Work vehicle and work vehicle control method

Abstract

To provide a work vehicle capable of improving fuel economy by the control to switch modes between an economy mode and a standard mode at an appropriate timing, and capable of eliminating the troublesomeness of manually switching the modes between the standard mode and the economy mode.SOLUTION: A work vehicle 1 includes an engine 20, a first hydraulic pump 31, a second hydraulic pump 32, a travelling device 6, a work device 9, an operation device 5, an ECU 30, and a vehicle controller 7. The vehicle controller 7 transmits a control command in a standard mode to the ECU 30 when the travelling device 6 is stopped, discharge pressure from the second hydraulic pump 32 is a reference value U1 or more, and a first period T1 passes with an engine load factor of a predetermined upper limit E1 or more, transmits a control command in an economy mode to the ECU 30 when a second period T2 passes with the engine load factor of a predetermined lower limit or less, and transmits a control command in the standard mode to the ECU 30 when the travelling device 6 is actuated.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a work vehicle using an engine as a drive source and a method for controlling a work vehicle. [Background technology]

[0002] BACKGROUND ART Work vehicles that allow the selection of an economy mode have been proposed in the past (Patent Document 1: JP 2011-001896 A, Patent Document 2: JP 2015-094070 A). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-001896 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-094070 Summary of the Invention [Problem to be solved by the invention]

[0004] Economy mode is sometimes used to reduce fuel consumption. However, when working in economy mode and a large amount of power is required for tasks such as digging, the operator must manually switch to standard mode. On the other hand, continuing to work in standard mode wastes energy. This results in a problem of reduced fuel consumption. [Means for solving the problem]

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a work vehicle that improves fuel efficiency by controlling switching between economy mode and standard mode at appropriate times, and that eliminates the hassle of the operator having to manually switch between standard mode and economy mode.

[0006] The present invention solves the above problems by the solution disclosed below as one embodiment.

[0007] A work vehicle according to the present invention includes an engine, a first hydraulic pump and a second hydraulic pump operated by the engine, a travel device operated by the first hydraulic pump, a working device operated by the second hydraulic pump, an operating device for operating the travel device and the working device, an ECU for controlling engine output, and a vehicle controller that issues an economy mode control command or a standard mode control command to the ECU, wherein the vehicle controller sends the standard mode control command to the ECU when the travel device is stopped, the discharge pressure from the second hydraulic pump is equal to or greater than a reference value, and the engine load factor is equal to or greater than a predetermined upper limit value for a first period of time, and sends the economy mode control command to the ECU when the engine load factor is equal to or less than a predetermined lower limit value for a second period of time, and sends the standard mode control command to the ECU when the travel device is operating. Here, the ECU is an Engine Control Unit. Alternatively, the ECU is an Electronic Control Unit.

[0008] This configuration allows the machine to quickly switch to standard mode when high working power is required, and quickly switch to economy mode when low working power is sufficient, thereby improving fuel efficiency. Furthermore, the operator does not have to go through the hassle of manually switching between standard mode and economy mode, improving usability.

[0009] As an example, a selection switch may be provided to enable the vehicle controller to issue the control command for the economy mode or the control command for the standard mode, and the vehicle controller selects the control command for the economy mode or the control command for the standard mode and transmits the selected control command to the ECU when the selection switch is enabled. With this configuration, when large working power is required, the required working power can be secured regardless of the engine load factor, which is convenient for the operator.

[0010] As an example, when the ECU receives the control command for the economy mode and performs control in the economy mode, the ECU limits the upper limit of the engine speed to within a range of 0.75 to 0.95 times that when performing control in the standard mode. With this configuration, when performing control in the economy mode, fuel consumption can be reduced within a range that does not impair workability.

[0011] As an example, the first period is set to 0.2 to 0.7 seconds. With this configuration, when high working power is required, the mode can be quickly switched to standard mode. Furthermore, it is possible to prevent a situation where the standard mode is switched to when it is not actually necessary due to a temporary high pressure during initial operation, etc. As an example, the second period is set to 0.8 to 1.4 seconds. With this configuration, when high working power is no longer required within a range that does not impair workability, the mode can be quickly switched to economy mode.

