Work vehicle, and operation device and control method for work vehicle

Abstract

To provide an operation device of a simple structure capable of changing an operation speed of an actuator for operating a device of a working vehicle, and capable of achieving both fine adjustment and improvement of work efficiency when operating the device, the working vehicle provided with the operation device, and a control method therefor.SOLUTION: This operation device for the working vehicle 1 provided with an actuator is provided with a control valve 64 for operating the actuator, an operation switch 92 for performing on-operation and off-operation, and a pressure variable mechanism 60 for changing a pilot pressure for operating the control valve 64 according to an operation time in the operation switch 92.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a work vehicle equipped with a hydraulically operated working device, and to an operating device and control method for the work vehicle. [Background technology]

[0002] Conventionally known examples of working vehicles include hydraulic excavators and track loaders, each of which has a lower body to which crawlers or tires for traveling are attached, an upper body disposed on the lower body, and a working device attached to the lower body or upper body and operated by hydraulic pressure (i.e., hydraulic oil at a predetermined pressure).

[0003] Taking a hydraulic excavator as an example of a work vehicle, it is generally configured with working devices such as a blade, a boom, an arm, and an attachment (e.g., a bucket), as well as actuators that operate these devices (see Patent Document 1: JP 2005-207197 A). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-207197 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for a configuration that allows the actuator described above to have a variable operating speed. However, as in the case of a conventional work vehicle exemplified by Patent Document 1, there is a problem in that the operating device becomes complicated. [Means for solving the problem]

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide an operating device with a simple structure that makes it possible to change the operating speed of an actuator that operates a device on a work vehicle, thereby enabling both fine adjustment when operating the device and improving work efficiency, a work vehicle equipped with the same, and a control method for the same.

[0007] The present invention solves the above problems by the solution means described below as one embodiment.

[0008] An operating device according to one embodiment is an operating device for a work vehicle equipped with an actuator, and includes a control valve that activates the actuator, an operating switch that performs on and off operations, and a pressure variable mechanism that changes the pilot pressure for operating the control valve depending on the operation time of the operating switch. [Effects of the Invention]

[0009] According to one embodiment of the operating device, it is possible to change the operating speed of an actuator that operates a device on a work vehicle using a simple mechanism, thereby realizing both fine adjustments when operating the device and improving work efficiency. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing an example of a work vehicle according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view showing an example of the work vehicle of FIG. [Figure 3] FIG. 3 is a perspective view showing an example of the driver's cab (interior) of the work vehicle of FIG. [Figure 4] FIG. 4 is a rear view showing an example of an operating device for the work vehicle of FIG. [Figure 5] FIG. 5 is a circuit diagram (part) of the work vehicle of FIG. [Figure 6] FIG. 6 is an explanatory diagram illustrating a control method for the working vehicle of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a perspective view (schematic diagram) of an example of a work vehicle 1 according to this embodiment, viewed from above the left front, and Fig. 2 is a perspective view (schematic diagram) of an example of a work vehicle 1 according to this embodiment, viewed from above the right front. 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 functions are designated by the same reference numerals, and repeated explanations of such members may be omitted.

[0012] First, the overall configuration of the work vehicle 1 will be described. A hydraulic excavator will be used as an example of the work vehicle 1. However, the work vehicle 1 is not limited to a hydraulic excavator.

[0013] As shown in Figures 1 and 2, the work vehicle 1 comprises a vehicle body including a lower body 2 and an upper body 3 disposed on top of the lower body 2 (note that the lower body 2 and the upper body 3 may be integrally configured).

[0014] The work vehicle 1 is equipped with working devices 12, 14 that are attached to the underbody 2 and upper body 3 and are operated by hydraulic pressure (hydraulic oil at a predetermined pressure). The underbody 2 is equipped with a traveling device 10 that enables travel. The upper body 3 is equipped with a driver's cab 16 at the front, where an operator sits and is equipped with various operating devices to operate the vehicle for travel and work. An enlarged view (schematic view) of the interior of the driver's cab 16 is shown in Figure 3.

