Control device, work vehicle and computer program

Abstract

To provide a control device capable of appropriately protecting an engine in cold weather.SOLUTION: A control device 100 controls engine speed of a work vehicle in cold weather. In the control device, a determination section 110 outputs speed control information to a speed control section 130 on the basis of an outside air temperature T1 detected by an outside air temperature sensor 35 and a cooling water temperature T2 detected by a cooling water temperature sensor 44, and outputs temperature information on the cooling water temperature T2 or the outside air temperature T1, whichever is lower, to a control time determination section 120. The control time determination section 120 determines a control time for controlling the engine speed on the basis of the temperature information, and outputs the control time to the speed control section 130. The speed control section 130 outputs a signal for limiting the engine speed to predetermined speed or lower on the basis of the speed control information to an engine 20, and controls the engine speed for a period set from the control time.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a control device, a work vehicle, and a computer program. [Background technology]

[0002] Conventionally, a vehicle control device is known that keeps the engine coolant (engine coolant) warm by warming the engine with a block heater in cold weather (see, for example, Patent Document 1). As a result, the engine is warmed by the warmed coolant, making it easier to start the engine.

[0003] In addition, in cold weather, engine oil cools and its fluidity decreases, which may prevent engine oil from reaching the entire engine, and in this case, if the engine, particularly a turbocharged engine, is operated, the turbo may be damaged. For this reason, a control device is known that performs control to reduce the engine speed to below the maximum speed in cold weather until the engine coolant temperature rises (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-142218 A [Patent Document 2] Japanese Utility Model Application Publication No. 61-076142 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in the invention described in Patent Document 2, the engine speed is controlled based on the engine coolant temperature. Therefore, when using a block heater to keep the coolant warm as in the invention described in Patent Document 1, the coolant temperature rises even though the outside air temperature and the temperature of the engine body have not risen sufficiently, and the control to reduce the engine speed to below the maximum speed is cancelled, which causes a problem that it is difficult to adequately protect the engine in cold weather.

[0006] The present invention has been made to solve the above problems, and has an object to provide a control device capable of appropriately protecting an engine in cold weather, a work vehicle equipped with such a control device, and a program for realizing control capable of appropriately protecting the engine in cold weather. [Means for solving the problem]

[0007] [1] The control device of the present invention is a control device that controls the engine speed of a work vehicle that is capable of warming the cooling water circulating through the engine using a block heater in cold weather, and the control device is equipped with a judgment unit, a control time determination unit, and a rotation speed control unit, and the judgment unit generates rotation speed control information based on an outside air temperature detected by an outside air temperature sensor and a cooling water temperature detected by a cooling water temperature sensor provided in the cooling water circulation path, and outputs the lower of the outside air temperature and the cooling water temperature as temperature information to the control time determination unit, the control time determination unit determines a control time for controlling the engine speed based on the temperature information and outputs it to the rotation speed control unit, and the rotation speed control unit outputs a signal to limit the engine speed to a predetermined speed or lower based on the rotation speed control information, and controls the engine speed for a period set by the control time.

[0008] [2] In the control device of the present invention, it is preferable that the judgment unit outputs the rotation speed control information to the rotation speed control unit and outputs the temperature information to the control time determination unit when the outside air temperature is lower than a predetermined first set temperature and the cooling water temperature is lower than a predetermined second set temperature.

[0009] [3] The control device of the present invention preferably further comprises an operation disable signal generating unit that generates an operation disable signal that disables operation of the operating lever for a predetermined period of time based on the cooling water temperature.

[0010] [4] The work vehicle of the present invention is a work vehicle capable of heating the cooling water circulating through the engine in cold weather using a block heater, and is characterized in that it is equipped with the control device described in [1] or [2] above, and the block heater is provided below the radiator.