[0012] For example, the vehicle controller transmits the control command for the economy mode and the control command for the standard mode to the ECU using the engine load factor calculated by the ECU based on the fuel injection rate of the engine. With this configuration, when a large torque is no longer required, the vehicle can be quickly switched to the economy mode.

[0013] A control method for a work vehicle according to the present invention is a control method for a work vehicle comprising an engine, a first hydraulic pump and a second hydraulic pump operated by the engine, a traveling device operated by the first hydraulic pump, a work device operated by the second hydraulic pump, an operating device for operating the traveling device and the work device, an ECU that controls engine output, and a vehicle controller that issues an economy mode control command or a standard mode control command to the ECU, wherein the vehicle controller sends the standard mode control command to the ECU when the traveling device is stopped, the discharge pressure from the second hydraulic pump is equal to or greater than a reference value, and the engine load factor is equal to or greater than a predetermined upper limit value for a first period, sends the economy mode control command to the ECU when the engine load factor is equal to or less than a predetermined lower limit value for a second period, and sends the standard mode control command to the ECU when the traveling device is operating.

[0014] With this configuration, the work vehicle can be quickly switched to standard mode when high working power is required, and quickly switched to economy mode when low working power is sufficient, thereby improving fuel efficiency. Furthermore, the operator does not have to go through the hassle of manually switching between standard mode and economy mode, improving usability. [Effects of the Invention]

[0015] According to the present invention, a work vehicle is realized that improves fuel efficiency by controlling switching between economy mode and standard mode at appropriate times, and eliminates the hassle of the operator having to manually switch between standard mode and economy mode. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic perspective view showing an example of a work vehicle according to this embodiment. [Figure 2]FIG. 2 is a schematic circuit diagram showing an example of a drive control system in the work vehicle shown in FIG. [Figure 3] FIG. 3 is a schematic flowchart illustrating an example of a control procedure for switching between economy mode and standard mode in the work vehicle shown in FIG. [Figure 4] FIG. 4 is a schematic graph showing an example of a control operation for switching between economy mode and standard mode in the work vehicle shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a work vehicle 1 according to this embodiment, and is a perspective view from above the left front. The work vehicle 1 is equipped with a traveling device 6 and a turning device 8. For ease of explanation, arrows may be used in the drawings to indicate up / down, left / right, and front / rear directions. In addition, in all drawings used to explain the embodiment, members having the same function are given the same reference numerals, and repeated explanations may be omitted.

[0018] A wheeled hydraulic excavator will be described as an example of the working vehicle 1 of this embodiment. As a configuration other than the above, the working vehicle 1 can be a track loader, a carrier, or the like.

[0019] As shown in Fig. 1, the work vehicle 1 comprises a travellable lower body 2, a swiveling upper body 3 disposed on the lower body 2, a working device 9 attached to the upper body 3, and a cab 4 disposed on the upper body 3. An operating device 5 is provided in the cab 4, where an operator sits and operates various tasks including traveling, swinging, and excavation. Here, the part surrounded by a dashed dotted line P1 in the figure is a schematic diagram of the interior of the cab 4 as viewed from above.

[0020] The operator's cab 4 is equipped with an operator seat 4a on which the operator sits, a display 98 located on the front right side of the operator seat 4a, and a selection switch 99 located on the rear right side of the operator seat 4a. The display 98 is configured to be able to display operation information for the traveling device 6, the swing device 8, the work device 9, and the blade device 19, as well as vehicle information. The selection switch 99 is a push button that can be used to sequentially select standard mode, economy mode, or switching mode.

[0021] When the selector switch 99 is operated, control is performed to switch between the standard mode, economy mode, and switching mode in that order. As an example, the display 98 indicates whether the current mode is the standard mode, economy mode, or switching mode.

[0022] For example, in standard mode, no icon is displayed on the display 98. In economy mode, an icon with a leaf pattern is displayed on the display 98. In switching mode, an icon combining a leaf pattern and a plus sign is displayed on the display 98.

[0023] The operator's cab 4 is provided with an operating device 5 that is operated by an operator. The operator operates the operating device 5 to operate the traveling device 6, the swing device 8, the working device 9, the blade device 19, or other working devices.

