Portable pile driver

Abstract

This portable pile driver has: a body; and a cylindrical holder part provided at a lower part of the body. The body has a built-in striking mechanism driven by an engine. The portable pile driver has a configuration in which the striking mechanism strikes the top of a pile inserted into the holder part from below. The holder part has a collar inserted thereinto, the collar having an insertion part that has an outer diameter corresponding to the inner diameter of the holder part, and an inner diameter corresponding to the outer diameter of the pile. The collar is prevented from falling off by a retaining ring mounted on the lower outer surface of the holder part.

Description

Portable pile driver

[0001] The present invention relates to a portable pile driver.

[0002] A portable pile driver that uses a small gasoline engine as a power source to operate a driving mechanism and drive wooden or metal pipe piles into the ground is proposed, for example, in Patent Document 1. This type of portable pile driver is configured so that the driving force of the driving mechanism is applied to the top of the pile with a cylindrical holder attached to the bottom of the machine body placed over the head of the pile.

[0003] At this time, the body of the pile driver rests on the top of the upright pile via the tubular holder, so in order to achieve a stable operating state, the tubular holder needs to stably hold the upper end of the pile to accommodate differences in pile thickness.

[0004] In the pile driver proposed in Patent Document 1, a centering means using multiple leaf springs is provided on the inner surface of the cylindrical holder, and the elastic force of the leaf springs elastically presses against the sides of the pile to accommodate differences in pile thickness, positioning the upper end of the pile in the center of the cylindrical holder.

[0005] However, although the pile driver described in Patent Document 1 can perform pile driving work in accordance with differences in pile thickness, the centering means uses a leaf spring that elastically deforms to position the upper end of the pile in the center of the cylindrical holder, which allows the machine to sway due to gravity, and therefore is still not satisfactory for performing stable pile driving work.

[0006] Japanese Patent Application Publication No. 10-266205

[0007] The present invention has been devised in light of the above-mentioned circumstances, and an object of the present invention is to provide a portable pile driver that can perform pile driving work more stably.

[0008] In order to solve the above problems, the present invention employs the following technical means.

[0009] In other words, the portable pile driver provided by the present invention has a main body incorporating a driving mechanism driven by an engine, and a cylindrical holder section provided at the bottom of the main body, and the driving mechanism drives the top of a pile inserted into the holder section from below, and is characterized in that a collar having an insertion section with an outer diameter corresponding to the inner diameter of the holder section and an inner diameter corresponding to the outer diameter of the pile is inserted into the holder section, and the collar is prevented from falling off by a retaining ring attached to the outer surface of the lower part of the holder section.

[0010] In a preferred embodiment, the retaining ring has an inner diameter slightly smaller than the outer diameter of the holder portion in its natural state, an elastically expandable cylindrical portion, and an inward flange portion provided at the bottom of the cylindrical portion for receiving the lower end of the collar, and is attached to the holder portion by the cylindrical portion elastically expanding and coming into close contact with the outer surface of the lower portion of the holder portion.

[0011] In a preferred embodiment, an annular groove is formed on the outer surface of the holder portion, and an annular protrusion that can be fitted into the annular groove is formed on the inner surface of the cylindrical portion of the retaining ring.

[0012] In a preferred embodiment, a plurality of types of collars having different inner diameters are prepared, and one selected from these is used.

[0013] Other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the drawings.

[0014] Fig. 2 is a cross-sectional view taken along line II-II of the portable pile driver shown in Fig. 1, which is a front view of the portable pile driver according to one embodiment of the present invention. Fig. 3 is a rear view of the portable pile driver shown in Fig. 1. Fig. 4 is an enlarged view of part C of Fig. 2. Fig. 5 is a cross-sectional view of a collar with different inner diameters. Fig. 6 is a cross-sectional view of a collar with different inner diameters.

[0015] Preferred embodiments of the present invention will now be described in detail with reference to the drawings.

[0016] As shown in Figures 1 to 3, the portable pile driver A1 has a main body 1 and an engine 2 mounted on the upper side of the main body 1. A small gasoline engine, for example, can be used as the engine 2. Because the portable pile driver A1 is equipped with the engine 2 as its own power source, it can be carried to a desired work site and drive piles B (Figure 2) into the ground without connecting to another power source.

