the main clutch 31 is provided on the rear side of the engine E. The motor generator 4 has both a function of a three-phase AC generator that generates electric power by the driving force of the engine E and a function of a three-phase AC motor that rotates by electric power supplied from the outside. Therefore, the inverter unit 70 converts the DC power from the battery B into three-phase AC power and supplies it to the motor generator 4. The inverter unit 70 converts the three-phase alternating current generated by the motor generator 4 into a direct current, boosts it, and supplies it to the battery B.

  As is apparent from FIG. 8, the engine E, the motor generator 4 and the main clutch 31 are provided in this order, and the motor housing 40 is connected to the rear end plate 40a connected to the rear portion of the engine E. The motor generator 4 and the main clutch 31 are accommodated in the housing 40.

  The motor generator 4 includes a rotor 42 having a permanent magnet 41 on the outer periphery, and a stator 43 disposed at a position surrounding the rotor 42. The stator 43 is formed on a plurality of teeth (not shown) of the stator core. It has a structure in which a coil is wound. Opposite the shaft end of the output shaft Ex (crankshaft) of the engine E, the rotor 42 of the motor generator 4 is arranged coaxially with the rotational axis X of the output shaft Ex, and of the rotor 42, the output shaft Ex The base plate 31a of the main clutch 31 is disposed on the opposite surface, and the output shaft Ex, the rotor 42, and the base plate 31a of the main clutch 31 are screw-connected. Although the base plate 31a also has a function as a flywheel, as described above, the motor generator 4 partially performs the inertial force function that the flywheel has performed, and thus is lighter than the conventional one.

  The motor housing 40 has a structure in which the front housing 40A and the rear housing 40B are connected in a separable manner. When the motor generator 4 is assembled, the stator 43 is provided on the inner surface of the front housing 40A. The front housing 40A is connected to the rear end plate 40a, and then the rotor 42 is connected to the rear end of the output shaft Ex.

  The main clutch 31 includes a clutch disk 31c, a pressure plate 31d, and a diaphragm spring 31e disposed in a clutch cover 31b connected to the rear surface of the base plate 31a, and a power transmission shaft that transmits the driving force from the clutch disk 31c. 30 and a clutch shaft 30a as one component, and is operated by a clutch pedal (not shown).

  The clutch shaft 30a is supported so as to be rotatable about the rotational axis X with respect to the rear housing 40B, and the clutch disk 31c is capable of transmitting torque to the clutch shaft 30a by a spline structure, and is connected to the rotational axis X. The diaphragm spring 31e has a configuration in which a biasing force in the clutch engagement direction is applied to the clutch disk 31c via the pressure plate 31d. The power of the clutch shaft 30a is transmitted to an intermediate transmission shaft 30b as one component of the power transmission shaft 30 that serves as an input shaft of the transmission 10 through a gear transmission mechanism.

  The capacity of the battery B mounted on the tractor is limited, and a considerable amount of power is required for torque assist during work travel. Therefore, if assist control is repeated during work, the battery B The amount of charge will soon disappear. In order to avoid this, it is necessary to execute the assist by the motor generator 4 while taking into account the charge amount of the battery B.

  For this reason, in this embodiment, the load information (engine load factor, rotation speed reduction amount) included in the load information generated by the load information generation unit 81 and the battery information sent from the battery management unit 82 are included. Based on the included charge amount, the assist control determination unit 52 determines whether the assist control is permitted or prohibited. An example of the determination map used at that time is shown in FIG. What can be understood from this determination map is that, in principle, the assist control is not performed unless the charge amount is sufficient. For example, an assist determination line is set where the amount of charge is about 80%, and torque assist is not performed below that to avoid the battery B from going up. However, if the engine load factor is close to 100%, there is a possibility of engine stall. Therefore, assist control is permitted even when the charge amount is 80% or less. At that time, the assist determination line is inclined from 90% to 100% of the engine load factor, that is, when the engine load factor is a predetermined amount (about 90% or more in this case), the charge amount is lower as the engine load factor is higher. But assist control is allowed. When the engine load factor is 100%, assist control is permitted even when the charge amount is about 30%. In this determination map, the assist determination line has a band shape, and the region above the upper boundary line of the assist determination line is an assist drive region, and assist control is permitted. A region below the lower boundary line of the assist determination line is a charge drive region. Further, the assist determination band surrounded by the upper boundary line and the lower boundary line of the assist determination line is a buffer area where neither assist control nor charging is performed. In this embodiment, zero torque drive control is performed on this buffer area. The zero-torque drive range. Assist control is prohibited in the charge drive region and the zero torque drive region.

