JP7810596B2 - Boom sprayer - Google Patents

Description

The present invention relates to a boom spraying device.

Boom sprayers and other boom spraying devices are installed on traveling vehicles such as tractors and towing vehicles that travel through fields. These boom spraying devices have a boom that extends (deploys) to the side, intersecting the traveling direction of the traveling vehicle, allowing them to spray a wide area corresponding to the boom length while traveling through the field.

The boom spraying device generally includes a mechanism for folding the boom into a predetermined storage position (also referred to as a stowed position, etc.) when not in use. Various types of folding mechanisms (also referred to as opening/closing mechanisms, etc.) are known, but one known is one that folds the boom, which extends out to the side intersecting the traveling direction of the traveling body, by approximately 90 degrees so that it faces in the traveling direction of the traveling body (see Patent Documents 1 and 2 below).

Furthermore, with this boom spraying device, the longer the boom, the wider the area that can be sprayed. However, a long boom can be a hindrance when moving or storing. Therefore, to eliminate the disadvantages of a long boom, a device has been proposed in which the tip of the boom folds in an approximately vertical direction (upward) (see Patent Document 3 below).

In a boom spraying device equipped with a boom that can be freely deployed and folded (opened and closed) as described above, when the boom is deployed from a folded state, the impact at the moment the boom is deployed in a straight line is transmitted to the connection between the base end and tip end of the boom, which could cause damage or malfunction to each boom. Similarly, when folding a boom from an deployed state, the impact at the moment the boom is folded could cause damage or malfunction to each boom. For this reason, when deploying or folding a boom, the operator must operate it slowly and carefully, which can be a cumbersome task at the start and end of work.

In other words, with a folding boom like the one described above, the tip of the boom is opened and used during spraying operations, and then folded (closed) when the operation is completed, resulting in a boom opening and closing operation. If this opening and closing operation is performed at a constant speed, a large impact will be applied between the base and tip of the boom at the moment of folding (also called fully folded or fully closed) or unfolding (also called fully opened), which could lead to damage or malfunction. To prevent this, the overall speed of the opening and closing operation needs to be slowed down, and the operator needs to operate the boom carefully, otherwise workability will be reduced.

Therefore, proposals have been made to reduce the impact between the booms when they are unfolded from a folded state and when they are folded from an unfolded state (see Patent Documents 3 and 4 below).

Patent Document 3 proposes reducing the rotational angular velocity (opening/closing speed) of the tip boom just before it is fully deployed (when the tip boom is deployed and aligned in series with the base boom) and just before it is fully folded (when the tip boom is folded above the base boom), thereby mitigating the impact that occurs when the tip boom is deployed and folded.

Patent Document 4 proposes reducing the swing speed (opening/closing speed) of the boom at the beginning (starting end) and end (terminal end) of the swing, thereby mitigating the impact during swing.

Patent No. 5941759 Japanese Patent Application Laid-Open No. 2004-132461 JP 2013-116078 A Japanese Utility Model Application Laid-Open Publication No. 60-005473

However, the prior art described in Patent Documents 3 and 4 maintain a constant cylinder operating (extending/retracting) speed, which drives the boom at the tip end and maintains its position through telescoping, while using a link arrangement to reduce the opening/closing speed of the boom at the tip end when it is fully opened or fully folded (closed). This results in issues such as a complex link arrangement, difficult layout, and increased costs. Furthermore, the opening/closing speed of the boom at the tip end also decreases when operating in the opposite direction from a fully opened or fully folded (closed) state, resulting in hydraulic pressure loss in the hydraulic cylinder.

The present invention was made in consideration of the above-mentioned problems, and its purpose is to provide a boom spraying device that can reduce the boom opening and closing speed only near the fully opened and folded (closed) positions without reducing the boom opening and closing speed in any other positions, thereby reducing the impact between the booms when opening and closing, and that can be laid out with a relatively simple structure.

To solve the above problems, the boom spraying device of the present invention comprises a boom for spraying operations pivotally supported on a machine frame installed on a traveling machine body so that it can swing open and closed, a first boom at the base end, a second boom at the tip end attached to the first boom so that it can swing open and closed, and a fluid pressure cylinder that extends and retracts to hold the second boom in a predetermined position relative to the first boom, and is characterized by the fact that flow rate is controlled in the fluid pressure circuit of the fluid pressure cylinder according to the position of the second boom relative to the first boom so that the amount of working fluid flowing into the fluid chamber of the fluid pressure cylinder decreases between the time when the second boom assumes the predetermined position relative to the first boom and just before that.

In a preferred embodiment, flow rate control is performed on the fluid pressure circuit of the fluid pressure cylinder to reduce the amount of hydraulic fluid flowing into the fluid chamber of the fluid pressure cylinder from the time when the second boom assumes the predetermined posture relative to the first boom until just before that time, thereby reducing the extension/retraction speed of the fluid pressure cylinder and reducing the swing speed of the second boom relative to the first boom.

In another preferred embodiment, the predetermined posture includes an unfolded posture in which the second boom is unfolded relative to the first boom, and a folded posture in which the second boom is folded relative to the first boom, and when the second boom is swung from the folded posture to the unfolded posture, flow rate control is performed on the fluid pressure circuit of the fluid pressure cylinder so that the amount of working fluid flowing into the fluid chamber in the fluid pressure cylinder is reduced just before the second boom assumes the unfolded posture.

In another preferred embodiment, the predetermined postures include an unfolded posture in which the second boom is unfolded relative to the first boom and a folded posture in which the second boom is folded relative to the first boom, and when the second boom is swung from the unfolded posture to the folded posture, flow rate control is performed on the fluid pressure circuit of the fluid pressure cylinder so that the amount of working fluid flowing into the fluid chamber in the fluid pressure cylinder is reduced just before the second boom assumes the folded posture.

In another preferred aspect, the fluid pressure circuit of the fluid pressure cylinder is provided in a switchable manner, with a first fluid pressure circuit that does not reduce the amount of hydraulic fluid flowing into the fluid chamber, and a second fluid pressure circuit that reduces the amount of hydraulic fluid flowing into the fluid chamber. When the second boom assumes the predetermined position relative to the first boom, the amount of hydraulic fluid flowing into the fluid chamber in the fluid pressure cylinder is reduced by switching the fluid pressure circuit from the first fluid pressure circuit to the second fluid pressure circuit just before the second boom assumes the predetermined position relative to the first boom.

In another preferred embodiment, a flow control valve is provided that controls the open/close state of a conduit communicating with the fluid chamber to adjust the flow rate of the hydraulic fluid in the conduit, and when the second boom assumes the predetermined position relative to the first boom, the flow rate of the hydraulic fluid flowing into the fluid chamber in the fluid pressure cylinder is reduced by controlling the flow control valve between the time when the second boom assumes the predetermined position relative to the first boom and just before that time.

In another preferred embodiment, an attitude detection device is provided that detects the attitude of the second boom relative to the first boom, and flow rate control is performed in the fluid pressure circuit of the fluid pressure cylinder based on the detection signal from the attitude detection device, thereby reducing the amount of hydraulic fluid flowing into the fluid chamber of the fluid pressure cylinder from the time when the second boom assumes the predetermined attitude relative to the first boom until just before that time.

In a further preferred embodiment, a first attitude detection device is provided at one end of the axial direction of the boom rotation shaft of the first boom and the second boom, which detects the attitude of the second boom relative to the first boom when the second boom is swung and displaced in one direction about the boom rotation shaft relative to the first boom, and a second attitude detection device is provided at the other axial end of the boom rotation shaft of the first boom and the second boom, which detects the attitude of the second boom relative to the first boom when the second boom is swung and displaced in the other direction about the boom rotation shaft relative to the first boom.

