JP7482766B2 - Work vehicle - Google Patents

Description

The present invention relates to a work vehicle equipped with an engine.

Conventionally, work vehicles equipped with engines have been used. One example of technology related to such work vehicles equipped with engines is described in Patent Document 1, the source of which is shown below.

Patent Document 1 describes an accelerator control structure for a work vehicle. In the work vehicle described in Patent Document 1, the engine speed set by operating the accelerator pedal (pedal set speed), the engine speed set by operating the accelerator lever (lever set speed), and the upper limit speed, which is the upper limit of the engine speed set by an upper limit setter, are selected by a target speed setting means. The target speed setting means compares these selected speeds, and if the pedal set speed and the lever set speed are lower than the upper limit speed, sets the higher of the pedal set speed and the lever set speed as the target speed, and if either the pedal set speed or the lever set speed is higher than the upper limit speed, sets the upper limit speed as the target speed.

JP 2009-287469 A

Some work vehicles are equipped with a work unit that is driven using the rotational force of the engine. If the technology described in Patent Document 1 is applied to such a work vehicle, operating the accelerator pedal to increase the vehicle speed will increase the number of rotations of the rotational force input to the work unit along with the vehicle speed. This can cause unevenness in some work (the work cannot be finished to a uniform degree), and there is room for improvement in the technology described in Patent Document 1.

Therefore, there is a demand for a work vehicle that can increase only the vehicle speed when the engine speed is increased.

A characteristic configuration of the work vehicle of the present invention is that it comprises an engine, a transmission that changes the input rotational force to a gear ratio corresponding to a desired vehicle speed and outputs the changed rotational force, a first operating device that changes the deceleration rate of the transmission along with the engine speed, a rotation speed control unit that controls the engine speed based on an input to the first operating device, and a second operating device to which a hold instruction to hold the engine speed constant is input, and when the hold instruction is input to the second operating device, the rotation speed control unit disables control of the engine speed based on the input to the first operating device and keeps the engine speed constant in response to the hold instruction , and the control of the engine speed by the rotation speed control unit is switchable between a first mode in which the engine speed is controlled based on the hold instruction and a second mode in which the engine speed is controlled to be the higher of the engine speed corresponding to the input to the first operating device and the engine speed corresponding to the hold instruction .

With such a configuration, in a work machine equipped with a first operating tool that serves both as an operating tool for changing the engine speed and an operating tool for changing the deceleration rate of a transmission, it is possible to run the work machine at a constant engine speed regardless of the vehicle speed even when the first operating tool is operated. Therefore, when the engine speed is increased, only the vehicle speed can be increased. In addition, this allows the speed of the device that uses the engine rotation (e.g., the work unit) to be constant, so that the work finish can be made uniform. In addition, the operator can focus on the work without worrying about the engine speed, so the effort required for setting the engine speed can be reduced. Therefore, it is possible to contribute to reducing the labor of the work.
Furthermore, this characteristic configuration allows for variation in the control of the engine speed, making it easy to set the engine speed according to the work situation. Therefore, for example, it is possible to control the engine speed optimally according to the input to the first operating tool, without being affected by the mechanism that transmits the rotational force of the engine to each device.

It is also preferable that the device further includes a setting unit that sets whether or not the holding instruction can be accepted by the second operating tool, and when the setting unit sets that the acceptance is not possible, the rotation speed control unit controls the rotation speed of the engine based on the input to the first operating tool.

With this configuration, when the hold command from the second operating tool is not being accepted, it is possible to automatically control the engine speed according to the input to the first operating tool without making any other settings.

It is also preferable to further include a notification unit that notifies the first operating tool that the hold instruction has been input.

With this configuration, it is possible to inform the operator that an input has been made to the first operating tool. Therefore, it is possible to clearly indicate an erroneous operation, such as when the first operating tool is operated by mistake.

In addition, when the engine speed control unit is controlling the engine speed in the first mode, it is preferable that switching from the first mode to the second mode is restricted.

