JP2013203235A - Hybrid work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid work vehicle which can perform work and can travel by using an appropriate work device with an internal combustion engine of a small output while avoiding a flat battery.SOLUTION: A hybrid work vehicle includes: a motor generator 4 which assists an internal combustion engine E for supplying a driving force through a power transmission shaft 30 to a traveling device 2 and a work device 9; a load amount calculating part 51 which calculates a load amount representing a rotation load that the internal combustion engine E receives based on an input parameter; a charging amount calculating part 54 which calculates a charging amount of a battery B; an operation mode selecting part 53 which selects a driving mode of either an assist driving mode for outputting power to the power transmission shaft 30 or a charge driving mode for outputting charging power to the battery B based on the load amount and the charging amount; and a motor control unit 7 which performs drive control on the motor generator 4 in the driving mode selected by the operation mode selecting part 53.

Description

  The present invention relates to a hybrid work vehicle that includes a power source that uses both an internal combustion engine and a motor generator, and the internal combustion engine is assisted by the motor generator.

  In a hybrid work vehicle in which the motor generator assists the internal combustion engine, the vehicle is driven by the power from the internal combustion engine, and the running conditions (vehicle speed, accelerator pedal operation amount (accelerator opening), internal combustion engine operating state, road surface condition) The motor generator is operated as a motor in accordance with the gear position, the remaining battery level, etc., and the vehicle travel is assisted by the power output from the motor generator. The motor generator can also be operated as a generator, and can be charged by supplying power to the battery. When this motor generator is operated as a motor, the generated torque of the motor generator is controlled, and the vehicle driving torque required by the driver (target vehicle driving torque, for example, based on the driver's accelerator pedal operation, etc.) The torque to be borne by the motor generator (assist torque) can be generated in accordance with the burden ratio between the internal combustion engine and the motor generator (the burden ratio is determined based on traveling conditions). It is configured.

  For example, according to Patent Document 1, a hybrid power unit including an electric motor that assists torque of an internal combustion engine when starting and accelerating a vehicle can detect a charged state of a battery and supply the internal combustion engine from the electric motor based on the detected charged state An auxiliary torque amount (assist amount) is calculated, and the amount of fuel applied to the internal combustion engine and the load ratio of the motor are changed from the auxiliary torque amount. As a result, when the charging rate is reduced, power supply to the electric motor is stopped to prevent the battery from rising.

  Further, in the hybrid power unit disclosed in Patent Document 2, two control maps having different motor generator assist patterns (relationship between engine speed and torque) for the internal combustion engine are prepared, and the battery charge capacity state (SOC), vehicle speed Assist control is performed by switching the control map according to state information such as the state of the transmission and the temperature of the internal combustion engine. As a result, good drivability is maintained while using a small horsepower internal combustion engine.

Japanese Laid-Open Patent Publication No. 4-32536 (paragraph [0006-0021], FIGS. 1 and 2) JP 2002-252904 A (paragraph number [0001-0026], FIG. 1, FIG. 2)

  However, the hybrid vehicle handled in Patent Document 1 and Patent Document 2 is a passenger car, and the necessity of torque assist for the internal combustion engine can be determined only by the amount of depression of the accelerator pedal operated by the driver. In Patent Document 1 and Patent Document 2, the torque assist process is controlled as such. On the other hand, an internal combustion engine that supplies driving force to the traveling device and the work device via a power transmission shaft, and a motor generator that assists the internal combustion engine by outputting power to the power transmission shaft are provided. In a hybrid work vehicle such as a tractor, since the large work load received by the work device reaches the power transmission shaft, the assist technology disclosed in Patent Document 1 and Patent Document 2 cannot be used as it is.

  An object of the present invention is to provide a hybrid work vehicle capable of working using an appropriate working device with an internal combustion engine having a small output while avoiding battery rise.

  In order to achieve the above object, a hybrid work vehicle according to the present invention includes an internal combustion engine that supplies a driving force to a traveling device and a work device via a power transmission shaft, and outputs the power to the power transmission shaft. A motor generator that assists the engine, a battery that receives charging power from the motor generator and supplies driving power to the motor generator, and a load amount calculation that calculates a load amount representing a rotational load received by the internal combustion engine based on input parameters A charge amount calculation unit for calculating a charge amount of the battery, an assist drive mode for outputting power to the power transmission shaft based on the load amount and the charge amount, or outputting charge power to the battery An operation mode selection unit that selects one of the drive modes of the charge drive mode, and a selection by the operation mode selection unit And a motor control unit for driving and controlling the motor-generator in the driving mode.