In a further preferred embodiment, the predetermined postures include an unfolded posture in which the second boom is unfolded relative to the first boom and a folded posture in which the second boom is folded relative to the first boom, and an unfolded-side posture detection device is provided at one end of the axial direction of the boom pivot shaft of the first and second booms, which detects the posture of the second boom relative to the first boom when the second boom is swung from the folded posture to the unfolded posture, and a folded-side posture detection device is provided at the other axial end of the boom pivot shaft of the first and second booms, which detects the posture of the second boom relative to the first boom when the second boom is swung from the unfolded posture to the folded posture.

In a further preferred embodiment, the attitude detection device is provided at the connection between the first boom and the second boom.

In a further preferred embodiment, the attitude detection device is provided on one of the first boom and the second boom.

In a further preferred embodiment, the fluid pressure circuit of the fluid pressure cylinder is switchably provided between a first fluid pressure circuit that does not reduce the amount of hydraulic fluid flowing into the fluid chamber, and a second fluid pressure circuit that reduces the amount of hydraulic fluid flowing into the fluid chamber, and when the second boom assumes the predetermined posture relative to the first boom, based on the detection signal from the posture detection device, the fluid pressure circuit is switched from the first fluid pressure circuit to the second fluid pressure circuit just before the second boom assumes the predetermined posture relative to the first boom, thereby reducing the amount of hydraulic fluid flowing into the fluid chamber of the fluid pressure cylinder.

In a further preferred embodiment, a flow control valve is provided that controls the open/close state of a conduit communicating with the fluid chamber to adjust the flow rate of the hydraulic fluid in the conduit, and when the second boom assumes the predetermined posture relative to the first boom, the flow control valve is controlled based on the detection signal from the posture detection device, between the time when the second boom assumes the predetermined posture relative to the first boom and just before that time, thereby reducing the amount of hydraulic fluid flowing into the fluid chamber in the fluid pressure cylinder.

In another preferred embodiment, the second boom is pivotally supported on the first boom so as to be able to swing freely within a vertical plane.

According to the present invention, by controlling the flow rate in the fluid pressure circuit of the fluid pressure cylinder in response to the attitude of the second boom relative to the first boom, the flow rate of hydraulic fluid in the fluid chamber of the fluid pressure cylinder is reduced (throttled) between the time when the second boom is swung to a predetermined position relative to the first boom and just before that (between the angle at which the second boom is swung to a predetermined position relative to the first boom and the angle just before that). For example, when the tip boom is swung from the folded position to the deployed position, the flow rate of hydraulic fluid in the fluid chamber of the fluid pressure cylinder is reduced (throttled) from just before the deployed position. Also, when the tip boom is swung from the deployed position to the folded position, the flow rate of hydraulic fluid in the fluid chamber of the fluid pressure cylinder is reduced (throttled) from just before the folded position. In other words, when the boom is deployed (opened), the flow rate of hydraulic fluid in the fluid chamber is reduced between the fully opened position of the boom and a predetermined angle before that position, thereby reducing the cylinder operation (extension/retraction) speed and braking the boom opening operation (i.e., reducing the opening speed). Furthermore, when folding (closing) the boom, the amount of hydraulic fluid flowing into the fluid chamber is reduced between the fully closed (folded) boom and a certain angle before that, thereby slowing the cylinder operation (extension/retraction) speed and braking the boom closing operation (i.e., slowing the closing speed). As a result, the brake is applied only to the parts necessary for opening and closing the boom, while the thrust of the fluid pressure cylinder is maximized in other parts. This effectively reduces the impact between the booms when opening and closing the boom, thereby effectively preventing damage or malfunction of the boom. Furthermore, the link parts driven by the fluid pressure cylinder can be laid out with a relatively simple structure.

Furthermore, for example, by providing separate sensors (on both sides of the boom pivot shaft in the axial direction) that detect the swing displacement of the boom at the tip end around the boom pivot shaft in one direction (for example, swing displacement due to an opening operation) and the boom at the tip end around the boom pivot shaft in the other direction (for example, swing displacement due to a closing operation), each sensor will only be relevant during the boom opening operation or the boom closing operation, and the brakes will not be applied to the boom opening/closing operation when the boom is closed from its fully opened position, or when the boom is opened from its fully closed position. This allows the brakes to be applied only to the parts of the boom that are necessary when opening or closing, and maximizes the thrust of the fluid pressure cylinder for other parts. This effectively reduces the impact between the booms when opening or closing the booms, thereby effectively preventing damage or malfunction of the booms.

Furthermore, when the booms swing in a vertical plane, the impact caused by the booms opening and closing is thought to be greater due to the effect of gravity than when the booms swing in a horizontal plane. According to the present invention, it is possible to effectively mitigate the impact caused by the booms opening and closing even in such situations.

1 is a perspective view showing the overall configuration of a boom spraying device according to an embodiment of the present invention. FIG. FIG. 2 is an enlarged perspective view of a main portion showing the configuration of a link mechanism at a connecting portion between an base boom and a tip boom in FIG. 1 . FIG. 3 is a cross-sectional view showing the internal configuration of the hydraulic cylinder shown in FIGS. 1 and 2. 2A and 2B are enlarged perspective views of the main part as seen from the rear side (opening limit switch side) and the front side (closing limit switch side), respectively, showing the configuration of the limit switch at the connection part between the base boom and the front boom in FIG. 1 . 2A and 2B show a part of the hydraulic circuit of the hydraulic cylinder in FIG. 1, where FIG. 2A is a hydraulic circuit diagram during normal operation (non-braking), FIG. 2B is a hydraulic circuit diagram during braking, and FIG. 2C is a diagram showing a part of the electrical circuit for switching the hydraulic circuit. In this embodiment, the state is shown just before the leading boom assumes the deployed position, with (A) being a cross-sectional view showing the internal configuration of the hydraulic cylinder, (B) being an enlarged front view of the main part of the connection between the leading boom and the base boom (as viewed from the closing limit switch side), and (C) being an enlarged rear view of the main part of the connection between the leading boom and the base boom (as viewed from the opening limit switch side). 1 shows the state in which the leading boom is in an extended position in this embodiment, where (A) is a cross-sectional view showing the internal configuration of the hydraulic cylinder, (B) is an enlarged front view of the main part of the connection between the leading boom and the base boom (as viewed from the closing limit switch side), and (C) is an enlarged rear view of the main part of the connection between the leading boom and the base boom (as viewed from the opening limit switch side). In this embodiment, the state is shown just before the leading boom assumes the folded position, with (A) being a cross-sectional view showing the internal configuration of the hydraulic cylinder, (B) being an enlarged front view of the main part of the connection between the leading boom and the base boom (seen from the closing limit switch side), and (C) being an enlarged rear view of the main part of the connection between the leading boom and the base boom (seen from the opening limit switch side). In this embodiment, the state in which the leading boom is in a folded position is shown, where (A) is a cross-sectional view showing the internal configuration of the hydraulic cylinder, (B) is an enlarged front view of the main part of the connection between the leading boom and the base boom (as seen from the closing limit switch side), and (C) is an enlarged rear view of the main part of the connection between the leading boom and the base boom (as seen from the opening limit switch side).

Embodiments of the present invention will be described below with reference to the drawings. Note that in the following description, identical elements will be given the same reference numerals, and duplicate explanations may be omitted. Furthermore, terms indicating directions such as up/down, left/right, front/rear, etc. are based on the normal direction of travel of the traveling vehicle body.

Figure 1 is a perspective view showing the overall configuration of a boom spraying device 1 according to an embodiment of the present invention. Figure 2 is an enlarged perspective view of the essential parts showing the configuration of the link mechanism at the connection between the base boom and tip boom in Figure 1.