[0011] [5] The computer program of the present invention is a computer program for controlling the engine speed of a work vehicle capable of warming the coolant circulating through the engine using a block heater in cold weather, and is characterized in that it causes a computer to execute the following processes: acquiring an outside air temperature detected by an outside air temperature sensor and a coolant temperature detected by a coolant temperature sensor provided in the coolant circulation path; controlling the engine speed based on the outside air temperature and the coolant temperature; determining a control time for controlling the engine speed based on temperature information that is the lower of the outside air temperature and the coolant temperature, and releasing the control to limit the engine speed after the control time has elapsed since applying control to limit the engine speed. Effect of the Invention

[0012] According to the control device, work vehicle, and computer program of the present invention, the judgment unit generates rotation speed control information based on the outside air temperature detected by the outside air temperature sensor and the coolant temperature detected by a coolant temperature sensor provided in the coolant circulation path, and outputs the information to the rotation speed control unit, and the rotation speed control unit outputs a signal to the engine to limit the engine rotation speed to a predetermined rotation speed or less based on the rotation speed control information. Therefore, when a block heater is used to keep the coolant warm, if the temperature of the engine body has not risen sufficiently, control to reduce the engine rotation speed to below the maximum rotation speed can be maintained even if the coolant temperature rises, and the engine can be appropriately protected in cold weather.

[0013] In addition, according to the control device, work vehicle, and computer program of the present invention, the judgment unit outputs the lower of the outside air temperature and the coolant temperature as temperature information to the control time determination unit, and the control time determination unit determines a control time for controlling the engine speed based on the temperature information and outputs it to the speed control unit, and the speed control unit controls the engine speed for a period set by the control time, so that it is possible to control the engine speed to be reduced to below the maximum speed for an appropriate time according to both the outside air temperature and the coolant temperature, and the engine can be more appropriately protected in cold weather. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a rear perspective view shown for explaining a work vehicle 1 according to an embodiment. [Diagram 2] FIG. 2 is a diagram for explaining the internal configuration of a work vehicle 1 according to an embodiment. [Diagram 3] FIG. 1 is a block diagram shown for explaining a control device 100 according to an embodiment. [Figure 4] 5 is a flowchart shown to explain control performed by the control device 100 according to the embodiment to reduce the engine speed to a maximum speed or less. [Diagram 5] 4 is a flowchart shown for explaining operation disable control performed by the control device 100 according to the embodiment. [Figure 6] FIG. 11 is a block diagram illustrating a computer 200 according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The control device, work vehicle, and computer program of the present invention will be described below based on the embodiments shown in the drawings. Note that the embodiments described below do not limit the invention according to the claims. Furthermore, not all of the elements and combinations thereof described in the embodiments are necessarily essential to the solution of the present invention.

[0016] [Embodiment] 1. Configuration of work vehicle 1 according to embodiment The work vehicle 1 according to the embodiment is a crawler-type skid steer loader with a bucket (not shown) attached to the tip of a work arm 16. However, the work vehicle is not limited to this and may be any suitable work vehicle.

[0017] First, the external configuration of a work vehicle 1 according to an embodiment will be described. Fig. 1 is a rear perspective view shown for explaining the work vehicle 1 according to an embodiment. Note that Fig. 1 is a view in which an engine cover 18 and a rear door 19 of the work vehicle 1 are in an open state. As shown in Fig. 1, the work vehicle 1 has a pair of left and right traveling devices 12 each having an endless track (crawler) 11, a main body frame 13 to which the traveling devices 12 are attached on the left and right, a cabin 15 provided at the upper center of the main body frame 13, and a working device (a working arm 16, etc.).

[0018] The cabin 15 is formed in a box shape. An operator seat on which an operator sits is provided inside the cabin 15, and the operator sits on the operator seat and operates an operating lever. In this way, the traveling device 12 is driven in response to the operation of the operating lever, causing the work vehicle 10 to travel and move.

[0019] The work vehicle 1 is provided with an engine 20 (see FIG. 2) at a position rearward of the cabin 15. The left and right sides of the engine 20 are covered by the main body frame 13, and the top and rear are covered by an engine cover 18 and a rear door 19, respectively. When the rear door 19 is in an open state, a radiator 40 is provided, and between the radiator 40 and the engine 20, a fan shroud (not shown) and a radiator fan (not shown) are provided.