[0017] The main body 1 has an upper crankcase 11 and a cylindrical tubular portion 12 connected to the lower part of the crankcase 11. The tubular portion 12 extends vertically, and the lower space of the crankcase 11 is connected to the internal space of the tubular portion 12.

[0018] 2, the crankcase 11 houses a crank mechanism 110 therein, which includes a rotatably supported pinion shaft 111, an idler gear 113 that rotates in mesh with a pinion 112 provided at the tip of the pinion shaft 111, a crank gear 114 that rotates in mesh with the idler gear 113, an eccentric shaft 116 provided at the other end of a crankshaft 115 that has the crank gear 114 at one end, and a crank arm 117 rotatably supported on the eccentric shaft 116. The pinion shaft 111 is concentric with the output shaft 20 of the engine 2 and extends horizontally. Accordingly, the crankshaft 115 and the eccentric shaft 116 also extend parallel to the pinion shaft 111, i.e., horizontally.

[0019] The tubular portion 12 houses a striking mechanism 120 operated by the crank mechanism 110. The striking mechanism 120 includes a cylindrical cylinder 121 provided along the inner wall of the tubular portion 12, a first piston 123 fitted into the cylinder 121 airtightly by an O-ring 122 so as to be vertically movable and to which the lower end of the crank arm 117 is swingably connected, a second piston 125 fitted into the lower part of the cylinder 121 airtightly by an O-ring 124 so as to be vertically movable, and a striking work body 127 supported so as to be vertically movable by a tubular portion 126 formed at the bottom of the tubular portion 12 so as to have an inner diameter smaller than that of the cylinder 121. The second piston 125 has a small-diameter portion 125a at its lower portion, which small-diameter portion 125a extends partially into the tubular portion 126. A cylindrical holder portion 13 is connected to the lower end of the tubular portion 12, into which the upper end of the pile B to be driven is inserted and held, and a flange 127a having an outer diameter corresponding to the inner diameter of the holder portion 13 is provided at the bottom of the driving work body 127. A collar 15 having an inner diameter D1 corresponding to the thickness of the pile B is provided below the holder portion 13, and this collar 15 is prevented from falling off by a cap-shaped retaining ring 16 attached to the lower end of the holder portion 13. The configurations of the collar 15 and retaining ring 16 will be described in further detail below.

[0020] The first piston 123 and the second piston 125 are both airtightly movable up and down within the cylinder 121, so that an airtight air chamber S is formed between the first piston 123 and the second piston 125. The first piston 123 is driven up and down by the crank mechanism 110, but as the first piston 123 moves upward, the second piston 125 is pulled up by the negative pressure generated in the air chamber S, causing it to move upward with a delay from the first piston 123. The next moment, the first piston 123 moves downward, causing a compressive force generated in the air chamber S, causing the second piston 125 to move downward at high speed and crash into the top of the striking body 127. The impact force at this time is extremely large, and by repeating this operation continuously, the striking body 127, which is in contact with the top of the pile B within the holder part 13, can effectively drive the pile B into the ground.

[0021] The engine 2 is mounted on the main body 1 so that the direction of the axis of its output shaft 20 basically coincides with the direction of the axis of the pinion shaft 111 and extends horizontally, and vibration-proof measures are taken between the engine 2 and the main body 1.

[0022] The first vibration-damping measure is to interpose a flexible coupling 21 between the output shaft 20 of the engine 2 and the pinion shaft 111, so that the output shaft 20 of the engine 2 and the pinion shaft 111 can be displaced relative to each other in the direction perpendicular to their axes. In this embodiment, the rotational power of the engine 2 is output via a centrifugal clutch 22, and the flexible coupling 21 is interposed between a clutch drum 221 of the centrifugal clutch and the pinion shaft 111. A known flexible coupling 21 can be used as the flexible coupling 21.

[0023] The second vibration-proofing measure is to support the engine 2 on the main body 1 via elastic members 41 and 42 .