The boom spraying device 1 of this embodiment is mounted on a traveling vehicle that travels through a field, and is used to spray chemicals and the like from a spray nozzle attached to a boom for spraying operations while traveling through the field. The basic configuration of this boom spraying device 1 is such that a boom equipped with a spray nozzle for spraying operations is pivotally supported on a vehicle frame installed on the traveling vehicle so that it can swing open and closed.

As shown in Figure 1, the boom spraying device 1 of this embodiment primarily comprises a machine frame 2, a boom 4 supported by the machine frame 2, a plurality of spray nozzles 5, 5... arranged on the boom 4, a tank 6 for storing chemical liquids, etc., and a pump (not shown) for supplying (pressurizing) the chemical liquids, etc. in the tank 6 to each of the spray nozzles 5, 5....

The machine frame 2 is installed on a traveling machine (not shown), such as a tractor or towing vehicle, that travels through the field, and supports the boom 4. In this embodiment, the machine frame 2 is installed at the rear of the traveling machine, but its installation location is not particularly limited, and it may also be installed at the front of the traveling machine, etc.

The boom 4 is a long member on which multiple spray nozzles 5, 5... are arranged. In this embodiment, to make it foldable (also referred to as storable or stowable), it is composed of three booms: a central boom 42 supported on the machine frame 2, a base boom 44 supported at the tip of the central boom 42, and a tip boom 46 supported at the tip of the base boom 44. Hereinafter, this boom 4 may be referred to as the boom assembly 4. Furthermore, a link mechanism (not shown) is provided at the connection between the central boom 42 and the base boom 44 to deploy and fold the central boom 42 and the base boom 44 so that they can rotate approximately horizontally. A link mechanism 10 is provided at the connection between the base boom 44 and the tip boom 46 to deploy and fold the base boom 44 and the tip boom 46 so that they can rotate approximately vertically (in other words, within an approximately vertical plane).

Note that the base boom 44 and tip boom 46 are configured as a pair on the left and right, and since the boom 4 in this embodiment has a symmetrical configuration, the left boom will be omitted in Figure 1 and only the right boom will be illustrated and explained.

The central boom 42 is supported (approximately horizontally) on the machine frame 2, extending to the left and right.

The base boom 44 is supported in an extended state on the left and right sides of the central boom 42. The base boom 44 is foldably connected to the tip (left and right ends) of the central boom 42 via a link mechanism (not shown) so that it faces diagonally forward of the central boom 42.

The front boom 46 is foldably connected to the top of the base boom 44 at the tip of the base boom 44 via a link mechanism 10 (described below). In this embodiment, it is pivotally supported by a boom rotation shaft 48 (extending substantially horizontally) that rotatably connects the top of the tip side of the base boom 44 and the top of the base end side of the front boom 46.

In addition, the boom 4 of this embodiment is provided with a collision prevention mechanism between the base boom 44 and the tip boom 46 that prevents collision between the base boom 44 and the tip boom 46 when the tip boom 46 is folded (superimposed) above the base boom 44. The collision prevention mechanism in this embodiment is composed of an H-shaped receiving member 45 fixed to the top surface of the base boom 44, and a fitting member 47 that is fixed to the top surface (bottom surface when folded) of the tip boom 46 and fits into the H-shaped receiving member 45.

As long as the booms are pivotally supported so that they can swing freely, the type and number of booms (central boom 42, base boom 44, front boom 46, etc.) that make up the boom assembly 4, the connection form between the booms, the swing direction (rotation direction) between the booms, the location and orientation of each boom, etc. are not particularly limited, and can be selected appropriately depending on the type, size and shape of the traveling machine, the size and shape of the field, etc.

The spray nozzles 5 spray chemicals, etc., pumped by a pump (described below), in the form of liquid, droplets, or mist, in any desired trajectory. In this embodiment, the spray nozzles 5 are arranged at approximately equal intervals on each of the central boom 42, base boom 44, and front boom 46 to prevent uneven spraying. The type, number, spacing, and location of the spray nozzles 5 are not particularly limited and can be selected appropriately depending on the type of chemicals, etc., to be sprayed, the crop to be sprayed, the length of the boom 4, etc.

The tank 6 is used to store chemical solutions to be supplied to each spray nozzle 5, 5... In this embodiment, the tank 6 is installed on the machine frame 2. There are no particular restrictions on where the tank 6 can be installed, and it can be installed anywhere on the traveling machine body, etc.

The pump is used to pressure-feed chemicals and the like from the tank 6 to each spray nozzle 5, 5.... The power source for the pump is not particularly limited and may be the power of the battery of the traveling machine or the rotational force of the engine. In this embodiment, the pump is installed on the machine frame 2. The installation location of the pump is not particularly limited and it can be installed anywhere on the traveling machine, etc. The pump and each spray nozzle 5, 5... are connected to each other via a pressure pipe 8 so that they can flow freely.

The boom 4 comprises a pair of left and right booms, a base boom 44 and a tip boom 46, which are connected to the left and right ends of the central boom 42 by link mechanisms (not shown) so that they can be folded (opened and closed). The base boom 44 and tip boom 46 are connected to each other so that they can swing freely by a link mechanism 10, and the tip boom 46 is connected to the base boom 44 by the link mechanism 10 so that it can be folded (opened and closed) in a substantially vertical direction.

In the boom 4, the base boom 44 (and tip boom 46) is configured to rotate (swing) by a link mechanism (not shown) at the base between an extended (open) position (deployed position) in the extension direction of the central boom 42 (outward in the left-right direction), and a folded (closed) position (folded position) in which it faces diagonally forward of the central boom 42.

The leading boom 46 is also configured by the link mechanism 10 at the tip end to rotate (swing) between an extended (open) position (deployed position) in the extension direction of the base boom 44 (outward in the left-right direction) and a folded (closed) position (folded position) above the base boom 44.

When the base boom 44 assumes an unfolded position relative to the central boom 42 and the tip boom 46 assumes an unfolded position relative to the base boom 44, the central boom 42, base boom 44, and tip boom 46 are deployed in a substantially straight line (substantially horizontal), and the boom 4 assumes a lateral (left-right) open position O that intersects with the traveling direction of the traveling machine body. Note that the open position O can be achieved by the base boom 44 assuming an unfolded position relative to the central boom 42 while the tip boom 46 is in a folded position relative to the base boom 44, and then the tip boom 46 assuming an unfolded position relative to the base boom 44; alternatively, when the base boom 44 assumes a folded position relative to the central boom 42, the tip boom 46 assumes an unfolded position relative to the base boom 44, and then the base boom 44 assumes an unfolded position relative to the central boom 42.

Furthermore, in the boom 4, when the base boom 44 assumes a folded position relative to the central boom 42 and the front boom 46 assumes a folded position relative to the base boom 44, the boom 4 assumes a closed position C in which the tip side along the traveling direction of the traveling machine body faces diagonally upward. Note that closed position C can be achieved by the front boom 46 assuming a folded position relative to the base boom 44 while the base boom 44 is in an unfolded position relative to the central boom 42, and then the base boom 44 assuming a folded position relative to the central boom 42, or by the base boom 44 assuming a folded position relative to the central boom 42 while the front boom 46 is in an unfolded position relative to the base boom 44, and then the front boom 46 assuming a folded position relative to the base boom 44.

In this way, the boom 4 opens and closes (is free to swing open and closed) between a lateral open position O that intersects with the traveling direction of the traveling machine body and a closed position C in which the tip side faces diagonally upward along the traveling direction of the traveling machine body, by means of a link mechanism (not shown) at the base and a link mechanism 10 at the tip.