The basic flow of the energy-saving shift process that brings about the energy-saving operation and is executed by the hybrid tractor described above will be described with reference to the flowchart of FIG. The energy saving speed change process includes an engine speed reduction process with a gear ratio adjustment and a motor assist process.
When the driver feels that the engine E has room during work traveling at a constant vehicle speed, the driver operates the lower button 90 (# 00) to perform energy-saving operation with a reduced engine speed, thereby saving energy. Processing starts. First, as described above, a rotational speed reduction process (# 02) for reducing the engine speed by a predetermined value, for example, 200 rpm, and a speed ratio changing process (# 04) for adjusting the speed ratio that cancels the reduction in the rotational speed. ) And are executed. Subsequently, it is checked whether or not a rotational load greater than a predetermined value is applied to the engine E as the rotational speed decreases (# 06). If it is determined in this load check that the current rotational load is still satisfactory (# 06 small load branch), a message to that effect and a decrease in engine speed for energy-saving operation are being performed, for example, a reduction The number of times the button 90 is operated and the amount of decrease in the rotation speed are displayed on the display 39 (# 08).

  If the driver still feels that the engine E has room, he can further operate the down button 90, and if this feels appropriate, this state can be continued. Therefore, in this routine, it is checked whether or not the lowering button 90 has been operated (# 10). If operated (# 10 ON branch), the routine returns to step # 02 and the speed reduction process and the gear ratio changing process are performed again. Executed. If the lower button 90 is not operated (# 10 OFF branch), the process returns to step # 06 to check the rotational load of the engine E.

  If it is determined in the load check in step # 06 that a rotational load of a predetermined value or more is applied to the engine E (# 06 large load branch), it is first checked whether motor assist using the motor generator 4 is possible. (# 12). If motor assist is possible (branch # 12), the motor assist process as described above is executed, and motor assist according to the load amount is performed (# 14). Then, returning to step # 06, the rotational load is checked.

  When the motor assist is not possible because the interval from the previous motor assist is short and it is in the motor assist prohibition time period or the charge amount of the battery B is insufficient (# 12 impossible branch) Further, it is checked whether the rotational load is an excessive load that immediately causes an engine stall or the like (# 16). If it is not an excessive load (No branch of # 16), it is not an emergency, but it is displayed on the display 39 that the rotational load is increasing (# 18), and the return button 91 is used to eliminate the increase in the rotational load. Then, it is checked whether or not the operation for returning the decrease in the rotational speed is performed, that is, the operation of the return button 91 (# 20). When the return button 91 is not operated (OFF branch of # 20), the process returns to step # 06 and the rotational load is checked. When the return button 91 is operated (ON branch at # 20), as described above, in order to eliminate the decrease in the rotational speed due to the previous lowering button 90, the rotational speed increasing process (# 22) and the gear ratio changing process (#) 24) is performed, and the process returns to step # 06.

If it is determined in step # 16 that there is an excessive load (Yes branch in # 16), this is an emergency situation, so a forcible return process for forcibly returning the decrease in the rotational speed by the lowering button 90 is performed (# 26). Therefore, the forced return process includes a rotation speed increasing process and a gear ratio changing process.
Note that this energy saving shift process is for easy understanding of the present invention, and in fact, interrupt processes based on various operations frequently occur, so control does not flow as in the flowchart of the figure.