[0020] A block heater 50 is provided below the radiator 40. In cold weather, the block heater 50 is connected to an external power source via a power cord and energized to keep the coolant warm and prevent it from freezing.

[0021] In addition, except in cold weather, a power cord connecting block heater 50 to an external power source is not required, so the power cord is stored in storage space 51 below lower tank 47 (see FIG. 2) of radiator 40. This is convenient because it can be quickly removed when powering block heater 50, and there is no need to provide a separate storage location even when not in use.

[0022] Next, the internal configuration of the work vehicle 1 will be described. Fig. 2 is a diagram shown to explain the internal configuration of the work vehicle 1 according to the embodiment. As shown in Fig. 2, the work vehicle 1 includes an engine 20, an air cleaner 31, an exhaust port 33, an intake pipe 32, an exhaust pipe 34, an outside air temperature sensor 35, a radiator 40, a first pipe 41, a water jacket 42, a second pipe 43, a coolant temperature sensor 44, a block heater 50, a display unit 60, and a lever control unit 70.

[0023] The engine 20 is composed of an engine section 21 and a turbo section 22. The engine 20 (turbo section 22) is connected to an intake pipe 32 and an exhaust pipe 34. An air cleaner 31 is connected to the tip side of the intake pipe 32, and an exhaust port 33 is connected to the tip side of the exhaust pipe 34. The engine section 21 rotates the engine by injecting fuel from a fuel injection valve (not shown). The turbo section 22 sends air taken in from the intake pipe 32 to the engine section 21, thereby increasing the output of the engine 20. An outside air temperature sensor 35 is attached to the air cleaner 31, which detects the outside air temperature and outputs it to the control device 100.

[0024] As shown in FIG. 2, engine 20 is connected to control device 100, and control device 100 generates and outputs a control signal for adjusting the fuel injection amount of a fuel injection valve (not shown) of engine 20, which is the object to be controlled, and can control the engine speed by adjusting the fuel injection amount.

[0025] In cold weather, the control device 100 controls the rotation speed of the engine 20 of the work vehicle 1 based on the outside air temperature T1 and the coolant temperature T2 input from the outside air temperature sensor 35. The control device 100 is connected to a display unit 60 and a lever control unit 70 in the cabin 15. Details of the control device 100 will be described later.

[0026] A cooling water circulation path for circulating cooling water (coolant) is provided around the engine 20. The cooling water circulation path is composed of a radiator 40, a first pipe 41 (low-temperature flow path), an inner pipe (water jacket) 42, and a second pipe 43 (high-temperature flow path). A thermostat valve (not shown) for adjusting the flow rate of the cooling water circulated to the radiator 40 is provided near the engine.

[0027] The radiator 40 has an upper tank 45 , fins 46 and a lower tank 47 .

[0028] The upper tank 45 is a tank that stores the cooling water that has cooled (exchanged heat) the engine 20. The cooling water in the upper tank 45 flows into the upper tank 45 through the second piping 43. The cooling water stored in the upper tank 45 flows into the fins 46. The fins 46 cool the cooling water by the wind generated during running or a radiator fan (not shown).

[0029] The lower tank 47 is a tank that stores cooled cooling water. The cooling water in the lower tank 47 flows into the water jacket 42 through the first piping 41. The water jacket 42 is disposed inside the engine 20. The cooling water flowing through the water jacket 42 cools (exchanges heat with) the engine 20 inside the engine. Then, the cooling water flows into the second piping 43.

[0030] The coolant temperature sensor 44 is provided in the coolant circulation path. In the embodiment, the coolant temperature sensor 44 is provided in the vicinity of a coolant outlet in the engine 20, but may be provided in a pipe (the first pipe 41, the second pipe 43, etc.) outside the engine 20.

[0031] A block heater 50 is disposed in the lower tank 47 of the radiator 40. In cold weather, the block heater 50 is connected to an external power source and energized to keep the coolant warm, thereby keeping the engine 20 warm.