With the boom spraying device 1, in the open position O, the pair of left and right base booms 44 and front booms 46 can be extended in a straight line outward in the left-right direction of the traveling body, and while traveling, the numerous spray nozzles 5, 5... can be used to spray a wide area of chemical solution, etc., at once on crops, etc. in the field.

In addition, when not in use, the pair of left and right base booms 44 and front booms 46, which extend out to the side intersecting the traveling direction of the traveling machine body, can be folded approximately 90 degrees in the closed position C and stored (stowed) so that they face in the traveling direction of the traveling machine body. Situations in which the closed position C is used include situations in which the booms 4 are stored in a temporary non-working state, such as to avoid obstacles during spraying work or to adapt to the shape of the field.

In the following description of the link portion between the base boom 44 and the tip boom 46, including the characteristic configuration of this embodiment, the position in which the tip boom 46 is extended in the extension direction of the base boom 44 (outward in the left-right direction) by the tip-end link mechanism 10 may be referred to as the deployed position E, and the position in which the tip boom 46 is folded above the base boom 44 may be referred to as the folded position F.

(Explanation of the link mechanism structure)
Next, a description will be given of the link mechanism 10 at the connection between the base boom 44 and the tip boom 46. The link mechanism 10 of this embodiment controls the deployment and folding of the boom by folding the tip boom 46 above the base boom 44 and by unfolding the folded tip boom 46 forward (in the extension direction) of the base boom 44. In particular, the link mechanism 10 of this embodiment is designed to reduce the impact between the base boom 44 and the tip boom 46 when the booms are deployed or folded.

As shown in Figures 1 and 2, the link mechanism 10 in this embodiment comprises a first link 14 rotatably connected to the tip end of the base boom 44, a second link 16 rotatably connected to the base end of the tip boom 46, a link connecting shaft 15 (extending horizontally) rotatably connecting the tip end of the first link 14 and the tip end of the second link 16, and a hydraulic cylinder (hereinafter sometimes simply referred to as the cylinder) 20 as boom deployment/folding control means that swings the first link 14 and the second link 16 to control the deployment and folding of the base boom 44 and the tip boom 46.

The hydraulic cylinder 20 of this embodiment uses hydraulic oil as the working fluid, but instead of hydraulic oil, a working fluid such as a water-soluble substitute liquid or a fluid such as gas may also be used.

The first link 14 has its base end rotatably connected to the tip of the main boom 44, and is swung by the cylinder 20 (which extends and retracts), thereby raising and lowering the second link 16.

The second link 16 has its base end rotatably connected to the base end of the front boom 46, and is raised and lowered by the swinging of the first link 14, thereby unfolding and folding the front boom 46.

The link connecting shaft 15 is a rotating shaft that rotatably connects the tip of the first link 14 and the tip of the second link 16. In this embodiment, it is inserted into bearings (not shown) provided at the tip of the first link 14 and the second link 16, axially supporting each tip so that it can rotate freely.

In this embodiment, the first link 14, second link 16, and link connecting shaft 15 are respectively provided on the opposing surfaces of the base boom 44 and tip boom 46 (the front and rear surfaces when in the deployed position E).

In this embodiment, the link mechanism 10 is provided with a link connection shaft 18 that connects the first link 14 and the cylinder 20. In this embodiment, the link connection shaft 18 is fixed (extending horizontally) to the tip ends of a pair of opposing first links 14 (provided on the front and rear surfaces when in the deployed position E).

The cylinder 20 performs extension and retraction operation (extension and retraction control) to swing the first link 14 and second link 16, which are connected by the link connecting shaft 15, thereby controlling the deployment and folding (opening and closing) of the boom. Therefore, when deploying the tip boom 46 that is folded relative to the base boom 44, the cylinder 20 positions the link connecting shaft 15 at the base end of the tip boom 46, while when folding the tip boom 46 that is deployed relative to the base boom 44, the cylinder 20 functions to position the link connecting shaft 15 at the tip end of the base boom 44.

In this embodiment, the telescopically controllable cylinder 20 is interposed between the base boom 44 and the link connection shaft 18 attached to the first link 14. In other words, the cylinder 20 is telescopically connected to the base boom 44 and the link connection shaft 18. In this embodiment, the inner end 22e of the cylinder tube 22 of the cylinder 20 (rear end of the cylinder 20) is connected to a mounting bracket 49 fixed to the top surface of the base boom 44 via a boom connection shaft 50 so as to be relatively rotatable. In addition, the outer end 28e of the piston rod 28 of the cylinder 20 (front end of the cylinder 20) is connected to the first link 14 and the second link 16 (first link 14 in this example) via the link connection shaft 18 so as to be relatively rotatable.

In this embodiment, the cylinder 20 contracts to swing the first link 14 from the tip boom 46 side to the base boom 44 side, positioning the link connecting shaft 15 at the tip end of the base boom 44 and folding the tip boom 46 that has been deployed relative to the base boom 44; the cylinder 20 extends to swing the first link 14 from the base boom 44 side to the tip boom 46 side, positioning the link connecting shaft 15 at the base end of the tip boom 46 and deploying the tip boom 46 that has been folded relative to the base boom 44.

In other words, when the cylinder 20 is in the maximum extended state, the leading boom 46 is held in an extended (open) position E relative to the base boom 44, and when the cylinder 20 is in the maximum retracted state, the leading boom 46 is held in a folded (closed) position F relative to the base boom 44.

As described above, the link mechanism 10, including the links 14 and 16, is driven by the cylinder 20 (which extends and retracts), and the extension and retraction of the cylinder 20 is remotely controlled, for example, by the driver operating a lever provided on the running machine body.

As long as the base boom 44 and tip boom 46 can be swung and displaced to maintain a predetermined posture, the type, number, and shape of the components constituting the link mechanism 10, as well as the location and form of connection between the components, are not particularly limited and can be modified as appropriate depending on the layout, etc. For example, in the above embodiment, the cylinder 20 is maintained in the deployed posture E when it is in the maximum extended state, and in the folded posture F when it is in the maximum retracted state. However, the cylinder 20 may be maintained in the folded posture F when it is in the maximum extended state, and in the deployed posture E when it is in the maximum retracted state. Furthermore, the cylinder 20 may be maintained in the deployed posture E or the folded posture F at a predetermined length between the maximum extended and maximum retracted states, or it may be maintained in a predetermined posture (position) other than the deployed posture E or the folded posture F.

(Explanation of the internal structure of the cylinder and hydraulic circuit)
Next, a description will be given of the internal structure and hydraulic circuit of the cylinder 20. Fig. 3 is a cross-sectional view showing the internal structure of the hydraulic cylinder 20 shown in Figs.

As shown in Figure 3, the cylinder 20 comprises a cylindrical cylinder tube 22 filled with hydraulic oil as a working fluid, a columnar piston 26 slidably inserted into the cylinder tube 22 to define two front and rear oil chambers (fluid chambers) 24A, 24B, and a piston rod (also referred to as a working rod or cylinder rod) 28 inserted into the cylinder tube 22 so as to be able to move back and forth and connected to the piston 26. Both ends (openings) of the cylinder tube 22 are closed air-and-liquid-tightly by a head-side lid 22A and a bottom-side lid 22B, which slidably receive the piston rod 28 in an air-and-liquid-tight manner.

In this embodiment, the piston 26 slides against the inner surface of the cylinder tube 22 in an air-liquid tight manner via a sealing member (O-ring) 27.

The cylinder tube 22 also has two ports (rod-side port 23A and anti-rod-side port 23B) formed in each of the oil chambers (rod-side oil chamber) 24A and 24B, respectively, for introducing and discharging hydraulic oil as a working fluid. The two ports 23A, 23B are spaced apart in the longitudinal (axial) direction of the cylinder 20 by a predetermined distance corresponding to the difference in extension length between the maximum extension state and the maximum contraction state of the cylinder 20.

