WO2007114601A2

WO2007114601A2 - Attachment coupler for heavy machinery having automatic safety device

Info

Publication number: WO2007114601A2
Application number: PCT/KR2007/001569
Authority: WO
Inventors: Jong-Hyuk Lim; Jong-Ho Park; Yong-Jeong Park
Original assignee: Everdigm Co., Ltd.
Priority date: 2006-03-31
Filing date: 2007-03-30
Publication date: 2007-10-11
Also published as: WO2007114601A3

Abstract

An attachment coupler for heavy machinery includes a fixed hook, a movable hook, and a hydraulic cylinder actuating the movable hook. An end of the movable hook is hinge coupled to a body of the coupler and the hydraulic cylinder and a safety device are pin coupled to another end of the movable hook. The safety device includes a cylinder housing, a cylinder rod having a step portion formed in a radial direction at a position separated from a leading end, a first piston coupled to a leading end of the cylinder rod, a second piston having a through hole at the center thereof, a spring installed between the first piston and the second piston, holes formed on the second piston, steel balls inserted in the holes, and locking grooves formed on an inner wall of the cylinder housing.

Description

ATTACHMENT COUPLER FOR HEAVY MACHINERY HAVING AUTOMATIC SAFETY

DEVICE

TECHNICAL FIELD

The present invention relates to an attachment coupler for heavy machinery having an automatic safety device, and more particularly, to an attachment coupler for heavy machinery which prevents an attachment from being accidentally separated from a coupler if a rod of a hydraulic cylinder of the attachment coupler breaks or pressurized oil leaks, by doubly supporting a movable hook of the coupler using the hydraulic cylinder and an automatic safety device cylinder and unlocking the automatic safety device cylinder only when the hydraulic cylinder is unlocked normally, so that when the hydraulic cylinder is locked normally, the automatic safety device cylinder is locked and thus the attachment can not be separated from the coupler.

BACKGROUND ART

In general, heavy machinery is widely used at construction sites, and is capable of using various attachments which can be attached by coupling as necessary. An excavator is a typical variety of heavy machinery that uses various attachments such as a bucket, a breaker, a vibrator, and a hammer, which can be attached or detached using a coupler installed between a lower end of an arm and a lower end of a link. A mechanical device to couple the attachment to the arm of the heavy machinery is referred to as the coupler. FIG. 1 illustrates an attachment coupler 10 for heavy machinery according to conventional technology. As shown in FIG. 1 , the attachment coupler 10 includes a fixed hook 60 and a movable hook 40. Coupling shafts 31a and 31 b of an attachment 30 are respectively inserted into the movable hook 40 and the fixed hook 60. The movable hook 40 has an end pin-coupled to the coupler 10 and another end pin-coupled to a rod 90 of a hydraulic cylinder 70. As the movable hook 40 is rotated by the hydraulic cylinder 70, the coupling shaft 31 a is locked or unlocked.

In the above conventional attachment coupler 10, if the pressurized oil supplied to the hydraulic cylinder 70 leaks or the rod 90 is broken or damaged, the attachment i 30 is separated from the coupler 10. That is, when the pressurized oil supplied to the hydraulic cylinder 70 leaks, the hydraulic cylinder 70 contracts quickly. Accordingly, as the movable hook 40 of the coupler 10 removes a force restricting the pin of the attachment 30 and no longer restricts the attachment 30, the attachment 30 is separated from the coupler 10.

Also, when the rod 90 of the hydraulic cylinder 70 breaks, the force pushing the movable hook 40 is removed and thus the movable hook 40 moves back and allows the attachment 30 to separate from the coupler 10.

DISCLOSURE OF INVENTION

To solve the above and/or other problems, the present invention provides an attachment coupler for heavy machinery having an automatic safety device which can prevent an attachment from separating from a coupler by locking an automatic safety device cylinder when the hydraulic cylinder is accidentally unlocked, for example, when a rod of a hydraulic cylinder of the attachment coupler is broken or pressurized oil leaks, by doubly supporting a movable hook of the coupler using the hydraulic cylinder and the automatic safety device cylinder and unlocking the automatic safety device cylinder only when the hydraulic cylinder is unlocked normally.

