Boom sprayer

Abstract

To provide a boom spraying device capable of relieving impact between booms when opening / closing a boom and of layout in a relatively simple structure by reducing opening / closing speed of the boom only in the fully-opened and folded (completely closed) areas without lowering the opening / closing speed of booms near areas other than the fully-opened and folded (completely closed) areas.SOLUTION: Flow control is performed on a hydraulic circuit of a cylinder 20 in accordance with a posture of a second boom (a tip boom 46) with respect to a first boom (an original boom 44) so that an inflow amount (an oil amount) of hydraulic operating fluid in oil chambers 24A, 24B in the cylinder 20 between when the second boom (the tip boom 46) takes a prescribed posture (an unfolding posture E, a folded posture F) with respect to the first boom (the original boom 44) and the time before that (in other words, before when the prescribed posture (the unfolding posture E, the folded posture F) is taken).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a boom spraying device. [Background technology]

[0002] 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, crossing the traveling direction of the traveling vehicle, and can spray a wide area corresponding to the length of the boom while traveling through the field.

[0003] The boom spraying device generally includes a mechanism for folding the boom to a predetermined storage position (also referred to as a storage position, etc.) when not in use. Various types of folding mechanisms (also referred to as an opening / closing mechanism, etc.) are known, and one that folds the boom, which extends outwardly in a direction intersecting the traveling direction of the traveling machine body, by approximately 90 degrees so that it faces the traveling direction of the traveling machine body (see Patent Documents 1 and 2 below).

[0004] 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. To overcome the disadvantages of a long boom, a device has been proposed in which the tip of the boom folds up in a substantially vertical direction (upward) (see Patent Document 3 below).

[0005] 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 when the boom is deployed in a straight line is transmitted to the connection between the base end boom and the tip end boom, which may cause damage or malfunction to each boom. Similarly, when the boom is folded from a deployed state, the impact at the moment when the boom is folded may cause damage or malfunction to each boom. For this reason, when deploying or folding the boom, the operator must operate it slowly and carefully, which is a cumbersome task at the start and end of work.

[0006] That is, with a folding boom like the one described above, the tip of the boom is opened and used during spraying work, and then folded (closed) when work is finished, creating a boom opening and closing motion. If this opening and closing motion 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 closed) or the moment of unfolding (also called fully opened), which could lead to damage or malfunction. To prevent this, the overall speed of the opening and closing motion must be slowed down, and the operator must operate the boom carefully, which will result in a decrease in workability.

[0007] Therefore, there have been proposals for reducing 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).

[0008] 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.

[0009] Patent Document 4 proposes slowing down the boom swing speed (opening / closing speed) at the start (starting end) and end (terminal end) of swing, thereby mitigating the impact during swing. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 5941759 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-132461 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-116078 [Patent Document 4] Japanese Utility Model Application Publication No. 60-005473 Summary of the Invention [Problem to be solved by the invention]

[0011] However, the prior art described in Patent Documents 3 and 4 maintain a constant cylinder operating (extending / retracting) speed, which drives the boom tip and maintains its position by extending / retracting, while reducing the opening / closing speed of the boom tip when fully opening and fully folding (closing) the boom by using a link arrangement. This results in problems such as a complex link arrangement, difficult layout, and increased costs. Furthermore, the opening / closing speed of the boom tip also decreases when operating in the opposite direction from a fully extended or fully folded (closed) state, resulting in a loss of hydraulic pressure in the hydraulic cylinder.

[0012] The present invention has been 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 other than near the fully opened and folded (closed) positions, thereby reducing the impact between the booms when opening and closing the booms, and that can be laid out with a relatively simple structure. [Means for solving the problem]

[0013] In order to solve the above problems, the boom spraying device of the present invention comprises a boom for spraying work pivoted to a body frame installed on a traveling body so that it can swing open and closed, a first boom at the base end, a second boom at the tip end that is swingable on the first boom, and a fluid pressure cylinder that operates to extend and retract to hold the second boom in a predetermined position relative to the first boom, and is characterized in that flow rate control is performed in the fluid pressure circuit of the fluid pressure cylinder depending on the position of the second boom relative to the first boom so that the amount of working fluid flowing into the fluid chamber in 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.

[0014] In a preferred aspect, by controlling the flow rate on the fluid pressure circuit of the fluid pressure cylinder, the amount of working fluid flowing into the fluid chamber of the fluid pressure cylinder is reduced during the period from 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.

[0015] In another preferred aspect, 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 and displaced 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 takes the unfolded posture.

[0016] In another preferred aspect, 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 and displaced 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.

[0017] In another preferred aspect, the fluid pressure circuit of the fluid pressure cylinder is provided in a switchable manner, and includes a first fluid pressure circuit that does not reduce the amount of working fluid that flows into the fluid chamber, and a second fluid pressure circuit that reduces the amount of working fluid that flows into the fluid chamber, and when the second boom assumes the predetermined posture relative to the first boom, the amount of working fluid that flows 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 posture.

[0018] In another preferred aspect, a flow control valve is provided that controls the open / close state of a pipe line communicating with the fluid chamber to adjust the flow rate of the working fluid in the pipe line, and when the second boom assumes the predetermined posture relative to the first boom, the amount of working 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 posture relative to the first boom and just before that time.