When the piston 26 (front end surface) abuts against the head-side lid 22A (inner end surface), and the piston rod 28 extends to its maximum extension state, the port 23A is closed by the piston 26, and the front boom 46 assumes the deployed position E (see also Figures 7(A) to 7(C)). When the piston 26 (rear end surface) abuts against the bottom-side lid 22B (inner end surface), and the piston rod 28 retracts to its maximum retraction state, the port 23B is closed by the piston 26, and the front boom 46 assumes the folded position F (see also Figures 9(A) to 9(C)).

Although not shown in the figures (see Patent Document 2 (JP 2004-132461 A) if necessary), the hydraulic pump serving as the fluid pumping means constituting the hydraulic circuit of the cylinder 20 is driven by the power (drive shaft) of the traveling machine body, etc., and pumps hydraulic oil from a hydraulic oil tank serving as a hydraulic fluid tank mounted on the boom spraying device 1 into a hydraulic oil discharge line. This hydraulic oil discharge line is connected to a directional control valve used to drive the boom opening and closing.

The directional control valve is connected to the two oil chambers 24A and 24B through a first oil supply line and a second oil supply line. The directional control valve is also connected to the hydraulic oil tank through a return line.

The directional control valve is, for example, a spring-return three-position four-port valve that is constantly biased in a direction that automatically returns it to a neutral position in which all four ports are closed. When a boom-open signal is issued, for example by the driver operating a lever attached to the traveling machine body, the directional control valve switches the hydraulic circuit, and hydraulic oil is pressure-fed from the hydraulic oil tank to the anti-rod-side oil chamber 24B via the second oil supply line. At the same time, hydraulic oil in the rod-side oil chamber 24A is returned to the hydraulic oil tank via the return line and the first oil supply line. This drives the piston rod 28 in the extension direction until the piston 26 abuts against the head-side cover 22A. When this piston rod 28 reaches its maximum extension state, the leading boom 46 assumes the deployed position E. By returning the directional control valve to the neutral position, the leading boom 46 can be maintained in the deployed position E.

When spraying operations are completed and a boom close signal is issued, for example by the operator operating a lever on the traveling machine body, the directional control valve switches the hydraulic circuit, and hydraulic oil is pressurized from the hydraulic oil tank to the rod-side oil chamber 24A through the first oil supply line, while hydraulic oil in the anti-rod-side oil chamber 24B is returned to the hydraulic oil tank via the return line through the second oil supply line, driving the piston rod 28 in the retracting direction until the piston 26 abuts against the bottom-side cover 22B. When this piston rod 28 reaches its maximum retracted state, the front boom 46 assumes the folded position F, and the front boom 46 can be maintained in the folded position F by returning the directional control valve to its neutral position.

The cylinder 20 of the link mechanism 10 in this embodiment has the following measures in place to reduce the impact between the base boom 44 and the tip boom 46 when the booms are deployed or folded, and to prevent damage or malfunction of the base boom 44 and tip boom 46.

In other words, in this embodiment, flow control is performed on the hydraulic circuit of the cylinder 20 at a predetermined timing according to the position (posture) of the leading boom 46 relative to the base boom 44, in other words, at a predetermined timing according to the extension and retraction of the cylinder 20 (piston rod 28), thereby slowing down the extension and retraction speed of the piston rod 28 and slowing down the boom swing speed (opening and closing speed).

In particular, in this embodiment, when the cylinder 20 (piston rod 28) is extended to its maximum extension state and the leading boom 46 assumes the deployed position E, and when the cylinder 20 (piston rod 28) is retracted to its maximum retraction state and the leading boom 46 assumes the folded position F, the position (position) of the leading boom 46 relative to the base boom 44 is detected, and the flow of hydraulic oil into and out of the cylinder 20 is switched and reduced (throttled) at a predetermined timing just before the deployed position E and the folded position F.

More specifically, the boom spraying device 1 of this embodiment is equipped with limit switches 36, 38 as position detection devices that detect the position (rotation angle) of the front boom 46 relative to the base boom 44. While this embodiment describes in detail an example in which limit switches are used as the position detection devices, potentiometers or other devices capable of detecting the rotation angle or amount of movement may also be used. Furthermore, the number and placement of limit switches are not limited to those of the following embodiment.

In this embodiment, the limit switches 36, 38 are provided for each position of the front boom 46 relative to the base boom 44 that needs to be detected.

The limit switch 36 is used to detect the position (rotation angle) of the leading boom 46 relative to the base boom 44 when the leading boom 46 is in the deployed position E. Hereinafter, this limit switch 36 may be referred to as the opening side limit switch 36 or the deployment side limit switch 36. On the other hand, the limit switch 38 is used to detect the position (rotation angle) of the leading boom 46 relative to the base boom 44 when the leading boom 46 is in the folded position F. Hereinafter, this limit switch 38 may be referred to as the closing side limit switch 38 or the folding side limit switch 38.

In this embodiment, as can be seen by referring to Figures 4(A) and (B) as well as Figures 1 and 2, the opening side limit switch 36 and the closing side limit switch 38 are mounted on the surface (rear and front) of the tip of the base boom 44, respectively, near one axial end and the other axial end (rear and front ends) of the boom rotation shaft 48 that connects the base boom 44 and the tip boom 46. In other words, the opening side limit switch 36 and the closing side limit switch 38 are mounted on the surface of the base boom 44, at the connection between the base boom 44 and the tip boom 46. Note that in this embodiment, the limit switches 36, 38 are disposed on the base boom 44 side (only) of the base boom 44 and the tip boom 46, but they may also be disposed on the tip boom 46 side, or on both the base boom 44 and the tip boom 46.

The tips of the switch levers 36A and 38A of the limit switches 36 and 38 are provided with rollers that come into contact with the target (detection portions 37A and 39A of the detection members 37 and 39, described below).

Detection members 37, 39 (opening-side detection member 37, closing-side detection member 39) for turning the opening-side limit switch 36 and closing-side limit switch 38 on and off are attached to one and the other axial ends (rear and front ends) of the boom rotation shaft 48. These detection members 37, 39 are generally disk-shaped and are non-circular members with a portion of their outer periphery (a portion within a specified angular range) extending outward. The portion of the outer periphery of the detection members 37, 39 (the portion extending outward) forms detection portions 37A, 39A that abut against the switch lever portions 36A, 38A of the limit switches 36, 38, turning the limit switches 36, 38 on.

When the tip boom 46 rotates (swings) in one direction around the boom rotation shaft 48 relative to the base boom 44 and deploys, the boom rotation shaft 48 rotates in conjunction with the rotation of the tip boom 46 relative to the base boom 44, and the detection members 37, 39 rotate (in one direction around the boom rotation shaft 48) integrally with this boom rotation shaft 48. Until a predetermined angle before the tip boom 46 assumes the deployed position E (fully extended), the switch lever portion 36A of the limit switch 36 does not come into contact with the detection portion 37A of the rotating detection member 37, and the limit switch 36 is in the OFF state. From a predetermined angle before the tip boom 46 is fully extended (in other words, from the time the tip boom 46 is fully extended to the predetermined angle before that), the switch lever portion 36A of the limit switch 36 comes into contact with the detection portion 37A of the rotating detection member 37, and the limit switch 36 is in the ON state.

In other words, in this embodiment, the opening limit switch 36 is arranged so that when the cylinder 20 (piston rod 28) is fully extended to its maximum extension state and the front boom 46 is held in the deployed position E, it remains off up to a certain angle (e.g., several tens of degrees) before that point, and remains on from that point onwards.

