Boom spraying device and hydraulic cylinder for opening and closing the boom

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 lowering opening / closing speed of the boom only at the fully-opened and folded (completely closed) areas without lowering opening / closing speed of booms other than near the fully-opened and folded (completely closed) areas.SOLUTION: Portions opposed to ports 23A, 23B in a piston 26 when a second boom (a tip boom 46) is fluctuated and displaced to a prescribed posture (an unfolded posture E, a folded posture F) with respect to a first boom (an original boom 44) are provided with tapered face parts 26A, 26B which are tapered (a diameter is reduced) in an axial direction of a cylinder 20.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a boom spraying device and a fluid pressure cylinder for opening and closing the boom. [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 disclosed in Patent Documents 3 and 4 keeps constant the cylinder operating (extending / retracting) speed that drives the boom at the tip end by extending and retracting and maintains its position, while using a link arrangement to reduce the opening and closing speed of the boom at the tip end when fully opening and retracting (fully closing) the boom. This results in problems such as a complex link arrangement, making the layout difficult and increasing costs.

[0012] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a boom spraying device and a fluid pressure cylinder for boom opening and closing that can reduce the impact between the booms when opening and closing the booms by reducing 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, 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, the fluid pressure cylinder having a cylindrical cylinder tube in which a working fluid is sealed, a piston rod that is inserted so as to be able to move back and forth within the cylinder tube, a piston connected to the piston rod and slidably inserted into the cylinder tube to define two front and rear fluid chambers, and two ports for letting working fluid in and out of each of the two fluid chambers, and is characterized in that when the second boom is swingably displaced to the predetermined position relative to the first boom, the part of the piston that faces the port is provided with a tapered surface portion that tapers toward the axial direction of the fluid pressure cylinder.

[0014] In a preferred aspect, when the second boom is swung and displaced to the predetermined posture relative to the first boom, the tapered surface portion restricts the amount of working fluid flowing out of the fluid chamber through the port, thereby reducing the extension and 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 the piston is provided with an unfolded-side tapered surface portion that tapers toward one end in the axial direction of the fluid pressure cylinder at a portion that faces one of the two ports when the second boom is swung and displaced to the unfolded posture, and a folded-side tapered surface portion that tapers toward the other end in the axial direction of the fluid pressure cylinder at a portion that faces the other of the two ports when the second boom is swung and displaced to the folded posture.

[0016] In a more preferred embodiment, the axial length of the deployment-side tapered surface portion is set to be longer than the axial length of the folding-side tapered surface portion.

[0017] In a more preferred embodiment, the inclination of the deployment-side tapered surface portion relative to the axial direction is set smaller than the inclination of the folding-side tapered surface portion relative to the axial direction.

[0018] In another preferred embodiment, the second boom is pivotally supported on the first boom so as to be swingable within a vertical plane.

[0019] Furthermore, the fluid pressure cylinder for opening and closing a boom according to the present invention is a fluid pressure cylinder for swinging a boom for spraying operation open and closed, and is a fluid pressure cylinder that holds a second boom, which is swingably attached to a first boom, in a predetermined position relative to the first boom by extending and contracting, and is characterized in that the fluid pressure cylinder has a cylindrical cylinder tube in which working fluid is sealed, a piston rod that is inserted into the cylinder tube so as to be able to move back and forth, a piston that is connected to the piston rod and is slidably inserted into the cylinder tube to define two front and rear fluid chambers, and two ports for letting working fluid in and out of each of the two fluid chambers, and a tapered surface portion that tapers in the axial direction of the fluid pressure cylinder is provided on the part of the piston that faces the port when the second boom is swingably displaced to the predetermined position relative to the first boom.

[0020] In a preferred aspect, the predetermined position includes two positions, and the piston is provided with a one-end tapered surface portion that tapers toward one end in the axial direction of the fluid pressure cylinder at a portion facing one of the two ports when the second boom is swung and displaced to one of the two positions, and an other-end tapered surface portion that tapers toward the other end in the axial direction of the fluid pressure cylinder at a portion facing the other of the two ports when the second boom is swung and displaced to the other of the two positions. [Effects of the Invention]