[0019] In another preferred aspect, 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 a detection signal from the attitude detection device, so that the amount of working fluid flowing into the fluid chamber of the fluid pressure cylinder is reduced during the period from when the second boom assumes the predetermined attitude relative to the first boom until that point.

[0020] In a further preferred aspect, a first attitude detection device is provided on one end side in the axial direction of the boom pivot shaft of the first boom and the second boom, for detecting 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 pivot shaft relative to the first boom, and a second attitude detection device is provided on the other end side in the axial direction of the boom pivot shaft of the first boom and the second boom, for detecting 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 pivot shaft relative to the first boom.

[0021] In a further preferred aspect, 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 a deployed-side posture detection device is provided at one end in the axial direction of a boom pivot shaft of the first boom and the second boom, 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 end in the axial direction of the boom pivot shaft of the first boom and the second boom, 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.

[0022] In a further preferred embodiment, the attitude detection device is provided at a connection between the first boom and the second boom.

[0023] In a further preferred embodiment, the attitude detection device is provided on one of the first boom and the second boom.

[0024] In a further preferred aspect, the fluid pressure circuit of the fluid pressure cylinder is provided in a switchable manner, and is configured to switch between a first fluid pressure circuit that does not reduce the amount of working fluid that flows into the fluid chamber, and a second fluid pressure circuit that reduces the amount of working fluid that flows into the fluid chamber, and when the second boom takes the predetermined attitude relative to the first boom, based on the detection signal from the attitude 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 takes the predetermined attitude relative to the first boom, thereby reducing the amount of working fluid that flows into the fluid chamber in the fluid pressure cylinder.

[0025] In a further preferred aspect, a flow control valve is provided that controls the open / close state of a pipe line communicating with the fluid chamber to adjust the flow rate of the working fluid in the pipe line, and when the second boom assumes the predetermined posture relative to the first boom, the amount of working 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 posture relative to the first boom and just before that time based on the detection signal from the posture detection device.

[0026] In another preferred embodiment, the second boom is pivotally supported on the first boom so as to be swingable within a vertical plane. [Effects of the Invention]

[0027] According to the present invention, by controlling the flow rate in the fluid pressure circuit of the fluid pressure cylinder in accordance with the attitude of the second boom relative to the first boom, the amount of working fluid flowing into 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 the 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 to the deployed position, the amount of working fluid flowing into the fluid chamber of the fluid pressure cylinder is reduced (throttled) from just before the deployed position. Also, when the tip end boom is swung from the deployed position to the folded position, the amount of working fluid flowing into 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 amount of working fluid flowing into the fluid chamber is reduced between the time when the boom is fully opened and just before that (a predetermined angle), thereby reducing the cylinder operation (extension / contraction) 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 point, thereby slowing down the cylinder operation (extension / retraction) speed and braking the boom closing operation (i.e., slowing down the closing speed). This allows the brake to be applied only to the parts of the boom that are necessary for opening and closing, while maximizing the thrust of the fluid pressure cylinder in other parts. This effectively reduces the impact between the booms when opening and closing, 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.

[0028] Furthermore, for example, by separately providing (on both sides of the axial direction of the boom pivot shaft) a sensor that detects the swing displacement of the tip-end boom around the boom pivot shaft in one direction (e.g., swing displacement due to an opening operation) and a sensor that detects the swing displacement of the tip-end boom around the boom pivot shaft in the other direction (e.g., swing displacement due to a closing operation), each sensor is relevant only during the boom opening operation or the boom closing operation. Therefore, the brake is not applied to the boom opening / closing operation when closing the boom from its fully opened position or when opening the boom from its fully closed position. Therefore, the brake is applied only to the parts of the boom that are necessary for opening and closing, and the thrust of the fluid pressure cylinder is maximized for other parts. This effectively reduces the impact between the booms when opening and closing the booms, thereby effectively preventing damage or malfunction of the booms.

[0029] Furthermore, when the booms swing in a vertical plane, the impact caused by the booms being opened or closed 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 being opened or closed even in such a situation. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a perspective view showing the overall configuration of a boom spraying device according to an embodiment of the present invention. FIG. [Figure 2] FIG. 2 is an enlarged perspective view of a main portion showing the configuration of a link mechanism at the connecting portion between the base boom and the tip boom in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view showing the internal configuration of the hydraulic cylinder shown in FIGS. 1 and 2. [Figure 4] 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. [Figure 5]2A and 2B show a part of the hydraulic circuit of the hydraulic cylinder in FIG. 1, where (A) is a hydraulic circuit diagram during normal operation (non-braking), (B) is a hydraulic circuit diagram during braking, and (C) is a diagram showing a part of the electrical circuit for switching the hydraulic circuit. [Figure 6] In this embodiment, this shows the state 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 connecting part 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 connecting part between the leading boom and the base boom (seen from the opening limit switch side). [Figure 7] This 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 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). [Figure 8] In this embodiment, this shows the state 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 connecting part 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 connecting part between the leading boom and the base boom (seen from the opening limit switch side). [Figure 9] This shows the state in which the leading boom is in a folded 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 connecting part between the leading boom and the base boom (seen from the closing limit switch side), and (C) is an enlarged rear view of the main part of the connecting part between the leading boom and the base boom (seen from the opening limit switch side). DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same 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 traveling direction of the traveling vehicle body.