This configuration makes it possible to prevent sudden changes in engine speed while the engine speed is being controlled in the first mode.

FIG. FIG. 2 is a block diagram showing a functional section relating to control of engine speed; FIG. FIG. 4 is a diagram showing a display example of a meter panel. FIG. 4 is a diagram showing a display example of a meter panel. FIG. 4 is a diagram showing a display example of a meter panel.

The work vehicle according to the present invention is configured so that only the vehicle speed can be increased when the engine speed is increased. The work vehicle according to this embodiment will be described below. Note that the following description will be given using a tractor 1 as an example of the work vehicle.

Figure 1 is a side view of the tractor 1, and Figure 2 is a plan view of the tractor 1. In the following description, the direction of the arrow F shown in Figures 1 and 2 is the "forward direction", the direction of the arrow B is the "rearward direction", the direction of the arrow U is the "upward direction", the direction of the arrow D is the "downward direction", the direction of the arrow L is the "leftward direction", and the direction of the arrow R is the "rightward direction" for the tractor 1.

The tractor 1 has a pair of left and right front wheels 2 and a pair of left and right rear wheels 3 on the machine body A, an engine E inside an engine bonnet 4 at the front of the machine body A, and a driver's section C located at the rear position of the machine body A.

In the tractor 1, a transmission case 5 that changes the driving force of the engine E is disposed in an area extending from the center of the machine body A to the rear end of the machine body A. In addition, at the rear end of the transmission case 5, an external power take-off shaft 8 (PTO shaft) for transmitting the driving force to, for example, a rotary tilling device (not shown) is provided in a form that protrudes rearward.

The driver's seat C is provided with a driver's seat 11 on which an operator sits, at the middle position between the left and right rear wheel fenders 10a, which have a lever guide 10 on the upper surface, and a steering wheel 12 for steering the vehicle A is provided in front of the driver's seat 11. A floor 13 is provided below the driver's seat 11, and a main speed change pedal 19 is provided on the floor 13, which is mainly used to change the rotation speed of the engine E when traveling on a road. The main speed change pedal 19 is configured to be depressed on both the forward and backward sides. When the forward side is depressed, the rotation speed of the engine E increases, and the rotation speed output from the main speed change device 31, which will be described later, increases. When the rearward side is depressed, the rotation speed of the engine E is maintained at a predetermined rotation speed (idle rotation speed), and the vehicle A is configured to move backward. When the foot is released from the main speed change pedal 19, the rotation speed of the engine E becomes the rotation speed set by the accelerator lever 18, which will be described later. As shown in FIG. 2, a main shift lever 21 and a sub shift lever 23 are arranged side by side on the lever guide 10 on the upper surface of the rear wheel fender 10a to the left of the driver's seat 11, protruding upward from the lever guide 10.

Protruding outward to the right from the right side of the steering post 12B, which is provided at the base end of the steering wheel 12, is an accelerator lever 18 that is used to change the RPM of the engine E, mainly during field work. The accelerator lever 18 is configured so that the RPM of the engine E increases when pulled toward the driver, and decreases when pushed forward. When the driver releases the accelerator lever 18, the RPM of the engine E is set to the RPM of the engine E at that position. Note that the RPM of the engine E can also be set using the main speed change pedal 19 described above, but the RPM of the engine E is determined by the RPM of the accelerator lever 18 or the main speed change pedal 19, whichever is faster.

A PTO shift lever 41 capable of changing the rotation speed of the external power take-off shaft 8 is arranged protruding upward from the lever guide 10 on the upper surface of the rear wheel fender 10a on the right side of the driver's seat 11. This PTO shift lever 41 may be configured to change not only the rotation speed of the external power take-off shaft 8 but also the rotation direction. The PTO shift lever 41 may be configured other than a lever type (for example, a switch, etc.). In addition, two brake pedals 20 capable of stopping the vehicle A are provided on the floor 13 in a state of being arranged side by side (along the width direction of the vehicle A) looking forward. These two brake pedals 20 are independent on the left and right, and are configured so that the left brake pedal 20 can be depressed to brake the left driving wheel of the tractor 1 (rear wheel 3 in this embodiment), and the right brake pedal 20 can be depressed to brake the right driving wheel of the tractor 1. In addition, for example, if the two brake pedals 20 are connected by a coupling device (not shown), the brakes of the driving wheels on both the left and right sides are simultaneously applied. Of course, if the front wheels 2 are used as the driving wheels, it is also possible to configure the brake pedal 20 to apply the brakes to the front wheels 2.