[0032] 2. Configuration of the control device 100 according to the embodiment Fig. 3 is a block diagram for explaining the control device 100 according to the embodiment. The control device 100 according to the embodiment controls the rotation speed of the engine 20 of the work vehicle 1 capable of warming the cooling water circulating through the engine 20 by the block heater 50 in cold weather. As shown in Fig. 3, the control device 100 includes a determination unit 110, a control time determination unit 120, a rotation speed control unit 130, a driving disable signal generation unit 140, a display signal generation unit 150, and an engine drive unit 160.

[0033] The judgment unit 110 generates rotation speed control information based on the outside air temperature T1 detected by the outside air temperature sensor 35 and the coolant temperature T2 detected by a coolant temperature sensor 44 provided in the coolant circulation path (near the coolant outlet in the engine) and outputs it to the rotation speed control unit 130, and also outputs the lower of the outside air temperature T1 and the coolant temperature T2 to the control time determination unit 120 as temperature information.

[0034] When the outside air temperature T1 is lower than a predetermined first set temperature T01 and the cooling water temperature T2 is lower than a predetermined second set temperature T02, the judgment unit 110 outputs rotation speed control information to the rotation speed control unit 130, and outputs temperature information of the lower of the outside air temperature T1 and the cooling water temperature T2 to the control time determination unit 120.

[0035] Specifically, the first set temperature T01 is set to -10°C, the second set temperature T02 is set to 10°C, and the rotation speed of the engine 20 is restricted to a maximum rotation speed or less when the outside air temperature T1 is -10°C or less and the cooling water temperature T2 is 10°C or less. In this way, by monitoring the outside air temperature T1 and the cooling water temperature T2, and restricting the engine rotation speed to a maximum rotation speed or less when the outside air temperature T1 is the first set temperature T01, which is -10°C or less, and the cooling water temperature T2 is the second set temperature T02, which is 10°C or less, a function for protecting the engine (particularly the turbo) (turbo protection function) can be realized.

[0036] Furthermore, the determination unit 110 outputs coolant temperature information to the operation disable signal generation unit 140 when the coolant temperature T2 is lower than a predetermined second set temperature T02.

[0037] The control time determination unit 120 determines a control time for controlling the engine speed based on temperature information which is the lower of the outside air temperature T1 and the cooling water temperature T2, and outputs the control time to the speed control unit 130. The control device 100 has a storage device (not shown) in which a table of time limits for limiting the engine speed corresponding to the temperature information is stored in advance, and the control time determination unit 120 calls up the time limit corresponding to the temperature information from the storage device and measures it with the timer 122. Then, when the time limit has elapsed, a release signal is output to the speed control unit 130.

[0038] The rotation speed control unit 130 outputs a signal to the engine driving unit 160 to limit the engine rotation speed to below the maximum rotation speed based on the rotation speed control information, and controls the engine rotation speed to below the maximum rotation speed for a period set by the control time, and outputs a signal to the engine driving unit 160 to release the limit on the engine rotation speed based on a release signal from the control time determination unit 120.

[0039] The engine drive unit 160 outputs a signal to the engine 20 to control the fuel injection amount and rotation speed of the engine 20 based on a signal from the rotation speed control unit 130 and a signal operated by an operator.

[0040] The operation-disabled signal generating unit 140 generates an operation-disabled signal that disables operation of the operating lever for a predetermined time based on the cooling water temperature information (cooling water temperature T2) output from the determination unit, and outputs the signal to the lever control unit. When the lever control unit receives the operation-disabled signal, it controls the lever so that the lever operation is disabled for a predetermined time. In addition, the operation-disabled signal generating unit 140 outputs a signal that cancels the operation-disabled state to the lever control unit after the predetermined time has elapsed. When the operation-disabled signal generating unit 140 outputs a signal that the operation-disabled signal is being output to the lever control unit or a signal that cancels the operation-disabled state, it transmits a signal to the display signal generating unit 150 to notify the operation-disabled state.

[0041] When either the determination unit 110 generates rotation speed control information and outputs it to the rotation speed control unit 130, or the operation disable signal generation unit 140 outputs an operation disable signal to a lever control unit (not shown), the display signal generation unit 150 generates an indication signal for indicating that the cooling water temperature is low, and outputs it to the display unit 60. When the rotation speed control is released and the operation disable control is also released, the output of the indication signal is stopped.

