JP2006097346A - Hydraulic hitch device of work machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent inconvenience of resultingly operating a work machine and an arm, without distractedly noticing the fact, though an operator is not gripped by a hitch mechanism due to damage of a hydraulic hose. <P>SOLUTION: In this hydraulic hitch device of the work machine, the hitch mechanism operating by hydraulic pressure is arranged on the arm; a control valve is arranged between the hydraulic pump side and the hitch mechanism side; the control valve is switched to the gripping side for sending the hydraulic pressure to the hitch mechanism side so that the hitch mechanism grips the work tool and the separating side for sending the hydraulic pressure to the hitch mechanism side so that the hitch mechanism separates the work tool; and the work tool is attached to and detached from the arm. An annunciator is arranged, and when the control valve is switched to the gripping side, the annunciator is operated when pressure of an outlet side oil passage of the control valve reduces more than predetermined pressure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydraulic hitch device for a working machine.

In some working machines such as backhoes and front loaders, a work tool such as a bucket is detachably attached to the tip of the arm, but in the hitch device of this type of conventional working machine, A hitch mechanism that operates by hydraulic pressure (hydraulic cylinder, etc.) is provided, a control valve is provided between the pump side and the hitch mechanism side, and a hitch mechanism that sends hydraulic pressure to the hitch mechanism side so that the hitch mechanism grabs the work implement, and a hitch There is a mechanism in which a control valve is switched to a release side that sends hydraulic pressure to the hitch mechanism side so that the mechanism releases the work tool, and the work tool is attached to and detached from the arm (for example, Patent Documents 1 to 3).
JP 2003-34948 A JP 2004-124382 A Japanese Utility Model Publication No. 5-87039

  However, conventionally, when the hydraulic hose is broken to supply and discharge hydraulic pressure to the hitch mechanism side, even if the control valve is switched to the grip side and the hitch mechanism operates to grip the work tool, Due to breakage of the hydraulic hose, the hydraulic pressure is not effectively supplied to the hitch mechanism, and the hitch mechanism may accidentally release the work tool. In such a case, there is a disadvantage that the operator moves the work implement or the arm without noticing this fact even though the operator does not grasp the work tool with the hitch mechanism.

  In view of the above-described problems, the present invention can prevent the problem of operating the work implement or arm without noticing this despite the fact that the work tool is not grasped by the hitch mechanism due to breakage of the hydraulic hose or the like. It is what I did.

The technical means of the present invention for solving this technical problem is that the arm is provided with a hitch mechanism that operates hydraulically, a control valve is provided between the hydraulic pump side and the hitch mechanism side, and the hitch mechanism Switch the control valve between the gripping side that sends hydraulic pressure to the hitch mechanism side to grip the work tool and the release side that sends hydraulic pressure to the hitch mechanism side so that the hitch mechanism releases the work tool, and attach / detach the work tool to the arm In the hydraulic hitch device of the work machine
When an alarm is provided and the control valve is switched to the gripping side, the alarm is activated when the pressure in the oil passage on the outlet side of the control valve drops below a predetermined pressure.

Another technical means of the present invention is that when the pressure in the oil passage on the inlet side of the control valve falls below a predetermined pressure, the operation of the alarm is stopped regardless of the pressure drop in the oil passage on the outlet side. It is in the point made to let it be.
Further, according to another technical means of the present invention, when the control valve is switched to the release side, the operation of the alarm is stopped regardless of a decrease in the pressure of the outlet side oil passage. It is in.
According to another technical means of the present invention, a hitch mechanism that is hydraulically operated is provided on the arm, a control valve is provided between the hydraulic pump side and the hitch mechanism side, and the work tool is released by the hitch mechanism. The control valve is switched between the release side that sends hydraulic pressure to the hitch mechanism side and the grip side that sends hydraulic pressure to the hitch mechanism side so that the work tool is gripped by the hitch mechanism, and the work tool is attached and detached by the hitch mechanism. In the hydraulic hitch device for work equipment,
The alarm is provided, a first pressure switch for detecting the pressure of the oil passage on the inlet side of the control valve is provided, and a second pressure switch for detecting the pressure of the oil passage on the outlet side of the control valve is provided, and the control When the valve is switched to the grip side, a notification control circuit is provided that activates the alarm if the first pressure switch detects a predetermined pressure or higher and the second pressure switch detects a predetermined pressure or lower. In the point.