[0024] As an example, operating the left operation lever 5a operates the slewing device 8 and the arm 51c. As an example, moving the left operation lever 5a leftward causes the upper body 3 to rotate counterclockwise, and the rotation speed is accelerated or decelerated depending on the amount of operation of the left operation lever 5a. As an example, moving the left operation lever 5a rightward causes the upper body 3 to rotate clockwise, and the rotation speed is accelerated or decelerated depending on the amount of operation of the left operation lever 5a. As an example, operating the right operation lever 5b operates the boom 51b and the bucket 51d.

[0025] As an example, the traveling device 6 has a pair of left and right front traveling wheels 6a and a pair of left and right rear traveling wheels 6b. The upper body 3 of the work vehicle 1 has a pair of left and right headlights 6c that illuminate the front. The driver's cab 4 has a handle 4b that is operated by the operator. As an example, the work vehicle 1 is a four-wheel drive vehicle that can be self-propelled on public roads. The operating device 5 has a blade lever, a traveling pedal, a brake pedal, and a boom swing / second boom pedal (not shown).

[0026] The work vehicle 1 is equipped with a working implement 9 that is operated by hydraulic oil (pressurized oil) and a blade device 19. The working implement 9 has a boom 51b, an arm 51c, and a bucket 51d. The boom 51b is attached to the upper body 3 so as to be swingable in the up-down direction and in the up-down direction, including a front-to-back component.

[0027] As an example, a boom bracket 51e is provided between the upper body 3 and the boom 51b. The boom 51b swings up and down relative to the upper body 3 by a boom cylinder 18d. The boom 51b swings left and right relative to the upper body 3, including left and right and front and rear components, by the boom bracket 51e. As an example, the boom 51b swings left and right relative to the upper body 3 by a swing cylinder (not shown).

[0028] The arm 51c is swung up and down relative to the boom 51b by an arm cylinder 18b. The bucket 51d is swung up and down relative to the arm 51c by a bucket cylinder 18c. Here, the bucket 51d may be changed to another work attachment.

[0029] The blade device 19 has a blade 51a. The blade 51a is swung up and down relative to the lower body 2 by a blade cylinder 18a.

[0030] Figure 2 is a schematic circuit diagram showing an example of a drive control system in the work vehicle 1. Solid lines in the figure simply show connections in the hydraulic system, and dashed lines in the figure simply show connections in the electrical signal system. Note that in the connections in the hydraulic system and electrical signal system, only essential parts are shown, and illustrations are omitted.

[0031] The traveling device 6 of this embodiment is equipped with a hydrostatic transmission (abbreviated as HST). The engine 20 is the drive source for the first hydraulic pump 31. As an example, the first hydraulic pump 31 is a variable displacement swash plate pump. The traveling hydraulic motor 16 is connected to a gear case, and power is transmitted from the gear case to the rear axle, and then to the left and right rear traveling wheels 6b. Power is also transmitted from the gear case to the front axle via a propeller shaft, and then to the left and right front traveling wheels 6a (not shown). Note that the above configuration is just an example, and the traveling device 6 may also be configured without an HST.

[0032] When the operator operates the selection switch 99, an output mode signal is transmitted to the vehicle controller 7. Upon receiving the output mode signal, the vehicle controller 7 transmits a predetermined control command to the ECU 30. When the standard mode is selected by the selection switch 99, the vehicle controller 7 transmits a control command for the standard mode to the ECU 30. When the economy mode is selected by the selection switch 99, the vehicle controller 7 transmits a control command for the economy mode to the ECU 30. When the switching mode (also referred to as Eco Plus mode) is selected by the selection switch 99, the vehicle controller 7 selects and transmits to the ECU 30 either a control command for the standard mode or a control command for the economy mode, depending on the engine load factor obtained by communication from the ECU 30 and the pump pressure obtained from a detection signal from the pressure sensor.

[0033] The vehicle controller 7 is signal-connected to the ECU 30 and can communicate with the ECU 30. As an example of a communication protocol for vehicle control including the vehicle controller 7 and the ECU 30, Controller Area Network (abbreviated as CAN) is applied.

[0034] The vehicle controller 7 sends a selection signal to the ECU 30 in response to an operator pressing the selection switch 99. Note that the above configuration is an example, and it is also possible to configure the selection signal to be sent by touching the touch panel display 98.