[0042] 3. Engine speed control method and operation disable control method The specific conditions and the manner in which the engine speed is controlled will be described below with reference to the flow chart of FIG.

[0043] Here, the work vehicle 10 has two modes: a stop mode and a work mode. The stop mode refers to a state in which the vehicle is idling and the engine is warming up (low-load operation for a while after the engine is started), and the work mode refers to a state in which the engine has finished warming up and pressurized oil (hydraulic oil) driven by the engine is being transmitted to the traveling device and the work device, that is, a state in which the vehicle can travel and the arms can be moved. Also, the stop mode refers to a state in which the work vehicle 10 is stopped, but the stop state does not simply mean that the vehicle is stopped, but refers to a state in which pressurized oil driven by the engine has not yet been transmitted to the traveling device and the work device.

[0044] Here, we will focus on the control in the stop mode when the engine is started in cold weather and the engine temperature has not yet risen, as this is one of the characteristics of this control. Once the engine has warmed up and the cold weather is no longer present, the vehicle will be put into an idling state or used as a work vehicle in work mode.

[0045] First, after the engine 20 is turned on (see step S101 in FIG. 4), the judgment unit 110 judges whether the coolant temperature (coolant temperature) detected by the coolant temperature sensor 44 is equal to or lower than a second set temperature T02 (e.g., 10°C) that has been set in advance (see step S102 in FIG. 4).

[0046] When the cooling water temperature T2 is equal to or lower than the second set temperature T02, the judgment unit 131 judges whether or not the outside air temperature T1 detected by the outside air temperature sensor 35 is equal to or lower than a first set temperature T01 (e.g., −10° C.) that is set in advance (see step S103 in FIG. 4). When the detected outside air temperature T1 is equal to or lower than the first set temperature T01, the control device 100 reduces the fuel injection amount of the fuel injection valve (not shown) and limits the engine speed to 1300 rpm or lower (see step S104 in FIG. 4).

[0047] Then, the rotation speed limit time is determined based on the lower of the outside air temperature T1 and the cooling water temperature T2 (see step S105 in FIG. 4), and the engine rotation speed is limited to a maximum rotation speed or less (1300 rpm or less) during the rotation speed limit time.

[0048] When it is determined that the rotation speed limit time has elapsed (see step S106 in FIG. 4), the limit on the engine 20 rotation speed is released, allowing the engine rotation speed to be 1300 rpm or higher (see step S107 in FIG. 4).

[0049] In this manner, the rotation speed of the engine 20 is controlled.

[0050] Next, the operation disable control will be described below. Fig. 5 is a flowchart shown for explaining the operation disable control performed by the control device 100 according to the embodiment.

[0051] First, after the engine 20 is turned on (see step S201 in FIG. 5), the judgment unit 110 judges whether the coolant temperature (coolant temperature) detected by the coolant temperature sensor 44 is equal to or lower than a second set temperature T02 (e.g., 10°C) that has been set in advance (see step S202 in FIG. 5).

[0052] When the coolant temperature T2 is equal to or lower than the second set temperature T02, the determination unit 110 outputs the coolant temperature information (coolant temperature T2) to the operation disable signal generation unit 140. Then, the operation disable signal generation unit 140 outputs an operation disable signal based on the coolant temperature information (coolant temperature T2) to disable lever operation (see step S203 in FIG. 5). Also, the operation disable signal generation unit 140 determines an operation disable period based on the coolant temperature information (coolant temperature T2) and disables lever operation during the operation disable period (see step S204 in FIG. 5).

[0053] When it is determined that the operation disabled period has elapsed (see step S205 in FIG. 5), the restriction on the lever operation disabled is lifted, and the state transitions to a state in which the lever operation is enabled (see step S206 in FIG. 5).

[0054] In this way, operation disable control (lever operation control) can be performed.