  According to the present invention, when the work tool is no longer gripped by the hitch mechanism due to breakage of the hydraulic hose or the like, the alarm is activated to notify the user, so that he / she is not aware of this even though the work tool is not gripped. The inconvenience of operating the working machine or arm can be prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIGS. 10 and 11 , reference numeral 1 denotes a quick hitch mechanism, which is mounted on the ground work device 2 such as a backhoe 20 or a hydraulic excavator. A work tool 5 such as a bucket is easily attached to and detached from the tip of the arm 3 by remote control. It is provided for.
The backhoe 20 includes a swivel base 22 supported on a traveling device 21 so as to be rotatable about a longitudinal axis, and the swivel base 22 is provided with a cabin 23 surrounding the driver's seat, equipment such as an engine, and the like. The ground work device 2 that performs excavation work and the like is provided at the front of the swivel base 22.

The ground work device 2 includes a swing bracket 25 attached to a support bracket 24 provided at the front portion of the swivel base 22 through a vertical axis so as to be swingable left and right. Boom 27 pivotably pivoted about a direction support shaft 26, arm 3 pivotably pivoted to the distal end of the boom 27, and work connected to the distal end side of the arm 3 And a tool 5 (bucket).
The boom 27 and the arm 3 are respectively swung by a boom cylinder 28 and an arm cylinder 29 which are hydraulic cylinders, and the arm 3 and the work tool 5 are connected by two connecting links 11. The work tool 5 is made to be able to perform a dumping operation by swinging at the position.

The work tool 5 is detachably attached to the tip of the arm 3 and the connecting link 11 via the hitch mechanism 1.
5-11 , the hitch mechanism 1 includes a mounting frame 4 pivotally supported by an arm 3 via a base shaft 33, a fixed hook 6 fixed to the mounting frame 4, and a pivot shaft supported by the mounting frame 4. 7 has a movable hook 8 pivotally supported via 7, and a hydraulic actuator 9 that swings the movable hook 8 around the pivot shaft 7.
The mounting frame 4 is formed by connecting a pair of left and right frame plate members 14 via a member 34 having a mountain shape in cross section, an upper member 35 and the like, and is fitted to the left and right frame plate members 14 to the base shaft 33 and the pivot shaft 7. Holes 14a and 14b are formed.

The fixing hook 6 is formed by connecting a pair of left and right plate members via a horizontal member, and is fixed to the inner surface of the left and right frame plate members 14 of the mounting frame 4 by welding or bolts. A reinforcing plate may be provided between the fixed hook 6 and the outer surface of the left and right frame plate members 14.
The fixed hook 6 has a hook portion 6A that engages with the first engagement portion 5A of the work tool 5 at the lower portion in a rearward opening shape, and passes through a mounting pin 36 that attaches the base portion of the hydraulic actuator 9 to the upper portion. Yes.
The movable hook 8 is formed by connecting a pair of left and right hook plate members 15 via a member 37 having a U-shaped or trapezoidal cross section, and is disposed inside the left and right frame plate members 15 and swings around the pivot shaft 7. Fits freely. A connecting link 11 for connecting to the work tool cylinder 30 is connected to the pivot shaft 7.

The movable hook 8 has a hook portion 8A that engages with the second engagement portion 5B of the work tool 5 at the lower portion, and an interlocking pin 38 that attaches the moving end portion (piston rod 9A) of the hydraulic actuator 9 to the upper portion. It penetrates. The hook portion 8A is arranged so that the engagement direction by the opening is opposite to the hook portion 6A of the fixed hook 6.
In the movable hook 8, the upper and lower halfway portions of the left and right hook plate members 15 are bent in an opposing S shape, the upper portion of the movable hook 8 positioned between the left and right frame plate members 15 is wide, and the hook portion 8 A and the interlocking pin 38 are provided. The lower part is narrow.