[0032] Fig. 1 is a perspective view showing the overall configuration of a boom spraying device 1 according to an embodiment of the present invention. Fig. 2 is an enlarged perspective view of a main part showing the configuration of a link mechanism at the connecting portion of the base boom and the tip boom in Fig. 1.

[0033] The boom spraying device 1 of this embodiment is a device that is installed on a traveling vehicle that travels through a field, and that sprays a chemical solution or the like from a spray nozzle provided on a spraying boom while traveling through the field. As a basic configuration, this boom spraying device 1 is configured such that a boom provided with a spray nozzle for spraying work is pivotally supported on a vehicle frame that is installed on the traveling vehicle so that it can swing open and closed.

[0034] As shown in Figure 1, the boom spraying device 1 of this embodiment mainly comprises a machine frame 2, a boom 4 supported by the machine frame 2, a plurality of spraying nozzles 5, 5... arranged on the boom 4, a tank 6 for storing chemical liquid etc., and a pump (not shown) for supplying (pressurizing) the chemical liquid etc. in the tank 6 to each spraying nozzle 5, 5...

[0035] The machine frame 2 is installed on a traveling machine body (not shown) such as a tractor or towing vehicle that travels in a field, and supports the boom 4. In this embodiment, the machine body frame 2 is installed at the rear of the traveling machine body, but the installation location is not particularly limited, and it may be installed at the front of the traveling machine body, etc.

[0036] The boom 4 is a long member on which multiple spray nozzles 5, 5... are arranged. In this embodiment, in order to make the boom 4 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, the boom 4 may be referred to as a boom assembly 4. In addition, 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 in a substantially horizontal direction. 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 in a substantially vertical direction (in other words, within a substantially vertical plane).

[0037] The base boom 44 and the tip boom 46 are configured as a pair on the left and right, and since the boom 4 in this embodiment has a left-right symmetrical configuration, the left boom will be omitted in Figure 1 and only the right boom will be shown and explained.

[0038] The central boom 42 is supported (substantially horizontally) on the machine frame 2 in a state in which it extends to the left and right.

[0039] The base boom 44 is supported in a state in which it extends to the left and right 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 as to face diagonally forward of the central boom 42.

[0040] 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, which will be described later. In this embodiment, the top of the tip side of the base boom 44 and the top of the base end side of the front boom 46 are pivotally supported by a boom rotation shaft 48 (extending in a substantially horizontal direction) 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.

[0041] Furthermore, in the boom 4 of this embodiment, a collision prevention mechanism is arranged between the base boom 44 and the front boom 46 to prevent collision between the base boom 44 and the front boom 46 when the front boom 46 is folded (superimposed) above the base boom 44. The collision prevention mechanism in this embodiment is made up of an H-shaped receiving member 45 fixed to the upper surface of the base boom 44, and a fitting member 47 fixed to the upper surface (underside when folded) of the front boom 46 and fitted into the H-shaped receiving member 45.

[0042] Furthermore, 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 body, the size and shape of the field, etc.

[0043] The spray nozzles 5 spray chemicals, etc., pumped by a pump (described later), in the form of liquid, droplets, or mist, so as to trace 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 are selected appropriately depending on the type of chemicals, etc., to be sprayed, the crops to which the chemicals, etc., are to be sprayed, the length of the boom 4, etc.

[0044] The tank 6 is used to store chemical solutions and the like to be supplied to each of the spray nozzles 5, 5, etc. In this embodiment, the tank 6 is installed on the machine frame 2. The installation location of the tank 6 is not particularly limited, and it can be installed in any location on the traveling machine body, etc.

[0045] 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 body or the rotational force of the engine, etc. In this embodiment, the pump is installed on the machine body frame 2. The installation location of the pump is not particularly limited and it can be installed anywhere on the traveling machine body, etc. The pump and each spray nozzle 5, 5... are connected to each other so that they can flow through a pressure pipe 8.

[0046] The boom 4 comprises a pair of left and right booms, a base boom 44 and a front boom 46, which are respectively connected to the left and right ends of a central boom 42 by link mechanisms (not shown) so as to be foldable (openable and closable). The base boom 44 and the front boom 46 are connected to each other so as to be swingable by a link mechanism 10, and the front boom 46 is connected to the base boom 44 by the link mechanism 10 so as to be foldable in a substantially vertical direction (upward).

[0047] In the boom 4, the base boom 44 (and the tip boom 46) is configured to rotate (swing) 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) so as to face diagonally forward of the central boom 42, by a link mechanism (not shown) at the base side.

[0048] In addition, the front boom 46 is configured to rotate (swing) between an extended (open) position (deployed position) in the extension direction (outward in the left-right direction) of the base boom 44 and a folded (closed) position (folded position) above the base boom 44 by the link mechanism 10 on the tip side.