[0055] 3. Effects of the control device 100 and the work vehicle 1 according to the embodiment According to the control device 100 and work vehicle 1 of the embodiment, the determination unit 110 generates rotation speed control information based on the outside air temperature T1 detected by the outside air temperature sensor 35 and the coolant temperature T2 detected by the coolant temperature sensor 44 provided in the coolant circulation path, and outputs the generated information to the rotation speed control unit 130. The rotation speed control unit 130 outputs a signal to the engine 20 to limit the engine rotation speed to a predetermined rotation speed or less based on the rotation speed control information. Therefore, when the block heater 50 is used to keep the coolant warm, if the temperature of the engine body has not risen sufficiently, control to reduce the engine rotation speed to below the maximum rotation speed can be maintained even if the coolant temperature rises, and the engine can be appropriately protected in cold weather.

[0056] Furthermore, according to the control device 100 and work vehicle 1 of the embodiment, the judgment unit 110 outputs the lower of the outside air temperature T1 and the coolant temperature T2 as temperature information to the control time determination unit 120, the control time determination unit 120 determines a control time for controlling the engine speed based on the temperature information and outputs it to the rotation speed control unit 130, and the rotation speed control unit 130 controls the engine speed for a period set by the control time, so that it is possible to control the engine speed to be reduced to below the maximum rotation speed for an appropriate time corresponding to both the outside air temperature T1 and the coolant temperature T2, and it is possible to more appropriately protect the engine in cold weather.

[0057] Furthermore, according to the control device 100 and work vehicle 1 of the embodiment, the determination unit 110 outputs rotation speed control information to the rotation speed control unit 130 when the outside air temperature T1 is lower than a predetermined first set temperature T01 and the cooling water temperature T2 is lower than a predetermined second set temperature T02, and outputs temperature information of the lower of the outside air temperature T1 and the cooling water temperature T2 to the control time determination unit 120, so that engine rotation speed control can be achieved in response to not only the cooling water temperature T2 but also the outside air temperature T1. Also, engine rotation speed control in response to the lower of the cooling water temperature T2 and the outside air temperature T1 can be achieved, making it less likely that engine malfunctions will occur when the engine is started in cold weather.

[0058] Furthermore, the control device 100 and work vehicle 1 according to the embodiment are further provided with an operation disable signal generating unit 140 that generates an operation disable signal that disables operation of the operating lever for a predetermined period of time based on the cooling water temperature T2, thereby preventing engine malfunctions caused by operating the lever to start work in cold weather.

[0059] Furthermore, according to the work vehicle 1 of the embodiment, the block heater 50 is provided in the lower tank 47 of the radiator 40, so that the coolant itself can be heated more efficiently than in the case where the block heater 50 is attached to the engine 20, and the coolant can be kept warm more efficiently.

[0060] [Variations] In the embodiment, the control device 100 is realized using a logic circuit, but the control device 100 may be realized using a computer program. That is, the computer program according to the modified example is a computer program for controlling the engine speed of the work vehicle 1 capable of warming the coolant circulating through the engine 20 by the block heater 50 in cold weather, and may cause the computer 200 to execute a process of acquiring the outside air temperature T1 detected by the outside air temperature sensor 35 and the coolant temperature T2 detected by the coolant temperature sensor 44 provided in the coolant circulation path, a process of controlling the engine speed based on the outside air temperature T1 and the coolant temperature T2, and a process of determining a control time for controlling the engine speed based on temperature information that is the lower temperature of the outside air temperature T1 and the coolant temperature T2, and a process of releasing the control for limiting the engine speed after the control time has elapsed since the control for limiting the engine speed was performed.

[0061] In this case, it is preferable to use a computer 200 having a receiving unit 201 that receives temperature information on the outside air temperature T1 and the coolant temperature T2, a CPU 202 that determines whether or not to control the engine speed based on the temperature information on the outside air temperature T1 and the coolant temperature T2, a ROM 203 that stores a table showing the relationship between the coolant temperature T2 and the speed limit time, a RAM 204 that stores the speed limit time and a speed control signal, and a transmitting unit 205 that transmits a speed control signal and a release signal to the engine 20, all of which are connected by a bus 206 (see Figure 6).

[0062] Although the present invention has been described based on the above embodiment, the present invention is not limited to the above embodiment. It can be embodied in various forms without departing from the spirit of the present invention, and for example, the following modifications are also possible.

