Work vehicle

Abstract

To suppress excessive power consumption and overload of electric motors compared to conventional technologies.SOLUTION: When the load on a second electric motor (52) increases but the amount of change in the load on the second electric motor (52) does not reach a predetermined threshold, the increase in the travel speed is suppressed even if input to increase the travel speed is performed. When the amount of change in the load on the second electric motor (52) reaches the threshold, the travel speed is reduced. This can suppress excessive power consumption and overload of the electric motors compared to conventional technologies.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a work vehicle, and more particularly to a work vehicle that electrically drives a traveling device and a work implement.

Background Art

[0002] In an electric vehicle equipped with a traveling device, by detecting the current value flowing through an electric motor, the presence or absence of grounding of a rotary tilling device is determined. When the rotary tilling device is lowered from the upper non-working position to the lower working position, if it is determined from the detection result of the current value that the rotary tilling device is grounded, a technique is known in which the electric motor is controlled so that the rotational speed of the PTO shaft gradually increases steplessly to a predetermined value (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the conventional technology described in Patent Document 1, traveling and the work implement are driven by a single electric motor, and control is performed to increase the speed of the electric motor so that the traveling speed does not decrease even if the load of the work implement increases due to grounding. In this control, the traveling speed is prioritized, and the control is performed so that there is a large margin with respect to the actual load of the work implement. That is, the electric motor is controlled in a state where it is driven in an overloaded (overload) state with respect to the actual load of the work implement. Therefore, there are problems such as a large loss (wasteful consumption) of electric power, the electric motor being likely to fail due to overload, and the life being shortened.

[0005] The technical problem of the present invention is to suppress overload of the electric motor and excessive consumption of electric power as compared with the conventional technology.

Means for Solving the Problems

[0006] The above-mentioned problems of the present invention are solved by the following means. The invention described in claim 1 provides a farm equipment comprising: a vehicle body (1a); traveling devices (2, 3) supported by the vehicle body (1a) and causing the vehicle body (1a) to travel; a work implement (18) supported by the vehicle body (1a) and performing work on a field; a first electric motor (4) that drives the traveling devices (2, 3); a second electric motor (52) that drives the work implement (18); a load detector (SN1) that detects a load on the second electric motor (52); and a load detector (SN2) that detects a load on the first electric motor ( and a control means (83) for controlling a travel speed of the second electric motor (52) based on a detection result of the load detector (SN1), the control means (83) suppressing an increase in the travel speed even if an input for increasing the travel speed is received, when the load of the second electric motor (52) has increased and an amount of change in the load of the second electric motor (52) has not reached a predetermined specified value (k), and decelerating the travel speed when the amount of change in the load of the second electric motor (52) reaches the specified value (k).

[0007] The invention described in claim 2 is the work vehicle described in claim 1, characterized in that it comprises: the load detector (SN1) that detects a load current value of the second electric motor (52) corresponding to the load of the second electric motor (52); and the control means (83) that controls the first electric motor (4) with PI control based on the load current value, a predetermined proportional constant (Kp), and a predetermined integral constant (Ki), and the control means (83) sets a suppression amount (x) of an increase in the traveling speed based on a control value of the first electric motor (4) calculated by the PI control.

[0008] The invention described in claim 3 is the work vehicle described in claim 2, characterized in that the amount of suppression (x) of the increase in the traveling speed is proportional to the magnitude (V) of the change per unit time of the load current value, and when the magnitude (V) of the change reaches the specified value (k), the amount of suppression (x) is set to an upper limit value.

[0009] The invention described in claim 4 is the work vehicle described in claim 1, characterized in that it comprises: the load detector that detects a change in the rotation speed of the second electric motor (52) according to the load on the second electric motor (52); and the control means (83) that controls the first electric motor (4) with PI control based on the value of the rotation speed, a predetermined proportional constant (Kp), and a predetermined integral constant (Ki), and the control means (83) sets an amount of suppression of an increase in the traveling speed based on a control value of the first electric motor (4) calculated by the PI control.

[0010] The invention described in claim 5 is the work vehicle described in claim 1, characterized in that it includes a battery (86) that supplies power to the first electric motor (4) and the second electric motor (52), and the control means (83) that calculates Ta = (T3 / T4) × T1 + (1 - T3 / T4) × T2, where T1 is a first available work time calculated based on an average power consumption (Va) from the start of work to a current time and the remaining power amount (V1) of the battery (86), T2 is a second available work time calculated based on a predetermined power consumption (Vb) for the work machine (18) attached to the vehicle body (1a) and the remaining power amount (V1), T3 is an elapsed time from the start of work to the current time, T4 is a predetermined specified time until the calculation of the first available work time (T1) becomes stable, and Ta is a remaining available work time. Effect of the Invention

[0011] According to the invention of claim 1, when the load on the second electric motor (52) increases and the amount of change in the load on the second electric motor (52) does not reach a predetermined specified value, an increase in the traveling speed is suppressed even if an input for increasing the traveling speed is received, and when the amount of change in the load on the second electric motor (52) reaches the specified value, the traveling speed is decelerated. As a result, it is possible to suppress overload of the electric motor and excessive consumption of power compared to the conventional technology.

[0012] According to the invention of claim 2, in addition to the effect of the invention of claim 1, by setting the suppression amount (x) of the increase in the traveling speed based on the control value of the first electric motor (4) calculated by the PI control based on the load current value as a reference, the first electric motor (4) can be appropriately controlled by the PI control.