  With this configuration, the load amount corresponding to the rotational load received by the internal combustion engine during work such as tillage work is calculated by the load amount calculation unit, and the load amount and the charge amount calculated by the charge amount calculation unit are calculated. Based on this, as long as there is no risk of the battery running out, the assist drive mode is determined, the motor generator is driven and controlled, and the internal combustion engine is assisted. Further, when the rotational load of the internal combustion engine is small and there is no need for assist, the motor generator is driven and controlled in the charge drive mode, and the amount of charge of the battery increases. Therefore, since the internal combustion engine is properly assisted by the motor generator while avoiding only the situation where the battery runs out, it is possible to employ an internal combustion engine with a small rated output and good fuel efficiency, and frequently during work traveling It is possible to set the engine speed to a low speed with good fuel consumption in the constant speed running operation that is performed to keep the engine speed (engine speed) constant.

  If the load of the internal combustion engine is not so large as to cause the internal combustion engine to stop (engine stall), it is better to give more weight to charging the battery than the assist for the internal combustion engine. . However, when the load amount of the internal combustion engine is so large as to cause a stop (engine stall) of the internal combustion engine, it is also important to place more emphasis on assisting the internal combustion engine than charging the battery. For this reason, in one preferred embodiment of the present invention, the assist drive mode is selected even when the load amount is higher than a predetermined amount and the charge amount is lower as the load amount is higher. .

  Further, when the power transmission by the power transmission shaft is interrupted while the assist drive mode is selected, the rotational load of the internal combustion engine is naturally reduced, so that the assist drive mode is forcibly switched to the charge drive mode. Convenient to configure. Examples of vehicle behavior that confirms the interruption of the power transmission by the power transmission shaft include the disconnection of the main clutch of the power transmission shaft, the neutralization of the shift clutch of the traveling transmission mechanism and the PTO clutch for the working device, and the stop of the work vehicle by the brake operation. Etc.

  Furthermore, when the clutch that transmits power on the power transmission shaft is in a half-clutch state, even if the rotational load is large, if the torque is assisted using the motor generator, a large torque is generated in the clutch. The clutch may seize. In order to avoid this problem, in one preferred embodiment of the present invention, when the assist driving mode is selected and the clutch transmitting the power on the power transmission shaft is in the half-clutch state, the Thus, the assist drive mode is interrupted.

  Whether or not the motor generator assists the internal combustion engine is determined based on the load amount and the charge amount, and the assist amount may be constant, but the assist amount may be adjusted based on the load amount and the charge amount. In other words, for example, by mapping the assist amount as a function of the load amount and the charge amount, higher-quality assist process control can be realized. For this purpose, in a preferred embodiment of the present invention, there is provided an assist calculation unit that calculates an assist amount for the internal combustion engine by the motor generator based on the load amount in the assist drive mode. .

  In one specific and preferred embodiment of the present invention when the internal combustion engine is driven by a common rail system, the load amount calculation unit calculates the load amount using common rail control information as the input parameter. In other words, the control unit that executes the common rail control estimates the load torque from internal combustion engine data such as fuel injection timing, fuel injection amount, engine speed, and vehicle data such as vehicle speed, and maintains a predetermined engine speed. In addition, it has a function of calculating and executing a fuel injection timing and a fuel injection amount necessary for maintaining a predetermined torque. Therefore, it is possible to detect or estimate a sudden decrease or increase in the engine speed by using the common rail control information related to the common rail control, and to easily calculate the load amount without additional components.

1 is a basic configuration diagram of a power system in a hybrid work vehicle according to the present invention. It is a schematic diagram which shows the flow of the data in a torque assist process. 1 is a perspective view of a general-purpose tractor that is one embodiment of a hybrid work vehicle according to the present invention. It is a schematic diagram which shows the power system of a tractor. 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).