[0035] The work vehicle 1 is equipped with a traveling hydraulic motor 16, a swing hydraulic motor 17, and hydraulic cylinders 18 such as a blade cylinder 18a, an arm cylinder 18b, a bucket cylinder 18c, and a boom cylinder 18d, as well as other known hydraulic cylinders. The work vehicle 1 also has connection ports (not shown) for hydraulically operating various attachments attached as options. The work vehicle 1 also has lead batteries (not shown) that supply power to the vehicle controller 7 and the ECU 30 when the work vehicle 1 is started.

[0036] The work vehicle 1 has a first hydraulic pump 31 and a traveling hydraulic motor 16 that is operated by pressure oil from the first hydraulic pump 31. In the example of Fig. 2, a first check valve 43 is provided on each of the output sides of the first hydraulic pump 31, and a first relief valve 41 is provided on the output side of each of the first check valves 43.

[0037] The work vehicle 1 has a second hydraulic pump 32 and a swing hydraulic motor 17 that is operated by pressure oil from the second hydraulic pump 32. In the example of Fig. 2, the swing hydraulic motor 17 is connected to the secondary side of the hydraulic motor control valve 11. The drive source of the second hydraulic pump 32 is the engine 20.

[0038] As an example, the control valve unit 10 has the primary sides of a swing hydraulic motor control valve 11, a hydraulic cylinder control valve 12a, a hydraulic cylinder control valve 12b, a hydraulic cylinder control valve 12c, a hydraulic cylinder control valve 12d, and a second relief valve 42 connected in parallel. The secondary side of the second relief valve 42 forms a return flow path, and hydraulic oil exceeding the set pressure returns to a hydraulic oil tank 54. Note that the number of various control valves constituting the control valve unit 10 may be increased or decreased, and a service port control valve may be included as needed.

[0039] 3 is a schematic flowchart showing an example of a control procedure relating to the switching mode in the work vehicle 1. Next, an example of control relating to the switching mode will be described below.

[0040] [Example of control related to switching mode] When the switching mode is selected by operating the selection switch 99, the vehicle controller 7 transmits a control command for the economy mode and a control command for the standard mode to the ECU 30 using the engine load factor calculated by the ECU 30 based on the fuel injection rate of the engine 20. When controlling in the economy mode, the ECU 30 controls the upper limit of the rotation speed of the engine 20 to be within a range of 0.75 to 0.95 times that of the standard mode.

[0041] 3, the vehicle controller 7 determines whether the traveling device 6 is stopped. If the traveling device 6 is stopped, the process proceeds from step S1 to step S2. On the other hand, if the traveling device 6 is operating, the process proceeds from step S1 to step S4.

[0042] 3, the vehicle controller 7 transmits an economy mode control command to the ECU 30. Then, the process proceeds from step S2 to step S3.

[0043] The first period T1 is set to 0.2 to 0.7 seconds. In the example of Fig. 4, the first period T1 is set to 0.4 seconds. The second period T2 is set to 0.8 to 1.4 seconds. In the example of Fig. 4, the second period T2 is set to 1.0 second.

[0044] 3, if the discharge pressure from the second hydraulic pump 32 is equal to or greater than the reference value U1 and the engine load factor is equal to or greater than the upper limit value E1 and the first period T1 has elapsed, the process transitions from step S3 to step S4. On the other hand, if the discharge pressure from the second hydraulic pump 32 is equal to or greater than the reference value U1 and the first period T1 has not elapsed, or if the engine load factor is equal to or greater than the upper limit value E1 and the first period T1 has not elapsed, the process returns from step S3 to step S2.

[0045] 3, the vehicle controller 7 transmits a control command for the standard mode, regardless of the engine load factor, to the ECU 30. Then, the process proceeds from step S4 to step S5.

[0046] 3, if the second period T2 has elapsed while the engine load factor is equal to or less than the lower limit E2, the process proceeds from step S5 to step S6. On the other hand, if the engine load factor is equal to or less than the lower limit E2 without elapsed the second period T2, the process returns from step S5 to step S4.

[0047] The second period T2 is set to 0.8 to 1.4 seconds. In the example of Fig. 4, the second period T2 is set to 1.0 second.

[0048] 3, the vehicle controller 7 transmits an economy mode control command to the ECU 30. Then, when the desired work by the working device 9 and the blade device 19 is completed, the series of control operations ends.