[0013] According to the invention of claim 3, in addition to the effects of the invention of claim 2, the suppression amount (x) can be easily calculated, and the operator is less likely to mistake it for a malfunction, compared to the case where no upper limit is set.

[0014] According to the invention of claim 4, in addition to the effect of the invention of claim 1, the suppression amount (x) of the increase in the traveling speed can be set based on the control value of the first electric motor (4) calculated by PI control based on the rotation speed, and the first electric motor (4) can be appropriately controlled by PI control.

[0015] According to the invention described in claim 5, in addition to the effects of the invention described in claim 1, the remaining workable time can be calculated with higher accuracy than when the remaining workable time is calculated only from the average power consumption (Va) from the start of work to the present time or only from the predetermined power consumption (Vb) for the work machine (18) attached to the vehicle body (1a). [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is an explanatory diagram of a tractor as an example of a work vehicle according to an embodiment, and is an explanatory diagram of a state in which a work implement is lowered to a height at which the work implement can be used. [Diagram 2] FIG. 2 is an explanatory diagram of a tractor as an example of a work vehicle according to an embodiment, with the work implement in a raised state. [Diagram 3] 3A and 3B are explanatory diagrams of an electric unit according to an embodiment of the present invention, in which FIG. 3A is an oblique view, FIG. 3B is a view from the direction of arrow IIIB in FIG. 3A, and FIG. 3C is a view from the direction of arrow IIIC in FIG. 3A. [Figure 4] FIG. 4 is a functional block diagram showing a transmission system of the work vehicle according to the embodiment. [Diagram 5]FIG. 5 is an explanatory diagram of an example of a display panel of the work vehicle according to the embodiment. [Figure 6] FIG. 6 is a functional block diagram of the control unit according to the embodiment. [Figure 7] FIG. 7 is an explanatory diagram of a configuration for heating a battery in cold climates according to an embodiment. [Figure 8] 8A and 8B are explanatory diagrams of other examples of the configuration for heating a battery, where FIG. 8A is an explanatory diagram of another example 1, and FIG. 8B is an explanatory diagram of another example 2. In FIG. [Figure 9] FIG. 9 is an explanatory diagram of the key cylinder portion for starting a work vehicle, FIG. 9(A) is an explanatory diagram of an embodiment, FIG. 9(B) is an explanatory diagram of another example 1 of an embodiment, FIG. 9(C) is an explanatory diagram of another example 2 of an embodiment, and FIG. 9(D) is an explanatory diagram of another example 3 of an embodiment. [Figure 10] 10A and 10B are explanatory diagrams of a key cylinder portion for starting a work vehicle, FIG. 10(A) being an explanatory diagram of a fourth embodiment, and FIG. 10(B) being an explanatory diagram of a fifth embodiment. [Figure 11] FIG. 11 is an explanatory diagram of the air conditioning function of the driver's seat, where FIG. 11(A) is a perspective view and FIG. 11(B) is a side view. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] FIG. 1 is an explanatory diagram of a tractor as an example of a work vehicle according to an embodiment, and is an explanatory diagram of a state in which a work implement is lowered to a height at which the work implement can be used. FIG. 2 is an explanatory diagram of a tractor as an example of a work vehicle according to an embodiment, with the work implement in a raised state. 1 and 2, a tiller tractor 1 as an example of a work vehicle of the present invention is provided with front wheels 2, 2 and rear wheels 3, 3 at the front and rear of a traveling body (an example of a vehicle main body) 1a. A traveling motor 4 as an example of a first electric motor is mounted inside a bonnet 6 at the front of the traveling body 1a. The rotational power of the traveling motor 4 is appropriately reduced by a speed change device in a transmission case (not shown) and is configured to be transmitted to the front wheels 2, 2 and the rear wheels 3, 3.

[0018] A working machine such as a tiller 18 for tilling the ground (field) behind the tractor 1 is attached to the rear of the tractor 1, and the working machine is driven by power transmitted via a PTO shaft (see FIG. 4). In the embodiment, the PTO shaft receives drive power from a PTO motor (not shown) as an example of a second electric motor. In this specification, the left and right sides in the forward direction of the tractor 1 are referred to as the left and right sides, respectively, and the forward direction is referred to as the front side and the reverse direction is referred to as the rear side.

[0019] A driver's seat (operating seat) 8 is disposed at the top of the traveling vehicle body 1a, and a steering wheel 10, a parking brake (not shown), and the like are disposed in front of the driver's seat 8. Also disposed in front of the driver's seat 8 are a display panel (meter panel) for a speedometer (not shown), various operation switches (not shown), and the like. Disposed in front of the driver's seat 8 at the bottom are travel operating tools such as a brake pedal 12 and an accelerator pedal (13) having a forward pedal and a reverse pedal.

[0020] In Fig. 1, lift arms 15, 15 are pivotally mounted to the rear of the traveling vehicle body 1a. Lift rods 17, 17 are interposed between the lift arms 15, 15 and lower links 16, 16, and a tiller 18, an example of a working machine, is connected to the rear of the lower links 16, 16.

[0021] The lift arm 15 is driven by a hydraulic cylinder (not shown). When the hydraulic pressure in the hydraulic cylinder increases and the lift arms 15, 15 are rotated upward, the work machine (cultivator) 18 is raised via the lift rod 17, lower link 16, etc. When the hydraulic oil is discharged and the hydraulic pressure decreases, the lift arms 15, 15 are lowered. In addition, the working machine mounted to the rear of the traveling body 1a, i.e., the working machine to which drive is transmitted from the PTO shaft extending along the lower link 16, is not limited to rotary tilling equipment for agricultural work, but includes working machines such as plows, seed sowing machines, seedling transplanters, fertilizer spreaders, and pesticide spreaders.