Hereinafter, before describing a specific embodiment of a hybrid work vehicle according to the present invention, a basic configuration of a power system employed in the present invention will be described with reference to FIG.
This hybrid work vehicle includes an internal combustion engine E and a motor generator 4 as drive sources, and travels by using a work device 9 mounted on the vehicle body while traveling by a travel device 2 composed of wheels and crawlers. . The power transmission system from the drive source includes a main clutch 31 that turns on and off the transmission of power from the drive source, a PTO shaft 90 that transmits power to the work device 9, and a power transmission shaft 30 that transmits power to the traveling device 2. And are included. A transmission 10 having a speed change mechanism is constructed on the power transmission shaft 30. The PTO shaft 90 is provided with a PTO clutch 91 for turning power transmission on and off, and the transmission 10 is also equipped with a transmission clutch 31a for turning on and off one or more power transmissions.

  The motor generator 4 generates rotational power as a power supply source from the battery B and runs the hybrid work vehicle in cooperation with the internal combustion engine E. However, the motor generator 4 is driven by the internal combustion engine E or is hybrid. The motor generator 4 can function as a generator for supplying electric power to the battery B under a situation where the work vehicle is decelerating or under an inertia traveling downhill.

  The rotation control of the internal combustion engine E is performed by the engine control unit 6 via an engine control device 60 such as an electronic governor mechanism or a common rail mechanism. The drive control of the motor generator 4 is performed by the motor control unit 7 via the inverter unit 70. The engine control unit 6 is a computer unit for controlling the fuel injection amount of the internal combustion engine E and has a constant speed control function for controlling the engine control device 60 so as to maintain the rotation speed of the internal combustion engine E constant. . The motor control unit 7 is also a computer unit, and gives a control signal to the inverter unit 70 in order to control the rotation speed and torque of the motor generator 4. Further, the motor control unit 7 includes an assist drive mode for outputting power to the power transmission shaft 30 and a charge drive mode for outputting charging power to the battery B as drive modes for the motor generator 4. Further, it is advantageous to have a zero torque drive mode that does not affect the power transmission shaft 30.

  As is well known, the inverter unit 70 converts the DC voltage of the battery B into an AC voltage and supplies it to the motor generator 4. When the motor generator 4 operates as a generator, the inverter unit 70 applies the DC voltage to the battery B. It also functions as a rectifier and a voltage regulator for supplying. That is, the battery B operates in a discharging process for supplying electric power to the motor generator 4 via the inverter unit 70, and is charged by the electric power generated by the motor generator 4 when the motor generator 4 operates as a generator. Works with the charging process.

  The power management unit 5 provides control commands to the engine control unit 6 and the motor control unit 7 so as to manage the assist control in which the motor generator 4 assists the internal combustion engine E. As a unit, a load amount calculation unit 51, an assist calculation unit 52, an operation mode selection unit 53, and a charge amount calculation unit 54 are included. The charge amount calculation unit 54 calculates the charge amount of the battery B. At that time, if the battery B is configured as an intelligent battery unit equipped with a computer, the amount of charge of the battery is calculated based on the battery state information from the battery B. The charge amount of the battery B is calculated based on the battery state information from the vehicle state detection unit S that has received the signal.

  The operation mode selection unit 53 outputs an assist drive mode for outputting power to the power transmission shaft 30 or outputs charging power to the battery B based on the load applied to the internal combustion engine E or the power transmission shaft 30 and the charge amount of the battery B. One of the charge drive modes to be selected is selected. Of course, if a zero torque drive mode is prepared, this drive mode is also selected as necessary. In addition, the operation mode selection unit 53 takes out the rotational power of a constant rotational speed from the PTO shaft 90 and performs work using the work device 9 that is used for work or when the work vehicle travels at a predetermined speed (cruising travel). A constant speed control mode is set to keep the rotation speed used for the constant. When the constant speed control mode is set, the engine control unit 6 controls the engine control device 60 so as to maintain the rotational speed of the internal combustion engine E at the set predetermined value. The motor control unit 7 controls the drive of the motor generator 4 using the inverter unit 70 in the drive mode selected by the operation mode selection unit 53.

  Although the operation of the internal combustion engine E in the constant speed control mode itself is well known, a sudden load is applied to the power transmission shaft 30 depending on the working condition of the working device 9 and the ground condition where the traveling device 2 is grounded. As a result, a situation occurs in which the rotational speed of the internal combustion engine E is reduced. At that time, due to delays in constant speed control by the engine control device 60, insufficient output of the internal combustion engine E itself, etc., the rotational speed of the internal combustion engine E decreases (vehicle speed decreases). In extreme cases, the internal combustion engine E stops. (Engine stall) occurs. In order to avoid this, the load applied to the power transmission shaft 30 is detected, the motor generator 4 is driven to at least partially cancel the load, and a torque assist process in which the internal combustion engine E is assisted is executed. For this torque assist process, a load amount calculation unit 51 and an assist calculation unit 52 are used.

