Farm work vehicle

Abstract

To enable the promotion of energy saving by curbing wasteful consumption of fuel by an engine, in a state in which there is no possibility that drive cannot be properly performed.SOLUTION: A farm work vehicle comprises an engine control part 101 that controls an operation of an engine, and a working state detection part JK that detects whether a working state is a normal working state or a low-load working state lower in engine load than the normal working state. The engine control part 101 performs engine reduction control for making the number of engine revolutions smaller than in the normal working state, when the low-load working state is detected by the working state detection part JK.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an agricultural vehicle, for example a combine harvester. [Background technology]

[0002] In a combine harvester, which is one example of an agricultural work vehicle, traditionally, when traveling in a field at or above a predetermined speed, the engine has been configured to operate at the rated speed regardless of whether the work equipment, such as the pre-harvesting processing unit or the threshing processing unit, is operating or not (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-90607 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above conventional configuration, a large driving load is applied when harvesting crops, so the work can be carried out smoothly by operating the engine at the rated speed. However, even when the working implement is not in operation, the engine operates at the rated speed, which has the disadvantage of wasting fuel, and there is room for improvement in this respect.

[0005] An object of the present invention is to promote energy conservation by suppressing wasteful consumption of fuel by an engine in a state where there is no risk of the engine not being able to drive properly. [Means for solving the problem]

[0006] The characteristic configuration of the agricultural work vehicle of the present invention is that it is equipped with an engine, an engine control unit that controls the operation of the engine, and a work state detection unit that detects whether the work state is a normal work state or a low-load work state in which the load on the engine is lower than that in the normal work state, and when the work state detection unit detects the low-load work state, the engine control unit executes engine reduction control to reduce the engine speed more than in the normal work state.

[0007] According to the present invention, in normal working conditions where the driving load on the engine is large, the engine speed is set high so that the load can be covered, allowing work to be performed efficiently. In low-load working conditions where the engine load is smaller than in the normal working conditions, the engine speed is reduced compared to the normal working conditions, allowing work to be performed with less fuel than when operating at the engine speed in the normal working conditions. At that time, because the driving load is small, there is no risk of the engine stalling or other problems that prevent the engine from operating properly.

[0008] Therefore, it is possible to suppress the wasteful consumption of fuel by the engine and promote energy conservation without the risk of the engine not being able to drive properly.

[0009] In the present invention, there is provided a traveling device driven by the engine, a transmission that changes the speed of the engine's power and transmits it to the traveling device, and a vehicle speed control unit that controls the operation of the transmission, and it is preferable that the vehicle speed control unit executes vehicle speed maintenance control to control the operation of the transmission so as to maintain the vehicle speed before the engine reduction control is executed as the engine control unit executes the engine reduction control.

[0010] According to this configuration, when engine reduction control is performed while the vehicle body is traveling, the vehicle speed control unit executes vehicle speed maintenance control, thereby preventing the traveling speed at that time from being significantly decelerated due to a reduction in engine speed, and the vehicle can continue traveling without reducing the traveling speed as much as possible.

[0011] In the present invention, it is preferable that a manually operated speed change device is provided, the speed change device is composed of a hydrostatic continuously variable speed device having a hydraulic pump and a hydraulic motor, and is configured to change the speed of the power transmitted to the traveling device by changing the swash angle of the hydraulic pump based on the operation of the speed change device, and the vehicle speed control unit is configured to maintain the previous vehicle speed by changing the swash angle of the hydraulic motor in the vehicle speed maintenance control.

[0012] According to this configuration, the vehicle speed can be adjusted to a value manually commanded by the driver by changing the swash plate angle of the hydraulic pump based on the operation of the speed change device. When the engine speed is reduced by the engine reduction control in a speed-adjusted state, the vehicle speed decreases without the driver having to operate the speed change device. Therefore, by changing the swash plate angle of the hydraulic motor, the gear ratio of the hydrostatic continuously variable transmission as a whole is changed to compensate for the deceleration caused by the reduction in engine speed, thereby maintaining the vehicle speed.

[0013] As a result, the vehicle speed is maintained even if the engine speed is reduced, so that the driver can perform satisfactory steering operation without decelerating against his will.

[0014] In the present invention, it is preferable that the hydraulic motor is configured so that the swash plate angle can be switched stepwise over a plurality of stages.

[0015] According to this configuration, it is easier to simplify the configuration compared to a configuration in which the swash plate angle can be changed steplessly.