[0022] (Explanation of the electric unit) 3A and 3B are explanatory diagrams of an electric unit according to an embodiment of the present invention, in which FIG. 3A is an oblique view, FIG. 3B is a view from the direction of arrow IIIB in FIG. 3A, and FIG. 3C is a view from the direction of arrow IIIC in FIG. 3A. 3, in the tractor 1 of the embodiment, an electric unit 51 inside a bonnet 6 has a travel motor 4 as an example of a first electric motor, a transmission case 5, a PTO motor 52 as an example of a second electric motor, and a hydraulic pump 53. In the embodiment, the travel motor 4, the PTO motor 52, and the hydraulic pump 53 are supported by a housing of the transmission case 5.

[0023] FIG. 4 is a functional block diagram showing a transmission system of the work vehicle according to the embodiment. The output of the traveling motor 4 is transmitted to a transmission case 5 and, after a speed change, is transmitted to the wheels 2, 3. In Fig. 4, specifically, the drive of the traveling motor 4 is changed in speed by a first traveling gear train 61 and a second traveling gear train 62, and then transmitted to the front wheels 2 via a differential 63 and a drive chain 64. The drive of the traveling motor 4 is also transmitted from the first traveling gear train 61 to a rear wheel clutch 66, and then transmitted to the rear wheels 3 via a universal joint 67 and a third traveling gear train 68.

[0024] The drive of the PTO motor 52 is changed in speed by a first PTO gear train 71 of the transmission case 5 and transmitted to a PTO shaft 9 (rear PTO shaft) as an example of a first PTO shaft via a first PTO clutch 72. The drive of the PTO motor 52 is also branched and transmitted to a mid PTO shaft 57 as an example of a second PTO shaft via a second PTO clutch 73 after being changed in speed by the first PTO gear train 71. The PTO shaft 9 drives the cultivator 18. Although not mounted on the tractor 1 of the embodiment, when a lawn mower (mower) or the like as an example of a second working machine (not shown) is mounted, the mid PTO shaft 57 can drive the second working machine.

[0025] Moreover, the hydraulic pump 53 in the embodiment is driven by the power of the PTO motor 52 being changed in speed by the hydraulic gear train 76 of the transmission case 5 and transmitted to operate the hydraulic circuit 77, which in turn operates the actuator and the power steering hydraulic cylinder. Therefore, it is also possible to operate only the hydraulic pump 53 by driving the PTO motor 52 with the PTO clutches 72, 73 in a disengaged state. Furthermore, when only the hydraulic pump 53 is driven, it is also possible to suppress unnecessary power consumption and improve energy efficiency by setting the rotation speed of the PTO motor 52 to a different rotation speed from the rotation speed when the tiller 18 is operated.

[0026] 4, the traveling motor 4 and the PTO motor 52 are connected to a VCU (Vehicle Control Unit) 83 as an example of a control unit via a traveling inverter 81 and a PTO inverter 82, respectively. Therefore, the inverters 81 and 82 are operated in response to control signals from the VCU 83, and the traveling motor 4 and the PTO motor 52 are operated. The traveling motor 4 and the PTO motor 52 are supplied with power from a high-voltage battery 86 via inverters 81, 82. That is, the amount of power and the amount of electric power supplied to the traveling motor 4 and the PTO motor 52 are controlled by controlling the inverters 81, 82. The power supply from the high-voltage battery 86 is controlled by a control signal from a VCU 83.

[0027] Charging of the high-voltage battery 86 is controlled by a charging system 87. An external connection terminal 88 is connected to the charging system 87, and the high-voltage battery 86 can be charged by power supplied from an external source. The external connection terminal 88 is provided with terminals that can accept alternating current (AC) input and direct current (DC) input, and the charging system 87 charges the high-voltage battery 86 by converting the AC input to DC or transforming the DC input to a voltage for the high-voltage battery 86 according to the connected terminal. The charging system 87 is controlled by a control signal from the VCU 83.

[0028] The voltage of the high-voltage battery 86 is transformed (stepped down) by a DC-DC converter 91 so as to be able to supply power to an auxiliary battery (low-voltage battery) 92 . The auxiliary battery 92 supplies power to a water-cooling pump 93 and a radiator fan 94 that cool the motors 4, 52 and the batteries 86, 92, and also supplies power to other devices 96 that operate on power from the low-voltage battery 92. Examples of the other devices 96 include various safety sensors, lights, and electric cylinders for electric brakes. The water-cooling pump 93, radiator fan 94, and other devices 96 are driven / stopped in response to control signals from the VCU 83, and transmit detection results to the VCU 83.

[0029] (Explanation of the meter panel) FIG. 5 is an explanatory diagram of an example of a display panel of the work vehicle according to the embodiment. In FIG. 5, a display panel (meter panel) 101 of the embodiment is provided with a main display panel 102 at the bottom center which displays 102a the remaining charge of the high-voltage battery 86, 102b the remaining available work time, 102c the RPM of the PTO motor 52, 102d the traveling speed, 102e the load of the work machine (load of the PTO motor 52), and 102f the temperature of the PTO motor 52. At the top center of the display panel 101 is disposed an upper display panel 103 which has left and right direction indicators 103a, a headlight on indicator 103b, a high beam indicator 103c, an indicator 103d indicating whether the rear PTO shaft 9 is in a drivable state, an indicator 103e indicating whether the mid PTO shaft 57 is in a drivable state, an indicator 103f indicating that the rear PTO shaft 9 is in operation, an indicator 103g indicating that the mid PTO shaft 57 is in operation, etc.