[0049] In the boom 4, when the base boom 44 assumes an unfolded position relative to the central boom 42 and the front boom 46 assumes an unfolded position relative to the base boom 44, the central boom 42, base boom 44, and front boom 46 assume positions in which they are extended 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 realized by the base boom 44 assuming an unfolded position relative to the central boom 42 while the front boom 46 is in a folded position relative to the base boom 44, and then the front boom 46 assuming an unfolded position relative to the base boom 44, or by the base boom 44 assuming a folded position relative to the central boom 42 while the front 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.

[0050] 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 the closed position C can be realized 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.

[0051] 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 direction of travel of the traveling body and a closed position C in which the tip side along the direction of travel of the traveling body faces diagonally upwards, by means of a link mechanism (not shown) at the base side and a link mechanism 10 at the tip side.

[0052] 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, a large number of spraying nozzles 5, 5... can be used to spray a wide area of ​​chemical solution, etc. at once on crops, etc. in the field.

[0053] Furthermore, 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 body, can be folded by approximately 90 degrees so as to face in the traveling direction of the traveling body and stored (stowed) in the closed position C. Situations in which the closed position C is taken also 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 respond to the shape of the field.

[0054] In the following description of the link portion of 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 link mechanism 10 on the tip side 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.

[0055] (Explanation of the link mechanism structure) Next, the link mechanism 10 at the connection between the base boom 44 and the tip boom 46 will be described. 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.

[0056] As shown in Figures 1 and 2, the link mechanism 10 in this embodiment has a first link 14 rotatably connected to the tip side of the base boom 44, a second link 16 rotatably connected to the base end side 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 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.

[0057] The hydraulic cylinder 20 of this embodiment uses hydraulic oil as a working fluid, but instead of hydraulic oil, a working fluid such as a water-soluble substitute liquid or a fluid such as gas may be used.

[0058] The first link 14 has its base end rotatably connected to the tip side of the base boom 44, and is swung by the cylinder 20 (the expansion and contraction operation of the cylinder 20), thereby raising and lowering the second link 16.

[0059] The second link 16 has its base end rotatably connected to the base end side 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.

[0060] The link connecting shaft 15 is a rotating shaft for rotatably connecting the tip end of the first link 14 and the tip end of the second link 16, and in this embodiment, it is inserted into bearings (not shown) provided at the tip end of the first link 14 and the second link 16 to rotatably support each tip end.

[0061] In this embodiment, the first link 14, the second link 16 and the link connecting shaft 15 are provided on the opposing surfaces of the base boom 44 and the tip boom 46 (the front and rear surfaces when in the deployed posture E).

[0062] The link mechanism 10 in this embodiment is provided with a link connecting shaft 18 that connects the first link 14 and the cylinder 20. In this embodiment, the link connecting shaft 18 is fixed (so as to extend horizontally) to and bridged at the tip ends of a pair of opposing first links 14 (provided on the front and rear surfaces when in the deployed posture E).

[0063] The cylinder 20 performs extension and contraction operation (extension and contraction control) to swing the first link 14 and the second link 16 connected by the link connecting shaft 15, thereby performing boom deployment control and boom folding control (opening and closing control). Therefore, when deploying the tip boom 46 that has been folded relative to the base boom 44, the cylinder 20 functions to position the link connecting shaft 15 on the base end side of the tip boom 46, and on the other hand, when folding the tip boom 46 that has been deployed relative to the base boom 44, the cylinder 20 functions to position the link connecting shaft 15 on the tip side of the base boom 44.

[0064] The telescopic cylinder 20 in this embodiment is interposed between the base boom 44 and the link connecting shaft 18 provided on the first link 14. In other words, the cylinder 20 is telescopically connected to the base boom 44 and the link connecting shaft 18. In this embodiment, an inner end 22e of a cylinder tube 22 of the cylinder 20 (rear end of the cylinder 20) is connected to a mounting bracket 49 fixed to the upper surface of the base boom 44 via a boom connecting shaft 50 so as to be relatively rotatable. In addition, an outer end 28e of a 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 connecting shaft 18 so as to be relatively rotatable.

[0065] In this embodiment, the cylinder 20 contracts to cause the first link 14 to swing 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 unfolded relative to the base boom 44, and the cylinder 20 extends to cause the first link 14 to swing 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 unfolding the tip boom 46 that has been folded relative to the base boom 44.

[0066] 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 contracted state, the leading boom 46 is held in a folded (closed) position F relative to the base boom 44.

[0067] As described above, the link mechanism 10 including the links 14 and 16 is driven by the cylinder 20 (which operates to extend and retract), 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.

[0068] Note that, as long as the base boom 44 and the tip boom 46 can be swung and displaced to maintain a predetermined posture, the types, number, and shapes of the members constituting the link mechanism 10, as well as the locations and manners of connection between the members, are not particularly limited and can be changed as appropriate depending on the layout, etc. For example, in the above embodiment, the cylinder 20 is held in the deployed posture E when it is in the maximum extended state, and is held in the folded posture F when it is in the maximum retracted state. However, the cylinder 20 may be held in the folded posture F when it is in the maximum extended state, and may be held in the deployed posture E when it is in the maximum retracted state. Furthermore, the cylinder 20 may be held in the deployed posture E or the folded posture F at a predetermined length between the maximum extended and maximum retracted states, or may be held in a predetermined posture (position) other than the deployed posture E or the folded posture F.