The control of the rotation speed of the engine E will be described below. Figure 3 is a block diagram showing the functional parts related to the control of the rotation speed of the engine E. As shown in Figure 3, the tractor 1 is equipped with a main transmission 31 (an example of a "transmission"), an auxiliary transmission 32, and a work transmission 33.

The main transmission 31 changes the input rotational force to a gear ratio corresponding to the desired vehicle speed and outputs the changed gear. In this embodiment, the main transmission 31 receives rotational force from the engine E. The desired vehicle speed is the vehicle speed at which the tractor 1 is to travel, and is set, for example, by an operator. Of course, it may be set automatically, such as by automatic control. The gear ratio is the ratio at which the input rotational speed is changed to the output rotational speed. Therefore, the main transmission 31 changes the rotational force input from the engine E to a gear ratio corresponding to the vehicle speed at which the tractor 1 is to travel, and outputs the changed gear. As such a main transmission 31, for example, a hydrostatic continuously variable transmission (HST: Hydro-Static Transmission) can be used.

The auxiliary transmission 32 is provided on the upstream or downstream side of the main transmission 31, and outputs the input rotational force by changing the speed at a gear ratio according to the work mode. The upstream side of the main transmission 31 corresponds to the side of the main transmission 31 where the rotational force from the engine E is input, and the downstream side of the main transmission 31 corresponds to the side of the main transmission 31 where the rotational force from the engine E input to the main transmission 31 is output. In this embodiment, as shown in FIG. 3, the auxiliary transmission 32 is provided on the downstream side of the main transmission 31, and the rotational force output from the main transmission 31 is input to the auxiliary transmission 32. The work mode corresponds to the mode in which the tractor 1 travels, and corresponds to, for example, a mode suitable for traveling in a field work or a mode suitable for moving to a field. In other words, it is preferable to set the mode according to the traveling speed of the tractor 1. Therefore, the sub-transmission device 32 is provided downstream of the main transmission device 31, and outputs the rotational force from the main transmission device 31 by changing the speed at a gear ratio according to the mode in which the tractor 1 is traveling.

The output of the sub-transmission 32 is transmitted to a traveling device 39 that controls the driving force of the driving wheels of the tractor 1. Of course, if the front wheels 2 are used as the driving wheels, it is also possible to configure the traveling device 39 to control the driving force of the front wheels 2.

The gear ratio of the main transmission 31 is controlled in response to the operation of the main transmission lever 21 described above. The gear ratio of the sub-transmission 32 is controlled in response to the operation of the sub-transmission lever 23 described above.

The output of the engine E is also input to the work transmission 33. The work transmission 33 changes the speed of the rotational force from the engine E and transmits it to the PTO shaft unit 51. Therefore, the output of the engine E is input to the PTO shaft unit 51. The PTO shaft unit 51 is equipped with the external power take-off shaft 8 described above, and transmits the rotational power for external output to the work unit 71 connected to this external power take-off shaft 8.

The reception unit 61 receives change information for changing the deceleration rate of the main transmission 31 together with the rotation speed of the engine E. The change information for changing the deceleration rate of the main transmission 31 together with the rotation speed of the engine E is information indicating the rotation speed required for the engine E and the deceleration rate required for the main transmission 31. The rotation speed required for the engine E and the deceleration rate required for the main transmission 31 can be set by the operator by operating the accelerator lever 18 or the main transmission pedal 19 as described above. Therefore, the accelerator lever 18 and the main transmission pedal 19 correspond to the first operating tool that changes the deceleration rate of the main transmission 31 together with the rotation speed of the engine E. The change information received by the reception unit 61 is transmitted to the rotation speed control unit 63 and the main transmission 31, which will be described later. Note that the operation input by the accelerator lever 18 or the main transmission pedal 19 may be transmitted to the main transmission 31 by wire (so-called by-wire type).