[0030] On the right side of the display panel 101, there are arranged input members 104 such as a dial 104a and buttons 104b for inputting information such as changing the rotation speed of the travel motor 4 and the PTO motor 52. On the left side of the display panel 101, there is disposed a left display panel 106 which displays, for example, an indication 106a indicating that the radiator fan 94 is rotating in reverse, an indication 106b indicating the 2WD / 4WD on / off status, an indication 106c indicating whether the parking brake is engaged or not, an indication 106d of an abnormality in the auxiliary battery 92, an indication 106e of a low remaining charge in the high-voltage battery 86, an indication 106f of an abnormality in the high-voltage battery 86, an indication 106g of an abnormality in the traction motor 4, and an indication 106h of an abnormality in the PTO motor 52.

[0031] (Explanation of the control unit) FIG. 6 is a functional block diagram of the control unit according to the embodiment. In the block diagram of FIG. 6, elements that are not related to the description of the embodiment of the present invention are not shown and are not described. 6, the VCU 83 as an example of a control unit (control means) of the embodiment is configured with a small information processing device, a so-called microcomputer. Therefore, the VCU 83 can realize various functions by executing programs stored in a ROM or the like.

[0032] The VCU 83 according to the embodiment has the following functional modules (program modules). The traveling speed setting means 201 sets the traveling speed of the tractor 1. In the embodiment, the traveling speed setting means 201 sets the traveling speed according to the operation amount of the accelerator pedal 13 during manual operation. During automatic operation such as a work mode, the traveling speed for work set in advance on the display panel 101 or the like is set as the traveling speed of the tractor 1. The traveling speed for work can be set to a different speed depending on the type of working machine (cultivator, plow, etc.), and can also be set to a different speed for each field depending on the traveling load such as the field condition (whether the field is hard or soft). When the traveling speed is changed by input from the display panel 101, the changed traveling speed is set as the traveling speed of the tractor 1.

[0033] The working machine speed setting means 202 sets the operating speed of the working machine (cultivator 18). The operating speed of the working machine can be set to an operating speed according to the type of working machine (cultivator, plow, etc.) attached to the tractor 1 and the work load, such as the condition of the field (hard, soft). Also, when the operating speed is changed by input from the display panel 101, the changed operating speed is set as the operating speed of the working machine.

[0034] The load detection means 203 detects the load of the PTO motor 52 that drives the working machine (cultivator 18). The load detection means 203 in the embodiment detects the load of the PTO motor 52 from the detection result of an ammeter (one example of a load detector) SN1 that detects the current value (load current value) of the PTO motor 52. That is, when the current value supplied to the PTO motor 52 to achieve the operating speed of the working machine changes (becomes a large value) with respect to a reference current value at the operating speed that is determined in advance by experiments, specifications, etc., it can be detected as a current value that has changed due to the load. Note that the reference current value is not limited to a specific value, but can be a numerical range that takes into account a margin, that is, can have a certain width.

[0035] In addition, detection of the load is not limited to detection of the load current value, and it is also possible to detect the load, for example, by detecting that the rotation speed of the PTO motor 52 has changed from a predetermined rotation speed due to the load.

[0036] The specified value storage means 204 stores a specified value for determining whether or not to decelerate the traveling speed. When the load detection means 203 detects an increase in the load, the load determination means 205 determines whether or not the rate of change in the load reaches the specified value stored in the specified value storage means 204 .

[0037] The work machine speed control means 206 controls the operating speed of the work machine (tiller 18). In the embodiment, the work machine speed control means 206 controls the PTO motor 52 based on the operating speed set by the work machine speed setting means 202. In the embodiment, when the operating speed is not reached due to the load of the tiller 18, the current value supplied to the PTO motor 52 is increased to control the operating speed to the target operating speed. In addition, when the load on the PTO motor 52 is large, it is desirable to suppress the load at the time of ground contact and the increase in the load current by lowering the descent speed of the tiller 18 at a slower speed than the normal descent speed so as not to exceed the maximum current value required for the operation of the tiller 18.

[0038] The traveling speed control means 207 controls the traveling speed of the tractor 1. The traveling speed control means 207 in this embodiment controls the traveling motor 4 based on the traveling speed set by the traveling speed setting means 201 (the control value of the traveling speed). The traveling speed control means 207 of the embodiment controls the traveling speed by so-called PI control (Proportional Integral control). That is, feedback control is performed using a transfer function (Kp+Ki / s) based on the load current value detected by the load detection means 203, a predetermined proportional constant (Kp), and a predetermined integral constant (Ki).

[0039] Furthermore, in the embodiment, when the load on the PTO motor 52 has increased based on the detection result of the load detection means 203 and the rate of change of the load on the PTO motor 52 has not reached a predetermined specified value (k), the traveling speed control means 207 suppresses an increase in the traveling speed even if an input to increase the traveling speed is input to the display panel 101 or the like or by operating the accelerator pedal 13. In the embodiment, as an example, if the magnitude of the amount of change in the load current value per unit time is V, the amount of suppression of the increase in the running speed is x, and the specified value is k, the increase in the running speed is suppressed based on x = (1 / k) x V. That is, if there is no suppression, the running speed would normally be increased by an amount equivalent to the amount of change V, but in the embodiment, the running speed is only increased by an amount equivalent to (Vx). When the magnitude of the change amount V reaches the specified value k, the suppression amount x becomes the upper limit. If the suppression amount x becomes too large, the deviation from the actual speed increase becomes too large, and the operator may mistake it for a malfunction or the like.