The work tool 5 exemplified by the bucket is configured such that two bracket plates 42 are fixed to a back wall of the bucket portion 41 capable of excavating and scooping earth and sand, and a pair of front and rear pins are fixed. A first engaging portion 5A and a second engaging portion 5B that are detachably engaged with the hook portions 6A and 8A are formed.
The first engaging portion 5A and the second engaging portion 5B use pins having the same shaft diameter as the pivot shaft 7 and the base shaft 33, and the hitch mechanism 1 is removed, so that the first engaging portion 5A and the second engaging portion 5B The two engaging portions 5B can be connected to the arm 3 and the connecting link 11, respectively.

The mounting frame 4 and the movable hook 8 are respectively formed with a plurality (four in the embodiment) of holes 4a and 8a in an arc arrangement centering on the pivot shaft 7, and a lock pin is formed in both the holes 4a and 8a. The movable hook 8 can be fixed to the mounting frame 4 through 10.
The holes 4a of the mounting frame 4 are formed in a long and different pitch from the holes 8a of the movable hook 8. Even if the movable hook 8 swings, one of the holes 8a is always the hole 4a of the mounting frame 4. The lock pin 10 can be penetrated.
The lock pin 10 has a flange 10a at one end and a hole into which a retaining member 39 as a retaining means is inserted at the other end. The lock pin 10 penetrates the left and right frame plate members 14 and the hook plate member 15 and is supported at both ends. .

In addition, a temporary placement pin hole 4 b for temporarily placing the lock pin 10 extracted from the hole 8 a of the movable hook 8 is formed in the mounting frame 4.
The hydraulic actuator 9 is composed of a hydraulic cylinder, and expands and contracts by hydraulic oil from a hydraulic pump P ( described later) driven by the engine of the backhoe 20. The hydraulic oil from the hydraulic pump P is attached to the mounting frame 4. The hydraulic actuator 9 is supplied to the hydraulic actuator 9 via a hose 43 connected to the control valve 71 and a control valve 71 ( to be described later) . The hydraulic actuator 9 moves the movable tool 8 away from the fixed hook 6 by an extension operation, thereby moving the work tool 5 to a hitch mechanism. Grab (attach) with 1 .

The hydraulic oil supply to the hydraulic actuator 9 is always performed while the engine is driven by the control valve 71. Therefore, the hook portion 8A of the movable hook 8 is always pushed away from the hook portion 6A. It is moved and the mounting state of the work tool 5 is maintained.
Therefore, if the engine is stopped when the work is not performed or the like, there is a possibility that the far direction pushing force applied to the movable hook 8 is canceled and the movable hook 8 moves in a direction approaching the fixed hook 6. Further, when the lock pin 10 is passed through the holes 4a and 8a, the movable hook 8 is prevented from moving in the near direction, the engagement with the work tool 5 is ensured, and the mounted state can be maintained.

Further, by the reduction operation of the hydraulic actuator 9, the movable hook 8 is brought close to the fixed hook 6 and the work tool 5 is separated by the hitch mechanism 1.
The hose 43 is guided to the side surface of the arm 3 and connected to the mounting frame 4 through the inside of the connecting link 11 to prevent damage due to bending or stretching due to the swing of the work tool 5, contact with an obstacle, or the like. For this purpose, a guide cover 44 on the side surface of the arm 3, a mounting frame 4, a guide rod 45 for the connecting link 11, and the like are provided.
A mounting frame 4, a movable hook 8, and a connecting link 11 are fitted and connected to the pivot shaft 7. The connecting link 11 is fitted to the center of the pivot shaft 7 via the bush 46, the left and right hook plate members 15 of the movable hook 8 are fitted to the left and right ends, and the left and right outer ends of the mounting frame 4 are fitted to the left and right ends. The frame plate material 14 is fitted.