[0015] An example of the traveling device 10 includes a pair of left and right crawlers 26. However, the traveling device 10 is not limited to the crawlers 26, and may be configured to include tires (not shown) instead of the crawlers 26. The crawlers 26 are configured to travel by driving a hydraulic motor (sometimes referred to as a "travel hydraulic motor") 28. However, the traveling device is not limited to the above configuration.

[0016] An example of the working device 12 includes a blade 22. The blade 22 is attached to the lower body 2 via a blade arm 24 and is configured to be swingable up and down (including forward and backward), allowing its angle to be changed. The blade 22 swings up and down by driving an actuator (for example, a hydraulic cylinder, sometimes referred to as a "blade cylinder") 32 that is connected to the blade 22 and the lower body 2. The angle is changed by driving an actuator (for example, a hydraulic cylinder, sometimes referred to as an "angle cylinder") 34 that is connected to the blade 22 and the blade arm 24. However, the configuration is not limited to the above. For example, an actuator (angle cylinder) may be connected to each of the left and right sides of the blade 22 (i.e., two actuators (angle cylinders) are provided) (not shown).

[0017] Examples of the working device 14 include a boom 42, an arm 44, and a detachable attachment 46. Note that in Figures 1 and 2, a bucket is shown as an example of the attachment 46. However, this is not limited to this, and there are various other types of attachments, such as a breaker, fork, and auger.

[0018] In this embodiment, the boom 42 is attached to the upper body 3 via a boom bracket 48 and is configured to be swingable left and right (including a front-to-back component) and up and down (including a front-to-back component). The left and right swinging motion of the boom 42 is achieved by driving an actuator (one example of which is a hydraulic cylinder, and may be referred to as a "swing cylinder") 58 that is connected to the boom 42 and the upper body 3. The up and down swinging motion is achieved by driving an actuator (one example of which is a hydraulic cylinder, and may be referred to as a "boom cylinder") 52 that is connected to the boom 42 and the boom bracket 48. However, the configuration is not limited to the above, and the boom bracket 48 may be omitted.

[0019] The arm 44 is attached to the boom 42 so as to be swingable up and down (including forward and backward). The arm 44 swings up and down by driving an actuator 54 (a hydraulic cylinder, for example, which may be referred to as an "arm cylinder") that is connected to the arm 44 and the boom 42.

[0020] The attachment 46 is attached to the arm 44 so as to be swingable up and down (including forward and backward). The up and down swinging movement of the attachment 46 is achieved by driving an actuator (for example, a hydraulic cylinder, which may be referred to as a "bucket cylinder") 56 that is connected to the attachment 46 and the arm 44. As described above, the attachment 46 is configured so that one suited to the work content is selected from multiple types and is detachably attached to the arm 44. Note that a quick hitch (not shown) may be interposed between the arm 44 and the attachment 46.

[0021] The drive mechanism for driving the traveling hydraulic motor 28 and the actuators (hydraulic cylinders 32, 34, 52, 54, 56, 58, etc.) described above is composed of, for example, a hydraulic pump 30, which is driven by the drive source 18 and will be described later, a control valve 64, etc. The operator operates a predetermined operating device to actuate the control valve 64, thereby controlling the supply of hydraulic oil at a predetermined pressure delivered from the hydraulic pump 30 to the actuators. This allows the traveling device 10 to travel, and the working devices 12, 14 to perform work. One or more hydraulic pumps 30 that make up the drive mechanism may be provided depending on the configuration and load of the working devices 12, 14 and the traveling device 10, etc.

[0022] Furthermore, in this embodiment, a pilot hydraulic pump 40 is provided that supplies pilot oil used to control the control valve 64 (details of the circuit etc. will be described later). As a modified example, instead of the pilot hydraulic pump 40, hydraulic oil supplied from another hydraulic pump (for example, hydraulic pump 30) may be diverted and reduced in pressure and used (not shown).

[0023] The work vehicle 1 is equipped with an engine (an internal combustion engine that burns fuel) as the drive source 18. As another example of the drive source 18, instead of or together with the engine, an electric motor (one or more depending on the number of hydraulic pumps, rated output, etc.) may be provided (not shown).