The rotation speed control unit 63 controls the rotation speed of the engine E based on input to the accelerator lever 18 or the main speed change pedal 19. Information corresponding to the input to the accelerator lever 18 or the main speed change pedal 19 is transmitted to the rotation speed control unit 63 via the reception unit 61. This information enables the rotation speed control unit 63 to control the rotation speed of the engine E to correspond to the gear ratio of the work transmission 33 based on the desired vehicle speed, and to set the rotation speed of the engine E to correspond to the rotation speed of the external output rotational power output from the PTO shaft unit 51.

In this embodiment, the operation switch 22 (an example of a "second operating tool") is configured to input a command to maintain the rotation speed of the engine E constant. Maintaining the rotation speed of the engine E constant means maintaining the rotation speed of the engine E at a constant rotation speed, unlike the rotation speed of the engine E related to the input to the accelerator lever 18 or the main shift pedal 19 described above. It is preferable to store such a constant rotation speed in a storage unit (not shown) in advance. In this embodiment, such a command to maintain the rotation speed of the engine E constant is treated as a hold command. Therefore, the operation switch 22 is configured to allow input of a command to maintain a preset rotation speed of the engine E at a constant rotation speed.

When a hold instruction is input to the operation switch 22, the rotation speed control unit 63 disables the control of the rotation speed of the engine E based on the input to the accelerator lever 18 or the main speed change pedal 19, and keeps the rotation speed of the engine E constant in response to the hold instruction. When a hold instruction is input, it is when a hold instruction to keep the rotation speed of the engine E constant is input via the operation switch 22. The input to the accelerator lever 18 or the main speed change pedal 19 is an input for changing the deceleration rate of the main transmission 31 together with the rotation speed of the engine E input via the accelerator lever 18 or the main speed change pedal 19. Therefore, when a hold instruction to keep the rotation speed of the engine E constant is input via the operation switch 22, the rotation speed control unit 63 disables the control of the rotation speed of the engine E among the inputs for changing the deceleration rate of the main transmission 31 together with the rotation speed of the engine E input via the accelerator lever 18 or the main speed change pedal 19. Furthermore, the rotation speed control unit 63 controls the rotation speed of the engine E to be kept constant based on a command to keep the rotation speed of the engine E constant input via the operation switch 22.

At this time, among the inputs for changing the deceleration rate of the main transmission 31 along with the engine speed of the engine E performed via the accelerator lever 18 or the main transmission pedal 19, the input for changing the deceleration rate of the main transmission 31 is valid, so it is possible to configure the deceleration rate of the main transmission 31 to change in response to that input.

Here, it is also possible to configure the setting unit 65 to set whether or not the hold instruction by the operation switch 22 can be accepted. "Whether or not the hold instruction by the operation switch 22 can be accepted" includes whether or not the hold instruction inputted through the operation switch 22 is valid, and whether or not the hold instruction can be inputted to the operation switch 22 itself. In other words, the setting unit 65 artificially turns on and off the function of instructing the engine E to hold the RPM by the operation switch 22. Such setting by the setting unit 65 can be configured so that it can be performed, for example, by the operator operating a setting switch (not shown). When the setting unit 65 is configured to set whether or not the hold instruction can be accepted, it is preferable to configure it so that the setting status by the setting unit 65 is transmitted to the reception unit 61 and transmitted to the rotation speed control unit 63 via the reception unit 61. Alternatively, it may be configured so that it is directly transmitted from the setting unit 65 to the rotation speed control unit 63. When the setting unit 65 is configured to not accept the hold instruction, the rotation speed control unit 63 controls the rotation speed of the engine E based on the input to the accelerator lever 18 or the main shift pedal 19. This makes it possible to maintain the rotation of the engine E at the desired speed.