The movable hook 8 is fitted to the pivot shaft 7 via a pair of left and right common bushes 12, and the mounting frame 4 is fitted to each common bush 12 via a dedicated bush 13, so that the relative rotation of the three members can be achieved. It is designed to be smooth.
The common bush 12 extends from the inside of the movable hook 8 to the inside of the mounting frame 4 and supports them over both of them. Therefore, even if the pivot shaft 7 is removed from the common bush 12, the left and right common bush 12 Thus, the connection between the mounting frame 4 and the movable hook 8 is maintained. Even if the pivot shaft 7 and the base shaft 33 are removed and the hitch mechanism 1 is detached from the arm 3 and the connection link 11, the mounting frame 4 and The movable hook 8 is not separated from the fixed hook 6, the assembled state can be maintained, the attachment / detachment is simple, and the parts management at the time of separation is easy.

The common bushing 12 is located at both ends of the pivot shaft 7 and has an annular retaining protrusion 12a that prevents it from coming off the shaft, and the dedicated bushing 13 is also an end portion on the movable hook 8 side. Is provided with an annular retaining protrusion 13a that prevents the shaft from being removed in the off-axis direction.
The hitch mechanism 1 is configured such that a dedicated bush 13 is inserted into the holes 14b of the left and right frame plate members 14 of the mounting frame 4, and the left and right hook plate members 15 of the movable hook 8 are arranged inside the left and right dedicated bushes 13 so 12 is inserted, the connecting link 11 having the bush 46 is disposed between the left and right common bushes 12, the pivot shaft 7 is passed through them, and the arm 3 is connected to the mounting frame 4 via the base shaft 33. It is done.

The pivot shaft 7 is secured to the outer surface of the mounting frame 4 by retaining means 47, and the base shaft 33, the mounting pin 36, the interlocking pin 38, and the like are retained and prevented from rotating.
FIG. 1 shows a hydraulic circuit of the hydraulic hitch device, and FIG. 2 shows a configuration diagram of a control system of the hydraulic hitch device. 1 and 2, MP is a main pump, P is a pilot pump (hydraulic pump), 71 is a control valve, 73 is a pilot check valve, and 74 is a throttle. These are the pilot pump P side and the hydraulic actuator 9 side. (Hitch mechanism 1 side). The control valve 71 has a solenoid 72. When the solenoid 72 is demagnetized, the control valve 71 switches to a gripping side that sends hydraulic pressure to the head side of the hydraulic actuator 9 of the hitch mechanism 1, and when the solenoid 72 is excited, the hydraulic pressure is applied to the cylinder side of the hydraulic actuator 9. Is configured to switch to the release side. That is, when the solenoid 72 is energized and shut off, the control valve 71 is switched between the gripping side and the release side, and when the control valve 71 is switched to the gripping side, the hitch mechanism 1 grips the work tool 5. When the hydraulic pressure is sent to the 1 side and the control valve 71 is switched to the release side, the hydraulic pressure is sent to the hitch mechanism 1 side so that the hitch mechanism 1 grasps the work implement 5.

  A first pressure switch 75 is provided in the oil passage 69 on the entry side of the control valve 71. The first pressure switch 75 is a normally closed switch that detects the pressure in the oil passage 69 on the entry side and turns on (energizes) when the pressure in the oil passage 69 on the entry side is lower than a predetermined pressure (predetermined pressure). The following is detected), and when the pressure of the oil passage 69 on the entry side becomes equal to or higher than a predetermined pressure, this is detected and turned off (blocked) (detected above the predetermined pressure). A second pressure switch 76 is provided in the oil passage 70 on the outlet side of the control valve 71 when the control valve 71 is switched to the grip side. The second pressure switch 76 is a normally closed switch that detects the pressure of the outlet oil passage 70 and is turned on (energized) when the pressure of the outlet oil passage 70 is lower than a predetermined pressure (predetermined pressure). The following is detected), and when the pressure of the oil passage 70 on the outlet side becomes equal to or higher than a predetermined pressure, this is detected and turned off (blocked) (detected above the predetermined pressure). Here, the predetermined pressure means that the hydraulic actuator 9 of the hitch mechanism 1 can be expanded and contracted so that the work tool 5 can be held by the hitch mechanism 1 so as not to fall off. The hydraulic pressure is sufficient to allow the hitch mechanism 1 to release.