[0016] In the present invention, there is provided a working device driven by the engine, and a work clutch that interrupts the transmission of power from the engine to the working device, and it is preferable that the work state detection unit detects that the normal work state is present when the work clutch is in an engaged state, and detects that the low-load work state is present when the work clutch is in a disengaged state.

[0017] According to this configuration, when the work clutch is engaged, the working condition is normal, and the working implement is appropriately driven by the power of the high-speed engine. On the other hand, when the work clutch is disengaged, the working condition is low-load, and there is no driving load on the engine from the working implement, so there is little risk of the engine stalling even if it is decelerated.

[0018] In the present invention, a vehicle speed detection means is provided for detecting the vehicle speed, and the engine control unit is configured to execute automatic accelerator control for controlling the operation of the engine so that the engine speed becomes a predetermined rotational speed if the vehicle speed detected by the vehicle speed detection means is equal to or higher than a set speed, and it is preferable that even if the vehicle speed is equal to or higher than the set speed, when the low-load work state is detected by the work state detection unit, the automatic accelerator control is stopped and the engine reduction control is executed.

[0019] According to this configuration, when the vehicle speed reaches or exceeds the set speed, automatic accelerator control is executed, so that even if the driver forgets to set the accelerator, the engine speed can be adjusted to a predetermined speed suitable for the work. Furthermore, when the work condition detection unit detects a low-load work condition, engine reduction control is executed, so that wasteful consumption of fuel in the case of low load can be suppressed.

[0020] In the present invention, it is preferable that the engine control unit is configured to be switchable between a first mode in which the engine reduction control is executed and a second mode in which the engine reduction control is not executed based on an instruction from a manually operated mode switching unit.

[0021] According to this configuration, the pilot can select either a state in which engine reduction control is executed or a state in which engine reduction control is not executed, depending on the pilot's intention, which is easy to use.

[0022] In the present invention, it is preferable that the driver's section of the vehicle body is provided with a fuel consumption status display section for displaying the consumption status of fuel consumed by the engine.

[0023] According to this configuration, the actual fuel consumption state of the engine can be visually confirmed on the fuel consumption state display unit, and this can be used to correct the subsequent working mode, etc.

[0024] In the present invention, it is preferable that the engine control unit does not execute the engine reduction control when a predetermined check condition is satisfied, even if the low-load work state is detected by the work state detection unit.

[0025] In agricultural vehicles, there are various work forms, and the engine state at that time must be set to an appropriate state according to the work form, and even in a low-load work state, there are cases where it is better to refrain from executing engine reduction control. Therefore, in this configuration, under conditions where engine reduction control should be refrained from, the engine reduction control is not executed. This makes it possible to set an appropriate state according to various work forms.

[0026] In the present invention, there is provided a traveling device driven by the engine, a mechanical sub-transmission device provided in a transmission system from the engine to the traveling device and switchable between a gear change state for work and a gear change state for crossing ridges, and sub-transmission state detection means for detecting the gear change state of the sub-transmission device, and it is preferable that the specified check condition is that the sub-transmission state detection means detects the gear change state for crossing ridges.

[0027] According to this configuration, when working in a farm field or traveling, the sub-transmission is switched to a work speed change state. Then, when climbing over a ridge to leave the farm field, the sub-transmission is switched to a ridge-crossing speed change state. In this ridge-crossing speed change state, the speed is changed to a low speed in order to climb over the convex part of the ridge, so when the ridge-crossing speed change state is set, the engine reduction control is not executed.

[0028] In the present invention, it is preferable that a tilt angle detection means is provided for detecting the longitudinal tilt angle of the vehicle body, and the predetermined restraining condition is that the longitudinal tilt angle detected by the tilt angle detection means is equal to or greater than a set tilt angle.

[0029] When the longitudinal inclination angle of the vehicle body is large, a large driving force is required to climb the slope while the vehicle body is traveling, which places a large load on the engine. Therefore, in this configuration, if the longitudinal inclination angle is equal to or larger than the set inclination angle, the engine reduction control is not executed.

[0030] In the present invention, a traveling device driven by the engine and a subsidence amount detection means for detecting the amount of subsidence of the traveling device from the field surface are provided, and it is preferable that the specified check condition is that the amount of subsidence is equal to or greater than a set amount.