In addition, when the setting unit 65 has been set to accept a hold command, it is preferable to configure the notification unit 66 to notify that an input has been made to the accelerator lever 18 or the main speed change pedal 19. This makes it possible for the operator to recognize that when an input is made via the accelerator lever 18 or the main speed change pedal 19, the engine E speed is not changed and only the deceleration rate of the main speed change device 31 can be changed. This notification by the notification unit 66 may be made by displaying text or images on the display device 80, or by using the display on the meter panel 82.

4 shows an example of the display of the meter panel 82 (part of the display device 80) incorporated in the front panel 81 provided in front of the driver's seat. The upper part of the RPM display area 83 in the meter panel 82 displays the current RPM of the engine E, and the lower part displays the RPM (preset RPM) for keeping the RPM of the engine E constant according to the hold instruction by the operation switch 22. In the example of FIG. 4, a situation in which the engine E is controlled by the RPM by the operation switch 22 is shown, and "2500" is displayed as the current RPM of the engine E per minute, and "2500" is displayed as the RPM per minute according to the operation switch 22. When the engine E is controlled by such a RPM by the operation switch 22, the current RPM "2500" is highlighted (for example, lit up, brighter than other displays, or bold). In the example of FIG. 4, an example in which the RPM shown in the upper part of the RPM display area 83 is lit up is shown. This makes it possible for the operator to grasp that the RPM of the engine E is being controlled according to the operation switch 22. Furthermore, by looking at this display, the operator can understand that the accelerator lever 18 and main shift pedal 19 are not being operated.

In addition, when an input is made to change the engine E RPM using the accelerator lever 18 or main speed change pedal 19 from the state shown in FIG. 4, and the RPM exceeds the RPM set by the operation switch 22 (a constant RPM), the current engine E RPM displayed in the upper section of the RPM display area 83 can be made to flash, as shown in FIG. 5. This allows the operator to know that the RPM set by the operation switch 22 has been exceeded as a result of operating the accelerator lever 18 or main speed change pedal 19.

Furthermore, when the operation switch 22 is pressed in the state shown in FIG. 5 to release the control of the engine speed according to the operation switch 22, the engine E speed input via the accelerator lever 18 or main speed change pedal 19 is displayed in the lower row of the engine speed display area 83, and the current engine E speed is displayed in the upper row, as shown in FIG. 6. In the example shown in FIG. 6, "2630" is displayed as the engine E speed input via the accelerator lever 18 or main speed change pedal 19, and "2550" is displayed as the current engine E speed. The engine E speed is controlled to follow the input from the accelerator lever 18 or main speed change pedal 19, and when the engine E speed becomes "2630", "2630" is displayed in the upper row.

In this embodiment, the rotation speed control unit 63 is configured to be able to control the rotation speed of the engine E by switching between either a first mode or a second mode. A mode setting unit 62, for example, may be provided as a functional unit that performs such switching. The mode setting unit 62 switches between either a first mode that controls the rotation speed of the engine E based on a hold command, and a second mode that controls the rotation speed of the engine E to the higher of the rotation speeds corresponding to the input to the accelerator lever 18 or the main shift pedal 19.

The first mode is a control form that is set as being capable of accepting a hold instruction when the setting unit 65 is provided and a hold instruction is input by the operation switch 22.

The second mode is a control form that is executed when the setting unit 65 is provided and it is set to be possible to accept a hold instruction, so that the engine E speed is set to the higher of the speed of the engine E according to the hold instruction input by the operation switch 22 and the speed of the engine E according to the input made via the accelerator lever 18 or the main shift pedal 19.

Such switching between the first mode and the second mode can be set by the operator operating the setting unit 65. For this reason, it is preferable to provide a switch or the like as the setting unit 65.

In addition, for example, when the rotation speed control unit 63 is controlling the rotation speed of the engine E in the first mode, it is possible to configure so that switching from the first mode to the second mode is restricted. This makes it possible to prevent the rotation speed from being changed to one corresponding to a change command from the accelerator lever 18 or the main shift pedal 19 if the setting unit 65 is mistakenly operated while the rotation speed of the engine E is being controlled to be kept constant.