Also, the present invention provides an attachment coupler for heavy machinery having an automatic safety device which can smoothly unlock the hydraulic cylinder and the automatic safety device cylinder by preparing an unlocking operation by unlocking the automatic safety device cylinder prior to unlocking the hydraulic cylinder, during the unlocking operation of the attachment coupler, when the attachment coupler is doubly supported by the hydraulic cylinder and the automatic safety device cylinder. According to an aspect of the present invention, an attachment coupler for heavy machinery having an automatic safety device comprises a fixed hook and a movable hook coupled to coupling pins formed at an attachment for heavy construction machinery, and a hydraulic cylinder actuating the movable hook, wherein an end of the movable hook is hinge coupled to a body of the coupler and the hydraulic cylinder and a safety device are pin coupled to another end of the movable hook. The safety device comprises a cylinder housing, a cylinder rod reciprocating linearly in the cylinder housing and having a step portion formed in a radial direction at a position separated from a leading end, a first piston having a through hole at the center thereof wherein the leading end of the cylinder rod is coupled to the through hole, a second piston capable of moving between the first piston and the step portion of the cylinder rod by being placed around the cylinder rod, a spring installed between the first piston and the second piston, a plurality of holes formed in a surface of a circumference of the second piston, a plurality of steel balls inserted in the holes, and a plurality of locking grooves formed on an inner wall of the cylinder housing.

According to another aspect of the present invention, an attachment coupler for heavy machinery having an automatic safety device comprises a fixed hook and a movable hook coupled to coupling pins formed at an attachment for heavy construction machinery, and a hydraulic cylinder actuating the movable hook, wherein an end of the movable hook is hinge coupled to a body of the coupler and the hydraulic cylinder and a safety device are pin coupled to another end of the movable hook, and further comprises a hydraulic pump generating hydraulic pressure to contract and extend the hydraulic cylinder, a coupler locking side hydraulic line providing a path through which pressurized oil is transferred from the hydraulic pump to a cylinder head side of the hydraulic cylinder and the safety device to extend the hydraulic cylinder, a coupler unlocking side hydraulic line providing a path through which the pressurized oil is transferred from the hydraulic pump to a cylinder rod side of the hydraulic cylinder and the safety device to contract the hydraulic cylinder, and a sequence valve installed between the coupler unlocking side hydraulic line and the cylinder rod side of the hydraulic cylinder and opening only when oil is applied at more than a predetermined pressure, wherein the coupler unlocking side hydraulic line branches in front of the sequence valve so that a line is connected to the sequence valve and another line is connected directly to the safety device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of the conventional attachment coupler 10 for heavy machinery; FIG. 2 is a perspective view of the attachment coupler 10a for heavy machinery according to an embodiment of the present invention;

FIG. 3 is an exploded perspective of the automatic safety device cylinder 110 of the attachment coupler 10a for heavy machinery of FIG. 2;

FIGS. 4 and 5 are sectional views illustrating the operation of the attachment coupler 10a for heavy machinery of FIG. 2, showing the hydraulic cylinder 70 and the automatic safety device cylinder 110 contracted in FIG. 4 and extended in FIG. 5; FIG. 6 is a sectional view showing the automatic safety device cylinder 110 locked in the attachment coupler 10a of FIG. 2;

FIG. 7A is a sectional view showing the automatic safety device cylinder 110 of FIG. 4 contracted;

FIG. 7B is a sectional view taken along line X-X of FIG. 7A; FIG. 8 is a sectional view showing the automatic safety device cylinder 110 of

FIG. 5 extended;

FIG. 9 is a sectional view showing the automatic safety device cylinder 110 locked as shown in FIG. 6;

FIG. 10 is a sectional view showing the automatic safety device cylinder 110 extended in the attachment coupler 10a of FIG. 2;

FIG. 11 is a sectional view showing the automatic safety device cylinder 110 contracted in the attachment coupler 10a of FIG. 2;

FIG. 12 is a sectional view illustrating the lubrication oil supply hole 270 and the air intake/exhaust path 260 added to the automatic safety device cylinder 110 of FIG. 7A;

FIG. 13 is a hydraulic circuit diagram of the attachment coupler 10a of FIG. 2;

FIG. 14 is a perspective view of the attachment coupler 10b for heavy machinery according to another embodiment of the present invention;

FIGS. 15 and 16 are hydraulic circuit diagrams of the attachment coupler 10b of FIG. 14, showing the sequence valve 72 closed in FIG. 15 and open in FIG. 16; and

FIG. 17 is a sectional view illustrating the operation of the attachment coupler 10b for heavy machinery of FIG. 14, in which the hydraulic cylinder 70 and the automatic safety device cylinder 110 of the attachment coupler 10b are extended.