[0040] In a situation where the work load on the work machine is large and the load current of the PTO motor 52 is large, if the traveling speed is further increased, the work load will become even larger, and there is a risk that it will be difficult to continue working. Therefore, in the embodiment, in the case where the load on the PTO motor 52 is increasing but the load increase is such that the rate of change does not reach a specified value, when the traveling speed is increased, the speed increase itself is performed, but the increase in the load is suppressed and reduced, and the inability to continue working is suppressed. Therefore, overload of the PTO motor 52 is suppressed, and burnout or the like of the PTO motor 52 is suppressed, and excessive power supply is also suppressed and reduced, wasteful power consumption is suppressed, and improvement in power consumption is expected.

[0041] Furthermore, the traveling speed control means 207 of the embodiment decelerates the traveling speed when the change amount V of the load of the PTO motor 52 reaches the specified value k. That is, in a situation where the load of the PTO motor 52 is too large so as to reach the specified value k, the traveling speed is decelerated even if the traveling speed is increased. The deceleration amount can be a fixed value, or the deceleration amount can be increased as the load current value increases. Therefore, when the load on the PTO motor 52 increases and the rate of change of the load increases so rapidly that it reaches a specified value, the travel speed is slowed down to suppress and reduce the increase in the load and prevent the work from being discontinued. This suppresses and reduces overload and burnout of the PTO motor 52 and excessive power supply to the PTO motor 52, suppresses unnecessary power consumption, and is expected to improve power efficiency.

[0042] In the embodiment, the speed increase is suppressed or the speed is reduced when the load current of the PTO motor 52 becomes large regardless of the type of the working machine, but the present invention is not limited to this. For example, when the rotary tiller 18 is attached as the working machine, unlike working machines that are a load on the traveling such as a mower (lawn mower), a tedder (weed turner), and a rake (grass collector), the tilling work increases the propulsive force of the traveling. Therefore, it is also possible to adopt a mode in which the traveling speed control means 207 switches the control according to the type of the working machine so that the speed increase is suppressed when a working machine that is a load on the traveling is attached, and the speed increase is not suppressed when a working machine that is not a load on the traveling is attached.

[0043] Furthermore, in the embodiment, the change rate of the load current is used as an example, but the present invention is not limited to this, and it is also possible to use the difference (difference) of the load current. The same applies to the case where the rotation speed is used instead of the load current as a parameter. Furthermore, the determination of the suppression amount x and the deceleration amount is not limited to the above-mentioned configuration. For example, the suppression amount x and the deceleration amount can be determined by any method, such as changing the values ​​of the proportional constant Kp and the integral constant Ki, or multiplying the entire transfer function by a coefficient. In other words, it is also possible to set the suppression amount x of the increase in the running speed and the deceleration amount based on the control value of the running motor 4 calculated by PI control.

[0044] Furthermore, it is preferable to suppress the traveling speed or to control the deceleration when the traveling speed before the control is equal to or higher than a predetermined speed. In other words, if the vehicle is decelerated while traveling at a low speed, it will stop, and there will be almost no effect in reducing the load, and the impact of the loss of work time (prolonged work time) will be greater. Therefore, it is preferable to suppress the traveling speed or to control the deceleration while traveling at a predetermined traveling speed or higher.

[0045] In addition, if the suppression amount x of the traveling speed or the deceleration amount is too large, the driver may feel a sudden deceleration, which may deteriorate the driving feeling and the operation feeling. Therefore, it is preferable to set an upper limit (so-called rate limit) for the suppression amount x or the deceleration amount to slow down the rate of change. Furthermore, if the speed increase is suppressed or the speed is reduced accordingly when the change in the load current is smaller than a predetermined value or for a short period of time, control such as suppressing the speed increase may be performed frequently depending on the state of the field. In particular, when moving forward or backward with the working machine operating in a corner of a field, frequent control may cause the driver's operating feel to deteriorate and work efficiency to decrease. Therefore, it is also preferable not to execute control such as suppressing the speed increase when the change in the load current is small or for a short period of time.

[0046] It is also possible to configure the device so that an operator can manually switch between execution and non-execution of control such as suppression of speed increase by inputting a switch. It is also possible to set the specified value k and the upper limit of the suppression amount x to be selectable in multiple stages, and to switch between stages with a switch. This allows the operator to select according to the field condition (grass height and water volume).

[0047] Furthermore, in the embodiment, the case where the suppression of the speed increase is executed only when the load current value is large is exemplified, but the present invention is not limited to this. It is also possible to execute the suppression of the speed increase when the load current is small (for example, to increase the speed when the load is small). It is also possible to configure the system to execute regenerative power generation without executing speed control when the load is small.

[0048] The remaining battery charge detection means 208 detects the current amount of power in the high voltage battery 86, that is, the remaining amount of power V1. The work time measurement means 209 measures a work time T3 which is the time that has elapsed since the work machine (cultivator 18) started working in the field. The average power consumption calculation means 210 calculates the average power consumption Va (=(V0-V1) / T3) per unit time from the start of work to the present time based on the power amount (initial remaining amount) V0 of the high-voltage battery 86 before work starts and the power amount V1 at the present time. That is, the average power consumption according to the actual load in the field (travel load and work load) is calculated as the average power consumption Va.