[0049] According to this embodiment, when a large amount of working power is required, the mode can be quickly changed to the standard mode. Furthermore, when a large amount of working power is no longer required within a range that does not impair workability, the mode can be quickly changed to the economy mode.

[0050] The drive source of the work vehicle 1 may be an engine or a hybrid configuration using both an engine and an electric motor. The traveling device 6 is not limited to a configuration with wheels, and may be a configuration with crawlers. In this way, the work vehicle 1 may be modified as appropriate to suit the specifications, etc. [Explanation of symbols]

[0051] 1. Work vehicles 2 Lower body 3. Upper body 4 Cab, 4a Operator seat, 4b Handle 5 Operating device, 5a left operating lever, 5b right operating lever 6. Running gear, 6a. Front running wheel, 6b. Rear running wheel, 6c. Headlight 7 Vehicle Controller 8 Swivel 9 Work equipment 10 Control valve unit 11. Control valve for hydraulic motor 12a, 12b, 12c, 12d Control valves for hydraulic cylinders 16 Hydraulic motor for travel 17 Swing hydraulic motor 18 hydraulic cylinder, 18a blade cylinder, 18b arm cylinder, 18c bucket cylinder, 18d boom cylinder 19 Blade Device 20 Engine 30 ECU 31 First hydraulic pump 32 Second hydraulic pump 41 First relief valve 42 Second relief valve 43 First check valve 44 Second check valve 51a Earth removal plate 51b Boom 51c Arm 51d Bucket 51e Boom Bracket 54 Hydraulic oil tank 98 Display 99 Selector Switch E1 upper limit E2 lower limit T1 1st period T2 2nd period U1 standard value

Claims

1. The vehicle comprises an engine, a first hydraulic pump and a second hydraulic pump operated by the engine, a traveling device operated by the first hydraulic pump, a working device operated by the second hydraulic pump, an operating device for operating the traveling device and the working device, an ECU for controlling engine output, and a vehicle controller for issuing an economy mode control command or a standard mode control command to the ECU, the vehicle controller transmits the control command for the standard mode to the ECU when the traveling device is stopped, the discharge pressure from the second hydraulic pump is equal to or higher than a reference value, and the engine load factor is equal to or higher than a predetermined upper limit value for a first period; transmits the control command for the economy mode to the ECU when the engine load factor is equal to or lower than a predetermined lower limit value for a second period; and transmits the control command for the standard mode to the ECU when the traveling device is operating. A work vehicle characterized by:

2. a selection switch for enabling the control command for the economy mode and the control command for the standard mode by the vehicle controller; the vehicle controller selects and transmits to the ECU a control command for the economy mode or a control command for the standard mode when the selection switch is enabled; 2. The work vehicle according to claim 1,

3. When the ECU receives the control command for the economy mode and performs control in the economy mode, the ECU limits the upper limit of the engine rotation speed to within a range of 0.75 to 0.95 times that when the ECU performs control in the standard mode.

2. The work vehicle according to claim 1,

4. The first period is set to 0.2 to 0.7 seconds, and the second period is set to 0.8 to 1.4 seconds.

2. The work vehicle according to claim 1,

5. the vehicle controller transmits a control command for the economy mode and a control command for the standard mode to the ECU using the engine load factor calculated by the ECU based on the fuel injection rate of the engine. The work vehicle according to any one of claims 1 to 4,

6. A control method for a work vehicle including an engine, a first hydraulic pump and a second hydraulic pump operated by the engine, a traveling device operated by the first hydraulic pump, a working device operated by the second hydraulic pump, an operating device for operating the traveling device and the working device, an ECU that controls engine output, and a vehicle controller that issues an economy mode control command or a standard mode control command to the ECU, the vehicle controller transmits the control command for the standard mode to the ECU when the traveling device is stopped, the discharge pressure from the second hydraulic pump is equal to or higher than a reference value, and the engine load factor is equal to or higher than a predetermined upper limit value for a first period; transmits the control command for the economy mode to the ECU when the engine load factor is equal to or lower than a predetermined lower limit value for a second period; and transmits the control command for the standard mode to the ECU when the traveling device is operating. A method for controlling a work vehicle, comprising:

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