This application claims priority to Italian Patent Application No. 102020000025864 filed Oct. 30, 2020, titled “Control methods for actuating the movement of a boom or an attachment in a work vehicle, corresponding control systems and work vehicles comprising such control systems”, and which is incorporated herein by reference.
The present invention relates generally to a work vehicle, such as for example a compact wheel loader, and particularly to control methods for actuating the movement of a boom or an attachment in a work vehicle, corresponding control systems and work vehicles comprising such control systems.
Motorized work vehicles are well known for use in material handling that carry an attachment (for example, a bucket) and have a hydraulically operated lifting arm for moving the attachment. Examples of such vehicles are tractors and loaders.
A loader is a heavy equipment machine used in construction to move aside on the ground or load materials such as asphalt, demolition debris, dirt, snow, feed, gravel, logs, raw minerals, recycled material, rock, sand, woodchips, etc. into or onto another type of machinery (such as a dump truck, conveyor belt, feed-hopper, or railroad car). There are many types of loader, which, depending on design and application, are called by various names, including attachment loader, front loader, front-end loader, payloader, scoop, shovel, skip loader, wheel loader, or skid-steer. In particular, compact wheel loaders are compact vehicles that have road wheels and carry a working attachment, such as an attachment, attached to a lift arm or boom, that is hydraulically powered.
Referring to
A compact wheel loader includes an attachment 2 connected to a frame 3 of the work vehicle for movement relative thereto. As shown, a boom 5 is pivotally connected at one end on opposite sides of frame 3. The attachment 2 is pivotally connected at the opposite end of the boom for tilting movement relative to the frame 3 about a generally horizontal axis. The above-described features form no substantial part of the present invention and are generally well known in the art. An attachment, e.g. a bucket, may be replaced in operation by any other type of attachment, e.g. a blade.
Usually, the movement of the boom 5 and of the attachment 2 is controlled by the operator through a joystick 7 placed inside an operator's cab or cabin 9 of the work vehicle 1.
As can be seen in
For example, each hydraulic actuator comprises an hydraulic cylinder operatively connected respectively to the boom and the attachment, that uses hydraulic power of a working fluid to facilitate mechanical operation, the working fluid being controlled by means of directional solenoid valves 18, 20, e.g. an open centre valve. As liquids are nearly impossible to compress, a hydraulic actuator can exert a large force. The rate of actuation of the boom and attachment is controlled by the opening degree of the respective directional solenoid valve 18, 20 by means of a driving current thereof as a function of the position of the joystick.
The hydraulic flow rate of the working fluid required to operate the boom and the attachment is produced by a hydraulic pump Pu connected to a fluid reservoir T and driven by an internal combustion engine or an electrical motor M (hereinafter simply referred to as motor) of the vehicle, e.g. by a mechanical linkage. The same motor is also used to drive the wheels as a propulsion means of the work vehicle.
A neutral region N around the neutral position of the joystick is a region where the boom and attachment are not actuated. A region externally surrounding the neutral region is defined a driving region and indicated D in this figure.
For example, according to the orientation depicted in
A combination of movement in both directions x and y of the joystick is allowed in order to move simultaneously the boom and the attachment.
In known work vehicles, even if the boom and/or the attachment reach their respective end-of-stroke positions, if the operator does not put the joystick into the neutral position N, the hydraulic actuator will keep actuated the boom and/or the attachment. Disadvantageously, this aspect involves a waste of fuel by the working machine.
The aim of the present invention is to provide a solution that avoids the drawbacks of the prior art.
Particularly, an aim of the present invention is to reduce the waste of fuel by the working machine when the boom and/or the attachment reach their respective end-of-stroke positions.
According to the invention, this aim is achieved by a control method for actuating the movement of a boom in a work vehicle powered by a motor, having the features claimed in claim 1, or a control method for actuating the movement of an attachment attached to a boom in a work vehicle powered by a motor, having the features claimed in claim 3.
Preferred embodiments are defined in the dependent claims, whose content is also to be considered an integral part of the present description. Features of the dependent claims may be combined with the features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.
Further subjects of the invention are control systems for a work vehicle powered by a motor, as well as work vehicles, as claimed.
In summary, an actuation strategy of a boom and/or an attachment of a work vehicle is disclosed. In the actuation strategy, the boom and attachment commands are deactivated when the boom and the attachment reach their respective end-of-stroke positions.