[0069] (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.

[0070] 3, the cylinder 20 includes 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 an operating 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 gas-liquid-tightly by a head-side lid 22A and a bottom-side lid 22B, which slidably receive the piston rod 28 gas-liquid-tightly.

[0071] The piston 26 in this embodiment is in sliding contact with the inner peripheral surface of the cylinder tube 22 in an air-liquid tight manner via a seal member (O-ring) 27 .

[0072] Furthermore, two ports (rod-side port 23A and anti-rod-side port 23B) for feeding and discharging hydraulic oil as a working fluid are formed in each of one oil chamber (rod-side oil chamber) 24A and the other oil chamber (anti-rod-side oil chamber) 24B in the cylinder tube 22. The two ports 23A, 23B are formed at positions spaced apart in the length direction (axial direction) of the cylinder 20 by a predetermined amount corresponding to the difference in extension length between the maximum extension state and the maximum contraction state of the cylinder 20.

[0073] Then, (the front end surface of) the piston 26 abuts against (the inner end surface of) the head side lid 22A, and the piston rod 28 extends to the maximum extended state, and at the same time, the port 23A is closed by the piston 26, and the front boom 46 takes the deployed position E (see also Figures 7(A) to (C)). Also, (the rear end surface of) the piston 26 abuts against (the inner end surface of) the bottom side lid 22B, and the piston rod 28 contracts to the maximum contracted state, and at the same time, the port 23B is closed by the piston 26, and the front boom 46 takes the folded position F (see also Figures 9(A) to (C)).

[0074] Although not shown in the drawings (see Patent Document 2 (JP 2004-132461 A) if necessary), a hydraulic pump as a fluid pressure-feeding means constituting the hydraulic circuit of cylinder 20 is driven by the power (drive shaft) of the traveling machine body, etc., and pressure-feeds hydraulic oil from a hydraulic oil tank as a hydraulic fluid tank mounted on boom spraying device 1 to a hydraulic oil discharge line. This hydraulic oil discharge line communicates with a directional control valve for driving the boom to open and close.

[0075] The directional control valve communicates with the two oil chambers 24A, 24B through a first oil supply line and a second oil supply line, and also communicates with the hydraulic oil tank through a return line.

[0076] 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 provided on 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 through the second oil feed line, and hydraulic oil in the rod-side oil chamber 24A is returned to the hydraulic oil tank from the return line through the first oil feed line, driving the piston rod 28 in the extension direction until the piston 26 abuts against the head-side cover 22A. When this piston rod 28 is fully extended, the front boom 46 is in the deployed position E, and by returning the directional control valve to the neutral position, the front boom 46 can be maintained in the deployed position E.

[0077] When spraying work is completed and a boom close signal is sent, for example by the operator operating a lever provided on the traveling machine body, the directional control valve switches the hydraulic circuit, and hydraulic oil is pressure-fed from the hydraulic oil tank to rod-side oil chamber 24A through the first oil feed line, and hydraulic oil in anti-rod-side oil chamber 24B is returned to the hydraulic oil tank from the return line through the second oil feed line, driving piston rod 28 in the retracting direction until piston 26 abuts against bottom-side lid 22B. When piston rod 28 is fully retracted, front boom 46 is in the folded position F, and by returning the directional control valve to the neutral position, front boom 46 can be maintained in the folded position F.

[0078] In this embodiment, the cylinder 20 of the link mechanism 10 reduces the impact between the base boom 44 and the tip boom 46 when the booms are extended or folded, and the following measures are taken to prevent damage or malfunction of the base boom 44 and tip boom 46.

[0079] That is, 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 front boom 46 relative to the base boom 44, in other words, at a predetermined timing according to the extension and contraction of the cylinder 20 (piston rod 28), thereby slowing down the extension and contraction speed of the piston rod 28 and slowing down the boom swing speed (opening and closing speed).

[0080] In particular, in this embodiment, when the cylinder 20 (piston rod 28) extends to its maximum extended state and the leading boom 46 takes on the deployed position E, and when the cylinder 20 (piston rod 28) retracts to its maximum retracted state and the leading boom 46 takes on the folded position F, the position (position) of the leading boom 46 relative to the base boom 44 is detected, and at a predetermined timing just before the deployed position E and the folded position F, the amount of hydraulic oil flowing in and out of the cylinder 20 is switched and reduced (throttled).

[0081] 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. Note that, in this embodiment, an example in which a limit switch is used as the position detection device will be described in detail, but a potentiometer or the like that can detect the rotation angle or amount of movement may also be used. Furthermore, the number and placement of the limit switches are not limited to those of the following embodiment.

[0082] The limit switches 36, 38 in this embodiment are provided at each position of the front boom 46 relative to the base boom 44 that is to be detected.

[0083] The limit switch 36 is for detecting the position (rotation angle) of the front boom 46 relative to the base boom 44 when the front boom 46 takes the deployed position E. Hereinafter, this limit switch 36 may be referred to as the opening side limit switch 36 or the deploying side limit switch 36. On the other hand, the limit switch 38 is for detecting the position (rotation angle) of the front boom 46 relative to the base boom 44 when the front boom 46 takes 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.