FIG. 3 shows an electric circuit diagram of a control system of the hydraulic hitch device. 2 and 3, reference numeral 77 denotes a main switch of the work machine, and reference numeral 78 denotes a harness coupler, which is connected to a power source such as a battery via the main switch 77.
Reference numeral 79 denotes an instrument box for a hydraulic hitch device. The instrument box 79 includes a power switch 81, a rotation switch 82, a first relay circuit 83, a second relay circuit 84, a third relay circuit 85, a fourth relay circuit 86, and a second relay circuit. A 1 red lamp 87, a second red lamp 88, and a buzzer (alarm) 89 are provided.

The power switch 81 has a key 81a, and the switch is operated by the key 81a. The rotation switch 82 has a movable contact 82a, a fixed fixed contact 82b, and a fixed fixed contact 82c. By manual operation, the rotary contact 82a is separated into a fixed fixed contact 82b and a fixed fixed contact 82c. In addition to being selectively connectable, the movable contact 82a is automatically returned to a neutral position that is disengaged from the fixed contacts 82b and 82c by a spring or the like.
The first relay circuit 83 includes a relay coil 83a and a normally open type relay switch 83b. The second relay circuit 84 includes a relay coil 84a and a normally closed relay switch 84b. The third relay circuit 85 includes a relay coil 85a and a normally closed relay switch 85b. The fourth relay circuit 86 includes a relay coil 86a and a normally closed relay switch 86b. A valve control circuit 91 that controls energization of the solenoid 72 of the control valve 71 is configured by the first relay circuit 83, the second relay circuit 84, and the like, and a buzzer 89 is configured by the second relay circuit 85, the second relay circuit 86, and the like. A notification control circuit 92 is configured to control the operation.

  Next, the operation will be described with reference to the operation table shown in FIG. Before the main switch 77 and the power switch 81 are turned on, the first red lamp 87 is turned off, the first relay circuit 83 is turned off, and the second relay circuit 84 is turned off. At this time, the second red lamp 88 is turned off and the solenoid 72 is demagnetized. Further, the third relay circuit 85 is in a demagnetization energization state, and the fourth relay circuit 84 is in a demagnetization energization state. Further, since the engine is not started, no pressure is generated in the oil passage 69 on the entry side and the oil passage 70 on the exit side, so that both the first pressure switch 75 and the second pressure switch 76 are in the on (energized) state. is there. At this time, since the main switch 77 is off, no current flows through the buzzer 89, so the buzzer 89 does not operate.

  When the main switch 77 is turned on, before the engine is started and before the power switch 81 is turned on, the first red lamp 87 is turned off, the first relay circuit 83 is turned off, and the second relay The circuit 84 is in a demagnetization energization state. At this time, the second red lamp 88 is turned off and the solenoid 72 is demagnetized. Further, the third relay circuit 85 is in a demagnetization energization state. Further, since the engine is not started, no pressure is generated in the oil passage 69 on the entry side and the oil passage 70 on the exit side, so that both the first pressure switch 75 and the second pressure switch 76 are in the on (energized) state. is there. At this time, since a current flows through the first pressure switch 75 to the relay coil 86a of the fourth relay circuit 86, the relay coil 86a is excited and the relay switch 86b is turned off (the fourth relay circuit 86 enters an excitation cut-off state). ). Accordingly, since the relay switch 86b is off, no current flows through the buzzer 89, and the buzzer 89 does not operate.

  When the main switch 77 is turned on and the engine is started, before the power switch 81 is turned on, the first red lamp 87 is turned off, the first relay circuit 83 is turned off, and the second relay circuit 84 is turned off. The power is on. At this time, the second red lamp 88 is turned off and the solenoid 72 is demagnetized. At this time, since the engine is started, pressure is generated in the oil passage 69 on the entry side and the oil passage 70 on the exit side, so that both the first pressure switch 75 and the second pressure switch 76 are turned off (blocked). At this time, since the first pressure switch 75 is turned off, no current flows through the relay coil 86a of the fourth relay circuit 86. Therefore, the relay coil 86a is demagnetized, the relay switch 86b is turned on, and the fourth relay circuit 86 is turned on. Becomes the demagnetization energized state together with the third relay circuit 85. At this time, since the second pressure switch 76 is off, no current flows through the buzzer 89, so the buzzer 89 does not operate.