[0021] According to the present invention, by providing a tapered surface portion on the piston of the fluid pressure cylinder that drives the distal boom to open and close, the outflow of hydraulic fluid is restricted near the length of the fluid pressure cylinder when swinging the distal boom to a predetermined position relative to the base boom (e.g., maximum extension or maximum retraction). Therefore, the extension / retraction speed of the fluid pressure cylinder decreases only near the position where the distal boom is held in a predetermined position relative to the base boom (e.g., near the position where the boom is fully extended or fully retracted), and the boom is braked and decelerated (i.e., the boom swing speed or opening / closing speed decreases). This allows for the shock generated when the boom is opened or closed to be mitigated without reducing the swing speed or opening / closing speed other than the position where the distal boom is held in a predetermined position relative to the base boom (e.g., near the position where the boom is fully extended or fully retracted), thereby preventing damage or malfunction of the boom. Furthermore, because control is possible solely through the operation of the fluid pressure cylinder, the link section driven by the fluid pressure cylinder can be laid out with a relatively simple structure.

[0022] Furthermore, folding booms are usually provided with a collision prevention mechanism that prevents the booms from colliding with each other when folded, and this collision prevention mechanism tends to reduce the impact when the boom is opened and closed when folded compared to when it is unfolded. According to the present invention, by setting the unfolding-side tapered surface portion to be longer in the axial direction than the folding-side tapered surface portion, or by setting the inclination relative to the axial direction to be smaller, the impact when the boom is fully unfolded can be more effectively reduced.

[0023] 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]

[0024] [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] 1A and 1B show a state just before the front boom assumes the deployed posture in this embodiment, where FIG. 1A is a cross-sectional view showing the internal configuration of the hydraulic cylinder, and FIG. 1B is an enlarged front view of the main part of the connecting portion between the base boom and the front boom. [Figure 5] 1A and 1B show a state in which the front boom is in a deployed position in this embodiment, where FIG. 1A is a cross-sectional view showing the internal configuration of the hydraulic cylinder, and FIG. 1B is an enlarged front view of the main part of the connecting portion between the base boom and the front boom. [Figure 6] 1A and 1B show the state just before the front boom assumes the folded position in this embodiment, where FIG. 1A is a cross-sectional view showing the internal configuration of the hydraulic cylinder, and FIG. 1B is an enlarged front view of the main part of the connecting portion between the base boom and the front boom. [Figure 7] 1A and 1B show a state in which the front boom is in a folded position in this embodiment, where FIG. 1A is a cross-sectional view showing the internal configuration of the hydraulic cylinder, and FIG. 1B is an enlarged front view of the main part of the connecting portion between the base boom and the front boom. DETAILED DESCRIPTION OF THE INVENTION

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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...

[0029] 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.

[0030] 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).

[0031] 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 illustrated and explained.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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).

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] (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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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).

[0056] 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).

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] (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.

[0064] 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.

[0065] 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 .

[0066] 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.

[0067] 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 throttled by the piston 26 (explained later), and the front boom 46 takes the deployed position E (see also Figures 5(A) and (B)). 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 retracts to the maximum retracted state, and at the same time, the port 23B is throttled by the piston 26 (explained later), and the front boom 46 takes the folded position F (see also Figures 7(A) and (B)).

[0068] 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.

[0069] The direction switching 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] That is, in this embodiment, by devising the shape of the piston 26 around the time when the front boom 46 takes the deployed position E (when the cylinder 20 (piston rod 28) is in the maximum extended state) and the time when the front boom 46 takes the folded position F (when the cylinder 20 (piston rod 28) is in the maximum retracted state), the extension / contraction speed of the piston rod 28 is reduced, and the boom swing speed (opening / closing speed) is reduced.

[0074] In detail, the piston 26 of this embodiment has a sliding surface portion 26C having a short cylindrical shape (in other words, an outer peripheral surface composed of a short cylindrical surface), and tapered surface portions 26A, 26B (rod-side tapered surface portion 26A, anti-rod-side tapered surface portion 26B) having a truncated cone shape (in other words, an outer peripheral surface composed of a truncated cone surface or a tapered surface) provided in front of and behind the sliding surface portion 26C.

[0075] In other words, the piston 26 of this embodiment has tapered surface portions 26A, 26B (rod-side tapered surface portion 26A, anti-rod-side tapered surface portion 26B) at each of its two end portions, and has a sliding surface portion 26C between the tapered surface portions 26A, 26B.

[0076] The sliding surface portion 26C is provided slightly rearward of the center in the longitudinal direction (axial direction) of the cylinder 20, and is slidably inserted into the cylinder tube 22. In other words, the sliding surface portion 26C is in sliding contact with the inner circumferential surface of the cylinder tube 22 in an air-liquid tight manner via the sealing member (O-ring) 27.