<List of major elements> 10, 10a, 10b: attachment coupler for heavy machinery

20: coupler body

30: attachment 40: movable hook 50: hinge shaft 60: fixed hook

70: hydraulic cylinder 80: hydraulic cylinder housing

90: hydraulic cylinder rod

100: hydraulic cylinder unlocking side port

101 : coupler unlocking side hydraulic line

102: coupler locking side hydraulic line

103: hydraulic line 104: return line

110: automatic safety device cylinder 120: cylinder housing

130; cylinder rod 140: first piston

150: second piston 160: spring

170: steel ball 171 : hole

180: hose union 181 , 181a: oil path

190: first stop step 200: second stop step

210: third stop step 220: fourth stop step

230: first tapered portion 231 : locking grooves

250: rounded portion

240: second tapered portion 260: air intake/exhaust hole

270: supply hole (grease nipple) 280: first fixing pin

290: second fixing pin 300: first fixing hole

310: second fixing hole 320: hydraulic line

330: solenoid valve

340: oil tank 350: hydraulic pump

BEST MODE FOR CARRYING OUT THE INVENTION The structure, function, and effect of an attachment coupler for heavy machinery according to the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 2 is a perspective view of an attachment coupler 10a for heavy machinery according to an embodiment of the present invention. Referring to FIG. 2, the attachment coupler 10a according to the present embodiment includes a coupler body

20. A fixed hook 60 and a movable hook 40 are installed under the coupler body 20, separated from each other. The fixed hook 60 is integrally formed with the coupler body 20. The movable hook 40 rotates around a hinge shaft 50. A hydraulic cylinder 70 for rotating the movable hook 40 is installed. The hydraulic cylinder 70 includes a hydraulic cylinder housing 80 and a hydraulic cylinder rod 90. The hydraulic cylinder housing 80 is fixed to the coupler body 20 by a second fixing pin 290. The hydraulic cylinder rod 90 is fixed by a first fixing pin 280 at a side of the movable hook 40.

The hydraulic cylinder 70 is extended or contracted by pressurized oil supplied from an excavator to rotate the movable hook 40. A first fixing hole 300 formed in a housing 120 of an automatic safety device cylinder 110 according to the present embodiment is coaxial with the first fixing pin 280 which couples the hydraulic cylinder rod 90 and the movable hook 40, and fixed together by the first fixing pin 280. Also, a second fixing hole 310 of a cylinder rod 130 of the automatic safety device cylinder 110 is coaxial with the second fixing pin 290 which couples the hydraulic cylinder housing 80 and the coupler body 20, and fixed together by the second fixing pin 290.

The automatic safety device cylinder 110 is extended and contracted as the hydraulic cylinder 80 is extended or contracted by the pressurized oil supplied from the excavator. The operation principle of the automatic safety device cylinder 110 is that it extends freely but contracts only in an unlocked state. The automatic safety device cylinder 110 is connected to an unlocking side port 100 of the hydraulic cylinder 70 by a hydraulic line 320. When the hydraulic cylinder 70 is extended, the automatic safety device cylinder 110 extends freely. Conversely, when the hydraulic cylinder 70 contracts due to leakage of the pressurized oil or the damage to the rod, it is determined whether the contraction is normal or abnormal. When the contraction is abnormal, the automatic safety device cylinder 110 is locked so as to prevent the hydraulic cylinder 70 from contracting further. When the contraction is normal, the automatic safety device cylinder 110 is unlocked to allow the contraction of the hydraulic cylinder 70.

FIG. 3 is an exploded perspective view of the automatic safety device cylinder 110 of the attachment coupler 10a for heavy machinery of FIG. 2. Referring to FIG. 3, a first piston 140 is assembled at a leading end of the cylinder rod 130, and a second piston 150 and a spring 160 are primarily assembled on the cylinder rod 130 of the automatic safety device cylinder 110. Each of the first and second pistons 140 and 150 has a through hole at its center. The cylinder rod 130 has a front end portion 131 having a smaller diameter than a rear end portion 132, so that the front end portion 131 and the rear end portion 132 form a step. The second piston 150 that is inserted around the front end portion 131 can move between the first piston 140 and a step portion (please refer to a third stop step 210 of FIGS. 3 and 7A). The cylinder rod 130 having the first and second pistons 140 and 150 and the spring 160 is inserted into the cylinder housing 120.

A plurality of holes 171 are formed around the circumference of the surface of the second piston 150. Steel balls 170 are inserted respectively into the holes 171. A hose union 180 is assembled at the cylinder rod 130 of the automatic safety device cylinder 110 to connect a pressurized oil pipe (not shown) to an unlocking side port of the hydraulic cylinder 70.

FIGS. 4 and 5 are sectional views illustrating the operation of the attachment coupler 10a for heavy machinery of FIG. 2, showing the hydraulic cylinder 70 and the automatic safety device cylinder 110 contracted in FIG. 4 and extended in FIG. 5. Referring to FIGS. 4 and 5, it can be seen that when the hydraulic cylinder 70 is extended or contracted by the pressurized oil supplied by the excavator, the automatic safety device cylinder 110 is simultaneously extended or contracted.