[0084] 1 and 2 as well as 4(A) and (B), in this embodiment, the opening side limit switch 36 and the closing side limit switch 38 are respectively attached on the surface (rear surface and front surface) of the tip of the base boom 44, near one end and the other axial end (rear end and front end) of a 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 attached 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 arranged on the base boom 44 side (only) of the base boom 44 and the tip boom 46, but they may also be arranged on the tip boom 46 side, or on both the base boom 44 and the tip boom 46.

[0085] The tip ends of the switch lever portions 36A, 38A of the limit switches 36, 38 are provided with rollers that come into contact with the target (detecting portions 37A, 39A of detecting members 37, 39, which will be described later).

[0086] Detector members 37, 39 (opening-side detector member 37, closing-side detector member 39) for turning on and off the opening-side limit switch 36 and the closing-side limit switch 38 are attached to one and the other axial ends (rear and front ends) of the boom rotation shaft 48. These detector members 37, 39 are configured as non-circular members having a generally disk shape with a portion of their outer periphery (a portion within a predetermined angular range) extending outward. The portion of the outer periphery of the detector members 37, 39 (the portion extending outward) serves as detector portions 37A, 39A that abut against switch lever portions 36A, 38A of the limit switches 36, 38 to turn on the limit switches 36, 38.

[0087] When the front boom 46 rotates (swings) in one direction about 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 front 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 about the boom rotation shaft 48). Until a predetermined angle before the front boom 46 assumes the deployed posture E (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. 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 detection portion 37A of the rotating detection member 37, and the limit switch 36 is in the ON state.

[0088] In other words, in this embodiment, the opening side 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 posture E, it is off up to a predetermined angle (for example, about several tens of degrees) before that, and is on from that angle (for example, about several tens of degrees) onwards.

[0089] Similarly, when the front boom 46 rotates (swings) in the other direction about the boom rotation shaft 48 relative to the base boom 44 and is 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 about the boom rotation shaft 48). Until a predetermined angle before the front boom 46 assumes the folding position F (fully closed (fully 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 is in the OFF state. From the predetermined angle before the front boom 46 is fully closed (fully folded) onwards (in other words, from the time the front boom 46 is fully closed (fully folded) to the predetermined angle before that), the switch lever portion 38A of the limit switch 38 comes into contact with the detection portion 39A of the rotating detection member 39, and the limit switch 38 is in the ON state.

[0090] In other words, in this embodiment, the closing side limit switch 38 is arranged so that when the cylinder 20 (piston rod 28) is fully contracted to the maximum contracted state and the front boom 46 is held in the folded position F, it is off up to a predetermined angle (for example, about several tens of degrees) before that, and is on from that predetermined angle (for example, about several tens of degrees) onwards.

[0091] 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. In addition, a flow path switching valve 30 with a check valve is interposed in order to switch the hydraulic circuit of the cylinder 20 between a hydraulic circuit 32L through the oil supply line 32 and a hydraulic circuit 34L through the oil supply line 34.

[0092] 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 provided on the traveling machine body and the on / off of the limit switches 36, 38, as follows:

[0093] 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 (FIG. 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 (FIG. 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 (FIG. 5(B)). When the boom open signal or the boom close signal is no longer received, or when the limit switches 36, 38 are turned off, the flow path switching valve 30 is automatically returned to the position that forms the hydraulic circuit 32L through the oil supply pipeline 32 (FIG. 5(A)).

[0094] That is, the boom spraying device 1 in this embodiment operates as follows when opening and closing the boom: Note that the spray 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.

[0095] 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 driver operating a lever provided on the traveling machine body, the piston rod 28 is driven in the extending direction, and the front 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 front 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 the front boom 46 reaches a predetermined angle before it 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. Therefore, hydraulic oil is pressurized from the hydraulic oil tank into the anti-rod side oil chamber 24B through the hydraulic circuit 32L using the oil supply pipe 32 in the second oil supply pipe, and the hydraulic oil in the rod side oil chamber 24A is returned to the hydraulic oil tank through the return pipe through the hydraulic circuit 32L using the oil supply pipe 32 in the first oil supply pipe, and the piston rod 28 is driven in the extension direction (without being decelerated) (until just before the state in Figure 6).

[0096] Subsequently, when a boom-open signal is issued, for example by the operator operating a lever provided on the traveling machine body, piston rod 28 is driven further in the extending direction, and front boom 46 further swings (deploys) relative to base boom 44. From a position a predetermined angle before the front boom 46 is fully opened (in other words, from the position where the front boom 46 is fully opened to the predetermined angle before that), switch lever portion 36A of limit switch 36 comes into contact with detecting portion 37A of rotating detecting member 37, and limit switch 36 is turned on. Therefore, the solenoid of flow path switching valve 30 is energized, flow path switching valve 30 switches the hydraulic circuit to form hydraulic circuit 34L through oil feed pipe 34, and hydraulic oil is pressure-fed from the hydraulic oil tank to anti-rod-side oil chamber 24B through hydraulic circuit 34L using oil feed pipe 34 (with throttle valve 33) in the second oil feed pipe, and hydraulic oil in rod-side oil chamber 24A is returned from the return pipe to the hydraulic oil tank through hydraulic circuit 34L using oil feed pipe 34 (with throttle valve 33) in the first oil feed pipe, driving (decelerating) piston rod 28 in the extension direction (the state shown in FIGS. 6 and 7). When this piston rod 28 reaches its maximum extension state, front boom 46 assumes (and is maintained in) the deployed position E.