  When the main switch 77 is turned on to start the engine and then the power switch 81 is turned on, a current flows through the power switch 81 to the first red lamp 87 and the first red lamp 87 is lit. At this time, the first relay circuit 83 is in a demagnetization cutoff state, and the second relay circuit 84 is in a demagnetization energization state. Further, the second red lamp 88 is turned off, and the solenoid 72 is demagnetized. At this time, both the first pressure switch 75 and the second pressure switch 76 are in an off (cutoff) state, and both the third relay circuit 85 and the fourth relay circuit 86 are in a demagnetization energization state.

At this time, since the second pressure switch 76 is off, no current flows through the buzzer 89, so the buzzer 89 does not operate.
Next, when the rotary switch 82 is operated to the release side (the movable contact 82a is connected to the release fixed contact 82b), a current is supplied to the relay coil 83a of the first relay circuit 83 through the power switch 81 and the rotary switch 82. Therefore, the relay coil 83a of the first relay circuit 83 is excited, the relay switch 83b is turned on (the first relay circuit 83 is energized), and a current flows to the solenoid 72 through the power switch 81 and the relay switch 83b. As a result, the solenoid 72 is excited, the control valve 71 is switched to the release side, the hydraulic pressure is sent to the cylinder side of the hydraulic actuator 9 via the control valve 71, the hydraulic actuator 9 is contracted, and the hitch mechanism 1 is It operates so that the work tool 5 is released. Therefore, at this time, if the hitch mechanism 1 is holding the work tool 5 and the work tool 5 is attached to the arm 3, the hitch mechanism 1 operates to release the work tool 5.

  At this time, since the current flows through the relay switch 85b of the third relay circuit 85 through the power switch 81, the rotation switch 82, and the relay switch 84b of the second relay circuit 84, the relay switch 85b is turned off (third relay circuit). 85 is an excitation cutoff state). The fourth relay circuit 86 remains in a demagnetization energized state. Further, a current flows through the second red lamp 88 through the power switch 81, the rotation switch 82, and the relay switch 84b of the second relay circuit 84, and the second red lamp 88 is lit. At this time, the first pressure switch 75 remains off (cut off), but the pressure in the return oil passage 70 on the hitch mechanism 1 side drops, so the second pressure switch 76 is turned on (energized). .

At this time, since the relay switch 85b of the third relay circuit 85 is off, no current flows through the buzzer 89, so the buzzer 89 does not operate. At this time, the lighting of the second red lamp 88 informs the operator that the hitch mechanism 1 has released the work implement 5.
Thereafter, when the rotary switch 82 is released, the movable contact 82a of the rotary switch 82 returns to the neutral position. Then, a current flows through the relay coil 83a through the power switch 81, the relay switch 83b, and the relay switch 84b, the first relay circuit 83 is held by itself, and a current flows through the solenoid 72 through the power switch 81 and the relay switch 83b. . As a result, the solenoid 72 is held in an excited state, and the control valve 71 remains switched to the release side.

  At this time, since a current flows through the relay coil 85a of the third relay circuit 85 through the power switch 81 and the relay switch 83b, the relay switch 85b remains off (the third relay circuit 85 is in the excitation cutoff state), and the fourth The relay circuit 86 also remains in a demagnetization energized state. In addition, a current flows through the second red lamp 88 through the power switch 81 and the relay switch 83b, and the second red lamp 88 maintains the lighting state. At this time, the first pressure switch 75 remains off (cut off), but the pressure in the return oil passage 70 on the hitch mechanism 1 side drops, so the second pressure switch 76 is turned on (energized). .

At this time, since the relay switch 85b of the third relay circuit 85 is off, no current flows through the buzzer 89, so the buzzer 89 does not operate. At this time, the lighting of the second red lamp 88 informs the operator that the hitch mechanism 1 has released the work implement 5.
Next, when the rotary switch 82 is operated to the grip side (the movable contact 82a is connected to the fixed contact 82c for gripping), a current flows through the relay coil 84a of the second relay circuit 84, and the relay switch 84b is turned off ( The second relay circuit 84 is in the excitation cut-off state), so that no current flows through the relay coil 83a, the relay switch 83b is turned off (the first relay circuit 83 is in the demagnetization cut-off state), and no current flows through the solenoid 72. As a result, the solenoid 72 is demagnetized, the control valve 71 is switched to the grip side, the hydraulic pressure is sent from the pilot pump P to the head side of the hydraulic actuator 9 via the control valve 71, and the hydraulic actuator 9 is extended. The hitch mechanism 1 operates to grip the work tool 5.