  The load amount calculation unit 51 has a function of generating a load amount representing a rotational load received by the internal combustion engine E or the power transmission shaft 30 based on input parameters. Since the PTO shaft 90 is a branch shaft of the power transmission shaft 30, the rotational load received by the power transmission shaft 30 naturally includes the rotational load received by the PTO shaft 90. The assist calculation unit 52 calculates the assist amount for the internal combustion engine E by the motor generator 4 based on the load amount generated by the load amount calculation unit 51 in the constant speed control mode. The input parameters used in the load amount calculation unit 51 include the rotational speed (rotational speed) of the internal combustion engine E, the rotational speed (rotational speed) of the power transmission shaft 30, the engine torque calculated by the engine control unit 6, and power transmission. The torque of the shaft 30, the vehicle speed, and the working state of the working device 9 (cultivation depth, traction force, acting force on the loader, etc.) can be mentioned, but the input parameters actually used are the sensors installed in the work vehicle. Dependent. Since there is a high possibility that the rotation detection sensor and the vehicle speed sensor of the power transmission shaft 30 are provided as standard, it is convenient to use the rotation speed fluctuation value and the vehicle speed fluctuation value of the power transmission shaft 30 as input parameters. These input parameters are sent through a vehicle state detection unit S that processes signals from various sensors.

  FIG. 2 schematically shows a data flow in the torque assist process. The driving state in FIG. 2 indicates that the vehicle is in operation, and the engine control unit 6 sends an engine control signal to the engine control device 60 based on the set value set by the accelerator setting device. The fuel injection amount and the like are adjusted based on the engine control signal, and the internal combustion engine E is driven. Since the fluctuation of the rotational speed of the internal combustion engine E is caused by the fluctuation of external factors, that is, load fluctuation such as traveling load and work load, the fuel injection is performed so that the unexpected fluctuation of the rotational speed and engine stall do not occur due to the load fluctuation amount. Adjust the amount and increase the torque. However, since the torque responsiveness of the internal combustion engine E is slower than that of a motor or the like, the engine cannot respond to a sudden increase in load, leading to a decrease in the rotational speed, and in the worst case, an engine stall. For this reason, the motor control unit 7 sends an assist signal to the inverter unit 70 and uses a motor (here, the motor generator 4) whose torque response is orders of magnitude faster than that of the internal combustion engine E. The internal combustion engine E is torque-assisted so as to cover the poor torque response.

  In this torque assist process, the load amount calculation unit 51 inputs measurement values such as the rotational speed (rotation speed) of the power transmission shaft 30 and the vehicle speed output from the vehicle state detection unit S as input parameters, thereby determining the load amount. Calculate. If the input parameters are p1, p2,..., The load amount associated with time: L [t] is derived from the conversion formula: L [t] = G (p1, p2,...). The conversion function: G (p1, p2,...) Is normally mapped. Based on the charging information from the battery B, the charge amount calculation unit 54 calculates the charge amount (generally called SOC): SC.

The operation mode selection unit 53 uses the determination map prepared in advance based on the calculated load amount: L [t] and the charge amount: SC, or when the assist drive mode or the charge drive mode is prepared. One of the zero torque drive modes is selected. When the operation mode selection unit 53 selects the assist drive mode, this load amount: L [t] is given to the assist calculation unit 52, so that the assist amount of the motor generator 4 for the internal combustion engine E: W (t) Is calculated by the conversion formula: W (t) = Γ [L [t]], but this conversion function: Γ [L [t]] is also normally mapped. Note that the load amount: L [t] is not necessarily related to time.
When the assist amount is calculated, the motor control unit 7 generates an assist control signal based on the assist amount, drives the motor generator 4 through the inverter unit 70, and controls at least a portion of the torque fluctuation generated in the power transmission shaft 30. Compensate. Since the torque responsiveness of the electric motor is orders of magnitude faster than that of the internal combustion engine E, a sudden decrease in the rotational speed is avoided even if a sudden traveling load or work load occurs. When the load increase continues, it can be dealt with by the control of the internal combustion engine E such as an increase in the fuel injection amount by the engine control unit 6.