[0097] As described above, when the front boom 46 takes on the deployed attitude E, the amount of hydraulic oil flowing in and out of (inflow rate) the cylinder 20 does not decrease (is not throttled) except in the range from when the front boom 46 is fully opened to a predetermined angle short of that, so the extension speed of the cylinder 20 does not decrease and the swing speed (opening speed) of the front boom 46 relative to the base boom 44 does not decrease. On the other hand, in the range from when the front boom 46 is fully opened to a predetermined angle short of that, the flow path switching valve 30, in response to a signal from the limit switch 36, switches the hydraulic circuit from the hydraulic circuit 32L to the hydraulic circuit 34L with the throttle valve 33, so the amount of hydraulic oil flowing in and out of (inflow rate) the cylinder 20 decreases (is throttled), so the extension speed of the cylinder 20 decreases and the swing speed (opening speed) of the front boom 46 relative to the base boom 44 decreases.

[0098] With regard to the closing side limit switch 38, in the angle range between when the front boom 46 is fully opened and when it is a certain angle short of that, 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 is in the off state (non-operating state).

[0099] As described above, in this embodiment, when the lead boom 46 is deployed and aligned in series with the base boom 44, the swing speed (opening / closing speed) of the lead boom 46 is reduced just before that, thereby mitigating the impact on the base boom 44 and lead boom 46 when the lead boom 46 completes deployment.

[0100] When spraying work is completed and a boom close signal is sent, for example by the operator operating a lever provided on the traveling machine body, piston rod 28 is driven in the retracting direction, and front boom 46 swings (folds) relative to base boom 44. At this time, boom rotation shaft 48 rotates in conjunction with the rotation of front boom 46 relative to base boom 44, and detection members 37, 39 rotate integrally with this boom rotation shaft 48 (in the other direction around boom rotation shaft 48). Until a predetermined angle before front boom 46 is fully closed (folded), switch lever portion 38A of limit switch 38 does not come into contact with detection portion 39A of rotating detection member 39, and limit switch 38 is in the OFF state. Therefore, hydraulic oil is pressurized from the hydraulic oil tank into the rod side oil chamber 24A through the hydraulic circuit 32L using the oil supply pipe 32 in the first oil supply pipe, and the hydraulic oil in the anti-rod side oil chamber 24B is returned to the hydraulic oil tank through the return pipe through the hydraulic circuit 32L using the oil supply pipe 32 in the second oil supply pipe, and the piston rod 28 is driven in the contraction direction (without being decelerated) (until just before the state in Figure 8).

[0101] Subsequently, when a boom close signal is issued, for example by the operator operating a lever provided on the traveling machine body, piston rod 28 is driven further in the retracting direction, and front boom 46 further swings (folds) relative to base boom 44. From a predetermined angle before front boom 46 is fully closed (fully folded) (in other words, from the time when front boom 46 is fully closed (fully folded) to the predetermined angle before that), switch lever portion 38A of limit switch 38 comes into contact with detecting portion 39A of rotating detecting member 39, and limit switch 38 is turned on. Therefore, the solenoid of flow path switching valve 30 is energized, and flow path switching valve 30 switches the hydraulic circuit to form hydraulic circuit 34L through oil feed pipe 34, and hydraulic oil is pressure-fed from the hydraulic oil tank to rod-side oil chamber 24A through hydraulic circuit 34L using oil feed pipe 34 (equipped with throttle valve 33) in the first oil feed pipe, and hydraulic oil in anti-rod-side oil chamber 24B is returned from the return pipe to the hydraulic oil tank through hydraulic circuit 34L using oil feed pipe 34 (equipped with throttle valve 33) in the second oil feed pipe, and piston rod 28 is driven (decelerated) in the retracting direction (the state shown in FIGS. 8 and 9). When piston rod 28 reaches the maximum retracted state, front boom 46 assumes (and is maintained in) the folding position F.

[0102] As described above, when the front boom 46 assumes the folding position F, the amount of hydraulic oil flowing in and out of (inflow rate) the cylinder 20 does not decrease (is not throttled) except during the period from when the front boom 46 is fully closed (folded) to just before that, so 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, the flow path switching valve 30, in response to a signal from the limit switch 38, switches the hydraulic circuit from the hydraulic circuit 32L to the hydraulic circuit 34L with the throttle valve 33, so the amount of hydraulic oil flowing in and out of (inflow rate) the cylinder 20 decreases (is throttled), 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.

[0103] With regard to the opening side limit switch 36, in the angle 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 detection portion 37A of the rotating detection member 37, and the limit switch 36 is in the off state (non-operating state).