Similarly, when the front boom 46 rotates (swings) in the other direction around the boom rotation shaft 48 relative to the base boom 44 to be folded, the boom rotation shaft 48 rotates in conjunction with the rotation of the front boom 46 relative to the base boom 44, and the detection members 37, 39 rotate integrally with this boom rotation shaft 48 (in the other direction around the boom rotation shaft 48). Until a predetermined angle before the front boom 46 assumes the folding position F (fully closed (folded)), the switch lever portion 38A of the limit switch 38 does not contact the detection portion 39A of the rotating detection member 39, and the limit switch 38 is in the OFF state. From a predetermined angle before the front boom 46 is fully closed (folded) (in other words, from the time the front boom 46 is fully closed (folded) to the predetermined angle before that), the switch lever portion 38A of the limit switch 38 contacts the detection portion 39A of the rotating detection member 39, and the limit switch 38 is in the ON state.

In other words, in this embodiment, the closing limit switch 38 is arranged so that when the cylinder 20 (piston rod 28) is fully retracted to its maximum retracted state and the front boom 46 is held in the folded position F, it remains off up to a predetermined angle (e.g., several tens of degrees) before that point, and remains on from that angle (e.g., several tens of degrees) onward.

In addition, in the boom spraying device 1 of this embodiment, in order to switch and reduce the amount of hydraulic oil flowing into and out of the cylinder 20, the first and second oil supply lines communicating with the two oil chambers 24A, 24B of the cylinder 20 are each provided with an oil supply line 32 without a throttle valve 33 and an oil supply line 34 with a throttle valve 33, as shown in Figures 5(A) and (B). This throttle valve 33 is provided to reduce the amount of hydraulic oil flowing into and out of the cylinder 20. Furthermore, a flow path switching valve 30 with a check valve is installed to switch the hydraulic circuit of the cylinder 20 between a hydraulic circuit 32L via the oil supply line 32 and a hydraulic circuit 34L via the oil supply line 34.

In this embodiment, the hydraulic circuit is switched by the flow path switching valve 30 based on signals (boom open signal, boom close signal) sent by the driver operating a lever attached to the traveling machine body and the on/off status of the limit switches 36, 38, as follows:

The flow path switching valve 30 is constantly biased in a direction that automatically returns it to a position that forms a hydraulic circuit 32L through the oil supply pipeline 32 (Figure 5(A)). When a boom open signal is issued and the opening limit switch 36 is turned on, for example, by the operator operating a lever provided on the traveling machine body, or when a boom close signal is issued and the closing limit switch 38 is turned on, the solenoid of the flow path switching valve 30 is energized (Figure 5(C)), and the flow path switching valve 30 switches the hydraulic circuit to form a hydraulic circuit 34L through the oil supply pipeline 34 (Figure 5(B)). When the boom open signal or boom close signal is no longer received, or when the limit switches 36, 38 are turned off, the flow path switching valve 30 automatically returns to a position that forms a hydraulic circuit 32L through the oil supply pipeline 32 (Figure 5(A)).

That is, the boom spraying device 1 in this embodiment operates as follows when opening and closing the boom. Note that the spraying nozzle 5 is not shown in Figures 6(C), 7(C), 8(C), and 9(C), which are referred to as appropriate in the following description.

The flow path switching valve 30 is constantly biased in a direction that automatically returns it to a position that forms a hydraulic circuit 32L through the oil supply pipeline 32. When a boom-open signal is issued, for example by the operator operating a lever provided on the traveling machine body, the piston rod 28 is driven in the extending direction, and the tip boom 46 swings (deploys) relative to the base boom 44. At this time, the boom rotation shaft 48 rotates in conjunction with the rotation of the tip boom 46 relative to the base boom 44, and the detection members 37, 39 rotate integrally with this boom rotation shaft 48 (in one direction around the boom rotation shaft 48). Until a certain angle before the tip boom 46 is fully opened, the switch lever portion 36A of the limit switch 36 does not come into contact with the detection portion 37A of the rotating detection member 37, and the limit switch 36 is in the OFF state. As a result, hydraulic oil is pumped from the hydraulic oil tank to the anti-rod-side oil chamber 24B through the hydraulic circuit 32L using the oil supply line 32 in the second oil supply line, and the hydraulic oil in the rod-side oil chamber 24A is returned to the hydraulic oil tank through the return line via the hydraulic circuit 32L using the oil supply line 32 in the first oil supply line, driving the piston rod 28 (without deceleration) in the extension direction (until just before the state shown in Figure 6).

Subsequently, when a boom-open signal is issued, for example by the operator operating a lever provided on the traveling machine body, the piston rod 28 is driven further in the extending direction, causing the front boom 46 to further swing (deploy) relative to the base boom 44. From a predetermined angle before the front boom 46 is fully opened (in other words, from the time the front boom 46 is fully opened to the predetermined angle before that), the switch lever portion 36A of the limit switch 36 comes into contact with the detecting portion 37A of the rotating detecting member 37, and the limit switch 36 is turned on. As a result, the solenoid of the flow path switching valve 30 is energized, switching the hydraulic circuit to form hydraulic circuit 34L through the oil supply line 34. Hydraulic oil is pumped from the hydraulic oil tank to the anti-rod-side oil chamber 24B via hydraulic circuit 34L using oil supply line 34 (with throttle valve 33) in the second oil supply line. At the same time, hydraulic oil in the rod-side oil chamber 24A is returned to the hydraulic oil tank via hydraulic circuit 34L using oil supply line 34 (with throttle valve 33) in the first oil supply line, driving the piston rod 28 (at reduced speed) in the extension direction (the state shown in Figures 6 and 7). When the piston rod 28 reaches its maximum extension state, the front boom 46 assumes (and is maintained in) the deployed position E.

As described above, when the tip boom 46 is in the deployed position E, the amount of hydraulic oil flowing in and out of the cylinder 20 (inflow amount) does not decrease (throttle) except between the tip boom 46 being fully opened and a certain angle short of that. This means that the extension speed of the cylinder 20 does not decrease, and the swing speed (opening speed) of the tip boom 46 relative to the base boom 44 does not decrease. On the other hand, between the tip boom 46 being fully opened and a certain angle short of that, the flow path switching valve 30 receives a signal from the limit switch 36 and switches the hydraulic circuit from hydraulic circuit 32L to hydraulic circuit 34L with throttle valve 33. This reduces (throttles) the amount of hydraulic oil flowing in and out of the cylinder 20, so the extension speed of the cylinder 20 decreases, and the swing speed (opening speed) of the tip boom 46 relative to the base boom 44 decreases.

Regarding the closing limit switch 38, in the angular range between when the front boom 46 is fully open and a certain angle short of that, the switch lever portion 38A of the limit switch 38 does not come into contact with the detecting portion 39A of the rotating detecting member 39, and the limit switch 38 is in the OFF state (non-operating state).

As described above, in this embodiment, when the tip boom 46 is deployed and aligned in series with the base boom 44, the swing speed (opening/closing speed) of the tip boom 46 is reduced just before that, thereby mitigating the impact on the base boom 44 and tip boom 46 when the tip boom 46 completes deployment.

When spraying is completed and a boom close signal is issued, for example by the operator operating a lever on the traveling machine body, the piston rod 28 is driven in the retracting direction, causing the front boom 46 to swing (fold) relative to the base boom 44. At this time, the boom rotation shaft 48 rotates in conjunction with the rotation of the front boom 46 relative to the base boom 44, and the detection members 37, 39 rotate integrally with this boom rotation shaft 48 (in the other direction around the boom rotation shaft 48). Until a certain angle before the front boom 46 is fully closed (folded), the switch lever portion 38A of the limit switch 38 does not come into contact with the detection portion 39A of the rotating detection member 39, and the limit switch 38 remains in the off state. As a result, hydraulic oil is pumped from the hydraulic oil tank into the rod-side oil chamber 24A through the hydraulic circuit 32L using the oil supply line 32 in the first oil supply line, and the hydraulic oil in the anti-rod-side oil chamber 24B is returned to the hydraulic oil tank through the return line through the hydraulic circuit 32L using the oil supply line 32 in the second oil supply line, driving the piston rod 28 in the retraction direction (without deceleration) (until just before the state shown in Figure 8).