  At this time, when the relay switch 83b is turned off, no current flows through the relay coil 85a and the second red lamp 88 of the third relay circuit 85, and the relay switch 85b is turned on by demagnetization of the relay coil 85a (the third relay circuit 85 is demagnetized). And the second red lamp 88 is turned off. At this time, since the first pressure switch 75 is in an off (cut-off) state, no current flows through the relay coil 86a of the fourth relay circuit 86, and the relay switch 86b is on (the fourth relay circuit 86). Is demagnetization energized state). However, at this time, the hydraulic pressure is sent from the pilot pump P to the head side of the hydraulic actuator 9 via the control valve 71, and pressure is generated in the outlet side oil passage 70. Therefore, the second pressure switch 75 is turned off. In this state, no current flows through the buzzer 89, so the buzzer 89 does not operate.

  Thereafter, when the rotary switch 82 is released, the movable contact 82a of the rotary switch 82 returns to the neutral position. Then, no current flows through the relay coil 84a of the second relay circuit 84, the relay coil 84a is demagnetized, and the relay switch 84b is turned on (the second relay circuit 84 is deenergized). At this time, the first relay circuit 83 remains in the demagnetization cutoff state. As a result, no current flows through the solenoid 72, the solenoid 72 is held in a demagnetized state, the control valve 71 remains switched to the grip side, and the head of the hydraulic actuator 9 is passed from the pilot pump P through the control valve 71. The hydraulic pressure is continuously fed to the side, and the hitch mechanism 1 continues to operate so as to grip the work implement 5.

  At this time, since the rotation switch 82 is in the neutral position and the relay switch 83b is OFF, no current flows through the relay coil 85a and the second red lamp 88 of the third relay circuit 85, and the relay switch 85a demagnetizes the relay switch 85a. 85b remains on (the third relay circuit 85 is in a demagnetization energized state), and the second red lamp 88 remains off. At this time, since both the first pressure switch 75 and the second pressure switch 76 are off (cut off), no current flows through the relay coil 86a of the fourth relay circuit 86, and the relay switch 86b is turned on ( The fourth relay circuit 86 is demagnetized and the relay switch 83b is on (the third relay circuit 85 is demagnetized and energized). At this time, the second pressure switch 76 is off (cut off). Therefore, no current flows through the buzzer 89 and the buzzer 89 does not operate.

  In this state, that is, after the rotation switch 82 is operated to the grip side, the rotation switch 82 is released, the work tool 5 is gripped by the hitch mechanism 1, and the work tool 5 is attached to the arm 3. When a hydraulic hose for supplying and discharging hydraulic pressure to and from the hydraulic actuator 9 is broken and the oil path from the control valve 71 to the hitch mechanism 1 is broken, pressure is applied to the oil path 69 on the entry side. However, since no pressure is generated in the oil passage 70 on the outlet side, the first pressure switch 75 is turned off and the second pressure switch 76 is turned on. At this time, the relay of the third relay circuit 85 is turned on. Since no current flows through the coil 83a and the relay switch 85b is on, the current flows to the buzzer 89 through the relay switch 85b, the relay switch 86b, and the second pressure switch 76, and the buzzer 89 is activated. That.