[0024] First, a mounting member 230 is fixedly attached to the engine 2 by screws or the like. The mounting member 230 has an upright portion 231 extending between the output side surface of the engine 2 and the opposing side surface of the main body 1 (crankcase 11), and a horizontal portion 232 that wraps around from the bottom of the upright portion 231 and below the bottom of the engine 2. This mounting member 230 can be formed by bending a metal plate or the like. In this specification, the term "engine 2" is a concept that includes this mounting member 230.

[0025] On the other hand, a support plate 119 extending above the top surface of the crankcase 11 is fixedly provided on the side of the main body 1 (crankcase 11) facing the engine 2, and a bracket 5 extending below the horizontal portion 232 of the mounting member 230 is fixedly provided.

[0026] The upper part of the engine 2 is supported on the crankcase 11 by interposing elastic members 41 at two locations, left and right, between the upright portion 231 of the mounting member 230 and the support plate 119 when viewed in the direction of the output shaft 20 of the engine 2, and the lower part of the engine 2 is supported on the main body 1 by interposing elastic members 42 at two locations, left and right, between the horizontal portion 232 of the mounting member 230 and the bracket 5.

[0027] In this embodiment, the bracket 5 is composed of a pair of left and right arm-like bracket elements 51, 52 and a connecting member 53 bridging the tips of the bracket elements 51, 52. The pair of left and right arm-like bracket elements 51, 52 extend in a substantially horizontal direction, and in order to increase bending rigidity, vertical walls 512 are integrated with the side edges of a substantially horizontal plate 511 over their entire length, thereby increasing the section modulus. The pair of left and right bracket elements 51, 52 are positioned so as to sandwich the main body 1 from the left and right sides, and are fixed to the main body 1 using the screw means (not shown) that connects the crankcase 11 and tubular portion 12 described above.

[0028] The portable pile driver A1 according to this embodiment is provided with a handle 6 including an inverted U-shaped lifting section 61 located at the top of the main body 1 and a pair of left and right work handles 62 extending vertically from both ends of the lifting section 61. When performing pile driving work, the operator holds the pair of left and right work handles 62 with both hands. The work handles 62 are provided with an operating section 63 for adjusting the throttle opening of the engine 2.

[0029] As described above, a collar 15 having an inner diameter corresponding to the thickness of the stake B is provided below the holder portion 13, and this collar 15 is prevented from falling off by a cap-shaped retaining ring 16 attached to the lower end of the holder portion 13, but more specifically, it is configured as follows.

[0030] As shown in Figure 4, the collar 15 is made of, for example, metal or hard resin and has an overall cylindrical shape with appropriate vertical dimensions. It has an insertion portion 151 with an inner diameter D1 corresponding to the outer diameter of the pile B and an outer diameter D2 corresponding to the inner diameter of the holder portion 13. An outward flange 152 is formed at the lower end of the insertion portion 151. The outer diameter of the outward flange 152 is set to be larger than the inner diameter of the holder portion 13 but equal to or slightly smaller than the outer diameter of the holder portion 13. When the outward flange 152 abuts against the lower end of the holder portion 13, the collar 15 is prevented from entering the holder portion 13 any further. To reduce weight, the collar 15 also has multiple recesses 153 recessed from the outer periphery of the insertion portion 151. As shown in Figures 5 and 6, multiple types of collars 15 with different inner diameters D1 are prepared.

[0031] The retaining ring 16 is made of, for example, hard synthetic rubber, and has an inner diameter slightly smaller than the outer diameter of the holder portion 13 in its natural state. It has a cylindrical portion 161 that is elastically expandable in diameter, and an inward flange portion 162 that is provided at the bottom of the cylindrical portion 161 and receives the lower end of the collar 15. The retaining ring 16 is attached to the holder portion 13 by the cylindrical portion 161 elastically coming into close contact with the outer surface of the lower part of the holder portion 13. When the retaining ring 16 is attached, the inward flange portion 162 receives the lower end of the collar 15, preventing it from falling off.