[0077] The tapered surface portion 26A is connected to the front side (piston rod 28 side) of the sliding surface portion 26C and is configured as a tapered surface that tapers (reduces in diameter) toward the front end in the axial direction of the cylinder 20. The tapered surface portion 26B is connected to the rear side (opposite the piston rod 28 side) of the sliding surface portion 26C and is configured as a tapered surface that tapers (reduces in diameter) toward the rear end in the axial direction of the cylinder 20. In this embodiment, the sliding surface portion 26C is provided slightly rearward of the center in the axial direction of the cylinder 20, and therefore the tapered surface portion 26A has a longer length in the axial direction of the cylinder 20 than the tapered surface portion 26B. The inclination of the tapered surface portion 26A with respect to the axial direction of the cylinder 20, i.e., the reduction rate of the piston cross-sectional area, is set smaller than that of the tapered surface portion 26B.

[0078] In this embodiment, when the cylinder 20 (piston rod 28) is in a maximum extended state, the sliding surface portion 26C is located on the bottom side of the port 23A, and the tapered surface portion 26A is set to face the port 23A (see also FIG. 5A). When the cylinder 20 (piston rod 28) is in a maximum retracted state, the sliding surface portion 26C is located on the head side of the port 23B, and the tapered surface portion 26B is set to face the port 23B (see also FIG. 7A).

[0079] A hydraulic oil flow gap SA that allows hydraulic oil to flow is formed between the outer peripheral surface of the tapered surface portion 26A of the piston 26 and the inner peripheral surface of the cylinder tube 22. When the cylinder 20 (piston rod 28) extends to the maximum extension state shown in FIG. 5 (that is, when the front boom 46 is swung and displaced to the deployed posture E), the tapered surface portion 26A of the piston 26 reaches the position of the rod-side port 23A of the cylinder tube 22, and the amount of hydraulic oil flowing in and out of the rod-side port 23A (here, the amount flowing out) suddenly decreases. This state is a predetermined amount before the maximum extension state of the cylinder 20 (piston rod 28), as shown in FIG. When the cylinder 20 (piston rod 28) is further extended from the state shown in Figure 4 to the maximum extended state shown in Figure 5, the tapered surface portion 26A of the piston 26 faces the rod side port 23A of the cylinder tube 22, the hydraulic oil flow gap SA in the rod side port 23A gradually decreases, and the amount of hydraulic oil flowing in and out (outflow amount) of the rod side port 23A gradually decreases.

[0080] As described above, the tapered surface portion 26A gradually throttles (reduces) the amount of hydraulic oil flowing in and out (amount of oil flowing out) from just before the maximum extension state shown in Fig. 4 to the maximum extension state shown in Fig. 5 (compared to just before the maximum extension state shown in Fig. 4), thereby applying a brake to the cylinder 20 (piston rod 28), reducing the extension speed of the cylinder 20 and reducing the swing speed (deployment speed) of the front boom 46 relative to the base boom 44. In other words, the boom is braked and decelerated only between the point where the boom is fully extended (Fig. 5) and just before that point (Fig. 4).

[0081] When the cylinder 20 (piston rod 28) is fully extended to the maximum extension state shown in FIG.

[0082] The period from just before the maximum extension state shown in FIG. 4 to the maximum extension state shown in FIG. 5, in other words, the period from when the boom is fully extended (FIG. 5) to just before that (FIG. 4), can also be called the cushion stroke, which reduces (decels off) the boom opening / closing speed.

[0083] 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.

[0084] Similarly, a hydraulic oil flow gap SB that allows hydraulic oil to flow is formed between the outer peripheral surface of the tapered surface portion 26B of the piston 26 and the inner peripheral surface of the cylinder tube 22. When the cylinder 20 (piston rod 28) contracts to the maximum contracted state shown in FIG. 7 (that is, when the front boom 46 is swung and displaced to the folded posture F), the tapered surface portion 26B of the piston 26 reaches the position of the anti-rod-side port 23B of the cylinder tube 22, and the amount of hydraulic oil flowing in and out of (here, the outflow amount) the anti-rod-side port 23B suddenly decreases. This state is a predetermined amount before the maximum contracted state of the cylinder 20 (piston rod 28), as shown in FIG. When the cylinder 20 (piston rod 28) further contracts from the state shown in Figure 6 to the maximum contracted state shown in Figure 7, the tapered surface portion 26B of the piston 26 faces the anti-rod side port 23B of the cylinder tube 22, the hydraulic oil flow gap SB in the anti-rod side port 23B gradually decreases, and the amount of hydraulic oil flowing in and out (amount flowing out) from the anti-rod side port 23B gradually decreases.