[0031] When the travel device sinks below the field surface by a large amount, the travel resistance is large during travel by the travel device, and a large driving load is applied to the engine. Therefore, in this configuration, when the sinking amount is equal to or greater than the set amount, the engine reduction control is not executed.

[0032] In the present invention, it is preferable that the system includes a harvesting section for harvesting crops and a storage section for storing the harvested product, and that the predetermined check condition is that the storage volume in the storage section exceeds a set storage volume.

[0033] When a large amount of harvested goods is stored in the storage section during harvesting work, the vehicle weight increases, which in turn increases the engine load. Therefore, in this configuration, when the storage amount exceeds the set storage amount, the engine reduction control is not executed.

[0034] In the present invention, a turning state detection means is provided for detecting that the vehicle body is in a turning state, and it is preferable that the specified check condition is that the turning state is detected by the turning state detection means.

[0035] According to this configuration, when turning in a farm field, the vehicle turns while pushing mud, which increases the traveling load and therefore the engine load. Therefore, with this configuration, the engine reduction control is not executed when the vehicle is turning. [Brief description of the drawings]

[0036] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] 4 is a flowchart of a control operation. [Figure 6] FIG. 4 is a diagram showing a time chart in engine control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Hereinafter, a head-feeding combine harvester, which is an example of an agricultural work vehicle according to the present invention, will be described with reference to the drawings. Note that the present invention is not limited to the following embodiment, and various modifications are possible without departing from the gist of the present invention.

[0038] [Overall structure] As shown in Figs. 1 and 2, the head-feeding combine is provided with a reaping unit 3 (an example of a harvesting unit) as a working device that harvests planted culms at the front of a traveling body 2 that is self-propelled by a pair of left and right crawler traveling devices (hereinafter referred to as traveling devices) 1,1. A driving unit 5, the periphery of which is covered by a cabin 4, is provided at the front right side of the traveling body 2. A threshing device 6 as a working device that threshes the culms reaped by the reaping unit 3, and a grain tank 7 as a storage unit that stores grains (harvested crops) obtained by the threshing process are arranged side by side behind the driving unit 5. An engine 9 as a power source that drives each part of the machine is provided below a driver's seat 8 in the driving unit 5. In this embodiment, in the drawings, the direction indicated by the symbol (FW) is the front side of the machine, and the direction indicated by the symbol (BW) is the rear side of the machine.

[0039] The harvesting section 3 is equipped with a weed dividing tool 10 that divides and guides the base of the planted culms to be harvested, a number of raising devices 11 that raise the divided planted culms into a vertical position, a clipper-type cutting blade 12 that cuts the base of the raised planted culms, and a transport device 13 that gradually changes the position of the harvested culms from a vertical position to a horizontal position while transporting them backward and supplying them to the threshing device 6. The upper side of the transport device 13 is covered with a dust cover 14.

[0040] On the left side of the threshing device 6, there is provided a feed chain 15 that transports the harvested stalks to the threshing device 6, and a clamping rail 16 that is provided above and facing the feed chain 15. On the rear of the threshing device 6, there is provided a straw discharge cutter 17 that cuts the straw discharged from the threshing device 6. The grain tank 7 is provided with a storage amount sensor S7 (see FIG. 4) 7S that detects the amount of grain stored in the grain tank 7, and a grain discharge device 18 that discharges the grains stored in the grain tank 7 outside the machine. The detection result of the storage amount sensor 7S can be displayed, for example, on a display unit (not shown) provided in the operation unit 5.

[0041] The threshing device 6 threshes the head side of the harvested culms in a threshing chamber 19 while clamping and transporting the base side of the harvested culms with a feed chain 15 and a clamping rail 16. A threshing drum 20 is provided in the threshing chamber 19.

[0042] [Transmission structure] As shown in Fig. 3, there is provided a transmission case 21 that transmits power from the engine 9 to the left and right traveling devices 1. On the upper part of the transmission case 21, there is provided a hydrostatic continuously variable transmission (hereinafter referred to as a continuously variable transmission) 22 that switches the traveling direction between forward and backward and changes the traveling speed continuously.

[0043] 4, the continuously variable transmission 22 is a well-known configuration and will not be described in detail, but is configured by connecting a swash plate plunger type hydraulic pump 23 and a swash plate plunger type hydraulic motor 24 via a hydraulic closed circuit, and is configured to variably control the tilt angle (swash plate angle) of the swash plate of the hydraulic pump 23 to change the input rotation of the hydraulic pump 23 and extract it as the output rotation of the hydraulic motor 24. In this embodiment, the tilt angle of not only the hydraulic pump 23 but also the swash plate of the hydraulic motor 24 is configured to be changeable.