  When the operation mode selection unit 53 selects the charging drive mode, the motor control unit 7 sends a power generation command to the inverter unit 70, whereby the inverter unit 70 operates as power generation control, and the electric power generated by the motor generator 4 is supplied to the battery B. The battery B is charged. When the operation mode selection unit 53 selects the zero torque drive mode, the motor control unit 7 sends the zero torque control signal to the inverter unit 70, so that the motor generator 4 performs the zero torque drive.

  Since the torque assist by the motor generator 4 is excellent in torque response, it is possible to at least partially fulfill the function of the flywheel that has been conventionally equipped, and it is possible to reduce the weight of the flywheel or omit the flywheel. to enable. Therefore, it is preferable to construct the above-described conversion function: G (p1, p2,...) And the conversion function: Γ [L [t]] so that the inertial characteristics of the flywheel are realized. The load amount calculation unit 51 and the assist calculation unit 52 may be integrated so that the assist amount is directly derived from the input parameters.

  Next, specific embodiments of the present invention will be described. In this embodiment, the hybrid work vehicle is a well-known form of general-purpose tractor as shown in FIG. This tractor power system is shown schematically in FIG. The tractor vehicle body includes an internal combustion engine E, a motor generator 4, a hydraulically driven main clutch 31, a transmission 10, a driving unit 20, a pair of left and right front wheels 2a and a rear wheel 2b as the traveling device 2. . Further, a tilling device is mounted as a working device 9 at the rear part of the vehicle body by a lifting mechanism (not shown). The lifting mechanism is operated by a hydraulic cylinder.

  As schematically shown in FIG. 4, the internal combustion engine E of this tractor is a diesel engine (hereinafter abbreviated as “engine E”) whose rotation is controlled by a common rail system, and a common rail control device is used as the engine control device 60. I have. 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 transmission shaft 30. Each of the forward / reverse switching device 13 and the gear transmission 14 is provided with a hydraulically driven transmission clutch 31a. Further, the tilling device 9 mounted on the tractor can receive the rotational power through the PTO shaft 90 that constitutes a part of the power transmission shaft 30 that transmits the rotational power of the engine E and the motor generator 4. 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 by displacing the cylinder that is linked to the swash plate of the hydraulic pump, so that the forward rotation state, the reverse rotation state, and the normal rotation state and the reverse rotation state are reversed. The hydraulic pump rotates by changing the rotational speed of the hydraulic pump steplessly, even when the gear is shifted to the neutral state located between the states and is shifted to the forward rotation state or the reverse rotation state. Change the speed (number of revolutions per hour) 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 is positioned in a 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 driving wheels steplessly by changing the swash plate angle of the hydrostatic transmission mechanism 12A. Can do. This swash plate control is realized by hydraulic control of a hydraulic control unit 80 that operates based on a control command from the transmission control unit 8. In addition, a hydraulic pump 81 is provided as a hydraulic source of the hydraulic actuator such as the above-described hydraulically driven cylinder, the main clutch 31, and the transmission clutch 31a. The hydraulic pump 81 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 a hydraulic control unit 80.

  Control of the motor generator 4 in this power system, that is, torque assist for the engine E is performed by the power management unit 5. Here, the power management unit 5 uses the configuration described with reference to FIGS. 1 and 2. doing. The power management unit 5, the engine control unit 6, and the vehicle state detection unit S are also connected to each other via an in-vehicle LAN so that data transmission is possible.

  The vehicle state detection unit S inputs signals from various sensors arranged in the tractor and operation input signals indicating the state of an operating device (clutch pedal or brake pedal) operated by the driver, and if necessary Then, signal conversion and evaluation calculation are performed, and the obtained signals and data are sent to the in-vehicle LAN.

  As an upper electronic device for giving a control command to the hydraulic control unit 80, a transmission control unit 8 for shifting operation in the transmission 10 and a work device control unit 99 for operating the tilling device 9 are connected to the hydraulic control unit 80. Yes. The transmission control unit 8 and the work device control unit 99 are also connected to the in-vehicle LAN, and data can be exchanged with other units.

  As shown in FIG. 5, 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, and a power transmission shaft 30 that protrudes from the rear portion of the motor housing 40 is further connected to the engine E. Power to the motor generator 4 is transmitted to a transmission 10 disposed near the rear wheel 2b.

  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. As described with reference to FIG. 1, 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 shown in FIG. 4, 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, whereby the motor housing is connected. 40 includes a motor generator 4 and a main clutch 31.

  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 via a gear transmission mechanism.