[0032] During operation of the portable pile driver A1, the machine body vibrates violently, but in order to withstand such vibrations and maintain the function of the retaining ring 16 in preventing the collar 15 from falling off, in this embodiment, an annular groove 131 is formed in an appropriate portion of the outer periphery of the holder portion 13, and an annular protrusion 163 that can fit into the annular groove 131 is formed on the inner surface of the tubular portion 161 of the retaining ring 16. This configuration, combined with the elastic adhesion of the tubular portion 161 to the outer periphery of the holder portion 13, reliably prevents the retaining ring 16 from shifting downward and falling off.

[0033] Next, the operation of the portable pile driver A1 having the above configuration will be described.

[0034] The portable driving device A1 is held by inserting the top end of a pile B set in the ground into the collar 15 inside the holder part 13. At this time, the weight of the portable pile driver A1 causes the driving body 127 of the driving mechanism 120 to rest on the top of the pile B (FIG. 2). When the operating part 63 is operated to increase the rotation speed of the engine 2, the centrifugal clutch is engaged and the rotation output of the engine 2 is transmitted to the crank mechanism 110. As already explained, the driving body 127 of the driving mechanism 120 repeatedly drives the top end of the pile B with a powerful driving force. In this way, the pile B is driven efficiently into the ground.

[0035] During the work, the pile B is held by the collar 15 having an inner diameter D1 corresponding to the outer diameter of the pile B, so that the machine body does not sway unintentionally, and the pile driving work can be carried out stably.

[0036] When the thickness of the pile B changes, the collar 15 is replaced with one having an inner diameter corresponding to the thickness of the pile B. The retaining ring 16 is formed from an elastically deformable material such as synthetic rubber, and is attached to the holder part 13 by elastically contacting the outer surface of the holder part 13 and by the engagement of the annular groove 131 and the annular protrusion 163. Therefore, the collar 15 can be replaced by a simple operation without requiring any special tools: the upper end of the retaining ring 16 is forcibly spread open to release the engagement between the annular protrusion 163 and the annular groove 131, and the collar 15 is then removed by sliding it downward; the replacement collar 15 is then inserted into the holder part 13, and the retaining ring 16 is then reinstalled.

[0037] Of course, the present invention is not limited to the above-described embodiments, and all design modifications within the scope of the claims are included within the scope of the present invention.

[0038] For example, the portable pile driver A1 according to the embodiment employs a striking mechanism 120 that moves the striking work body 127 up and down via a crank mechanism 110, but the configuration of the striking mechanism 120 is not limited to this and any mechanism that can continuously strike the top of the pile B may be employed, and various types of striking mechanisms may be employed, such as a rotary hammer type striking mechanism as shown in Patent Document 1.

[0039] A1 Portable pile driver B Pile 1 Main body 120 Driving mechanism 13 Holder portion 131 Annular groove 15 Collar D1 Inner diameter D2 Outer diameter 151 Insertion portion 16 Retaining ring 161 Cylindrical portion 162 Inward flange 163 Annular protrusion 2 Engine

Claims

1. A portable pile driver having a main body incorporating a driving mechanism driven by an engine and a cylindrical holder part provided at the bottom of the main body, the driving mechanism driving the top of a pile inserted into the holder part from below, wherein a collar having an insertion part with an outer diameter corresponding to the inner diameter of the holder part and an inner diameter corresponding to the outer diameter of the pile is inserted into the holder part, and the collar is prevented from falling off by a retaining ring attached to the outer surface of the lower part of the holder part.

2. A portable pile driver as described in claim 1, wherein the retaining ring has an inner diameter slightly smaller than the outer diameter of the holder portion in its natural state, has an elastically expandable tubular portion, and an inward flange portion provided at the lower part of the tubular portion and receiving the lower end of the collar, and is attached to the holder portion by the tubular portion elastically expanding and coming into close contact with the outer surface of the lower part of the holder portion.

3. A portable pile driver as described in claim 2, wherein an annular groove is formed on the outer surface of said holder portion, and an annular protrusion capable of fitting into said annular groove is formed on the inner surface of said cylindrical portion of said retaining ring.

4. A portable pile driver as claimed in any one of claims 1 to 3, wherein a plurality of types of collars having different inner diameters are prepared, and a selected one of them is used.

5. A combination of said collar and said retaining ring for use in a portable pile driver as claimed in any one of claims 1 to 4.

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