[0044] A main speed change lever 25 is provided as a manually operated speed changer in the driving section 5. By changing the swash plate angle of the hydraulic pump 23 based on the operation of the main speed change lever 25, the speed of the power transmitted to the traveling device 1 can be changed steplessly in both the forward and reverse directions.

[0045] The main speed change lever 25 is provided on the driver's section 5 so as to be swingable in the front-rear direction of the traveling machine body. The continuously variable transmission 22 is switched to a forward drive state when the main speed change lever 25 is operated to a forward range Fa in which the main speed change lever 25 is swung from the neutral position N to the front side of the traveling machine body, and converts the driving force from the engine 9 into a forward drive force and transmits it to the left and right traveling devices 1, 1. The continuously variable transmission 22 is switched to a reverse drive state when the main speed change lever 25 is operated to a reverse range Ba in which the main speed change lever 25 is swung from the neutral position N to the rear side of the traveling machine body, and converts the driving force from the engine 9 into a reverse drive force and transmits it to the left and right traveling devices 1, 1. A main speed change position sensor 25S that detects the operating state of the main speed change lever 25 is provided near the main speed change lever 25, and the detection information of the main speed change position sensor 25S is input to a control device 26 described later.

[0046] The continuously variable transmission 22 also includes a hydraulic operating cylinder 27 linked to an operating shaft that changes the swash plate angle of the hydraulic motor 24, and an electromagnetic control valve 28 that controls the operating cylinder 27. The operating cylinder 27 changes the swash plate angle of the hydraulic motor 24, allowing it to be switched between two speed positions: a high-speed position for travel and a low-speed position for work. By changing the swash plate angle of the hydraulic motor 24, the speed ratio of the entire continuously variable transmission 22 can be changed even if the operating position of the main speed change lever 25 is the same. The swash plate angle of the hydraulic motor 24 is set to the low-speed position during work in the field, and is set to the high-speed position when travelling along ridges or the like.

[0047] Power is transmitted by winding an endless belt 31 around a first output pulley 9a provided on the output shaft of the engine 9 and an input pulley 22a of the continuously variable transmission 22. The power after a speed change of the continuously variable transmission 22 is input to the transmission case 21. The power after the speed change is transmitted to a traveling transmission system in the transmission case 21 and is also output to the cutting unit 3.

[0048] An endless belt 36 is wound around an output pulley 33 provided on the output shaft of the transmission case 21 and an input pulley 35 of the mowing input shaft, and the power after the speed change is transmitted to the mowing drive shaft. The endless belt 36 constitutes a belt tension type mowing clutch 37, which can turn the power transmission on and off. The mowing clutch 37 can be turned on and off by an operating motor 39 serving as an actuator, based on the operation of an operating lever 38 (see FIG. 4) provided on the driver's unit 5.

[0049] The transmission case 21 is equipped with a mechanical (gear-changing) sub-transmission device 40 that switches the speed transmitted from the continuously variable transmission device 22 between two high and low speed stages, and a hydraulically operated traveling drive mechanism 41 that distributes and transmits power to the driving sprockets 1S of the left and right crawler traveling devices 1.

[0050] The sub-speed change device 40 can be switched between a high-speed state for work used when working in a field and a low-speed state for crossing a ridge used when crossing a ridge after working in the field, based on the operation of a manually operated sub-speed change lever 42 (see FIG. 4). A low-speed position sensor 43 is provided near the sub-speed change lever 42 as sub-speed change state detection means for detecting whether the sub-speed change lever 42 is switched to the low-speed state.

[0051] The traveling drive mechanism 41 is a well-known configuration and will not be described in detail, but it is configured to be switchable between a straight-line state in which the left and right traveling devices 1 are driven at the same speed, and a turning state in which the left and right traveling devices 1 are driven with a speed difference, and the drive state is switched based on the operation of a steering lever 44 (see FIG. 4) provided on the driver's section 5. The steering lever 44 can be swung left and right, and the traveling drive mechanism 41 is operated so that a larger turning angle is obtained as the left and right tilt angle is larger. A potentiometer-type operation angle sensor 45 is provided as a turning state detection means for detecting the swing operation angle of the steering lever 44, and the control device 26 controls the operation of the traveling drive mechanism 41 based on the detection information of this operation angle sensor 45.