Accordingly, the operation of the buzzer 89 allows the operator to know that the hitch mechanism 1 has unexpectedly released the work tool 5 due to the breakage of the hydraulic hose 43 or the like. It is possible to prevent the arm 3 from being lifted or the work machine from being moved without knowing that the 5 is released.
Moreover, while the control valve 71 is switched to the release side and the solenoid 72 is energized, a current flows through the relay coil 83a of the third relay circuit 85 and the relay switch 83b is turned off, so that the buzzer 89 operates. There is no longer to do. Therefore, while the control valve 71 is switched to the release side, the buzzer 89 does not operate even though no pressure is applied to the outlet oil passage 70, so that the control valve 71 becomes the release side. The buzzer 89 will not operate unnecessarily when

Before the engine is started, both the first pressure switch 75 and the second pressure switch 76 are on, but the relay coil 86a of the fourth relay circuit 86 is excited and the relay switch 86b is turned off. Does not work. Therefore, before the engine is started, the buzzer 89 does not operate regardless of the switching state of the control valve 71 regardless of whether the pressure in the return oil passage 70 is not raised. Therefore, the buzzer 89 is not activated unnecessarily.
In the above-described embodiment, the buzzer 89 is used as the alarm. However, instead of this, an alarm lamp or the like that blinks may be used as the alarm, or the buzzer 89 may be used as the alarm. And a notification lamp or the like may be used.

It is an electric circuit diagram of a control system of a hydraulic hitch device showing an embodiment of the present invention. It is a hydraulic circuit of the hydraulic hitch device. It is a block diagram of the control system of the hydraulic hitch device. It is an operation | movement table | surface for the operation | movement description. It is a side view of a part of the backhoe. It is a partial exploded side view of the backhoe. It is a partial top view of the backhoe. It is a cross-sectional top view of a part of the backhoe. It is a one part perspective view of the backhoe. It is a side view of the whole backhoe equipped with a hitch mechanism. It is a side view of the front-end | tip of the ground work apparatus equipped with the hitch mechanism.

Explanation of symbols

1 Hitch mechanism 3 Arm 5 Work tool (bucket)
69 Inlet oil passage 70 Outlet oil passage 71 Control valve 75 First pressure switch 89 Buzzer (notifier)
92 Notification control circuit

Claims (4)

The arm (3) is provided with a hydraulic hitch mechanism (1), and a control valve (71) is provided between the hydraulic pump (P) side and the hitch mechanism (1) side, and the hitch mechanism (1) A gripping side that sends hydraulic pressure to the hitch mechanism (1) side so that the work tool (5) is gripped, and a release that sends hydraulic pressure to the hitch mechanism (1) side so that the hitch mechanism (1) releases the work tool (5). In the hydraulic hitch device of the working machine in which the control valve (71) is switched to the side and the work tool (5) is attached to and detached from the arm (3),
When the alarm (89) is provided and the control valve (71) is switched to the gripping side, the alarm when the pressure in the oil passage (70) on the outlet side of the control valve (71) falls below a predetermined pressure. (89) A hydraulic hitch device for a work machine, wherein the hydraulic hitch device is operated.   When the pressure in the oil passage (69) on the inlet side of the control valve (71) falls below a predetermined pressure, the operation of the alarm (89) is stopped regardless of the pressure drop in the oil passage (70) on the outlet side. The hydraulic hitch device for a working machine according to claim 1, wherein the hydraulic hitch device is provided.   When the control valve (71) is switched to the release side, the operation of the alarm (89) is stopped regardless of the pressure drop in the outlet oil passage (70). The hydraulic hitch device for a working machine according to claim 1. The arm (3) is provided with a hydraulic hitch mechanism (1), and a control valve (71) is provided between the hydraulic pump (P) side and the hitch mechanism (1) side, and the hitch mechanism (1) The release side that sends hydraulic pressure to the hitch mechanism (1) side to release the work tool (5), and the grip that sends hydraulic pressure to the hitch mechanism (1) side to hold the work tool (5) by the hitch mechanism (1) In the hydraulic hitch device of the working machine in which the control valve (71) is switched to the side and the work tool (5) is attached and detached with the hitch mechanism (1),
A notification device (89) is provided, a first pressure switch (75) for detecting the pressure in the oil passage (69) on the inlet side of the control valve (71) is provided, and an oil passage on the outlet side of the control valve (71). When a second pressure switch (76) for detecting the pressure of (70) is provided and the control valve (71) is switched to the gripping side, the first pressure switch (75) detects a predetermined pressure or more. A hydraulic hitch device for a working machine is provided with a notification control circuit (92) that activates the alarm (89) when the second pressure switch (76) detects a predetermined pressure or less.

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