Subsequently, when a boom close signal is issued, for example by the operator operating a lever provided on the traveling machine body, the piston rod 28 is driven further in the retracting direction, causing the front boom 46 to further swing (fold) relative to the base boom 44. From a position a certain angle before the front boom 46 is fully closed (fully folded) (in other words, from the position between the front boom 46 being fully closed (fully folded) and that certain angle before), the switch lever portion 38A of the limit switch 38 comes into contact with the detecting portion 39A of the rotating detecting member 39, and the limit switch 38 is turned on. As a result, the solenoid of the flow path switching valve 30 is energized, switching the hydraulic circuit to form hydraulic circuit 34L through the oil supply line 34. Hydraulic oil is pumped from the hydraulic oil tank to the rod-side oil chamber 24A via hydraulic circuit 34L using oil supply line 34 (with throttle valve 33) in the first oil supply line. At the same time, hydraulic oil in the anti-rod-side oil chamber 24B is returned to the hydraulic oil tank via hydraulic circuit 34L using oil supply line 34 (with throttle valve 33) in the second oil supply line, driving the piston rod 28 (at reduced speed) in the retracting direction (the state shown in Figures 8 and 9). When the piston rod 28 is fully retracted, the front boom 46 assumes (and is maintained in) the folding position F.

As described above, when the front boom 46 is in the folding position F, the amount of hydraulic oil flowing in and out of the cylinder 20 does not decrease (throttle) except during the period from when the front boom 46 is fully closed (folded) to just before that point. This means that the retraction speed of the cylinder 20 does not decrease, and the swing speed (closing speed) of the front boom 46 relative to the base boom 44 does not decrease. On the other hand, during the period from when the front boom 46 is fully closed (folded) to just before that point, the flow path switching valve 30 receives a signal from the limit switch 38 and switches the hydraulic circuit from hydraulic circuit 32L to hydraulic circuit 34L with throttle valve 33. This reduces (throttles) the amount of hydraulic oil flowing in and out of the cylinder 20, so the retraction speed of the cylinder 20 decreases, and the swing speed (closing speed) of the front boom 46 relative to the base boom 44 decreases.

Regarding the opening-side limit switch 36, in the angular range between when the front boom 46 is fully closed (folded) and just before that, the switch lever portion 36A of the limit switch 36 does not come into contact with the detecting portion 37A of the rotating detecting member 37, and the limit switch 36 is in the OFF state (non-operating state).

As described above, in this embodiment, when the leading boom 46 is folded above the base boom 44, the swing speed (opening/closing speed) of the leading boom 46 is reduced before that point, thereby mitigating the impact on the base boom 44 and leading boom 46 when the leading boom 46 completes folding.

In other words, the boom spraying device 1 of this embodiment can reduce the swing speed (opening/closing speed) of the front boom 46 just before the boom is fully deployed and just before the boom is fully folded, thereby mitigating the impact on the base boom 44 and front boom 46 that occurs when the front boom 46 is deployed and folded.

As described above, in the boom spraying device 1 of this embodiment, the cylinder 20 extends and retracts (controls extension and retraction) between the base-side first boom (base boom 44) and the tip-side second boom (lead boom 46), thereby maintaining the second boom (lead boom 46) in a predetermined position (deployed position E, folded position F) relative to the first boom (base boom 44). Flow control is performed in the hydraulic circuit of the cylinder 20 in response to the position of the second boom (lead boom 46) relative to the first boom (base boom 44) so that the amount of hydraulic oil flowing into the oil chambers 24A, 24B in the cylinder 20 is reduced (throttled) from the time when the second boom (lead boom 46) assumes the predetermined position (deployed position E, folded position F) relative to the first boom (base boom 44) until just before that (in other words, just before the time when the predetermined position (deployed position E, folded position F) is assumed).

Furthermore, by controlling the flow rate in the hydraulic circuit of the cylinder 20, the amount of hydraulic oil flowing into the oil chambers 24A, 24B in the cylinder 20 is reduced (throttled) from the time when the second boom (leading boom 46) assumes the predetermined position (deployed position E, folded position F) relative to the first boom (base boom 44) until just before that time, thereby reducing the extension/retraction speed of the cylinder 20 and reducing the swing speed of the second boom (leading boom 46) relative to the first boom (base boom 44).

According to this embodiment, by controlling the flow rate in the hydraulic circuit of the hydraulic cylinder 20 in accordance with the attitude of the second boom relative to the first boom, the amount of hydraulic oil flowing into the oil chambers 24A and 24B in the hydraulic cylinder 20 is reduced (throttled) between the time when the second boom is swung to a predetermined position relative to the first boom and just before that (between the angle at which the second boom is swung to a predetermined position relative to the first boom and the angle just before that). For example, when the tip-end boom is swung from the folded position F to the deployed position E, the amount of hydraulic oil flowing into the oil chambers 24A and 24B in the hydraulic cylinder 20 is reduced (throttled) just before the deployed position E. Furthermore, when the tip-end boom is swung from the deployed position E to the folded position F, the amount of hydraulic oil flowing into the oil chambers 24A and 24B in the hydraulic cylinder 20 is reduced (throttled) just before the folded position F. That is, when deploying (opening) the boom, the amount of hydraulic oil flowing into the oil chambers 24A and 24B is reduced between the fully extended position and a predetermined angle before that (from Figures 6 to 7), thereby slowing the cylinder operation (extension/retraction) speed and braking the boom opening operation (i.e., slowing the opening speed). Similarly, when folding (closing) the boom, the amount of hydraulic oil flowing into the oil chambers 24A and 24B is reduced between the fully closed position and a predetermined angle before that (from Figures 8 to 9), thereby slowing the cylinder operation (extension/retraction) speed and braking the boom closing operation (i.e., slowing the closing speed). This allows the brake to be applied only where necessary when opening or closing the boom, while maximizing the thrust of the hydraulic cylinder 20 in other areas. This effectively reduces the impact between the booms when opening or closing the boom, thereby effectively preventing damage or malfunction of the boom. Furthermore, the link section driven by the hydraulic cylinder 20 can be laid out with a relatively simple structure.

Furthermore, for example, by providing a sensor that detects the swinging displacement of the tip-end boom around the boom pivot shaft 48 in one direction (e.g., swinging displacement due to an opening operation) and a sensor that detects the swinging displacement of the tip-end boom around the boom pivot shaft 48 in the other direction (e.g., swinging displacement due to a closing operation) separately (on both sides of the boom pivot shaft 48 in the axial direction), the respective sensors (limit switches 36, 38, etc.) are relevant only during the boom opening operation or the boom closing operation. Therefore, the brakes are not applied to the boom opening/closing operation when the boom is closed from its fully opened position, or when the boom is opened from its fully closed position. Therefore, the brakes are applied only to the parts necessary for boom opening/closing, and the thrust of the hydraulic cylinder 20 is maximized otherwise. This effectively reduces the impact between the booms when they are opened or closed, thereby effectively preventing damage or malfunction of the boom.

Furthermore, when the booms swing in a vertical plane, the impact caused by the booms opening and closing is thought to be greater due to the effect of gravity than when the booms swing in a horizontal plane. According to this embodiment, it is possible to effectively mitigate the impact caused by the booms opening and closing even in such a situation.