[0052] An endless belt 29 is wound around a second output pulley 9b provided on the output shaft of the engine 9 and an input pulley 6a of the threshing input shaft, and the power of the engine 9 is transmitted to the threshing device 6. The endless belt 29 constitutes a belt tension type threshing clutch 30 as an operating clutch, and is capable of turning on and off the power transmission. The threshing clutch 30 is turned on and off by an operating motor 39 as an actuator based on the operation of an operating lever 38 (see FIG. 4) provided on the driving unit 5. Although not shown, a cam mechanism operated by the operating motor 39 is linked to the threshing clutch 30 and the reaping clutch 37 via a linking mechanism such as an operating wire.

[0053] The working lever 38 can be swung back and forth and can be switched to any one of the following operating positions: a disengaged position (OFF) where the threshing clutch 30 and the reaping clutch 37 are both disengaged, a threshing operation position (M) where the threshing clutch 30 is engaged and the reaping clutch 37 is disengaged, and a reaping operation position (ON) where the threshing clutch 30 and the reaping clutch 37 are both engaged. A threshing position sensor 51 that detects when the working lever 38 is in the threshing operation position (M) and a reaping position sensor 52 that detects when the working lever 38 is in the reaping operation position are provided.

[0054] [Control configuration] As shown in Fig. 4, the vehicle is equipped with a control device 26 that controls the operation of each part of the vehicle body. The control device 26 is equipped with a microcomputer and is configured to execute various operations in the form of a control program. The functions of each functional part are realized by executing the program.

[0055] The control device 26 includes, as a functional part, a travel control part (not shown) that controls the operation of the travel drive mechanism 41 so that a larger turning angle is obtained as the left / right tilt angle increases based on the detection information from the operation angle sensor 45. The control device 26 also includes, as functional parts, a clutch control part 100 that controls the on / off of the threshing clutch 30 and the reaping clutch 37, an engine control part 101 that changes and adjusts the engine speed, and a vehicle speed control part 102 that controls the operation of the continuously variable transmission 22 in accordance with the engine control.

[0056] The clutch control unit 100 controls the operation of an operating motor 39 for switching the threshing clutch 30 and the reaping clutch 37 on and off based on the operation of an operating lever 38 provided on the driving unit 5. The normal working state corresponds to when the threshing clutch 30 is on and when both the threshing clutch 30 and the reaping clutch 37 are on. The low-load working state corresponds to when both the threshing clutch 30 and the reaping clutch 37 are off and the vehicle body is traveling. Therefore, the threshing position sensor 51 functions as a working state detection unit JK that detects whether the working state is the normal working state or a low-load working state in which the load on the engine 9 is smaller than that in the normal working state.

[0057] When the threshing position sensor 51 detects that the working lever 38 is in the threshing position (M), the clutch control unit 100 operates the operation motor 39 so that the threshing clutch 30 is engaged. At this time, the reaping clutch 37 is disengaged. When the reaping position sensor 52 detects that the working lever 38 is in the reaping position, the clutch control unit 100 operates the operation motor 39 so that both the threshing clutch 30 and the reaping clutch 37 are engaged. If neither the threshing position sensor nor the reaping position sensor 52 is detected, the clutch control unit 100 operates the operation motor 39 so that both the threshing clutch 30 and the reaping clutch 37 are disengaged.

[0058] The vehicle is provided with an accelerator setter 54 which sets a target rotation speed of the engine 9 in response to operation of the accelerator setting dial 47, an automatic switch 55 as a mode switching unit which switches between an automatic mode (automatic on state) as a first mode in which the engine rotation speed is automatically set as described later, and a manual mode (automatic off state) in which the second motor is set to the target rotation speed set by the accelerator setter 54, and a vehicle speed sensor 56 as vehicle speed detection means which detects the vehicle speed.

[0059] In the automatic mode, if the vehicle speed detected by the vehicle speed sensor 50 is equal to or higher than a set vehicle speed, the engine control unit 101 executes automatic accelerator control to control the operation of the speed governor 57 for the engine 9 so that the rotation speed of the engine 9 becomes the rated rotation speed as a predetermined rotation speed. The set vehicle speed is an extremely low speed value (for example, 0.4 m / sec), and the condition that the vehicle speed is equal to or higher than the set vehicle speed is for confirming whether or not the vehicle body is traveling. The vehicle speed sensor 50 detects the rotation speed of the axle that drives the traveling device 1.