Further functional and structural characteristics and advantages of the present invention are set out in the detailed description below, provided purely as a non-limiting example, with reference to the attached drawings, in which:
In the following description, unless otherwise defined, all terms (including technical and scientific terms) are to be interpreted as is customary in the art. It will be further understood that terms in common usage should also be interpreted as is customary in the relevant art and not in an idealized or overly formal sense unless expressly so defined herein. All orientation terms, such as upper and lower, are used in relation to the drawings and should not be interpreted as limiting the invention.
In the following, a preferred embodiment of a control method for actuating the movement of a boom in a work vehicle powered by a motor is described. Reference is made to the control diagram of
As disclosed above and with further reference to
The hydraulic actuating means include an hydraulic cylinder operatively connected the boom, and a directional solenoid valve whose opening degree is adapted to control the flow of a working fluid to the hydraulic cylinder.
The rate of actuation of the boom is controlled by the opening degree of the directional solenoid valve by means of a driving current thereof as a function of a component of the position of the joystick along the preset boom actuation axis in the control area.
The control method comprises the following steps of:
For example, the first time instant and the second time instant may be determined according to a predetermined sampling period.
In a preferred embodiment, the control method for actuating the movement of a boom may further comprise the step of acquiring a signal or data indicative of a rotational speed of the motor over time. The values of the predetermined joystick position difference threshold may be determined based on the rotational speed of the motor indicated by the signal or data indicative of the rotational speed of the motor.
For example, the predetermined joystick position difference threshold may be reduced for high rotational speeds of the motor or may be increased for low rotational speeds of the motor.
In a preferred embodiment, the control method for actuating the movement of a boom may further comprise the step of acquiring a signal or data indicative of operating mode of the work vehicle over time. The value of the predetermined boom position difference threshold may be determined based on the operating mode indicated by the signal or data indicative of the operating mode of the work vehicle.
For example, the work vehicle may have a plurality of operating modes, selectable by the operator. The following explanation refers to an exemplary case of three different operating modes, see for example
In view of the above, the time interval between the first time instant of the first position of the boom and the second time instant of the second position of the boom, may be determined based on the operating mode indicated by the signal or data indicative of operating mode of the work vehicle. For example, the time interval of the high aggressiveness mode may be lower than the time interval of the medium aggressiveness mode, and the time interval of the medium aggressiveness mode may be lower than the time interval of the low aggressiveness mode.
Moreover, for example, the predetermined boom position difference threshold of the medium aggressiveness mode may be lower than the predetermined boom position difference threshold of the high aggressiveness mode, and the predetermined boom position difference threshold of the low aggressiveness mode may be lower than the predetermined boom position difference threshold of the medium aggressiveness mode.
The present invention relates also to a control method for actuating the movement of an attachment attached to a boom in a work vehicle powered by a motor.
The actuation of the attachment occurs again by means of the joystick controlled by an operator. A movement of the joystick in a predetermined control area according to a preset attachment actuation axis causes the actuation of the attachment by hydraulic actuating means. The preset attachment actuation axis for actuating the attachment may be for example an axis parallel to the preset boom actuation axis for the actuation of the boom.
The hydraulic actuating means include an hydraulic cylinder operatively connected the attachment, and a directional solenoid valve whose opening degree is adapted to control the flow of a working fluid to the hydraulic cylinder.
The rate of actuation of the attachment is controlled by the opening degree of the directional solenoid valve by means of a driving current thereof as a function of a component of the position of the joystick along the preset attachment actuation axis in the control area.
The control method comprises the steps of:
In a preferred embodiment, the control method for actuating the movement of an attachment may further comprise the step of acquiring a signal or data indicative of operating mode of the work vehicle over time. In such a case, the value of the predetermined attachment position difference threshold may be determined based on the operating mode indicated by the signal or data indicative of operating mode of the work vehicle.
Also in this case, the time interval between the first time instant of the first position of the attachment and the second time instant of the second position of the attachment, may be determined over time based on the operating mode indicated by the signal or data indicative of operating mode of the work vehicle.
Also for the control method for actuating the movement of an attachment, the control method may further comprise the step of acquiring a signal or data indicative of the rotational speed of the motor of the work vehicle. The values of the predetermined joystick position difference threshold may be determined based on the rotational speed of the motor indicated by the signal or data indicative of the rotational speed of the motor of the work vehicle.