[0049] The storage means 211 for the power consumption of the working machine stores the power consumption per unit time, which is defined in advance by experiments, specifications, etc., for each type of working machine (such as the tiller 18 and plow, etc.), that is, the predetermined power consumption Vb for the working machine. Therefore, the power consumption Vb uses the machine-specific power consumption defined for each type of working machine based on information collected by working in various fields, etc. in advance, rather than the actual load in the field. The storage means 212 for the specified time stores the predetermined specified time T4 until the calculation of the average power consumption Va stabilizes. Note that the specified time can be set to values such as 30 minutes or 1 hour as an example.

[0050] The first available working time calculation means 213 calculates the first available working time T1 based on the average power consumption Va from the start of work to the current time and the remaining power amount (remaining amount V1) of the high-voltage battery 86. As an example, by setting T1 = V1 / Va, it is calculated that the work with the average power consumption Va can be executed for the first available working time T1 using the remaining amount V1. The second available working time calculation means 214 calculates the second available working time T2 based on the predetermined power consumption Vb for the working machine (tiller 18) mounted on the vehicle body 1a and the remaining power amount (remaining amount V1). As an example, by setting T2 = V1 / Vb, it is calculated that the work with the power consumption Vb can be executed for the second available working time T2 using the remaining amount V1.

[0051] The available working time calculation means 215 calculates the remaining available working time Ta, which is the time available for working with the tractor 1 using the remaining amount of the high-voltage battery 86. The available working time calculation means 215 in the embodiment calculates the remaining available working time Ta based on the following formulas (1) and (2). Ta = (T3 / T4) × T1 + (1 - T3 / T4) × T2 (T3 < T4) … Formula (1) Ta = T1 (T3 ≥ T4) … Formula (2) According to formula (1), until the elapsed time T3 from the start of work reaches the specified time T4, that is, immediately after the start of work, a large load may be applied momentarily, and the calculation of the average power consumption Va may not be stable. Therefore, the first available work time T1 and the second available work time T2, which is calculated stably, are combined to calculate the remaining available work time Ta. At this time, the closer the elapsed time T3 is to the specified time T4, the more likely the calculation of the average power consumption Va becomes stable, so the ratio (weighting) of the first available work time T1 is increased. Therefore, when the elapsed time T3 from the start of work is short, the remaining available work time Ta can be calculated more accurately than when the remaining available work time Ta is calculated only from the first available work time T1.

[0052] When the elapsed time T3 from the start of work reaches a specified time T4, the first available work time T1 is displayed as the remaining available work time Ta on the display panel 101, as shown in formula (2). Therefore, the remaining available work time Ta can be calculated with high accuracy according to the actual field conditions, compared to the case where the remaining available work time Ta is calculated only from the second available work time T2, which is calculated regardless of the actual field conditions.

[0053] FIG. 7 is an explanatory diagram of a configuration for heating a battery in cold climates according to an embodiment. The high voltage battery 86 and the auxiliary battery 92 have a temperature range within which their functionality is guaranteed according to their specifications. Therefore, in the winter in cold regions, the temperature may fall below the lower limit, causing problems such as a decrease in the performance of the batteries 86, 92 and, in the worst case, the tractor 1 not starting. In Fig. 7, in the tractor 1 of the embodiment, a heat source (heater) 301 is disposed near the batteries 86, 92, and the heat source 301 is connected to a hand-cranked generator 303 via a thermostat 302. The temperatures of the batteries 86, 92 are monitored by a temperature monitoring unit (temperature sensor) 304. Therefore, when an operator manually turns the hand-cranked generator 303 to generate electricity, the heat source 301 generates heat and warms the batteries 86, 92. The power generated by the hand-cranked generator 303 is also supplied to the temperature monitoring unit 304, which monitors and detects the temperatures of the batteries 86, 92 and displays them on the display panel 101. Therefore, the operator can operate the hand-cranked generator 303 while checking the temperatures of the batteries 86, 92, and start the tractor 1 after the temperatures have risen to a sufficient level.

[0054] 8A and 8B are explanatory diagrams of other examples of the configuration for heating a battery, where FIG. 8A is an explanatory diagram of another example 1, and FIG. 8B is an explanatory diagram of another example 2. In FIG. The monitoring result of the temperature monitoring unit 304 is not limited to being displayed on the display panel 101, and as shown in Fig. 8(A), it is also possible to connect an LED light 306 as an example of an alarm to the temperature monitoring unit 304 and display the result on the LED light 306. For example, it is possible to make the LED light 306 turn off when the temperature of the battery 86, 92 falls below a lower limit temperature and turn on when the temperature exceeds the lower limit temperature, or turn on in red when the temperature falls below the lower limit temperature and turn on in green when the temperature exceeds the lower limit temperature.

[0055] 8(B), a dry cell 311 as an example of a power source is connected to the heat source 301 and the thermostat 302, and a hand-cranked generator 303 is connected to a second heat source (heater) 312 that heats the dry cell 311 via a second thermostat 313. Therefore, by operating the hand-cranked generator 303 to generate power, the dry cell 311 is heated to function sufficiently, and the batteries 86, 92 can be heated by the power supplied from the dry cell 311. 8(B), the batteries 86 and 92 are heated by simply operating the hand-cranked generator 303 until the dry cell 311, which has a smaller volume than the batteries 86 and 92, is heated to a predetermined temperature. Therefore, it is not necessary to operate the hand-cranked generator 303 until the batteries 86 and 92, which have a larger volume, are heated to a predetermined temperature, and the burden on the operator can be reduced.