[0085] As described above, the tapered surface portion 26B gradually throttles (reduces) the amount of hydraulic oil flowing in and out (amount of oil flowing out) from just before the maximum contraction state shown in Fig. 6 to the maximum contraction state shown in Fig. 7 (more than just before the maximum contraction state shown in Fig. 6), thereby applying a brake to the cylinder 20 (piston rod 28), reducing the contraction speed of the cylinder 20 and reducing the swing speed (folding speed) of the front boom 46 relative to the base boom 44. In other words, the boom is braked and decelerated only between the time when the boom is fully closed (Fig. 7) and just before that (Fig. 6).

[0086] When the cylinder 20 (piston rod 28) is fully contracted to the maximum contracted state shown in FIG.

[0087] The period from just before the maximum contraction state shown in FIG. 6 to the maximum contraction state shown in FIG. 7, in other words, the period from when the boom is fully closed (FIG. 7) to just before that (FIG. 6), can also be called a cushion stroke, which reduces (decels off) the opening and closing speed of the boom.

[0088] 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.

[0089] 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.

[0090] Furthermore, the folding boom 4 of this embodiment is provided with a collision prevention mechanism (receiving member 45, fitting member 47) that prevents collision between the base boom 44 and the front boom 46 when the front boom 46 is folded (overlapped) above the base boom 44, as described above (see Figure 1).

[0091] In the present embodiment, it is believed that the collision prevention mechanism reduces the impact on the base boom 44 and the tip boom 46 when the tip boom 46 is folded above the base boom 44. Therefore, in order to more effectively reduce the impact on the base boom 44 and the tip boom 46 when unfolding than when folding, as described above, the tapered surface portion 26A is set to have a longer length in the axial direction of the cylinder 20 than the tapered surface portion 26B (conversely, the tapered surface portion 26B is set to have a shorter length in the axial direction of the cylinder 20 than the tapered surface portion 26A), and the inclination with respect to the axial direction of the cylinder 20 is set to be small.

[0092] 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 (front boom 46) on the tip end side, thereby holding the second boom (front boom 46) in a predetermined position (deployed position E, folded position F) relative to the first boom (base boom 44). Tapered surface portions 26A, 26B that taper (reduced in diameter) toward the axial direction of the cylinder 20 are provided in portions of the piston 26 that face the ports 23A, 23B when the second boom (front boom 46) is swung and displaced to the predetermined position (deployed position E, folded position F) relative to the first boom (base boom 44).

[0093] When the second boom (leading boom 46) is swung and displaced to the predetermined position (deployed position E, folded position F) relative to the first boom (base boom 44), the tapered surface portions 26A, 26B restrict (reduce) the amount of hydraulic oil flowing out of the oil chambers 24A, 24B through the ports 23A, 23B (the amount of hydraulic oil flowing out at the ports 23A, 23B), thereby reducing the extension / retraction speed of the cylinder 20 and reducing the swing speed (opening / closing speed) of the second boom (leading boom 46) relative to the first boom (base boom 44).

[0094] According to this embodiment, by providing tapered surfaces 26A, 26B on the piston 26 of the hydraulic cylinder 20 that drives the distal boom to open and close, the outflow rate (oil volume) of hydraulic oil is throttled near the length (e.g., maximum extension or maximum retraction) of the hydraulic cylinder 20 (within the cushion stroke range) when the distal boom is swung and displaced to a predetermined position relative to the base boom. Therefore, the extension / retraction speed of the hydraulic cylinder 20 decreases only near the position where the distal boom is held in a predetermined position relative to the base boom (e.g., near the end of the boom's full extension or retraction), and the boom is braked and decelerated (i.e., the boom's swing speed or opening / closing speed decreases). This makes it possible to mitigate the impact when the boom is opened or closed without reducing the swing speed or opening / closing speed other than the position where the distal boom is held in a predetermined position relative to the base boom (e.g., near the end of the boom's full extension or retraction). This makes it possible to prevent damage to or malfunction of the boom. Furthermore, since control is possible only through the operation of the hydraulic cylinder 20, the link portion driven by the hydraulic cylinder 20 can be laid out with a relatively simple structure.