  Drive control of the engine E and the motor generator 4 is performed by the power management unit 5 as described in FIG. In order to control fuel injection by a common rail type fuel injection device as the engine control device 60, the engine control unit 6 includes a signal from an accelerator pedal sensor, an engine rotation signal, a fuel pressure signal in the common rail, and an intake pressure signal at the intake portion. Etc. are acquired and control which determines the operation timing of an injector is performed. From such a configuration, the engine control unit 6 can also calculate the load factor (engine load factor) of the engine E, and gives this engine load factor to the power management unit 5 for use in the torque assist process. Can do.

  A parameter that can be easily used in the calculation of the load amount in the load amount calculation unit 51 of the power management unit 5 is a change in the rotational speed (rotational speed) of the power transmission shaft 30. In this embodiment, the rotational speed sensor S1 that detects the rotational speed of the power transmission shaft 30 is inserted into a hole that penetrates the wall surface of the motor housing 40, and the sensing portion at the lower end is the outer periphery of the base plate 31a of the main clutch 31. Located near the surface. That is, the rotational speed sensor S1 is configured as a pickup type that counts the rotation of the base plate 31a from the change in magnetic flux density. Of course, an optical sensor may be employed as the rotational speed sensor S1, or a configuration for detecting the rotational speed of the power transmission shaft 30 may be employed.

  In the tractor having the above-described configuration, basically, it is important for the engine control unit 6 included in the power management unit 5 to operate the engine E in a low speed region where fuel efficiency is good in order to improve fuel efficiency. . When it is considered that the load acting on the engine E exceeds the threshold value, the electric power from the battery B is three-phased via the inverter unit 70 driven based on the control signal from the motor control unit 7. AC power is supplied to the motor generator 4, and the driving force of the motor generator 4 assists the engine E. In particular, when a decrease in engine speed is detected due to a sudden increase in engine load during constant speed work, a torque assist process using the motor generator 4 to at least partially compensate for the increase in engine load. Is executed to avoid unexpected decrease in engine speed and engine stall. If the load acting on the engine E is considered to be less than the threshold value based on the engine information that the engine control unit 6 acquires and the vehicle state information sent from the vehicle state detection unit, the motor generator The control is performed to supply the generated power from 4 to the battery B via the inverter unit 70 and charge the battery B.

  However, the capacity of the battery B mounted on the tractor is limited, and torque assist during work travel requires considerable power consumption, so torque assist is easily allowed during work. The battery B will go up. In order to avoid the battery B from running up, the assist by the motor generator 4 must be executed in consideration of the charge amount of the battery B.

  In this embodiment, the load amount calculation unit 51 calculates the engine load factor as the load amount of the engine E from the information regarding the engine load acquired from the vehicle state detection unit S or the engine control unit 6. Further, the operation mode selection unit 53 determines the assist drive mode, the charge drive mode, and the zero torque drive from the charge amount SC of the battery B calculated by the charge amount calculation unit 54 and the engine load factor calculated by the load amount calculation unit 51. Select one of the drive modes. In this selection process, the operation mode selection unit 53 uses the determination map shown in FIG. What can be understood from this determination map is that, in principle, torque assist is not performed unless the charge amount SC is sufficient. For example, the assist determination line is used when the charge amount is about 80%, and torque assist is performed below that. Therefore, the battery B is prevented from rising. However, if the engine load factor is close to 100%, there is a possibility of engine stall, so torque assist is performed 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, the engine load factor is a predetermined amount (here, about 90% or more 9 and the higher the engine load factor, the lower the charge amount). However, when the engine load factor is 100%, the torque assist is performed even when the charging amount is about 30% .In this determination map, the assist determination line is a belt shape. The region above the upper boundary line of the assist determination line is the assist drive mode region, the region below the lower boundary line of the assist determination line is the charge drive mode region, and the upper boundary of the assist determination line. The assist determination zone surrounded by the line and the lower boundary line is a buffer area where neither torque assist nor charging is performed. The state, the buffer area zero torque drive control is set to zero torque drive mode area is performed.

Further, in this embodiment, when the following information is input, the operation mode selection unit 53 is prepared with an exception process for forcibly selecting the charge drive mode.
(1) Information indicating a situation where the main clutch 31 or the transmission clutch 31a is disconnected and the transmission torque of the power transmission shaft 30 is lost.
(2) Information indicating that the main clutch 31 or the transmission clutch 31a is in a half-clutch state and there is a risk that the main clutch 31 or the transmission clutch 31a will burn.
(3) Information indicating that the work vehicle is stopped and the work device 9 is not performing substantial work.
In this way, when a situation that does not require torque assist occurs exceptionally or when such a situation is expected, the charging opportunity is increased by switching from the assist drive mode to the charge drive mode.