[0060] In this way, the rotation speed of the engine 9 is set to the rated rotation speed not only when the threshing clutch 30 and the reaping clutch 37 are engaged, but also when the vehicle body is traveling even if both the threshing clutch 30 and the reaping clutch 37 are disengaged.

[0061] When the work state detection unit JK detects a low-load work state, the engine control unit 101 is configured to execute engine reduction control to reduce the rotation speed of the engine 9 compared to when the work state detection unit JK detects a low-load work state. In other words, even if the vehicle speed is equal to or higher than a set speed, when the work state detection unit JK detects a low-load work state, the engine control unit 101 stops the automatic accelerator control and executes the engine reduction control.

[0062] As the engine control unit 101 executes the engine reduction control, the vehicle speed control unit 102 executes vehicle speed maintenance control for controlling the operation of the continuously variable transmission 22 so as to maintain the vehicle speed before the engine reduction control was executed. The vehicle speed control unit 102 is configured to change the swash plate angle of the hydraulic motor 24 in the vehicle speed maintenance control to maintain the previous vehicle speed.

[0063] A selection switch 58 is provided as a mode switching unit that can switch between a first mode in which engine reduction control as described above is executed, and a second mode in which engine reduction control is not executed, allowing the driver to select a state in which engine reduction control is not executed.

[0064] The control of the rotation speed of the engine 9 by the control device 26 will be described with reference to the control flow chart of FIG.

[0065] If the automatic switch 55 is in the OFF state, the operation of the governor 57 is controlled so that the engine speed becomes the target speed set by the accelerator setting dial 47 (steps #1 and #2). If the automatic switch 55 is in the ON state, the engine control described below is executed.

[0066] If the working lever 38 is in the off position (OFF) and the main shift lever 25 is in the stop position (ST), then since this is a non-working state in which no work is being performed, the operation of the governor 57 is controlled so that the engine speed becomes idling speed (steps #3, #4, #5).

[0067] When the work lever 38 is not in the off position (OFF), i.e., when the work lever 38 is in either the threshing position (M) or the reaping position (ON), the operation of the speed governor 57 is controlled so that the engine speed becomes the rated speed (Step #6). Also, even if the work lever 38 is in the off position (OFF), when the main speed change lever 25 is not in the stop position (ST) but is operated to the forward range Fa or reverse range Ba, specifically, when the vehicle speed detected by the vehicle speed sensor 50 is equal to or higher than a predetermined speed (e.g., 0.4 m / s), the operation of the speed governor 57 is controlled so that the engine speed becomes the rated speed.

[0068] If the working lever 38 is not switched to the off position (OFF) while the engine 9 is set at the rated speed, the process returns to step #1 (step #7). Therefore, the engine 9 is maintained at the rated speed while continuing to travel thereafter, and is switched to idling speed when travel is stopped.

[0069] When the working lever 38 is switched to the off position (OFF) while the engine 9 is set at the rated speed, if the judgment conditions of steps #8 and #9 are negative (NO), the operation of the speed governor 57 is controlled so that the engine speed is switched from the rated speed N1 to a lower speed N2 by a predetermined amount, for example, as shown in Fig. 6 (step #10). This control is the engine reduction control.

[0070] The first judgment condition (step #8) is that the selection switch 58 is turned off when the engine 9 is set to the rated speed. When the selection switch 58 is turned off, the driver does not want such engine reduction control. Therefore, when the selection switch 58 is turned off, the engine reduction control is not performed thereafter, and the engine 9 maintains the rated speed.

[0071] The second determination condition (step #9) is whether a predetermined check condition that has been set in advance is not met. The constraints include the following conditions: The low speed position sensor 43 detects that the sub-transmission device 40 is in a low speed state. The storage volume sensor 7S detects that the storage volume in the grain tank 7 is equal to or greater than the set storage volume. The operation angle sensor 45 detects a state in which the vehicle body is turning at a large turning angle. The restraining conditions are not limited to these conditions, and various other conditions can be set. In such a state, it is expected that a large load will be applied to the engine 9, so the engine reduction control is not performed and the engine 9 will maintain the rated rotation.