FIG. 6 is a sectional view showing the automatic safety device cylinder 110 locked in the attachment coupler 10a of FIG. 2. Referring to FIG. 6, when the hydraulic cylinder 70 is damaged, for example, the pressurized oil leaks or the rod is broken, the automatic safety device cylinder 110 is locked, preventing further contraction of the hydraulic cylinder 70 and unlocking rotation of the movable hook 40.

Thus, an attachment 30 is prevented from separating from the attachment coupler 10a.

FIG. 7A is a sectional view showing the automatic safety device cylinder 110 of FIG. 4 contracted. FIG. 7B is a sectional view taken along line X-X of FIG. 7A. FIG. 8 is a sectional view showing the automatic safety device cylinder 110 of FIG. 5 extended. FIG. 9 is a sectional view showing the automatic safety device cylinder 110 locked as shown in FIG. 6.

A plurality of locking grooves 231 are continuously formed on the inner wall of the housing 120 of the automatic safety device cylinder 110. When the automatic safety device cylinder 110 is extended, as shown in FIG. 11 , the steel balls 170 pass through the locking grooves 231 while moving in and out of the holes 171 in the second piston 150.

Thθ locking grooves 231 work as a stopper for locking the automatic safety device cylinder 110 to prevent further contraction of the automatic safety device cylinder 110. Each of the locking grooves 231 is formed such that a surface 230 in the direction in which the cylinder is extended (to the right in FIG. 7A) has a different internal shape from a surface 250 in the direction in which the cylinder is contracted (to the left in FIG. 7A). While the surface 230 of each of the locking grooves 231 in the direction in which the cylinder is extended is tapered to form an angle, the surface 250 of each of the locking grooves 231 in the direction in which the cylinder is contracted is rounded to form a curve.

Referring to FIGS. 7A and 8, a first stop step 190 and a second stop step 200 are formed at both end portions of the second piston 150. A third stop step 210 capable of contacting the first stop step 190 of the second piston 150 is formed at the step portion of the cylinder rod 130. A fourth stop step 220 capable of contacting the second stop step 200 of the second piston 150 is formed on the first piston 140. As shown in FIGS. 7A and 8, the spring 160 is assembled between the first piston 140 and the second piston 150 coupled to the rod 130 of the automatic safety device cylinder 110. Accordingly, the second piston 150 can reciprocate axially until the first stop step 190 contacts the third stop step 210 of the rod 130 and the second stop step 200 contacts the fourth stop step 220 of the first piston 140.

The steel balls 170 are inserted into the holes 171 in the second piston 150 and can be lowered to the bottom of the holes 171 , that is, toward the rod, or raised upward in the holes 171 , that is, toward the housing, as the second piston 150 is moved to contact the first piston 140 (the case of FIG. 7A) or moved to contact the third stop step 210 of FIG. 7A of the cylinder rod 130 (the case of FIG. 8), as shown in FIGS. 7A and 8.

When no additional force is applied from the outside to the inside of the automatic safety device cylinder 110, the second piston 150 is always biased toward the third stop step 210 by the spring 160. In this state, when the automatic safety device cylinder 110 is extended, the steel ball 170 is not caught by the locking grooves 231 , and moves smoothly along the first tapered portion 230 so that the cylinder can be extended (please refer to FIG. 8). Conversely, when the automatic safety device cylinder 110 is contracted, the steel ball 170 is caught by the rounded portion 250 of the locking grooves 231 , locking the cylinder into position and preventing further contraction (please refer to FIG. 9).

In FIG. 7A, a reference numeral 131 indicates an inclined portion at the front of the third stop step 210 of the rod 130, and a reference numeral 132 indicates a flat portion connected to the inclined portion 131. In FIGS. 9 through 11 , a reference numeral 240 indicates a second tapered portion formed on the inner wall of the second piston 140 (please refer to a partially enlarged portion of FIG. 11).

FIG. 10 is a sectional view showing the automatic safety device cylinder 110 extended in the attachment coupler 10a of FIG. 2. FIG. 11 is a sectional view showing the automatic safety device cylinder 110 contracted in the attachment coupler 10a of FIG. 2.