[0095] Furthermore, folding booms are usually provided with a collision prevention mechanism that prevents the booms from colliding with each other when folded, and this collision prevention mechanism tends to reduce the impact when the boom is opened and closed when folded compared to when it is unfolded. According to this embodiment, by setting the axial length of unfolding-side tapered surface portion 26A to be longer than that of folding-side tapered surface portion 26B, or by setting the inclination relative to the axial direction to be smaller, the impact when the boom is fully unfolded can be more effectively reduced.

[0096] 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.

[0097] Furthermore, the effectiveness of the cushion stroke of the boom spraying device 1 can be adjusted by changing the position of the outer end (front end) 28e of the piston rod 28 of the cylinder 20, so it can be used with a common component configuration even if the weight of the front boom 46 changes depending on, for example, the length of the boom 4.

[0098] In the above embodiment, an example is described in which two tapered surface portions 26A, 26B (rod-side tapered surface portion 26A and anti-rod-side tapered surface portion 26B) are provided on one piston 26, but it is of course possible to provide only one of the two tapered surface portions 26A, 26B. In addition, the positions, sizes, etc. of the tapered surface portions 26A, 26B on the piston 26 are not particularly limited.

[0099] 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.

[0100] 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]

[0101] 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 26A Tapered surface (Rod side tapered surface) (Deployment side tapered surface) 26B Tapered surface (opposite rod side tapered surface) (folding side tapered surface) 26C Sliding surface part 27 Sealing material (O-ring) 28 Piston rod 28e Outer end (front end) of piston rod 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 SA Hydraulic oil flow gap SB Hydraulic oil flow gap

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, The fluid pressure cylinder includes a cylindrical cylinder tube filled with hydraulic fluid, a piston rod inserted into the cylinder tube so as to be able to move back and forth, a piston connected to the piston rod and slidably inserted into the cylinder tube to define two fluid chambers, one in front and one in back, and two ports for feeding and discharging hydraulic fluid into and from the two fluid chambers, respectively. 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, the piston is provided with an extension-side tapered surface portion that tapers toward one end in the axial direction of the fluid pressure cylinder at one end that faces one of the two ports when the second boom is pivotally displaced to the extended posture, and a folding-side tapered surface portion that tapers toward the other end in the axial direction of the fluid pressure cylinder at the other end that faces the other of the two ports when the second boom is pivotally displaced to the folded posture, the axial length of the deployment-side tapered surface portion is set to be longer than the axial length of the folding-side tapered surface portion, A boom spraying device characterized in that the inclination of the unfolding side tapered surface portion relative to the axial direction is set to be smaller than the inclination of the folding side tapered surface portion relative to the axial direction.

2. when the second boom is swung and displaced to the deployed posture, the deployment-side tapered surface portion restricts the outflow amount of the working fluid from the fluid chamber through the one port, thereby reducing the extension / contraction speed of the fluid pressure cylinder and reducing the swing speed of the second boom relative to the first boom, 2. The boom spraying device of claim 1, wherein when the second boom is swung to the folded posture, the folding side tapered surface portion narrows the amount of working fluid flowing out of the fluid chamber through the other port, thereby reducing the extension / contraction speed of the fluid pressure cylinder and reducing the swing speed of the second boom relative to the first boom.

3. 3. 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.

4. A fluid pressure cylinder for swinging a boom for spraying work open and closed, the fluid pressure cylinder extending and contracting to hold a second boom swingably attached to a first boom in a predetermined position relative to the first boom, The fluid pressure cylinder includes a cylindrical cylinder tube filled with hydraulic fluid, a piston rod inserted into the cylinder tube so as to be able to move back and forth, a piston connected to the piston rod and slidably inserted into the cylinder tube to define two fluid chambers, one in front and one in back, and two ports for feeding and discharging hydraulic fluid into and from the two fluid chambers, respectively. The predetermined posture includes two postures, the piston is provided with a one-end tapered surface portion that tapers toward one end in the axial direction of the fluid pressure cylinder at one end that faces one of the two ports when the second boom is swung and displaced to one of the two positions, and an other-end tapered surface portion that tapers toward the other end in the axial direction of the fluid pressure cylinder at the other end that faces the other of the two ports when the second boom is swung and displaced to the other of the two positions, The axial length of the one-end side tapered surface portion is set to be longer than the axial length of the other-end side tapered surface portion, 10. A fluid pressure cylinder for opening and closing a boom, wherein the inclination of the tapered surface portion on one end side relative to the axial direction is set smaller than the inclination of the tapered surface portion on the other end side relative to the axial direction.

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