[0063] (1) The positions, connections, quantities, etc. described in the above embodiment (including modified examples; the same applies below) are merely examples and may be changed without impairing the effects of the present invention.

[0064] (2) In the above embodiment, the limit value of the engine speed is set to a constant value of 1300 rpm, but the present invention is not limited to this. Any other appropriate speed may be used.

[0065] (3) In the above embodiment, the limit value of the engine speed is a constant value, but the present invention is not limited to this. The limit value may be changed according to the cooling water temperature or the outside air temperature. In this case, the limit value may be read from a preset table, or may be calculated from a preset formula.

[0066] (4) In the above embodiment, the outside air temperature sensor 35 is provided in the air cleaner 31. However, the outside air temperature sensor 35 may be provided in any suitable position where the outside air temperature can be detected.

[0067] (5) In the above embodiment, the block heater is disposed inside the lower tank of the radiator. However, the block heater may be disposed in any suitable position adjacent to the radiator. [Explanation of symbols]

[0068] 1...work vehicle, 12...running gear, 13...main body frame, 15...cabin, 16...working arm, 18...engine cover, 19...rear door, 20...engine, 21...engine section, 22...turbo section, 31...air cleaner, 32...intake pipe, 33...exhaust port, 34...exhaust pipe, 35...outside air temperature sensor, 40...radiator, 41...first pipe, 42...internal pipe, 43...second pipe, 44...coolant temperature sensor, 45...upper tank, 46...fin, 47...lower tank , 50...block heater, 60...display unit, 70...lever control unit, 100...control device, 110...judgment unit, 120...control time determination unit, 122...timer, 130...rotation speed control unit, 140...operation disable signal generation unit, 150...display signal generation unit, 200...computer, 201...receiving unit, 202...CPU, 203...ROM, 204...RAM, 205...transmitting unit, 206...bus, T01...first set temperature, T02...second set temperature, T1...outside air temperature, T2...cooling water temperature

Claims

1. A control device for controlling an engine speed of a work vehicle capable of warming cooling water circulating through the engine by a block heater in cold weather, comprising: The control device includes a determination unit, a control time determination unit, and a rotation speed control unit. the determination unit generates rotation speed control information based on an outside air temperature detected by an outside air temperature sensor and a coolant temperature detected by a coolant temperature sensor provided in a coolant circulation path, and outputs the generated information to the rotation speed control unit, and also outputs a lower temperature of the outside air temperature and the coolant temperature to the control time determination unit as temperature information; the control time determination unit determines a control time for controlling an engine speed based on the temperature information, and outputs the control time to the speed control unit; The control device is characterized in that the rotation speed control unit outputs a signal to limit the engine rotation speed to a predetermined rotation speed or less based on the rotation speed control information, and controls the engine rotation speed for a period set by the control time.

2. 2. The control device according to claim 1, wherein the judgment unit outputs the rotation speed control information to the rotation speed control unit and outputs the temperature information to the control time determination unit when the outside air temperature is lower than a predetermined first set temperature and the cooling water temperature is lower than a predetermined second set temperature.

3. 3. The control device according to claim 1, further comprising an operation disable signal generating unit that generates an operation disable signal for disabling operation of an operating lever for a predetermined time based on the cooling water temperature.

4. A work vehicle capable of warming the cooling water circulating through the engine with a block heater in cold weather, The control device according to claim 1 or 2 is provided, A work vehicle, wherein the block heater is provided in a lower tank of a radiator.

5. A computer program for controlling an engine speed of a work vehicle capable of warming a cooling water circulating through the engine by a block heater in cold weather, comprising: On the computer, A process of acquiring an outside air temperature detected by an outside air temperature sensor and a coolant temperature detected by a coolant temperature sensor provided in a coolant circulation path; A process of controlling a rotation speed of the engine based on the outside air temperature and the cooling water temperature; determining a control time for controlling an engine speed based on temperature information which is the lower of the outside air temperature and the cooling water temperature, and performing control to limit the engine speed and then releasing the control to limit the engine speed after the control time has elapsed.

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