FIGS. 8 and 10 show the automatic safety device cylinder 110 extended. At this time, since the pressurized oil is not supplied to the unlocking side port of the hydraulic cylinder, the pressurized oil is not supplied to inner oil paths 181 and 181a in the rod 130. Thus, spring 160 pushes the second piston 150 toward the third stop step 210 of the rod 130, placing the steel ball 170 on the inclined portion 131 just before the third stop step 210 of the rod 130, so that the steel ball 170 moves into the locking groove 231 of the housing 120. When the steel ball 170 moves into the locking groove 231 of the housing 120, since the first tapered portion 230 of the locking groove 231 has a gentle tapered shape, the steel ball 170 can move over the groove. Consequently, even when the pressurized oil is not supplied to the inside of the automatic safety device cylinder 110, the automatic safety device cylinder 110 can be extended at the same time as the hydraulic cylinder 110. However, as shown in FIGS. 9 and 11 , the automatic safety device cylinder 110 can be contracted only when the pressurized oil is supplied through the inner oil paths 181 and 181 a of the cylinder rod 130 to an inner space formed by the cylinder rod 130 and the second tapered portion 240 of the second piston 150. When the pressurized oil is supplied to the inside of the second tapered portion 240 of the second piston 150, the second piston 150 is moved toward the first piston 140, overcoming the force of the spring 160. Then, the steel ball 170 is pressed into the hole 171 and allowed to pass the locking grooves 231. When the pressurized oil is not supplied to the inside of the second tapered portion 240, the second piston 150 contacts with the third stop step 210 so that the steel ball 170 is caught by the locking grooves 231 and the automatic safety device cylinder 110 is prevented from contracting further.

FIG. 9 illustrates the steel ball 170 caught by the locking groove 231 when the pressurized oil is not supplied to the second tapered portion 240 of the second piston 150 of the automatic safety device cylinder 110, when the hydraulic cylinder contracts abnormally. In contrast, FIG. 11 illustrates the steel ball 170 inserted into the hole 171 allowing the cylinder 110 to contract smoothly when the pressurized oil is supplied to the inner space formed by the cylinder rod 130 and the second tapered portion 240 of the second piston 150 of the automatic safety device cylinder 110, when the hydraulic cylinder contracts normally.

When the pressurized oil coming from the unlocking side port of the hydraulic cylinder enters the inner space between the cylinder rod 130 and the second tapered portion 240 of the second piston 150 through the hose union 180 and the inner oil paths 181 and 181 a as shown in FIG. 11 , the second piston 150 is pushed in the axial direction (to the left in FIG. 11 ) toward the first piston 140 by the force of the pressurized oil until the second stop step 200 of the second piston 150 contacts the fourth stop step 220 of the first piston 140.

FIG. 12 is a sectional view illustrating a lubrication oil supply hole 270 and an air intake/exhaust path 260 added to the automatic safety device cylinder 110 of FIG. 7A. Referring to FIG. 12, (1 ) the lubrication oil supply hole 270 for lubricating the inside of the housing 120 of the automatic safety device cylinder 110 and (2) the air intake/exhaust path 260 are added to the automatic safety device cylinder 110 of FIG. 7A. The intake/exhaust path 260 is formed to aid the smooth movement of the rod 130 by allowing air to move smoothly in and out of the otherwise sealed inner space during the extension or contraction of the automatic safety device cylinder 110.

FIG. 13 is a hydraulic circuit diagram of the attachment coupler 10a of FIG. 2. Referring to FIG. 13, during the unlocking operation of the attachment coupler 10a according to the present embodiment, the oil pressurized by a hydraulic pump 350 is transferred to the hydraulic cylinder 70 through a solenoid valve 330. The solenoid valve 330 and a hydraulic cylinder rod side 70a are connected by a coupler unlocking side hydraulic line 101. The hydraulic line 320 branches at a hydraulic cylinder unlocking side port 100 and supplies the pressurized oil to both the hydraulic cylinder rod side 70a and the automatic safety device cylinder 110.

The pressurized oil coming from the hydraulic cylinder unlocking side port 100 and therefore supplied to the automatic safety device cylinder 110 through the hydraulic line 320 prepares the unlocking operation of the safety device, and that supplied to the hydraulic cylinder rod side 70a actuates the unlocking (contraction) operation of the hydraulic cylinder 70.

The hydraulic cylinder 70 and the automatic safety device cylinder 110 are fixed by the same first and second fixing pins 280 and 290 of FIG. 2, so that during the unlocking (contraction) operation of the hydraulic cylinder 70, the automatic safety device cylinder 110 performs the same unlocking (contraction) operation.

During the normal operation of the attachment coupler for heavy machinery having the automatic safety device cylinder according to the present embodiment, the automatic safety device cylinder 110 repeats the same contraction and extension as the hydraulic cylinder 70. Although the hydraulic cylinder always applies a load to the movable hook to restrict the attachment due to the structure of the coupler, the automatic safety device cylinder 110 receives no load at all. However, if the hydraulic cylinder is damaged, for example by oil leakage or rod damage, the automatic safety device cylinder 110 automatically locks as shown in FIGS. 6 and 9, preventing the attachment 30 from accidentally separating from the coupler 10a.