[0024] Next, an explanation will be given of an operating device that operates the actuator and its circuit configuration in the work vehicle 1 according to this embodiment. Here, the actuator that changes the angle of the blade 22 (i.e., angle cylinder 34) will be used as an example, and a circuit diagram (schematic diagram) thereof is shown in FIG.

[0025] 5, the operating device according to this embodiment includes a pilot circuit 62 (reference numerals 70, 71, and 72 denote oil passages for the pilot oil) that supplies pilot oil to operate a control valve 64. The operating device also includes a pressure variable mechanism 60 that changes the pressure of the pilot oil (hereinafter, sometimes referred to as "pilot pressure").

[0026] Moreover, the pressure varying mechanism 60 includes, for example, an operation switch 92 for performing an on / off operation, a controller 80, and an electromagnetic proportional pressure reducing valve 66 (one for each of the branched pilot oil paths in this embodiment) for changing the pilot pressure. As a specific control method for changing the pilot pressure, the controller 80 measures the operation time of the on operation of the operation switch 92, and outputs a control current of a current value that is preset and stored in the controller 80 according to the operation time to the electromagnetic proportional pressure reducing valve 66. For example, the longer the operation time of the on operation of the operation switch 92, the larger the control current (output current) from the controller 80 becomes, and the larger the pilot pressure controlled by the electromagnetic proportional pressure reducing valve 66 becomes. Conversely, the shorter the operation time of the on operation of the operation switch 92, the smaller the control current (output current) becomes, and the smaller the pilot pressure controlled by the electromagnetic proportional pressure reducing valve 66 becomes.

[0027] In this embodiment, the operation switch 92 is a button switch that is turned on when pressed and turned off when not pressed (i.e., in the initial position). Two button switches 92 (a first button switch 92a and a second button switch 92b) are arranged side by side on an operation lever 90 that operates the blade 22. As an example, the operation lever 90 is configured to move only in the forward and backward directions (a rear view from the rear is shown in FIG. 4). Alternatively, as a modification of the operation switch 92, a slide switch (not shown) may be used instead of the button switch. In this case, it is possible to consider a configuration in which the switch is turned on when slid and turned off when not slid (i.e., in the initial position). Note that the operation switch 92 is not limited to the button switch or slide switch described above, and may be arranged in a position other than on the operation lever 90.

[0028] Next, the operation performed by operating the operating device will be described.

[0029] First, when the operation switch (button switch in this example) 92 is pressed (turned on), a signal current corresponding to the turn-on operation is input to the controller 80, which then outputs a control current to the electromagnetic proportional pressure reducing valve 66. At this time, the pilot oil flowing from the pilot hydraulic pump 40 to the control valve 64 is adjusted by the electromagnetic proportional pressure reducing valve 66 to a pilot pressure corresponding to the control current. In response to this pilot pressure, the control valve 64 operates (the spool moves), and hydraulic oil corresponding to the operating state (amount of movement of the spool) is sent from the control valve 64 to the actuator (angle cylinder 34). As a result, the piston of the actuator (angle cylinder 34) is pushed out (or pulled in), and the blade 22 operates (the angle changes). As an example, in this embodiment, when the first button switch 92a is pressed (turned on), the piston of the actuator (angle cylinder 34) is pushed out, changing the angle of the blade 22 (rotating so that the right end moves forward and the left end moves backward), and when the second button switch 92b is pressed (turned on), the piston of the actuator (angle cylinder 34) is retracted, changing the angle of the blade 22 (rotating so that the right end moves backward and the left end moves forward). In either case, while the switches are pressed (turned on), the actuator (angle cylinder 34) and the target device (blade 22) continue to operate (however, there are structural limitations on their operation (position)).

[0030] In this embodiment, the pilot pressure output from the electromagnetic proportional pressure reducing valve 66 is configured to change depending on the operation time of the ON operation of the operation switch 92. Specifically, as shown in the correlation diagram (schematic diagram) between operation time T and pilot pressure P in Fig. 6, the pilot pressure P increases as the operation time T of the ON operation of the operation switch 92 increases (however, there is an upper limit depending on the rating of the pilot hydraulic pump 40), and the pilot pressure P decreases as the operation time T decreases.