Other embodiments
In the above embodiment, the accelerator lever 18 and the main speed change pedal 19 are exemplified as the first operating tool, but the first operating tool may be either the accelerator lever 18 or the main speed change pedal 19. In addition, the operation switch 22 is exemplified as the second operating tool, but the second operating tool may be configured using a device (e.g., a lever) different from the operation switch 22.

In the above embodiment, the setting unit 65 is described as being provided, but the configuration can also be made without the setting unit 65. In such a case, for example, when an input is made using the second operating tool, it is preferable to control the input of the second operating tool as being valid. Also, when the setting unit 65 is not provided and a command to keep the number of revolutions of the engine E constant is input via the operating switch 22, it is also possible to configure the notification unit 66 to notify that an input has been made to the first operating part when the first operating tool is operated.

In the above embodiment, the notification unit 66 is described as being provided, but it is also possible to configure the device without the notification unit 66.

In the above embodiment, the control of the engine E speed by the speed control unit 63 is described as being switchable between a first mode in which the engine E speed is controlled based on a hold command, and a second mode in which the engine E speed is controlled to the higher of the engine E speed corresponding to the input to the accelerator lever 18 or the main shift pedal 19 and the engine E speed corresponding to the hold command. However, the control of the engine E speed by the speed control unit 63 can also be configured so that it cannot be switched between the first mode and the second mode, that is, it can be configured to control only the second mode.

In the above embodiment, it has been described that when the rotation speed control unit 63 is controlling the rotation speed of the engine E in the first mode, switching from the first mode to the second mode is restricted. However, it is also possible to configure the rotation speed control unit 63 so that switching to the second mode can be performed even when the rotation speed of the engine E is being controlled in the first mode.

In the above embodiment, the output of the engine E is input, and the work transmission 33 is provided to change the speed and transmit the output of the engine E to the PTO shaft unit 51. However, the work transmission 33 does not necessarily have to be provided.

In the above embodiment, the tractor 1 has been described as an example of a working machine, but the working machine may be a working machine other than the tractor 1, such as a rice transplanter, a combine harvester, a construction machine, a lawnmower, or a working machine for civil engineering work, forestry work, snow removal, etc.

The present invention can be used in a work machine equipped with an engine.

1: Tractor (work vehicle)
18: Accelerator lever (first operating tool)
19: Main speed change pedal (first operating tool)
22: Operation switch (second operation tool)
31: Main transmission (transmission)
63: Rotation speed control unit 65: Setting unit 66: Notification unit E: Engine

Claims (4)

The engine,
a transmission that changes the input rotational force to a gear ratio corresponding to a desired vehicle speed and outputs the changed gear;
a first operating tool for changing a deceleration ratio of the transmission in conjunction with a rotation speed of the engine;
a rotation speed control unit that controls a rotation speed of the engine based on an input to the first operating tool;
a second operating tool for inputting a command to maintain the engine speed constant,
the rotation speed control unit, when the hold instruction is input to the second operating tool, disables control of the engine rotation speed based on the input to the first operating tool and keeps the engine rotation speed constant in response to the hold instruction ;
The control of the engine speed by the speed control unit can be switched between either a first mode in which the engine speed is controlled based on the hold instruction, and a second mode in which the engine speed is controlled to be the higher of the engine speed in response to the input to the first operating device and the engine speed in response to the hold instruction . a setting unit that sets whether or not the holding instruction by the second operating tool can be accepted,
The work vehicle according to claim 1 , wherein when the setting unit sets that the input is not acceptable, the rotation speed control unit controls the rotation speed of the engine based on the input to the first operating tool. The work vehicle according to claim 1 or 2, further comprising a notification unit that notifies the first operating tool that the hold command has been input. 4. The work vehicle according to claim 1, wherein when the engine speed control unit controls the engine speed in the first mode, switching from the first mode to the second mode is restricted.

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