In FIG. 13, a reference numeral 70b indicates a hydraulic cylinder head side which receives oil pressure from a pilot check valve 71 to extend the hydraulic cylinder 70, a reference numeral 340 indicates an oil tank, a reference numeral 102 indicates a coupler locking side hydraulic line connecting the pilot check valve 71 to the solenoid valve 330, a reference numeral 103 indicates a hydraulic line connecting the hydraulic pump 350 to the solenoid valve 330, and a reference numeral 104 indicates a return line through which the oil returns to the oil tank 340.

Although the above-described embodiment has the advantage that the movable hook 40 of the attachment coupler 10a is doubly supported by the automatic safety device cylinder 110 and the hydraulic cylinder 70 to prevent the accidental separation of the attachment, it has the problem that the automatic safety device cylinder 110 may not unlock when the retreating operation of the hydraulic cylinder 70 occurs earlier than the operation of the automatic safety device cylinder 110 during the supply of the pressurized oil simultaneously to the automatic safety device cylinder 110 and the hydraulic cylinder 70. When the automatic safety device cylinder 110 is unlocked, the hydraulic cylinder 70 fixed by the same fixing pins 280 and 290 is not unlocked as well, so that the unlocking operation is not smoothly performed even when the attachment is separated normally. Thus, to solve the problem, an attachment coupler for heavy machinery having an improved automatic safety function according to another embodiment is provided.

FIG. 14 is a perspective view of the attachment coupler 10b for heavy machinery according to another embodiment of the present invention. The structure of the attachment coupler 10b shown in FIG. 14 differs from the above-described attachment coupler 10a of FIG. 2 in having a sequence valve 72 added to the hydraulic cylinder 70 of the attachment coupler 10b. The sequence valve 72 is connected to the hydraulic cylinder unlocking side port 100, and the pressurized oil supplied by the hydraulic pump passes through the sequence valve 72 to enter the hydraulic cylinder unlocking side port 100 for the contraction (unlocking) of the hydraulic cylinder 70.

In general, the sequence valve remains closed until a set pressure is reached, and then opens. It is used to control the operational sequence of a circuit according to the pressure of the fluid in a hydraulic circuit. That is, in order to operate a plurality of actuators in a hydraulic circuit in a predetermined operation sequence, the sequence valves are installed in front of the respective actuators and the set pressure of each sequence valve is adjusted so that the actuators are operated in the set sequence according to the time difference to open the sequence valves.

In the present embodiment, by adding the sequence valve 72 to the hydraulic cylinder 70 of the attachment coupler 10b, during the unlocking operation of the attachment coupler 10, the unlocking operation of the hydraulic cylinder 70 is performed after preparing the unlocking operation of the automatic safety device cylinder 110. That is, the automatic safety device cylinder 110 and the hydraulic cylinder 70 operate sequentially, so that the unlocking operation of the automatic safety device cylinder 110 is prepared and then the hydraulic cylinder 70 is unlocked. This prevents accidental locking in the middle of a quick contraction of the automatic safety device cylinder 110. Since the other elements shown in FIG. 14 are the same as those of the attachment coupler 10a of FIG. 2, detailed descriptions thereof will not be repeated.

FIGS. 15 and 16 are hydraulic circuit diagrams of the attachment coupler 10b of FIG. 14, showing the sequence valve 72 closed in FIG. 15 and open in FIG. 16.

In the hydraulic circuit diagram of FIG. 15, the sequence valve 72 is applied to the attachment coupler 10b for heavy machinery having an automatic safety device according to the present embodiment so that the hydraulic cylinder 70 and the automatic safety device cylinder 110 can be operated sequentially during the unlocking operation. Referring to FIG. 15, the attachment coupler 10b is the same as the attachment coupler 10a of FIG. 13, in that the pressurized oil generated by the hydraulic pump 350 is transferred to the hydraulic cylinder 70 and the automatic safety device cylinder 110 through the solenoid valve 330. However, the attachment coupler 10b differs from the attachment coupler 10a in the pressurized oil transfer route among the solenoid valve 330, the hydraulic cylinder. 70, and the automatic safety device cylinder 110. In the present embodiment shown in FIGS. 15 and 16, the solenoid valve 330 and the automatic safety device cylinder 110 are connected by the coupler unlocking side hydraulic line 101 and the hydraulic line 320. The solenoid valve 330 and the hydraulic cylinder rod side 70a are connected via the sequence valve 72 at the coupler unlocking side hydraulic line 101. According to the above structure, in the attachment coupler 10b according to the present embodiment, during the unlocking operation, the pressurized oil is supplied by hydraulic pump 350 first to the automatic safety device cylinder 110 through the solenoid valve 330, the coupler unlocking side hydraulic line 101 , and the hydraulic line 320, to prepare the unlocking operation. Pressurized oil is not supplied from the coupler unlocking side hydraulic line 101 to the hydraulic cylinder rod side 70a until the set pressure of the sequence valve 72 is reached (please refer to FIG. 15). Then, when the set pressure is reached (please refer to FIG. 16), the sequence valve 72 opens, supplying the pressurized oil to the hydraulic cylinder rod side 70a to unlock (contract) the hydraulic cylinder 70. The preparation of the unlocking operation of the automatic safety device cylinder 110 signifies unlocking of the automatic safety device cylinder 110. The locking and unlocking operation of the automatic safety device cylinder 110 are described with reference to FIGS. 8 through 12 in relation with the above-described embodiment.