[Other Embodiments]
(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, the load detection sensor is provided directly on the work device 9 to detect the load. The drive mode may be selected using a signal.
(2) As the map used for the assist calculation unit 52 to calculate the assist amount from the input parameters, a dedicated map optimized for each type of the work device 9 and its usage pattern is created in advance, You may make it choose suitably.
(3) In the above-described embodiment, the engine E and the motor generator 4 are directly connected, and the main clutch 31 is then mounted and the power is transmitted to the power transmission shaft 30. The main clutch 31 may be mounted between the motor generator 4 and the motor generator 4.
(4) In the above-described embodiment, the continuously variable transmission using the HMT 12 is employed in the transmission 10, but a multi-stage transmission using a multi-stage gear transmission may be employed.
(5) As a map used for calculating the assist amount from the input parameters, a dedicated map optimized for the type of the work device 9 and its use form is created in advance, and the map is appropriately selected. May be. For example, a work load characteristic setting unit for setting the work load characteristic of the work device 9 to be mounted on the work vehicle is constructed in the power management unit 5, and the work load characteristic of the work device 9 that is actually mounted and used is The data is read from the load characteristic setting unit and given to the load amount calculation unit 51 as an auxiliary parameter. As a result, the load information generation unit 51 can estimate from the work load characteristics how much the fluctuation in the rotational speed obtained from the vehicle state detection unit S will be, for example, from the work load characteristics in the future. A quantity can be generated.

  The present invention can be applied to various hybrid work vehicles including a drive source composed of an internal combustion engine and a motor generator and a work device operated by the drive source. For example, in addition to a tractor, such a hybrid work vehicle includes a riding rice transplanter, a lawn mower, and a combine.

2: Traveling device 2a: Front wheel (traveling device)
2b: Rear wheel (traveling device)
20: Driving unit 9: Work device 90: PTO shaft 91: PTO clutch 4: Motor generator 40: Motor housing 30: Power transmission shaft 31: Clutch 10: Transmission 16: Shift clutch 5: Power management unit 51: Load amount calculation unit 52: Assist calculation unit 53: Operation mode selection unit 54: Charge amount calculation unit 6: Engine control unit 60: Engine control device (common rail)
7: Motor control unit 70: Inverter unit 81: Hydraulic pump S: Vehicle state detection unit B: Battery E: Internal combustion engine

Claims (6)

An internal combustion engine that supplies driving force to the traveling device and the working device via a power transmission shaft;
A motor generator that assists the internal combustion engine by outputting power to the power transmission shaft;
A battery that receives charging power by the motor generator and provides driving power to the motor generator;
A load amount calculation unit for calculating a load amount representing a rotational load received by the internal combustion engine based on an input parameter;
A charge amount calculation unit for calculating a charge amount of the battery;
An operation mode selection unit that selects one of an assist drive mode for outputting power to the power transmission shaft or a charge drive mode for outputting charge power to the battery based on the load amount and the charge amount; ,
A motor control unit that drives and controls the motor generator in the drive mode selected by the operation mode selection unit;
Hybrid work vehicle equipped with.   The hybrid work vehicle according to claim 1, wherein the assist drive mode is selected even when the load amount is equal to or greater than a predetermined amount and the charge amount is low as the load amount is high.   3. The hybrid work vehicle according to claim 1, wherein, when power transmission by the power transmission shaft is interrupted during selection of the assist drive mode, the hybrid work vehicle is forcibly switched from the assist drive mode to the charge drive mode. 4.   4. The assist drive mode is forcibly interrupted when the assist drive mode is selected and the clutch transmitting power on the power transmission shaft is in a half-clutch state. 5. The hybrid work vehicle according to one item.   5. The hybrid work vehicle according to claim 1, further comprising: an assist calculation unit that calculates an assist amount for the internal combustion engine by the motor generator based on the load amount in the assist drive mode.   The hybrid work vehicle according to any one of claims 1 to 5, wherein the internal combustion engine is driven by a common rail system, and the load amount calculation unit generates the load amount using common rail control information as the input parameter.

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