[0031] The conventional work vehicle exemplified in the aforementioned Patent Document 1 is configured to enable the angle of the blade (front surface) (hereinafter sometimes referred to as the "angle") to be changed in the left-right direction of the vehicle body (i.e., the blade rotates relative to the vehicle body's vertical axis). Specifically, the vehicle is configured with an actuator (e.g., a hydraulic cylinder) connected to the blade to change the angle. The driver's cab of the work vehicle is also provided with an operating lever that can be moved in the front-rear and left-right directions as a blade operating device. For example, when the operating lever is operated in the front-rear direction, the blade moves up and down via the actuator (hydraulic cylinder). On the other hand, when the operating lever is operated in the left-right direction, the angle of the blade changes via the actuator (hydraulic cylinder). Incidentally, the work vehicle is also configured to enable tilting of the blade (rotation of the blade relative to the vehicle body's front-rear axis) by switching a button. However, providing an operating lever that can be operated in the front-rear and left-right directions as described above creates problems such as a complex mechanism and increased costs.

[0032] Therefore, the inventors conducted extensive research into a configuration in which the blade operating lever is configured to operate only in the forward and backward directions, while the operating lever is provided with a button for changing the blade angle, allowing the angle to be changed by pressing the button. Specifically, two buttons are provided, and when one button is pressed, the blade rotates in a predetermined direction to create an angle, and when the other button is pressed, the blade rotates in the opposite direction to create an angle. This configuration makes it possible to change the blade angle even when the operating lever is not configured to operate in the left-right direction. However, when the device was actually installed on a work vehicle and tested, it became clear that when pressing the button to change the blade angle, the operation was faster than the operator desired, making it impossible to fine-tune the angle, or conversely, the operation was slower than the operator desired, resulting in reduced work efficiency.

[0033] Furthermore, the above-mentioned problem does not only occur with respect to the blade, but can also occur with respect to other devices.

[0034] According to the configuration of this embodiment, which was conceived based on such research, by pressing the operation switch 92 for a relatively short time (i.e., by relatively shortening the operation time of the ON operation), the pilot pressure is set to a relatively low level, and the actuator (the angle cylinder 34 in the above example) can be operated slowly. Therefore, the operation of the working device (the operation of rotating the blade 22 to change the angle in the above example) can be performed slowly, making fine adjustments easy. On the other hand, by pressing the operation switch 92 for a relatively long time (i.e., by relatively lengthening the operation time of the ON operation), the pilot pressure is set to a relatively high level, and the actuator (the angle cylinder 34 in the above example) can be operated quickly. Therefore, the operation of the working device (the operation of rotating the blade 22 to change the angle in the above example) can be performed quickly, preventing a decrease in work efficiency. In this way, it is possible to change the operating speed of the target device to a speed desired by the operator, thereby solving the above-mentioned problem.

[0035] In particular, in this embodiment, as shown in FIG. 6, the pilot pressure P is set to increase exponentially with an increase in the operation time T. Therefore, when it is desired to increase the amount of operation of the actuator, it can be operated in a shorter time, thereby further improving work efficiency. Furthermore, when the operation time T reaches a predetermined time, the pilot pressure P is set to a constant pressure. Therefore, it is possible to prevent the actuator from operating at a higher speed than necessary, which is effective from the viewpoint of realizing good operability and preventing accidents.

[0036] In this embodiment, a button switch is used as the operation switch 92, and is arranged on the operation lever 90 (but is not limited to this) which moves only in the forward and backward directions. Therefore, with an extremely simple configuration, the above-mentioned effects can be obtained, and good operability is also realized because the operator can operate the operation lever 90 without taking his / her hand off it.

[0037] As an example of an embodiment, the case where the target device is the blade 22 and the actuator is the hydraulic cylinder (angle cylinder) 34 has been described as an example, but the present invention is not limited to this. As other examples, the present invention can be applied to various configurations, such as when the target device is the boom 42 and the actuator is the hydraulic cylinder (swing cylinder) 58, or when the target device is the swing mechanism of the upper body 3 and the actuator is a hydraulic motor (swing motor) (not shown).

[0038] As described above, the present invention preferably has the following configuration.