[0072] When engine reduction control is performed in step #10, the swash plate angle of the hydraulic motor 24 is accordingly switched from "low speed" to "high speed" (step #11) (see FIG. 6). Specifically, the operation of the electromagnetic control valve 28 is controlled to operate the operating cylinder 27 to switch the swash plate angle. This maintains the vehicle speed before engine reduction control was performed. This process corresponds to vehicle speed maintenance control.

[0073] After the swash plate angle of the hydraulic motor 24 is switched to "high speed", the rotation speed of the engine 9 is finely adjusted so that the vehicle speed becomes the same as the vehicle speed before the engine reduction control was performed (step #12). Specifically, the operation of the speed governor 57 is controlled so that the vehicle speed detected by the vehicle speed sensor 56 becomes the same as the previous vehicle speed. This rotation speed adjustment process is performed until the working lever 38 is not in the off position (OFF), that is, until the working lever 38 is switched to either the threshing operation position (M) or the reaping operation position (ON). By performing this rotation speed adjustment process, the driver can continue traveling with as little discomfort as possible.

[0074] When the operation lever 38 is switched to either the threshing operation position (M) or the harvesting operation position (ON), the operation of the governor 57 is returned to a state in which it controls the operation so that the engine speed becomes the rated speed (step #13) (see Figure 6).

[0075] [Another embodiment] (1) In the above embodiment, the hydraulic motor 24 is configured to switch between two levels, high and low. However, the hydraulic motor 24 may be configured to switch between three or more levels or to switch continuously.

[0076] (2) In the above embodiment, the vehicle speed control unit 102 is configured to maintain the previous vehicle speed by changing the swash plate angle of the hydraulic motor 24. However, instead of this configuration, the swash plate angle of the hydraulic pump 23 may be configured to be operable by an actuator, and the previous vehicle speed may be maintained by controlling the actuator to change the swash plate angle of the hydraulic pump 23 from its current position as engine reduction control is performed.

[0077] (3) In the above embodiment, when engine reduction control is executed, vehicle speed maintenance control is executed to control the operation of the continuously variable transmission 22 so as to maintain the vehicle speed before engine reduction control was executed. However, the configuration may be such that such vehicle speed maintenance control is not executed.

[0078] (4) In the above embodiment, three conditions are exemplified as the check condition in step #9, but any one or more of the conditions may be used. In addition, the following conditions may be set instead of those conditions.

[0079] (4-1) An inclination angle sensor is provided as an inclination angle detection means for detecting the longitudinal inclination angle of the vehicle body, and the restraining condition is that the longitudinal inclination angle detected by the inclination angle sensor is equal to or greater than a set inclination angle.

[0080] (4-2) A subsidence amount detection sensor is provided as a subsidence amount detection means for detecting the amount of subsidence of the crawler traveling device from the field surface when the crawler traveling device sinks into the field surface, and the amount of subsidence is equal to or greater than a set amount. In short, it is sufficient if the engine load is expected to be large, and various other conditions are also possible.

[0081] (5) In the above embodiment, the predetermined rotation speed in the automatic accelerator control is controlled to be the rated rotation speed. However, the predetermined rotation speed is not limited to the rated rotation speed, and the rotation speed may be a predetermined amount lower than the rated rotation speed. The amount of reduction in engine rotation in the engine reduction control can also be changed to various different values.

[0082] (6) The driver's section 5 of the vehicle body may be provided with a fuel economy status display section (not shown) that displays the state of fuel consumption by the engine 9. For example, the fuel consumption per unit distance traveled may be displayed numerically, or the distance traveled required to consume a unit amount of fuel may be displayed numerically. This allows the degree of energy saving achieved when engine reduction control is executed to be visually confirmed.

[0083] (7) In the above embodiment, a combine harvester was shown as an agricultural work vehicle. However, the present invention is not limited to combine harvesters and can be applied to various agricultural work vehicles such as tractors and rice transplanters. [Industrial Applicability]

[0084] The present invention can be applied to agricultural vehicles such as combine harvesters. [Explanation of symbols]

[0085] 1 Running gear 6 Threshing equipment (work equipment) 7 Grain tank (storage section) 9 Engine 22 Hydrostatic continuously variable transmission (transmission) 23 Hydraulic Pump 24 Hydraulic motor 25 Main gear shift lever (gear shifting device) 30 Threshing clutch (working clutch) 40 Auxiliary transmission 43 Low speed position sensor (auxiliary transmission state detection means) 45 Operation angle sensor (turning state detection means) 56 Vehicle speed sensor (vehicle speed detection means) 58 Selection switch (mode change section) 101 Engine control unit 102 Vehicle speed control unit JK Working state detection unit

Claims

1. the vehicle is provided with an engine, an engine control unit that controls the operation of the engine, and a work state detection unit that detects whether the vehicle is in a normal work state or a low-load work state in which the load on the engine is smaller than that of the normal work state, The engine control unit of the agricultural work vehicle executes engine reduction control to reduce the rotation speed of the engine below that in the normal work state when the low-load work state is detected by the work state detection unit.