[0056] 8(B), a buzzer 314 as an example of an alarm is connected to the temperature monitoring unit 304. Therefore, it is possible to alarm by sounding the buzzer 314 when the temperature of the dry battery 311 is equal to or lower than the lower limit temperature, and conversely, it is also possible to alarm by sounding the buzzer 314 when the temperature exceeds the lower limit temperature. 8(B), it is preferable to cover the dry battery 311, the second heat source 312, and the second thermostat 313 with a heat insulating cover 316. If the heat insulating cover 316 is not provided, even if the dry battery 311 is heated by working with the hand-cranked generator 303 in a low-temperature environment, if the dry battery 311 is cooled by the outside air, it takes time to heat up the dry battery 311 to a predetermined temperature, and there is a problem that the worker has to work hard to operate the hand-cranked generator 303. Therefore, by covering the dry battery 311 with the heat insulating cover 316, the dry battery 311 heated by the second heat source 312 is less likely to cool, and the worker's work can be reduced. It is preferable that the insulating cover 316 does not cover the batteries 86, 92. The batteries 86, 92 may generate heat during operation, and the insulating cover 316 may hinder heat dissipation, so it is preferable that the batteries 86, 92 are not covered with the insulating cover 316.

[0057] FIG. 9 is an explanatory diagram of the key cylinder portion for starting a work vehicle, FIG. 9(A) is an explanatory diagram of an embodiment, FIG. 9(B) is an explanatory diagram of another example 1 of an embodiment, FIG. 9(C) is an explanatory diagram of another example 2 of an embodiment, and FIG. 9(D) is an explanatory diagram of another example 3 of an embodiment. In FIG. 9(A), in the tractor 1 of the embodiment, a key cylinder 411 into which a starting key is inserted has a lock position 411a where the tractor 1 stops, a key-on position 411b where electrical components can be used, and a system ready position 411c where electrical components can be used and each of the motors 4 and 52 can be started. Further, between the lock position 411a and the key-on position 411b, a battery heat position 411d is arranged for monitoring the temperature of the batteries 86 and 92 and performing a heating operation with the hand generator 303. Therefore, the operator can switch the state of the tractor 1 by inserting a key (not shown) into the key cylinder 411 and rotating the key between the lock position 411a, the battery heat position 411d, the key-on position 411b, and the system ready position 411c.

[0058] When the hand generator 303 is used at the key-on position 411b or the system ready position 411c, power is supplied to electrical components (such as sensors) and the motors 4 and 52, and a load is applied to the batteries 86 and 92 whose functions deteriorate at low temperatures. Therefore, by operating the hand generator 303 at the battery heat position 411d, which is different from the key-on position 411b and the system ready position 411c, an unnecessary load on the batteries 86 and 92 is suppressed. Also, when using the hand generator 303, it is possible to switch with a button or the like, but by making it possible to switch with the key cylinder 411, there is no need to install an additional button, and the operator also does not need to operate a button separate from the key, thus suppressing the annoyance.

[0059] The battery heating position 411d is not limited to the form shown in Fig. 9(A), and as shown in Fig. 9(B), the battery heating position 411d can be disposed outside the system ready position 411c. In Fig. 9(A), the battery heating position 411d is used only during limited periods such as winter, while the lock position 411a, the key on position 411b, and the system ready position 411c are used throughout the year. Therefore, if the battery heating position 411d is disposed between the lock position 411a and the key on position 411b, there is a risk that the battery heating position 411d will be mistaken for the key on position 411b during normal use, but by disposing the battery heating position 411d outside the system ready position 411c, this misidentification is likely to be suppressed. In the case of the configuration shown in FIG. 9(B), if the power is turned on when the key reaches the key-on position 411b or the system ready position 411c before reaching the battery heat position 411d, unnecessary load will be placed on the battery 86, 92 when power supply begins, so it is desirable to deliberately provide a time lag before power supply from the battery 86, 92 begins when the key reaches the key-on position 411b or the system ready position 411c.

[0060] Also, as shown in Fig. 9(C), it is possible to provide a configuration in which the key-on position 411b is not provided, and instead a battery heat position 411d is provided instead of the key-on position 411b. In the embodiment of Fig. 9(C), the key operation positions are limited to three, the lock position 411a, the battery heat position 411d, and the system ready position 411c, which is easier for the user to operate than the embodiment of Fig. 9(A) in which there are four positions. In addition, by combining the embodiment of Figure 9(B) with the embodiment of Figure 9(C), it is also possible to eliminate the key-on position 411b and position the battery heat position 411d outside the system ready position 411c, as shown in Figure 9(D).

[0061] 10A and 10B are explanatory diagrams of a key cylinder portion for starting a work vehicle, FIG. 10(A) being an explanatory diagram of a fourth embodiment, and FIG. 10(B) being an explanatory diagram of a fifth embodiment. Also, as shown in Fig. 10(A), it is possible to configure the lock position 411a and the battery heating position 411d to be a common position. In the embodiment of Fig. 10(A), as in the embodiments of Fig. 9(C) and Fig. 9(D), only three key operation positions are required, making operation easier for the user. Also, when using the hand-cranked generator 303, the key had to be operated to the battery heating position 411d in the embodiments of Fig. 9(A) to (D), but in the embodiment shown in Fig. 10(A), this operation is not necessary, improving operability.

[0062] 10(A) is a configuration in which, when the key is inserted into the key cylinder 411, the mode switches to one in which the temperature of the batteries 86, 92 is monitored, but the present invention is not limited to this. For example, it is also possible to switch to a mode in which the temperature of the batteries 86, 92 is constantly monitored with the key removed. In this case, it is no longer necessary to insert the key when using the hand-cranked generator 303, improving operability for the operator.