[Another embodiment]
(1) In the above-described embodiment, the engine speed or the transmission shaft speed is used to detect the load acting on the engine E. However, a load detection sensor is provided directly on the work device W to detect this load. A signal may be used to determine whether assist control is necessary.
(2) In the above embodiment, the engine E and the motor generator 4 are directly connected, and the main clutch 31 is then attached and power is transmitted to the power transmission shaft 30, but instead, the engine E The main clutch 31 may be mounted between the motor generator 4 and the motor generator 4.
(3) In the above embodiment, the continuously variable transmission using the HMT 12 is adopted for the transmission 10, but a multi-stage transmission using a multi-stage gear transmission may be adopted.
(4) As the assist characteristics, individual assist characteristics optimized for the type of the work device W and the usage pattern thereof may be created in advance and appropriately selected. For example, a work device type detection unit for detecting the type of the work device W mounted on the work vehicle or a manual work device type setting unit is provided, and the assist characteristics using the type of the work device W actually mounted and used as an auxiliary parameter. The determination unit 61 is given. Thereby, the assist characteristic determination unit 61 can determine an appropriate assist characteristic depending on the type of work apparatus used.

The present invention can be applied to various hybrid vehicles including a drive source composed of an internal combustion engine and a motor generator, and a transmission that shifts the rotational power from the drive source and outputs it to the traveling device. In particular, the present invention is suitable for a work vehicle, and examples of such a hybrid work vehicle include a riding rice transplanter, a lawn mower, a combiner, and a front Rosa in addition to a tractor.

2: traveling device 10: transmission 20: transmission control unit 4: motor generator 40: motor housing 5A: engine control unit 50: engine control device 5B: motor control unit 51: inverter unit 6: assist control module 61: assist characteristic determination Unit 61a: Assist characteristic map storage unit 62: Assist control determination unit 7: Energy saving speed change module 71: Speed reduction command generation unit 72: Gear ratio change command generation unit 73: Lowering history memory 74: Load determination unit 75: Forced return control Unit 8: Power management module 81: Load information generation unit 82: Battery management unit 83: Operation mode selection unit 9: Vehicle state detection unit 90: Down button (operator)
91: Return button (operator)
E: Engine B: Battery W: External work machine

Claims (9)

An engine for supplying driving force to the traveling device via power transmission means;
An engine control unit for setting the engine speed of the engine;
A transmission provided in the power transmission means;
A transmission control unit for adjusting a transmission ratio of the transmission,
A motor unit that assists the engine by outputting power to the power transmission means;
A load information generating unit that generates load information representing an increase in rotational load received by the engine;
A motor control unit for performing assist control for outputting power from the motor unit to the power transmission means based on the load information;
A battery for supplying driving power to the motor unit;
An operation device that sends out operation commands by the driver's operation is provided.
Based on the operation command, a rotation speed reduction command for reducing the engine rotation speed set in the engine control unit by a predetermined amount is given to the engine control unit, and the rotation speed reduction command is used to maintain the vehicle speed. A transmission module for giving a transmission ratio change command for requesting the transmission control unit to change the transmission ratio so as to compensate for a decrease in engine speed;
Hybrid vehicle with   The hybrid vehicle according to claim 1, wherein the assist control is performed with respect to an increase in rotational load that occurs after the rotation speed reduction command is given to the engine control unit.   The hybrid vehicle according to claim 1, wherein the motor unit is configured as a motor generator, and the battery can receive charging power from the motor generator.   An assist characteristic determining unit that determines an assist characteristic that defines an assist amount and an assist time in the assist control based on the load information is provided, and the motor control unit performs assist control by the motor unit based on the assist characteristic. The hybrid vehicle according to any one of claims 1 to 3.   The hybrid according to any one of claims 1 to 4, wherein the assist characteristic includes an initial assist characteristic area for maintaining a constant assist amount for a predetermined time and an end assist characteristic area for decreasing the assist amount to zero over time. vehicle.   6. The hybrid vehicle according to claim 5, wherein the initial assist characteristic region has a time interval of 1.5 seconds to 2.5 seconds, and the final assist characteristic region has a time interval of 1.5 seconds to 2.5 seconds. .   The hybrid vehicle according to any one of claims 1 to 6, wherein execution of the next assist control is prohibited for a predetermined time after the assist control is executed.   A load determination unit that determines whether or not the engine load exceeds a predetermined level based on the load information, and when the engine load that exceeds the predetermined level is determined in the prohibition period of assist control, the engine based on the operation command The hybrid vehicle according to claim 7, wherein a return operation command for canceling the decrease in the rotational speed and the change in the compensation gear ratio is output.   The hybrid vehicle according to any one of claims 1 to 8, wherein the operating device is capable of sending a return operation command for canceling a decrease in engine speed and a change in the compensation gear ratio based on the operation command.

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