2. A traveling device driven by the engine; a transmission that changes the speed of the power of the engine and transmits it to the traveling device; A vehicle speed control unit that controls the operation of the transmission is provided. The agricultural vehicle according to claim 1, wherein the vehicle speed control unit executes a vehicle speed maintenance control that controls operation of the transmission so as to maintain the vehicle speed before the engine reduction control is executed, as the engine control unit executes the engine reduction control.

3. A manually operated gear shifter is provided, The transmission is configured as a hydrostatic continuously variable transmission having a hydraulic pump and a hydraulic motor, and is configured to change the speed of the power transmitted to the traveling device by changing a swash plate angle of the hydraulic pump based on the operation of the speed change operating tool, The agricultural work vehicle according to claim 2 , wherein the vehicle speed control unit is configured to maintain the previous vehicle speed by changing a swash plate angle of the hydraulic motor during the vehicle speed maintenance control.

4. 4. The agricultural work vehicle according to claim 3, wherein the hydraulic motor is configured so that the swash plate angle can be changed in a plurality of stages.

5. A working device driven by the engine; and a work clutch that interrupts the power transmission from the engine to the working device, 2. The agricultural vehicle according to claim 1, wherein the work state detection unit detects the normal work state when the work clutch is engaged, and detects the low-load work state when the work clutch is disengaged.

6. A vehicle speed detection means is provided for detecting the vehicle speed, The engine control unit includes:

2. The agricultural work vehicle of claim 1, wherein, if the vehicle speed detected by the vehicle speed detection means is equal to or higher than a set speed, an automatic accelerator control is executed to control the operation of the engine so that the engine speed becomes a predetermined rotational speed, and, even if the vehicle speed is equal to or higher than the set speed, if the work condition detection unit detects the low-load work condition, the automatic accelerator control is stopped and the engine reduction control is executed.

7. The agricultural vehicle according to claim 1, wherein the engine control unit is configured to be switchable between a first mode in which the engine reduction control is performed and a second mode in which the engine reduction control is not performed based on a command from a manually operated mode switching unit.

8. 8. The agricultural vehicle according to claim 1, further comprising a fuel consumption status display unit provided in a driver's section of the vehicle body for displaying the status of fuel consumption by the engine.

9. 2. The agricultural vehicle according to claim 1, wherein the engine control unit does not execute the engine reduction control when a predetermined check condition is met, even if the low-load work state is detected by the work state detection unit.

10. A traveling device driven by the engine; a mechanical sub-transmission device provided in a transmission system from the engine to the traveling device and switchable between a work speed change state and a ridge-crossing speed change state; and an auxiliary transmission state detection means for detecting a transmission state of the auxiliary transmission device, 10. The agricultural work vehicle according to claim 9, wherein the check condition is that the auxiliary speed change state detection means detects the speed change state for crossing the ridge.

11. An inclination angle detection means is provided for detecting the longitudinal inclination angle of the vehicle body, 10. The agricultural vehicle according to claim 9, wherein the restraining condition is that the longitudinal inclination angle detected by the inclination angle detection means is equal to or larger than a set inclination angle.

12. A traveling device driven by the engine; a sinking amount detection means for detecting an amount of sinking of the traveling device from a field surface, The agricultural work vehicle according to claim 9 , wherein the restraining condition is that the amount of sinking is equal to or greater than a set amount.

13. The present invention includes a harvesting section for harvesting crops and a storage section for storing the harvested crops, The agricultural work vehicle according to claim 9 , wherein the check condition is that the storage amount in the storage section exceeds a set storage amount.

14. A turning state detection means is provided for detecting that the vehicle body is in a turning state, 10. The agricultural work vehicle according to claim 9, wherein the inhibit condition is that the turning state is detected by the turning state detection means.

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