[0063] In Fig. 10(B), it is also possible to combine the mode shown in Fig. 10(A) with the modes shown in Fig. 9(C) and Fig. 9(D) to eliminate the key-on position 411b and to make the lock position 411a and the battery heat position 411d common. In the mode shown in Fig. 10(B), the number of key operation positions is reduced to two, further improving operability. As described above, it is also possible to configure the device to switch to a mode for monitoring the temperatures of the batteries 86, 92 when the key is inserted, or to switch to a mode for monitoring the temperatures of the batteries 86, 92 even when the key is not inserted.

[0064] FIG. 11 is an explanatory diagram of the air conditioning function of the driver's seat, where FIG. 11(A) is a perspective view and FIG. 11(B) is a side view. In FIG. 11, an air conditioner 511 is installed so that an operator seated in the driver's seat 8 can be comfortable in the summer or the like. The air conditioner 511 has a bracket 512 attached to the back of the backrest 8a of the driver's seat 8. A pair of left and right telescopic frames 513 extending upward are supported by the bracket 512. The telescopic frames 513 have an outer cylinder 513a fixed to the bracket 512 and a shaft 513b that can slide up and down relative to the outer cylinder 513a. An air conditioning battery 514 is supported at the upper end of the shaft 513b so as to straddle the left and right shafts 513b. A solar panel 516 as an example of a generator is supported at the upper part of the air conditioning battery 514. The solar panel 516 can generate electricity by receiving sunlight, and the generated electricity is charged into the air conditioning battery 514. An air conditioning fan 517 is supported at the upper part of the pair of left and right shafts 513b. Air conditioning fan 517 is powered by air conditioning battery 514. Air conditioning fan 517 is supported by shaft 513b in a state in which its direction can be adjusted in the left-right direction.

[0065] 11 is installed, the height of the air conditioning fan 517 can be adjusted with the extendable frame 513, and the direction of the air conditioning fan 517 can be adjusted, allowing air to be blown to a position preferred by the operator seated in the driver's seat 8. Therefore, even in a tractor 1 that does not have a cabin, a simple air conditioning function can be added, and compared to a configuration that includes a cabin and an air conditioner, this is a relatively low-cost configuration that allows comfortable work to be performed even in summer, etc. [Explanation of symbols]

[0066] 1...Work vehicle, 1a…Vehicle body, 2,3...Travel gear, 4…first electric motor, 18...Work equipment, 52...second electric motor, 83...Control means, 86…Battery, k: specified value, Kp…constant of proportionality, Ki...integral constant, SN1: Load detector, Ta: remaining available work time, T1: First available time T2: Second available time T3: Time elapsed from the start of the work to the present time, T4: A predetermined time until the calculation of the first available work time becomes stable. V: The magnitude of change in load current per unit time, V1: remaining power, Va: Average power consumption from the start of work to the present time, Vb: power consumption determined in advance for the work machine; x…Suppression amount.

Claims

1. A vehicle body (1a); a traveling device (2, 3) supported by the vehicle body (1a) to cause the vehicle body (1a) to travel; a work machine (18) supported by the vehicle body (1a) for performing work on a farm field; A first electric motor (4) for driving the traveling device (2, 3); A second electric motor (52) for driving the working machine (18); a load detector (SN1) for detecting a load on the second electric motor (52); a control means (83) for controlling the first electric motor (4) based on a traveling speed of the traveling device (2, 3), the control means (83) suppressing an increase in the traveling speed even if an input for an increase in the traveling speed is received when the load of the second electric motor (52) increases and a change amount of the load of the second electric motor (52) does not reach a predetermined specified value (k) based on a detection result of the load detector (SN1), and decelerating the traveling speed when the change amount of the load of the second electric motor (52) reaches the specified value (k); A work vehicle comprising:

2. the load detector (SN1) for detecting a load current value of the second motor (52) corresponding to a load of the second motor (52); the control means (83) for controlling the first electric motor (4) by PI control based on the load current value, a predetermined proportional constant (Kp), and a predetermined integral constant (Ki), the control means (83) setting a suppression amount (x) of an increase in the traveling speed based on a control value of the first electric motor (4) calculated by the PI control; The work vehicle according to claim 1, further comprising:

3. The suppression amount (x) of the increase in the traveling speed is made proportional to the magnitude (V) of the change amount per unit time of the load current value, and when the magnitude (V) of the change amount reaches the specified value (k), the suppression amount (x) is set as an upper limit value.

3. The work vehicle according to claim 2.

4. the load detector detecting a change in the rotation speed of the second motor (52) according to the load of the second motor (52); a control means (83) for controlling the first electric motor (4) by PI control based on the value of the rotation speed, a predetermined proportional constant (Kp), and a predetermined integral constant (Ki), the control means (83) setting an amount of suppression of an increase in the traveling speed based on a control value of the first electric motor (4) calculated by the PI control; The work vehicle according to claim 1, further comprising:

5. a battery (86) for powering the first electric motor (4) and the second electric motor (52); the control means (83) for calculating Ta=(T3 / T4)×T1+(1−T3 / T4)×T2, where T1 is a first available work time calculated based on an average power consumption (Va) from the start of work to the present time and the remaining power amount (V1) of the battery (86), T2 is a second available work time calculated based on a predetermined power consumption (Vb) for the work machine (18) attached to the vehicle body (1a) and the remaining power amount (V1), T3 is an elapsed time from the start of work to the present time, T4 is a predetermined specified time until the calculation of the first available work time (T1) becomes stable, and Ta is a remaining available work time; The work vehicle according to claim 1, further comprising:

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