When the hydraulic cylinder 70 is to be unlocked (contracted), the pressurized oil is transferred to the hydraulic cylinder rod side 70a through the hydraulic cylinder unlocking side port 100 of FIG. 14. The pressurized oil is also transferred to the rod

130 of the automatic safety device cylinder 110 that is connected to the hydraulic cylinder unlocking side port 100 by the hydraulic line.

Referring to FIG. 9, the pressurized oil supplied through the hose union 180 coupled to the rod 130 of the automatic safety device cylinder 110 passes through the inner oil path 181 of the cylinder rod 130 and enters the second tapered portion 240 of the second piston 150 through the vertical inner oil path 181a connected to the inner oil path 181. The oil pressure in the second tapered portion 240 pushes the second piston 150 to the left from the position shown in FIG. 9 to almost contact the first piston 140 as shown in FIG. 11. When the second piston 150 moves axially toward the first piston 140 until the second stop step 200 of the second piston 150 reaches the fourth stop step 220 of the first piston 140, the steel balls 170 of the second piston 150 are lowered to the bottom of the holes 171 , toward the cylinder rod 130, so that the automatic safety device cylinder 110 can be contracted (please refer to FIG. 11 ). Since the hydraulic cylinder 70 and the automatic safety device cylinder 110 are fixed together by the first and second fixing pins 280 and 290 of FIG. 14, the automatic safety device cylinder 110 can perform the unlocking operation during the unlocking operation of the hydraulic cylinder 70.

However, when the steel balls 170 are not lowered to the bottom of the holes 171 (toward the cylinder rod 130), the steel balls 170 are caught by the rounded portions 250 of the locking grooves 231 during the contraction of the automatic safety device cylinder 110, so that the automatic safety device cylinder 110 is locked and does not contract (please refer to FIG. 9).

In FIGS. 15 and 16, a reference numeral 72a indicates a bypass line through which the pressurized oil to be supplied to the sequence valve 72 bypasses the sequence valve 72.

As shown in FIG. 15, when the pressurized oil is supplied to the coupler unlocking side hydraulic line 101 to separate the attachment coupler, the pressurized oil does not instantly reach the rod side 70a of the hydraulic cylinder 70, since it is delayed by the sequence valve 72. However, the automatic safety device cylinder 110 is directly connected by the coupler unlocking side hydraulic line 101 and the hydraulic line 320 and instantly receives the pressurized oil. The pressurized oil in the second tapered portion 240 pushes the second piston 150 toward the first piston 140. As a result, the steel ball 170 is moved to the bottom of the hole 171 , toward the cylinder rod 130, unlocking the automatic safety device cylinder 110.

Referring to FIGS. 9 and 11 , the pressurized oil transferred through the coupler unlocking side hydraulic line 101 and the hydraulic line 320 is transferred to an inner space between the cylinder rod 130 and the second tapered portion 240 of the second piston 150 through the hose union 180 and the inner oil paths 181 and 181a. Then, the second piston 150 is pushed by the pressurized oil in the axial direction (to the left in FIG. 11 ) toward the first piston 140 until the second stop step 200 of the second piston 150 contacts the fourth stop step 220 of the first piston 140.

As described above, in the attachment coupler for heavy machinery having an automatic safety device according to the first present embodiment, since the movable hook of the coupler is doubly supported by the hydraulic cylinder and the automatic safety device cylinder, and the automatic safety device cylinder is unlocked only when the hydraulic cylinder is unlocked normally, the accidental separation of the attachment from the coupler due to damage to the rod or oil leakage during the operation of construction heavy machinery can be prevented.

In the attachment coupler for heavy machinery having an automatic safety device according to the second present embodiment which is improved to operate more smoothly, since the sequence valve is further installed on the hydraulic line through which the pressurized oil is supplied for the unlocking (contraction) of the hydraulic cylinder, during the unlocking operation of the attachment coupler, the automatic safety device cylinder and the hydraulic cylinder are unlocked sequentially. Thus, when the attachment coupler is separated normally, the automatic safety device cylinder is prevented from being unnecessarily locked.