In the above embodiment, flow control in the hydraulic circuit of the cylinder 20 is performed by switching the hydraulic circuit using the flow path switching valve 30 or the like. However, a configuration may also be adopted in which a flow control valve (solenoid valve) is installed in the oil supply pipeline communicating with the oil chambers 24A, 24B, and the control board receives detection signals from a position detection device composed of limit switches 36, 38, etc. to PWM-control the flow control valve (solenoid valve), controlling the open/close state (degree of open/close) of the oil supply pipeline and adjusting the flow rate of hydraulic oil in the oil supply pipeline, thereby controlling the inflow rate (oil volume) of hydraulic oil into the oil chambers 24A, 24B of the cylinder 20. Furthermore, the directional control valve for the boom opening/closing drive may be PWM-controlled (in other words, the directional control valve for the boom opening/closing drive may be used as the flow control valve) to control the inflow rate (oil volume) of hydraulic oil into the oil chambers 24A, 24B of the cylinder 20.

In addition, while the above embodiment describes an example in which the present invention is applied to the link mechanism 10 at the connection between the base boom 44 and the tip boom 46, it may also be applied to the link mechanism at the connection between the central boom 42 and the base boom 44, for example.

Furthermore, the boom spraying device 1 in the above embodiment may be a tractor-mounted type, a towed type, or a self-propelled type (rider type).

1 Boom spraying device 2 Machine frame 4 Boom (boom assembly)
5 Spray nozzle 6 Tank 8 Pressure pipe 10 Link mechanism 14 First link 15 Link connecting shaft 16 Second link 18 Link connecting shaft 20 Hydraulic cylinder (fluid pressure cylinder)
22 Cylinder tube 22e Inner end (rear end) of cylinder tube
22A Head side lid 22B Bottom side lid 23A Port (rod side port)
23B port (opposite rod side port)
24A Oil chamber (rod side oil chamber) (fluid chamber)
24B Oil chamber (opposite rod side oil chamber) (fluid chamber)
26 Piston 27 Sealing member (O-ring)
28 Piston rod 28e Outer end (front end) of piston rod
30 Flow path switching valve 32 Oil supply line 32L Hydraulic circuit (first fluid pressure circuit)
33 Throttle valve 34 Oil supply line with throttle valve 34L Hydraulic circuit with throttle valve (second fluid pressure circuit)
36 Opening side limit switch (first, deployment side attitude detection device)
36A Switch lever portion 37 Opening side detection member 37A Detection portion 38 Closing side limit switch (second, folding side posture detection device)
38A Switch lever portion 39 Closing side detection member 39A Detection portion 42 Central boom 44 Base boom 45 Receiving member 46 Front boom 47 Fitting member 48 Boom rotation shaft 49 Mounting bracket 50 Boom connection shaft C Closed position E Unfolded position F Folded position O Open position

Claims (11)

A boom spraying device in which a boom for spraying work is pivotally supported so as to be able to swing open and close on a machine frame installed on a traveling machine body,
a first boom on the base end side;
a second boom on the tip side that is swingably attached to the first boom;
a fluid pressure cylinder that extends and retracts to hold the second boom in a predetermined position relative to the first boom,
a flow rate control is performed in a fluid pressure circuit of the fluid pressure cylinder in accordance with the attitude of the second boom relative to the first boom so that the amount of working fluid flowing into the fluid chamber of the fluid pressure cylinder decreases during the period from when the second boom assumes the predetermined attitude relative to the first boom to just before that time ,
an attitude detection device is provided that detects an attitude of the second boom relative to the first boom;
A boom spraying device characterized in that flow rate control is performed on the fluid pressure circuit of the fluid pressure cylinder based on the detection signal of the posture detection device, so that the amount of working fluid flowing into the fluid chamber in the fluid pressure cylinder is reduced between the time when the second boom assumes the predetermined posture relative to the first boom and just before that time. The boom spraying device described in claim 1, characterized in that by controlling the flow rate in the fluid pressure circuit of the fluid pressure cylinder, the amount of hydraulic fluid flowing into the fluid chamber of the fluid pressure cylinder is reduced from the time when the second boom assumes the predetermined posture relative to the first boom until just before that time, thereby reducing the extension/retraction speed of the fluid pressure cylinder and reducing the swing speed of the second boom relative to the first boom. the predetermined position includes an unfolded position in which the second boom is unfolded relative to the first boom, and a folded position in which the second boom is folded relative to the first boom,
2. The boom spraying device according to claim 1, wherein, when the second boom is swung from the folded position to the deployed position, flow rate control is performed on the fluid pressure circuit of the fluid pressure cylinder so that the amount of working fluid flowing into the fluid chamber in the fluid pressure cylinder decreases just before the second boom assumes the deployed position. the predetermined position includes an unfolded position in which the second boom is unfolded relative to the first boom, and a folded position in which the second boom is folded relative to the first boom,
2. The boom spraying device according to claim 1, wherein, when the second boom is swung from the unfolded position to the folded position, flow rate control is performed on the fluid pressure circuit of the fluid pressure cylinder so that the amount of working fluid flowing into the fluid chamber in the fluid pressure cylinder decreases just before the second boom assumes the folded position. a first attitude detection device is provided on one end side of an axial direction of a boom rotation shaft of the first boom and the second boom, the first attitude detection device detecting an attitude of the second boom relative to the first boom when the second boom is swung and displaced in one direction around the boom rotation shaft relative to the first boom,
A boom spraying device as described in claim 1, characterized in that a second attitude detection device is provided on the other axial end side of the boom pivot axis of the first boom and the second boom, which detects the attitude of the second boom relative to the first boom when the second boom is swung and displaced in the other direction around the boom pivot axis relative to the first boom. the predetermined position includes an unfolded position in which the second boom is unfolded relative to the first boom, and a folded position in which the second boom is folded relative to the first boom,
a deployment-side attitude detection device is provided at one end side of an axial direction of a boom rotation shaft of the first boom and the second boom, the deployment-side attitude detection device detecting an attitude of the second boom relative to the first boom when the second boom is pivotally displaced from the folded attitude to the deployed attitude,
2. The boom spraying device according to claim 1, wherein a folding side attitude detection device is provided on the other axial end side of the boom pivot shaft of the first boom and the second boom, which detects the attitude of the second boom relative to the first boom when the second boom is swung from the unfolded attitude to the folded attitude. 2. The boom spraying device according to claim 1 , wherein the attitude detection device is provided at a connection between the first boom and the second boom. 8. The boom spraying device according to claim 7 , wherein the attitude detection device is provided on one of the first boom and the second boom. a first fluid pressure circuit that does not reduce the amount of working fluid flowing into the fluid chamber and a second fluid pressure circuit that reduces the amount of working fluid flowing into the fluid chamber are provided as a fluid pressure circuit of the fluid pressure cylinder in a switchable manner;
2. The boom spraying device of claim 1, wherein, when the second boom assumes the predetermined posture relative to the first boom, the fluid pressure circuit is switched from the first fluid pressure circuit to the second fluid pressure circuit between the time when the second boom assumes the predetermined posture relative to the first boom and just before that time, thereby reducing the amount of working fluid flowing into the fluid chamber in the fluid pressure cylinder. a flow rate regulating valve is provided that controls an open/close state of a conduit communicating with the fluid chamber to regulate the flow rate of the working fluid in the conduit;
A boom spraying device as described in claim 1, characterized in that when the second boom takes the predetermined posture relative to the first boom, the flow rate control valve is controlled between the time when the second boom takes the predetermined posture relative to the first boom and just before that time, thereby reducing the amount of working fluid flowing into the fluid chamber in the fluid pressure cylinder. 11. A boom spraying device according to claim 1, wherein the second boom is pivotally supported on the first boom so as to be swingable within a vertical plane.