It is clear that the inventions regarding the control method for actuating the movement of a boom and the control method for actuating the movement of an attachment may be combined.
In such a case, the control method will be a control method for actuating the movement of the boom and the attachment attached to the boom in a work vehicle powered by a motor.
Accordingly, the actuation of the boom occurs by means of a joystick controlled by the operator. A movement of the joystick in a predetermined control area according to the preset boom actuation axis causes the actuation of the boom by first hydraulic actuating means. The actuation of the attachment occurs again by means of the joystick controlled by the operator, a movement of the joystick in the predetermined control area according to the preset attachment actuation axis, different from the preset boom actuation axis, causes the actuation of the attachment by second hydraulic actuating means.
The first hydraulic actuating means include a first hydraulic cylinder operatively connected the boom, and a first directional solenoid valve whose opening degree is adapted to control the flow of a working fluid to the first hydraulic cylinder. The rate of actuation of the boom is controlled by the opening degree of the first directional solenoid valve by means of a driving current thereof as a function of a component of the position of the joystick along the preset boom actuation axis in the control area.
The second hydraulic actuating means include a second hydraulic cylinder operatively connected the attachment, and a second directional solenoid valve whose opening degree is adapted to control the flow of a working fluid to the second hydraulic cylinder. The rate of actuation of the attachment is controlled by the opening degree of the second directional solenoid valve by means of a driving current thereof as a function of a component of the position of the joystick along the preset attachment actuation axis in the control area.
For example, the rate of actuation of the boom 5 is controlled by the opening degree of the first directional solenoid valve 18 by means of the driving current thereof as a function of a first component of the position P of the joystick 7 along the preset boom actuation axis y in the control area A. The rate of actuation of the attachment 2 is controlled by the opening degree of the second directional solenoid valve 20 by means of the driving current thereof as a function of a second component of the position P of the joystick 7 along the preset attachment actuation axis x in the control area A. The first component of the position P of the joystick 7 along direction y is indicated yP in
As a further example, a travel of the joystick along a straight direction at an angle from the x axis and the y axis and passing through the neutral position corresponds to an inversion manoeuvre of both the movement of the boom—from lifting to lowering or vice versa—and the attachment—from dumping to rollback or vice versa.
The control method for actuating both the boom and the attachment comprises the steps of:
All the preferred embodiments described above for the control method for actuating the movement of a boom and for the control method for actuating the movement of an attachment may be applied also to the control method for actuating the movement of the boom and the attachment attached to the boom in a work vehicle powered by a motor.
The present invention relates also to a control system for a work vehicle, comprising:
This control system is arranged to carry out a control method for actuating the movement of a boom according to the embodiments described above.
The invention relates also to a control system for a work vehicle, comprising:
This control system is arranged to carry out a control method for actuating the movement of an attachment according to the embodiments described above.
Clearly, a control system may be provided also for the control method for actuating the movement of the boom and the attachment attached to the boom in a work vehicle powered by a motor.
In such a case, the control system comprises:
The control system will be arranged to carry out a control method for actuating the movement of the boom and the attachment attached to the boom according to example provided before.
The present invention relates also to a work vehicle, in particular compact wheel loader, comprising:
As indicated in
In a further aspect, the invention relates to a work vehicle, in particular compact wheel loader, comprising:
As indicated in
In addition, may be also provided a work vehicle, in particular compact wheel loader, comprising:
As indicated in
As an example, the boom position sensor 40 may be an angle detection sensor, or a linear sensor coupled to a cylinder of the boom, or a pressure sensor coupled to a bottom chamber of a cylinder of the boom. As an example, the attachment position sensor 42 may be an angle detection sensor, or a linear sensor coupled to a cylinder of the attachment, or a pressure sensor coupled to a bottom chamber of a cylinder of the attachment.
The example embodiments are described in sufficient detail to enable those of ordinary skill in the art to implement a control system in a work vehicle arranged to carry out the disclosed control method herein described.
Naturally, the principle of the invention remaining unchanged, the embodiments and the constructional details may vary widely from those described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the invention as defined in the appended claims.
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Entry |
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Search Report for Italian application 102020000025864, dated Aug. 5, 2021 (10 pages). |
Number | Date | Country | |
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20220136213 A1 | May 2022 | US |