Claims

1. An attachment coupler for heavy machinery, having an automatic safety device, the attachment coupler comprising: a fixed hook and a movable hook coupled to coupling pins formed on an attachment for heavy construction machinery; and a hydraulic cylinder actuating the movable hook, wherein an end of the movable hook is hinge coupled to a body of the coupler and the hydraulic cylinder and a safety device are pin coupled to the other end of the movable hook.

2. The attachment coupler of claim 1 , wherein the safety device comprises: a cylinder housing; a cylinder rod reciprocating linearly in the cylinder housing and having a step portion formed in a radial direction at a position separated from a leading end; a first piston having a through hole at the center thereof wherein the leading end of the cylinder rod is coupled to the through hole; a second piston capable of moving between the first piston and the step portion of the cylinder rod by being placed around the cylinder rod; a spring installed between the first piston and the second piston; a plurality of holes formed in a surface of a circumference of the second piston; a plurality of steel balls inserted in the holes; and a plurality of locking grooves formed on an inner wall of the cylinder housing.

3. The attachment coupler of claim 2, wherein an inner oil path is formed in the cylinder rod in a lengthwise direction and the inner oil path is connected to a vertical inner oil path connected to a surface of the cylinder rod, a tapered portion is formed on an inner wall surface of the second piston in a circumferential direction at a position meeting the vertical inner oil path, and the inner oil path of the cylinder rod is connected to an unlocking port of the hydraulic cylinder via a hydraulic line so that only when the hydraulic cylinder contracts normally, pressurized oil passes from the unlocking port of the hydraulic cylinder through the inner oil path and the vertical inner oil path and enters the tapered portion.

4. The attachment coupler of claim 2, wherein in a surface of the locking groove, a portion located toward a direction in which the cylinder rod moves when the safety device contracts is rounded and a portion located toward a direction in which the cylinder rod moves when the safety device is extended is tapered.

5. The attachment coupler of claim 2, wherein the cylinder housing further comprises an air intake/exhaust path connected to an inner closed space between the cylinder rod and the cylinder housing.

6. The attachment coupler of any of claims 2 through 5, wherein the cylinder housing further comprises a lubrication oil supply hole for lubrication of the inside of the cylinder housing.

7. The attachment coupler of claim 1 , further comprising: a hydraulic pump generating hydraulic pressure to contract and extend the hydraulic cylinder; a coupler locking side hydraulic line providing a path through which pressurized oil is transferred from the hydraulic pump to a cylinder head side of the hydraulic cylinder to extend the hydraulic cylinder; a coupler unlocking side hydraulic line providing a path through which the pressurized oil is transferred from the hydraulic pump to a cylinder rod side of the hydraulic cylinder and the safety device to contract the hydraulic cylinder; and a sequence valve installed between the coupler unlocking side hydraulic line and the cylinder rod side of the hydraulic cylinder and opening only when oil is supplied at more than a predetermined pressure, wherein the coupler unlocking side hydraulic line branches in front of the sequence valve so that a line is connected to the sequence valve and another line is connected directly to the safety device.

8. The attachment coupler of claim 7, wherein the safety device comprises: a cylinder housing; a cylinder rod reciprocating linearly in the cylinder housing and having a step portion formed in a radial direction at a position separated from a leading end; a first piston having a through hole at the center thereof wherein the leading end of the cylinder rod is coupled to the through hole; a second piston capable of moving between the first piston and the step portion of the cylinder rod by being placed around the cylinder rod; a spring installed between the first piston and the second piston; a plurality of holes formed in a surface of a circumference of the second piston; a plurality of steel balls inserted in the holes; and a plurality of locking grooves formed on an inner wall of the cylinder housing.

9. The attachment coupler of claim 8, wherein the an inner oil path is formed in the cylinder rod in a lengthwise direction and the inner oil path is connected to a vertical inner oil path connected to a surface of the cylinder rod, a tapered portion is formed on an inner wall surface of the second piston in a circumferential direction at a position meeting the vertical inner oil path, and the inner oil path of the cylinder rod is connected to the coupler unlocking side hydraulic line so that, only when the hydraulic cylinder is contracts normally, pressurized oil supplied from the hydraulic pump passes through the inner oil path and the vertical inner oil path and enters the tapered portion.

10. The attachment coupler of claim 9, wherein in a surface of the locking groove, a portion located toward a direction in which the cylinder rod moves when the safety device contracts is rounded and a portion located toward a direction in which the cylinder rod moves when the safety device extends is tapered.

11. The attachment coupler of claim 8, wherein the cylinder housing further comprises an air intake/exhaust path connected to an inner closed space between the cylinder rod and the cylinder housing.

12. The attachment coupler of any of claims 8 through 11 , wherein the cylinder housing further comprises a lubrication oil supply hole for lubrication of the inside of the cylinder housing.