[0039] (1) In one embodiment, the operating device is an operating device for a work vehicle that has an actuator that operates via a control valve, and includes an operating switch that performs on / off operation, and a pressure variable mechanism that changes the pilot pressure that operates the control valve depending on the operating time of the on operation of the operating switch.

[0040] (2) In the operating device according to the above aspect (1), it is preferable that the pilot pressure is set to increase exponentially with an increase in the operation time.

[0041] (3) In the operating device according to the above aspect (1) or (2), it is preferable that the pilot pressure be set to a constant pressure when the operation time reaches a predetermined time.

[0042] (4) In the operating device according to any one of the above aspects (1) to (3), the pressure variable mechanism preferably includes an electromagnetic proportional pressure reducing valve.

[0043] (5) In the operating device according to any one of the above aspects (1) to (4), the operating switch is preferably a button switch that is turned on when pressed down.

[0044] (6) In the operating device according to any one of the above aspects (1) to (5), it is preferable that the operating switch is disposed on an operating lever for driving the actuator.

[0045] (7) In the operating device according to any one of the above aspects (1) to (6), the actuator is preferably a hydraulic cylinder or a hydraulic motor.

[0046] (8) A work vehicle according to one embodiment includes the operating device according to any one of the above aspects (1) to (7).

[0047] (9) In one embodiment, a control method for a work vehicle is a control method for a work vehicle equipped with an actuator that operates via a control valve, wherein the work vehicle is equipped with an operation switch that performs on and off operations, and controls to change the pilot pressure for operating the control valve depending on the operation time of the on operation of the operation switch.

[0048] (10) In the method for controlling a work vehicle according to aspect (9) above, it is preferable that the pilot pressure is controlled to increase exponentially with an increase in the operation time.

[0049] (11) In the method for controlling a work vehicle according to the above aspect (9) or (10), it is preferable that the pilot pressure is controlled to be a constant pressure when the operation time reaches a predetermined time.

[0050] According to the present invention, it is possible to change the operating speed of an actuator that operates a device on a work vehicle using a simple mechanism, thereby enabling both fine adjustment of the device operation and improved work efficiency.

[0051] The present invention is not limited to the above embodiment (hydraulic excavator), but can also be applied to a work vehicle (such as a track loader) in which the upper body does not rotate relative to the lower body. [Explanation of symbols]

[0052] 1. Work vehicles 10 Running gear 12, 14 Work equipment 32, 34, 52, 54, 56, 58 Actuator (hydraulic cylinder) 60 Variable pressure mechanism 66 Electromagnetic proportional pressure reducing valve 90 Operating lever 92 Operation switch (button switch)

Claims

1. An operating device for a work vehicle having an actuator that operates via a control valve, an operation switch for performing an on operation and an off operation; a pressure variable mechanism that changes the pilot pressure for operating the control valve in accordance with the operation time of the ON operation of the operation switch. An operating device characterized by:

2. The pilot pressure is set to increase exponentially with the increase in the operation time. The operating device according to claim 1 .

3. The pilot pressure is set to a constant pressure when the operation time reaches a predetermined time. The operating device according to claim 1 .

4. The pressure variable mechanism is provided with an electromagnetic proportional pressure reducing valve. The operating device according to any one of claims 1 to 3,

5. The operation switch is a button switch that is turned on when pressed. The operating device according to any one of claims 1 to 3,

6. The operation switch is disposed on an operation lever for driving the actuator. The operating device according to any one of claims 1 to 3,

7. The actuator is a hydraulic cylinder or a hydraulic motor. The operating device according to any one of claims 1 to 3,

8. A work vehicle equipped with the operating device according to any one of claims 1 to 3.

9. 1. A control method for a work vehicle having an actuator that operates via a control valve, comprising: The work vehicle is provided with an operation switch for performing an on-operation and an off-operation, Control is performed to change the pilot pressure for operating the control valve according to the operation time of the ON operation of the operation switch. A method for controlling a work vehicle, comprising:

10. Controlling the pilot pressure so that it increases exponentially with an increase in the operation time.

10. The method for controlling a work vehicle according to claim 9,

11. When the operation time reaches a predetermined time, the pilot pressure is controlled to be a constant pressure.

11. The control method for a work vehicle according to claim 9 or 10, wherein:

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