[0104] As described above, in this embodiment, when the front boom 46 is folded above the base boom 44, the swing speed (opening / closing speed) of the front boom 46 is reduced just before that, thereby mitigating the impact on the base boom 44 and the front boom 46 when the front boom 46 completes folding.

[0105] 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, and can mitigate the impact on the base boom 44 and the front boom 46 that occurs when the front boom 46 is deployed and folded.

[0106] As described above, in the boom spraying device 1 of this embodiment, the cylinder 20 performs telescopic operation (telescopic control) between the first boom (base boom 44) on the base end side and the second boom (lead boom 46) on the tip end side, thereby holding the second boom (lead boom 46) in a predetermined position (deployed position E, folded position F) relative to the first boom (base boom 44). Then, flow rate control is performed in the hydraulic circuit of the cylinder 20 in accordance with 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).

[0107] Then, by controlling the flow rate on 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) takes on the predetermined posture (deployed posture E, folded posture 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).

[0108] According to this embodiment, by performing flow control 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, 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 the predetermined position relative to the first boom and the angle just before that). For example, when the boom at the tip end is swung from the folded position F to the unfolded position E, the amount of hydraulic oil flowing into the oil chambers 24A, 24B in the hydraulic cylinder 20 is reduced (throttled) just before the unfolded position E. Also, when the boom at the tip end is swung from the unfolded position E to the folded position F, the amount of hydraulic oil flowing into the oil chambers 24A, 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 opened position and a predetermined angle before that (from FIGS. 6 to 7), thereby reducing the cylinder operation (extension / retraction) speed and braking the boom opening operation (i.e., reducing the opening speed). Also, 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 FIGS. 8 to 9), thereby reducing the cylinder operation (extension / retraction) speed and braking the boom closing operation (i.e., reducing the closing speed). Therefore, the brake is applied only to the necessary parts when opening or closing the boom, and the thrust of the hydraulic cylinder 20 is maximized in other parts. 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 parts driven by the hydraulic cylinder 20 can be laid out with a relatively simple structure.

[0109] Furthermore, for example, by separately providing (on both sides of the axial direction of the boom pivot shaft 48) a sensor that detects the swing displacement of the distal boom about the boom pivot shaft 48 in one direction (e.g., swing displacement due to an opening operation) and a sensor that detects the swing displacement of the distal boom about the boom pivot shaft 48 in the other direction (e.g., swing displacement due to a closing operation), the respective sensors (limit switches 36, 38, etc.) are relevant only during the boom opening operation or the boom closing operation. Therefore, the brake is 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 brake is applied only to the portion required for the boom opening / closing operation, and the thrust of the hydraulic cylinder 20 is maximized otherwise. This effectively reduces the impact between the booms when the booms are opened or closed, thereby effectively preventing damage or malfunction of the boom.

[0110] Furthermore, when the booms swing in a vertical plane, the impact caused by opening and closing the booms 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 opening and closing the booms even in such a situation.

[0111] In the above embodiment, an example has been described in which the flow rate 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 rate adjustment valve (solenoid valve) is installed in the oil supply pipeline communicating with the oil chambers 24A, 24B, and the control board receives a detection signal from a position detection device composed of limit switches 36, 38 or the like to PWM-control the flow rate adjustment valve (solenoid valve), thereby controlling the open / closed state (degree of opening / closing) of the oil supply pipeline and adjusting the flow rate of the hydraulic oil in the oil supply pipeline, thereby controlling the inflow rate (oil amount) of the hydraulic oil into the oil chambers 24A, 24B in the cylinder 20. Also, the inflow rate (oil amount) of the hydraulic oil into the oil chambers 24A, 24B in the cylinder 20 may be controlled by PWM-controlling a directional control valve for driving the boom opening / closing operation (in other words, using the directional control valve for driving the boom opening / closing operation as the flow rate adjustment valve).

[0112] Furthermore, in the above embodiment, an example has been described 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, but it may also be applied to the link mechanism at the connection between the central boom 42 and the base boom 44, for example.

[0113] Furthermore, the boom spraying device 1 of the above embodiment may be a tractor-mounted type, a towed type, or a self-propelled type (rider type). [Explanation of symbols]

[0114] 1 boom sprayer 2 Aircraft 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 cover 22B Bottom 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 material (O-ring) 28 Piston rod 28e Outer end (front end) of piston rod 30 Flow path switching valve 32 Oil pipeline 32L Hydraulic circuit (first fluid pressure circuit) 33 Throttle valve 34 Oil pipeline 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 37 Opening side detection member 37A Detector 38 Closing limit switch (second, folding position detection device) 38A Switch lever 39 Closing side detection member 39A Detector 42 Central Boom 44 Former Boom 45 Receiving member 46 Front boom 47 Fitting member 48 Boom rotation axis 49 Mounting bracket 50 Boom connection shaft C Closed position E Deployed posture F Folded position O open position

Claims

1. 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.

2. 2. The boom spraying device of claim 1, wherein by controlling the flow rate on the fluid pressure circuit of the fluid pressure cylinder, 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 extension / retraction speed of the fluid pressure cylinder is reduced, and the swing speed of the second boom relative to the first boom is reduced.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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. 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.

9. 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.

10. 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. 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.

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